JAERI-Tech JP9950431 99-048
DEVELOPMENT OF PIPE WELDING, CUTTING & INSPECTION TOOLS FOR THE ITER BLANKET
KiyoshiOKA, Akira ITO, Kou TAGUCHI, Yuji TAKIGUCHI, Hiroyuki TAKAHASHI and Eisuke TADA
Japan Atomic Energy Research Institute , Xw^tjWffitft&uffiftfflu (1=319-1195
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This report is issued irregularly. Inquiries about availability of the reports should be addressed to Research Information Division, Department of Intellectual Resources, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan.
© Japan Atomic Energy Research Institute, 1999 JAERI-Tech 99-048
Development of Pipe Welding, Cutting & Inspection Tools for the ITER Blanket
Kiyoshi OKA, Akira ITO, Kou TAGUCHI, Yuji TAKIGUCHI, Hiroyuki TAKAHASHI and Eisuke TADA
Department of Fusion Engineering Research (Tokai Site) Naka Fusion Research Establishment Japan Atomic Energy Research Institute Tokai-mura, Naka-gun, Ibaraki-ken
(Received May 25, 1999)
In D-T burning reactors such as International Thermonuclear Experimental Reactor (ITER), an internal access welding/cutting of blanket cooling pipe with bend sections is inevitably required because of spatial constraint due to nuclear shield and available port opening space. For this purpose, internal access pipe welding/cutting/inspection tools for manifolds and branch pipes are being developed according to the agreement of the ITER R&D task (T329). A design concept of welding/cutting processing head with a flexible optical fiber has been developed and the basic feasibility studies on welding, cutting and rewelding are performed using stainless steel plate (SS316L). In the same way, a design concept of inspection head with a non-destructive inspection probe (including a leak-testing probe) has been developed and the basic characteristic tests are performed using welded stainless steel pipes. In this report, the details of welding/ cutting/ inspection heads for manifolds and branch pipes are described, together with the basic experiment results relating to the welding/cutting and inspection. In addition, details of a composite type optical fiber, which can transmit both the high-power YAG laser and visible rays, is described.
Keywords : ITER, In-pipe Access Tools, Blanket Cooling Pipe Maintenance, YAG Laser, Welding and Cutting, Non-destructive Inspection, Leak Test, Composite Fiber
This work is conducted as a ITER Technology R&D and this report corresponds to ITER R&D Task Agreement (T329). JAERI-Tech 99-048
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Contents
1. Introduction 1 1-1. Task Objective 1 1-2. Scope of the Report 1 2. Design Concept for the Blanket Maintenance 3 2-1. Design Conditions 3 2-2. Design Concept of a Cask for Bore Tools 4 3. Branch Pipe Welding/cutting Tool 6 3-1. Constitution of Welding/cutting Tool 6 3-2. Performance Tests of Welding/cutting Tool 8 3-3. Welding/cutting Tests with Bore Tool 10 3-4. Conclusion 27 4. Manifold Welding/cutting Tool 28 4-1. Constitution of Welding/cutting Tool 28 4-2. Performance Test of Welding/cutting Tool 30 4-3. Alignment Characteristic Test 30 4-4. Welding/cutting Tests 31 4-5. Conclusion 33 5. Non-destructive Inspection Tool for the Branch Pipe 35 5-1. Sensor Arrangement 35 5-2. Constitution of Non-destructive Inspection Tool 37 5-3. Performance Test of the Non-destructive Inspection Tool 38 5-4. Inspection Characteristic Test 38 5-5. Conclusion 39 6. Branch Pipe Leak Detection Tool 41 6-1. General 41 6-2. Constitution of Leak Detection Equipment 42 6-3. Performance Test of Leak Detection Head 43 6-4. Leak Detection Performance Test 43 6-5. Leak Detection Performance Test Results 44 7. Composite Fiber for YAG Laser Welding/cutting Tool 45 7-1. Constitution of the Composite Fiber 45 7-2. Observation Test 46 7-3. Conclusion 46 8. Conclusions 48 Acknowledgments 50 References 50 JAERI-Tech 99-048
Appendix 163 A. YAG Laser Welding/cutting Characteristics 163 A-l. Welding/cutting Tests with Dual YAG Laser 163 A-2. Welding/cutting Tests with High Power YAG Laser 168 B. Leak Detection Methods and Tests 209 B-l. Experimental Data on Leak Detection and Localization 209
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1. Introduction
1-1. Task objective The objective of this task is to develop the remote bore tools for welding, cutting and inspection of the blanket cooling pipe from the inside. The bore tools are inevitably required for the blanket cooling pipe maintenance since an external space around the pipe to be welded, cut and inspected is too narrow to access. According to the current machine layout, the bore tools should be designed to move at least 15 m along the cooling pipe so as to reach the position where the pipe is welded, cut and inspected. In addition, the operation of welding, cutting and inspection has to be performed under high gamma radiation dose rate of 3xlO6 R/h.
1-2. Scope of the report The development of the remote maintenance technology is essential to realize ITER , because the reactor components are activated by 14-MeV neutrons. Particularly, the in-vessel components, such as divertor cassettes and blanket modules, are the most critical ones in terms of maintenance of the reactor. The blanket module is categorized into the scheduled maintenance which includes complete change out from shielding to breeding. Therefore, reliable and quick maintenance operations are highly required for the blanket module. Figure 1.1 shows a schematic view of the blanket module maintenance proposed for ITER. After the cooling pipes of the blanket module are cut, blanket modules are removed through the horizontal port using an in-vessel manipulator and transporter. A number of cooling pipes are connected to the modules through a relatively narrow space located behind the modules, so that the external space around the pipes is not sufficient to allow an access of an ordinary TIG welder or mechanical cutter. [2,3,4] [5] A new maintenance technology based on a CCh laser beam and a YAG laser beam has been developed for welding and cutting of cooling pipes by the internal access. The YAG laser system based on laser beam transmission using a flexible optical fiber inside the pipe has been selected since the pipe welding/cutting by the internal access can be available even for the pipes with bend and branch. The remote bore tools based on YAG laser for welding/cutting are essential technology with regard to the realization of the current modular type blanket concept. The main issues relating to this technology are mobility of the tool to move inside the pipe through several bend sections for accessing to the branch pipe, controllability for positioning, welding and cutting, and qualification of welding and cutting including edge preparation and misalignment. A prototypical processing head was fabricated and tested to demonstrate the fundamental mobility for traveling inside a 100 mm pipe with a bend radius of 400 mm and for accessing from the 100 mm pipe to a branch pipe with a diameter of 50 mm . In addition, welding and cutting experiments using the ordinary YAG laser system was conducted in order to specify the welding and cutting conditionsI61. As next development, this head has been improved to be compacted and to add the traveling mechanism. The welding and cutting experiments using the optical parts of this head has been also
- 1 - JAERI-Tech 99-048 conducted in order to specify the welding and cutting conditions including effects such as gaps, filler and so on. In parallel, the welding/cutting tool for the manifold, the non-destructive inspection head and the leak detection head for the branch pipe have been designed and fabricated. This report covers the following results obtained from the prototypical processing head fabrication and welding, cutting and inspection experiments. (1) Second step branch pipe tool for welding/cutting using YAG laser with the traveling mechanism Design, fabrication and functioning tests of a prototypical processing head and traveling mechanism developed for welding/cutting of branch pipe from cooling manifold (2) Manifold tool for welding/cutting using YAG laser with the alignment mechanism for the manifold pipe Design, fabrication and functioning tests of a prototypical processing head and alignment mechanism developed for welding/cutting of manifold (3) YAG laser welding and cutting for pipe and thick plate 1) Welding experiments including effects of gaps, laser power and process speed on weldability 2) Cutting experiments as a function of process speed, laser power and assist gas 3) Rewelding experiments using samples cut by YAG laser 4) Mechanical tests of welded samples with different conditions 5) Filler welding and inter layer metal welding experiments with gaps (4) Non-destructive inspection tool for branch pipe with the traveling mechanism Design, fabrication and functioning tests of a prototypical non-destructive inspection head and traveling mechanism developed for the welded region inspection of branch pipe from cooling manifold (5) Leak detection tool for branch pipe Design, fabrication and functioning tests of a prototypical leak detection head developed for the welded region inspection of branch pipe from cooling manifold (6) Complex fiber for the YAG laser welding/cutting Design, fabrication and basic test of a prototypical complex fiber developed for the welding, cutting and observing at the processing point
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2. Design Concept for The Blanket Maintenance
2-1. Design conditions According to the ITER EDA design, the blanket is composed of blanket modules poloidally segmented, strong back plates and cooling manifolds located between the modules and the back plates. The cooling manifolds are attached to the back plate and each module is connected to the back plate individually. In this configuration, a branch pipe has to be connected between the manifold and the module for cooling. The proposed bore tool systems are based on the internal access type equipment. The welding/cutting tools for branch pipe and manifold can be available even for the pipes with bend section and branch because the laser beam transmission using a flexible optical fiber installed inside the pipe. The non-destructive inspection tool and leak detection tool can be also available inside the pipe because the compact and easy handling type sensor is installed on each tool. Figure 2.1 shows a schematic view of the procedure of branch pipe maintenance from the inside of the cooling manifold: these heads can be moved through the cooling manifold with a minimum bending radius of 400 mm. They have the following features; (1) Traveling mechanism through the cooling manifold with curved sections (2) Telescopic mechanism to approach from the manifold to branch pipe for welding/cutting/inspecting (3) Position adjustment and fixing mechanism for welding/cutting/inspecting In this study, specifications of the blanket cooling pipe are considered as listed in Table 2.1 and the environmental conditions are listed in Table 2.2, which are prepared by JCT as the design guideline. Figure 2.2 shows the basic pipe layout proposed in the upper area of the blanket for allowing the access of the bore tools from outside.
Table 2.1 Specifications of the blanket cooling pipe Main pipe (manifold) SS316L, 100A, thickness of 6 mm Branch pipe SS316L, 50A, thickness of 3 mm Minimum radius of curvature 400 mm
Table 2.2 Environmental conditions Item Condition Atmosphere dry nitrogen or ambient air Pressure 1 bar Temperature <50°C Radiation < 3 x 106 R/hr Contamination tritium, activated dust, beryllium Magnetic field zero
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Figure 2.3 shows a schematic view of the procedure of manifold maintenance from the inside of the cooling manifold: these heads can be moved through the cooling manifold with a minimum bending radius of 400 mm. They have the following features; (1) Traveling mechanism through the cooling manifold with curved sections (2) Alignment mechanism for fixing the manifold in order to weld/cut/inspect (3) Position adjustment and fixing mechanism for welding/cutting/inspecting head
2-2. Design concept of a cask for bore tools A cask of the bore tools is located outside of the bio-shield and the tools for welding/cutting/inspecting are inserted from the end of the pipe vertically extended. Figure 2.4 shows a schematic view of the cask desired for this purpose. In the cask, a tool changer system is installed for inserting/extracting the welding/cutting/inspecting equipment. The details are described as follows; (1) Cask conditions for the bore tools To design the bore tool cask, the following conditions are assumed; - Vertical access to approach the blanket cooling manifolds - Several casks located around the reactor - Movable range of 90 degrees per one cask - Four types cask 1) Double seal door cask The handling tool of double seal door and plug handling tool are installed in a cask. 2) Bore tool cask for branch pipe The welding/cutting tool and weld inspection tool for branch pipe are installed in a cask. 3) Bore tool cask for main pipe The welding/cutting tool and weld inspection tool for main pipe are installed in a cask. 4) Leak detection cask The leak detection tool for main pipe and branch pipe are installed in a cask. (2) Specifications of the bore tool cask - Toloidal movement around the reactor - Four cable winding tools are installed in the cask - Two welding/cutting tools and two weld inspection tools are installed in the cask. (3) Specifications of cable handling unit a) Winding drum - Method : spring back style, simple line, multiple layered drum - Cable winding length : about 25 m - Cable winding layer : 7 layers - Cable tension : 2 ~ 7.2 kgf - Winding torque : 1400 ~ 4900 kgf-mm b) Supply drum - Method : rubber disk with pinching drum
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- Cable feeding speed : max. 3 m/min - Drum rotation torque : ~ 16000 kgf-mm - Cable sending force : 34.1 kgf - Cable pinch force : 22.7 kgf (4) Specifications of tool changer unit - Positioning method : offset guide pipe - Pushing system : gas cylinder - Rotation system : warm gear - Adjustment speed and method • X axis : 10 mm/sec - screw drive • Z axis : 94.2 mm/sec - gas cylinder, lac&pinion • 9 axis : 5 rpm - turn gear
Figures 2.5 and 2.6 show schematic views of the cask layout for the bore tools and power source. They are installed in the crane hall and the distance should be minimized in terms of data acquisition. In order to operate the 4 sets of systems at the same time, each cask is installed at 90 degree intervals. After the blanket branch pipes are cut, the blanket modules are removed through the horizontal ports using in-vessel manipulators and transporters.
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3. Branch Pipe Welding/Cutting Tool
In the previous study, the processing head of welding/cutting tool has been designed161. It is consisted of four vehicles in order to realize the functions of welding, cutting and positioning. Each head is connected by universal joints and driving power is transmitted by flexible tubes. Though some issues were remained, the first trial of the development of welding/cutting tool was successful. To resolve the remaining issues, a new welding/cutting tool has been designed and its key features are described in the following sections.
3-1. Constitution of welding/cutting tool The proposed YAG laser welder/cutter is based on laser beam transmission using a flexible optical fiber installed inside the pipe. Therefore, welding/cutting by means of internal access can be performed even for the pipes with bends and branches. The YAG laser welder/cutter and weld inspection tools (see chapter 5) for the branch pipes have been designed to satisfy the following requirements. 1) Axial traveling mechanism through the cooling manifold with an inner diameter of 102.3 mm and the curved sections with a bend radius of 400 mm (minimum). 2) Telescopic mechanism to access from the cooling manifold to the branch pipe with an inner diameter of 54.5 mm for welding and cutting. 3) Position detection, adjustment and fixing mechanism for welding and cutting. Figure 3.1 shows the fabricated YAG laser processing head and Fig. 3.2 shows structural design of the welding/cutting processing head. This system is composed of four vehicles which are processing heads and traveling heads. Their external diameters are below 97 mm. The main components of this system are optical fiber, lens and mirrors for the laser transmission, motors for drives, and sensors for positioning. (1) Optical transmission mechanism This is to transmit the YAG laser beam from the external source. The optical fiber is made of synthetic quartz to tolerable for radiation hardness and covered by the flexible tube which is also used to supply assist and shield gases for the welding/cutting processes. Figure 3.3 shows a schematic view of the transmission tube. Total length of the optical fiber is 20 m and the core diameter is 0.6 mm. In order to reflect and focus the laser, lens and mirror are installed in front of the fiber. Lenses are made of synthetic quartz and mirrors are made of Oxygen Free Hard Copper (OFHC), which are also chosen in terms of radiation hardness. (2) Positioning mechanism Since accurate positioning of the processing head within the range of 0.1 mm is required for welding by YAG laser, this system is designed to have 4-axes freedom, which are Z, 9, R and p axes as shown in Fig. 3.4. Due to the space constraint and minimum curvature requirement, the system is divided into 2 vehicles. For final adjustment, a sleeve of R axis and a disk type positioning pin which are driven by air cylinders on the second head are also
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installed on the first head. These vehicles are connected by a flexible tube made of stainless steel. The major specifications of the positioning mechanism of each axis are described below. 1) Zaxis Movement direction : movement for fine adjustment of the processing head along the axis of the manifold Allowable stroke : 20 mm Movement speed : 30 mm/sec The driving air is transmitted using a tube from the outside to the Z axis movement mechanism composed of a pneumatic cylinder. 2) 0 axis Movement direction : rotation of the processing head around the axis of the manifold Rotation angle : < 360 degree Rotation speed : 16 sec/rev 3) R axis Movement direction : telescopic movement of the welding/cutting nozzle into a branch pipe axis Allowable stroke : 37 mm Movement speed : 0.3 mm/sec Operational range of the nozzle is between 14.4 mm and 22.4 mm from the surface of manifold outside diameter. 4) p axis Movement direction : rotation of the welding/cutting nozzle around the axis of the branch pipe Rotation angle : < 360 degree Rotation speed : 15 sec/rev 5) sleeve of R axis Function : final adjustment of the welding/cutting nozzle into a branch pipe axis The driving air is transmitted using a tube from the outside to the sleeve movement mechanism composed of a pneumatic cylinder. 6) disk type positioning pin Function : final adjustment to the direction of the manifold axis The driving air is transmitted using a tube from the outside to the disk type positioning pin movement mechanism composed of a pneumatic cylinder.
(3) Sensors for detecting the position of a branch pipe A sensor for detecting the position of a branch pipe are installed at the top of the processing head. Eddy current type sensor is chosen due to its compactness and precision.
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By traveling the processing head in the manifold, the edge of a branch pipe can be detected while the head moves along the manifold. In addition, two rollers are installed on the second head in order to measure the traveling distance. These are pushed against internal surface of the manifold and are rolled along the one. In this way, the position of the processing head can be measured to the branch pipe to be welded/cut. (4) Centering mechanism Centering mechanisms based on motor and air cylinder are installed in the welding/cutting processing head. Four pins, which are driven by DC-servo motor, are arranged in front of the welding/cutting processing head and can be contacted to the internal surface of the manifold so as to adjust the center of the head to the manifold axis. In addition, back supports, which are driven by air cylinder, are also arranged on backside of the processing head. (5) Traveling mechanism Figure 3.5 shows details of the traveling trucks. Each truck is composed of two pads connected to pushing and sliding mechanisms for axial movement like an inchworm as shown in Fig. 3.6. The pads surface is grooved to increase friction between pads and pipe wall. The flexible stainless tube containing the utility cables, gas tube and fiber is deployed from a storage drum follow the axial movement of the trucks. The desired specifications of the trucks are described below. - Tractive force : 30 Kg - Traveling distance : 30 m with 4 bending parts - Moving posture : all direction - Function • To pass through the cable into the body • To increase the traveling head
3-2. Performance tests of welding/cutting tool In order to verify the basic functions and characteristics of the fabricated YAG laser system, the processing head for welding/cutting has been tested and the results are as follows: (1) Driving mechanisms of the processing head All driving mechanisms were tested to verify the allowable movement stroke, rotation angle and operation speed. The results are summarized in Table 3.1 and it is concluded that the driving mechanisms can be operated satisfactorily and their operation ranges meet the design values. JAERI-Tech 99-048
Table 3.1 Test results of each mechanism movement Axis name Range of Movement speed Actuator movement RF 9 mm 0.20 mm/s DC motor x 4 (front support) RS 10 mm (20 mm/s)* Air cylinder x2 (back support) Z 20 mm (20 mm/s)* Traveling mechanism
P 360° 12.9s/rev DC motor x 1 R 37 mm 1.27 mm/s DC motor x 1 e 0 ~ 360 ° 14.8 sec/rev DC motor x 1
Disk pin 6 mm (30 mm/s)* Air cylinder x 1
Sleeve stopper 5 mm (30 mm/s)* Air cylinder x 1 * design value
(2) Traveling mechanism All driving mechanisms were tested to verify the allowable movement stroke and operation speed. The results are summarized in Table 3.2 and it is concluded that the traveling mechanisms can be operated satisfactorily and their operation ranges meet the design values. It is found that the real traveling speed of the bore tool is 0.5 m/min. The storage drum has the sensor which can detect the cable looseness for the cable sending/rewinding. The rotation of the storage drum is synchronized with the traveling of the tool movement using the sensor.
Table 3.2 Test results of traveling mechanism Axis name Range of Movement speed Actuator movement Truck A 8 mm 3 mm/s DC motor x 2 pushing pad Truck A 60 mm 20 mm/s DC motor x 4 sliding screw Truck B 8 mm 3 mm/s DC motor x 2 pushing pad Truck B 60 mm 20 mm/s DC motor x 4 sliding screw Cable winding 4 rotation 0.5 m/min DC motor x 1
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3-3. Welding/cutting tests with bore tool As mentioned above, the welding/cutting processing head by YAG laser for the blanket maintenance has been fabricated for branch pipe welding/cutting. In parallel with this development, welding, cutting and rewelding tests and more advanced tests have been conducted using the fabricated welding/cutting tool and the industrial 2 kW YAG laser source system in order to qualify the welding, cutting and rewelding conditions, including the effect of gaps and processing position. Figure 3.7 shows the mock-up tests system which is composed of two bent pipes, one straight pipe and one straight pipe with a branch part. Inner diameter of all pipes is about 100 mm. The detailed specifications of the pipes are listed below. This system can provide the various posture of welding/cutting tool in order to adapt each blanket position as shown in Fig.3.8. The laser source has an optical fiber with a core diameter of 0.6 mm and a length of 20 m. The fiber is connected to the welding/cutting tool. When welding/cutting tests are conducted, a test pipe is attached to the branch part. Test pipe Material :SS316L (Fe=bal., Cr=16.3%, Ni=12.7%, Mo=2.1%, C=0.02%, P=0.023< Manifold Inner diameter : 102.3 mm Thickness : 6 mm Maximum curvature :400 mm Branch pipe Inner diameter : 54.5 mm Thickness : 3 mm
3-3-1. Basic welding test In this test, the welding conditions were surveyed using SS316L pipes with a thickness of 3 mm as functions of laser power, welding speed, defocus distance and gaps, as listed below. The edge preparation of the test pipes was machined and the groove was inclined with the angle of 20 degrees. Laser power : 900, 1000, 1100 W Frequency : 40 Hz Duty : 50 % Welding speed : 0.4, 0.5, 0.6 m/min Shield gas : Nitrogen Gap quantity : 0,0.5, 1.0, 1.5 mm Work distance : 2 mm Defocus distance : -1.0, 0, +1.0, +1.5 mm Tool posture : level (similar to No.7 blanket)
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3-3-1-1. Dependency of defocus, laser power and welding speed The dependency of defocus, laser power and welding speed on the welding quality has been investigated. In this test, the butt weld without gaps was adopted. The following tests were performed for the qualification; (1) appearance and macroscopic test, (2) radiographic testing (RT) and (3) tensile test. (1) Appearance and macroscopic test Figure 3.9 shows the results of bead appearance and macroscopic test as a parameter of defocus. In all cases of defocus, the bead penetration to the back surface was observed at the laser power of 1100 W and the welding speed of 0.5 m/min. This result shows that the misalignment of the nozzle positioning between -1.0 and +1.5 mm is allowed. Figure 3.10 shows the results of bead appearance and macroscopic test as a parameter of laser power. In the case of 900 W, partial penetration was observed at the defocus of +1 mm and the welding speed of 0.5 m/min. Other cases have shown full penetration welding. Figure 3.11 shows the results of bead appearance and macroscopic test as a parameter of welding speed. In the case of 0.6 m/min, the bead penetration to the back surface was barely observed. Other cases have shown full penetration welding. (2) Radiographic testing (RT) All test pipes welded satisfied the RT regulation(lst grade) and there was no blowhole. (3) Tensile test Tensile tests were carried out for all test pipes welded. Table 3.3, 3.4 and 3.5 show the tensile test results of various cases. The characteristics of the base metal is shown as follows: 1) tensile strength is 529 MPa, 2) proof stress is 249 MPa, 3) elongation is 65 %, here, each value is average of three test pieces. Tensile strength and elongation were remarkably decreased in case of laser power of 900 W due to less welding penetration. It seems that the values of the others did not change very much.
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Table 3.3 Results of tensile tests in the parameter of defocus Defocus No. Proof stress Tensile Elongation (%) Break part (mm) (MPa) strength (MPa) 1 273 522 57 welded part -1.0 2 270 524 48 base metal 3 282 540 54 base metal Ave. 275 529 53 - 1 244 516 56 welded part 0 2 256 514 46 welded part 3 274 524 56 base metal Ave. 258 518 53 - 1 281 528 54 base metal +1.0 2 255 495 55 base metal 3 264 530 46 base metal Ave. 267 518 52 - 1 289 559 59 base metal +1.5 2 282 534 52 base metal 3 285 553 44 base metal Ave. 285 549 52 - [Welding conditions] Laser power : 1100 W, Welding speed : 0.5 m/min
Table 3.4 Results of tensile tests in the parameter of laser power Laser No. Proof stress Tensile Elongation (%) Break part power (W) (MPa) strength (MPa) 1 231 466 36 welded part 900 2 257 532 50 base metal 3 252 503 39 welded part Ave. 247 500 42 - 1 231 532 57 welded part 1000 2 264 521 54 base metal 3 271 533 59 base metal Ave. 255 529 57 - 1 281 528 54 base metal 1100 2 255 495 55 base metal 3 -264 530 46 base metal Ave. 267 518 52 - [Welding conditions] Welding speed : 0.5 m/min, Defocus : 0 mm
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Table 3.5 Results of tensile tests in the parameter of welding speed Speed No. Proof stress Tensile Elongation (%) Break part (m/min) (MPa) strength (MPa) 1 258 532 55 base metal 0.4 2 277 518 51 base metal 3 259 509 52 base metal Ave. 265 520 53 - 1 231 532 57 welded part 0.5 2 264 521 54 base metal 3 271 533 59 base metal Ave. 255 529 57 - 1 285 521 32 welded part 0.6 2 272 532 51 base metal 3 262 510 42 base metal Ave. 273 521 42 - [Welding conditions] Laser power : 1000 W, Defocus : 0 mm
3-3-1-2. Effect of gaps The dependency of gaps(sliding gap) at the edge preparation on the welding quality has been investigated. In this test, the gaps ranging from 0 to 1.5 mm were examined under the conditions of 1100 W laser power and 0.5 m/min welding speed. The following tests of all samples were performed for the qualification; (1) appearance test, (2) radiographic testing (RT), (3) macroscopic test, (4) tensile test. (1) Appearance test Figure 3.12 shows the appearance test results. In the case of the 1.0 and 1.5 mm gaps, partial penetration was observed in sliding part. Other cases have shown full penetration welding. (2) Radiographic testing (RT) All samples satisfied the 1st grade in the RT regulation and there was no blowhole although the penetration was lacked in the cases of both 1.0 and 1.5 mm gap. (3) Macroscopic test Figure 3.13 shows the cross section of welding penetration and a wine cup type penetration was observed. In the case of 0.5 mm gap, however, the bead on the backside is not appeared and the cases of 1.0 and 1.5 mm gap have clearly shown the under cut penetration. (4) Tensile test The tensile test results are shown in Table 3.6. The tensile strength and elongation are decreased with increasing of gap. As a whole, the maximum allowable gap for YAG laser
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welding without filler material is considered to be around 0.5 mm from the tensile test results and the macroscopic tests.
3-3-1-3. Summary of basic welding tests 1) Optimum conditions of welding From the test results, the optimum conditions as the parameters of defocus, laser power and welding speed are shown as follows.
Defocus Laser power : 1100 W Welding speed : 0.5 m/min
2) Allowable gap A maximum allowable gap is estimated to be around 0.5 mm.
Table 3.6 Results of tensile tests in the parameter of gaps Gap No. Proof stress Tensile Elongation (%) Break part (mm) (MPa) strength (MPa) 1 244 516 56 welded part 0 2 256 514 46 welded part 3 274 524 56 base metal Ave. 258 518 53 - 1 275 520 33 welded part 0.5 2 290 547 47 base metal 3 276 559 40 base metal Ave. 280 542 40 - 1 224 332 15 welded part 1.0 2 264 510 45 base metal 3 222 533 43 welded part Ave. 237 458 34 - 1 - - - - 1.5 2 276 544 48 base metal 3 205 489 37 welded part Ave. 241 517 43 - [Welding conditions] Laser power: 1100 W, Welding speed : 0.5 m/min, Defocus : 0 mm
3-3-2. Basic cutting test In this test, various of cutting conditions have been surveyed using SS316L pipe with a thickness of 3 mm. Cutting conditions of examined are as follows:
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Laser power : 900, 1000, 1100 W Frequency : 40 Hz Duty : 50 % Cutting speed : 0.7, 0.8, 0.9 m/min Assist gas : Nitrogen, 100 1/min Work distance : 2 mm Defocus distance : -1.0, 0, +1.0 mm Tool posture : level (similar to No.7 blanket)
3-3-2-1. Cutting test The dependency of laser power, cutting speed and defocus on the cutting characteristics has been investigated using assist gas of nitrogen. The following items were performed for the qualification; (1) appearance test and macroscopic test, (2) measurement of cutting surface roughness. (1) Appearance and macroscopic test Cutting tests were carried out under various conditions of laser power, cutting speed and defocus. In all conditions, it is not found the striking change on the appearance and macroscopic. Figure 3.14, 3.15 and 3.16 show the appearance and macroscopic test results. In addition, the dross height was measured under various conditions. The dross height was between 1.1 and 1.6 mm. It is not found the striking change. (2) Roughness of cutting surface Table 3.7 shows the results of roughness measurement of cutting surface as a parameter of defocus. In the case of -1.0 mm, Ra and Rmax are the largest value compared with other cases. Table 3.8 shows the results of roughness of cutting surface as a parameter of laser power. In the case of 900 W, Ra and Rmax are the largest value compared with other cases. Table 3.9 shows the results of roughness of cutting surface as a parameter of cutting speed. In the case of 0.9 m/min, Ra and Rmax are the largest value compared with other cases.
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Table 3.7 Results of the roughness of cutting surface in the parameter of defocus Defocus (mm) No. Ra (jim) Rmax (p,m) 1 10.2 72.2 -1.0 2 9.4 79.4 3 11.0 76.0 Ave. 10.2 75.9 1 7.0 46.0 0.0 2 12.2 82.6 3 7.6 64.6 Ave. 8.9 64.4 1 10.4 62.6 +1.0 2 6.6 45.0 3 8.0 68.4 Ave. 8.3 58.7 [Cutting conditions] Laser power : 1000 W, Cutting speed : 0.8 m/min
Table 3.8 Results of the roughness of cutting surface in the parameter of laser power Power (W) No. Ra (|im) Rmax (|im) 1 10.4 78.0 900 2 12.6 85.2 3 8.4 80.6 Ave. 10.5 81.3 1 10.4 62.6 1000 2 6.6 45.0 3 8.0 68.4 Ave. 8.3 58.6 1 9.6 60.6 1100 2 8.0 56.4 3 9.4 59.2 Ave. 9.0 58.7 [Cutting conditions] Defocus : +1.0 mm, Cutting speed : 0.8 m/min
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Table 3.9 Results of the roughness of cutting surface in the parameter of cutting speed Speed (mm) No. Ra (u.m) Rmax (p.m) 1 6.8 53.2 0.7 2 9.4 54.4 3 8.6 66.6 Ave. 8.3 58.1 1 10.4 62.6 0.8 2 6.6 45.0 3 8.0 68.4 Ave. 8.3 58.6 1 10.4 68.6 0.9 2 9.6 71.4 3 9.8 88.0 Ave. 9.9 76.0 [Cutting conditions] Defocus : +1.0 mm, Laser power : 1000 W
3-3-2-2. Summary of cutting tests From these test results mentioned above, the following cutting conditions should be adopted: Defocus : 0 mm Laser power : 1000 W Cutting speed : 0.8 m/min Following rewelding tests mentioned below were carried out using these samples.
3-3-3. Rewelding test To verify the reweldability of the laser cutting surface, rewelding tests were performed under the following conditions. In this test, the laser cutting samples with assist gas of nitrogen was welded to new SS316L pipe with machining surface. After the rewelding tests, (1) bead appearance tests, (2) radiographic testing (RT), (3) macroscopic observation and (4) tensile tests were performed for the welding qualification: Laser power : 1100 W Frequency :40Hz Duty :50% Rewelding speed : 0.5 m/min Shield gas : Nitrogen Work distance : 2mm Defocus distance : 0 mm Tool posture : level (similar to No.7 blanket)
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(1) Appearance and macroscopic tests Figure 3.17 shows the bead appearance and the cross-section of welding penetration after the rewelding. Full penetration was observed on welded part although the dross was attached around the pipe. (2) Radiographic testing (RT) This sample has shown the 1st grade in the RT regulation. (3) Tensile test Tensile tests were carried out after rewelding. Table 3.10 shows the tensile test results. From this result, the mechanical properties of laser cutting sample is very similar to the normal welding sample which is described in the section of the basic welding. As a result, rewelding of the laser cutting samples can be possible.
Table 3.10 Results of tensile tests in the rewelding Combination No. Proof stress Tensile Elongation Break part (MPa) strength (MPa) (%) Machining 1 264 533 62 base metal + 2 267 514 54 base metal Laser cutting 3 266 526 60 base metal Ave. 266 524 59 - [Rewelding conditions] Defocus : 0 mm, Laser power : 1100 W, Welding speed : 0.5 m/min
3-3-4. Welding/cutting test on different posture To verify the welding/cutting qualification on the different posture of the bore tool, the welding/cutting quality tests were performed on No. 1, 7 and 13 blanket positions. In this test, the location of No. 1 blanket was assumed to the manifold angle of 28 degree against the ground. In the same way, No.7 was 83 degree and No. 13 was 8 degree. [Welding conditions] Laser power : 150 W (positioning test), 1100 W (qualification test) Frequency :40Hz Duty :50% Welding speed : 0.5 m/min Shield gas : Nitrogen Work distance : 2 mm Defocus distance : 0 mm Tool posture : No.l (= 28°), No.7 (= 83°) and No. 13 (= 8°) [Cutting conditions] Laser power :1000 W Frequency :40Hz
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Duty :50% Welding speed : 0.8 m/min Assist gas : Nitrogen, 100 1/min Work distance : 2 mm Defocus distance : 0 mm Tool posture :No.l (=28°), No.7 (= 83°) and No. 13 (= °)
3-3-4-1. Positioning accuracy test in the welding The dependency of the blanket location on the welding characteristics has been investigated using the mock-up tests system. The gap between a half of the weld zone width and the groove was measured after the welding. The measurement positions were 0, 90, 180 and 270 degree of the branch pipe, respectively. The welding conditions are listed below: Table 3.11 shows the test result of the positioning accuracy in the welding. In the case of No. 1 blanket, the positioning gap per one loop of the branch pipe was ±0.12 mm. In the same way, No.7 was ±0.19 mm and No. 13 was ±0.11 mm. The maximum error range between greatest and smallest value per a measurement position was 0.34 mm in the case of the blanket position changed.
Table 3.11 Results of the positioning accuracy tests in the welding Blanket No. Measurement No.1 No.7 No.13 Error Position (angle = 28°)* (angle = 83°) (angle =8°) 1 -0.12 -0.05 -0.29 0.24 2 -0.35 -0.25 -0.43 0.18 3 -0.31 -0.04 -0.27 0.27 4 -0.18 0.13 -0.21 0.34 Error ±0.12 ±0.19 ±0.11 - * angle means the tool position against the ground unit: [mm]
3-3-4-2. Positioning accuracy test in the cutting The dependency of the blanket location on the cutting characteristics has been investigated using the mock-up tests system. The length of the cut branch pipe was measured after the cutting. The measurement positions were 0, 90, 180 and 270 degree of the branch pipe. Table 3.12 shows the test result of the positioning accuracy in the cutting. Each value means the branch pipe length from the edge. In the case of No. 13 blanket, the positioning error per one loop of the branch pipe was ±0.27 mm, which was maximum value in this test. The maximum error in all test results on repeatability was ±0.30 mm on the No.3 position.
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Table 3.12 Results of the positioning accuracy tests in the cutting Blanket No. Test No. Measurement position Error 1 2 3 4 No.1 1 50.80 50.97 50.93 50.77 ±0.10 (angle =28°) 2 50.79 50.95 50.90 50.75 ±0.10 3 50.74 50.94 50.90 50.76 ±0.10 No.7 1 50.50 50.62 50.38 50.29 ±0.17 (angle =83°) 2 50.40 50.65 50.34 50.26 ±0.20 3 50.49 50.67 50.45 50.40 ±0.14 No.13 1 50.57 50.92 50.79 50.40 ±0.27 (angle =8°) 2 50.41 50.93 50.78 50.47 ±0.27 3 50.45 50.97 50.74 50.51 ±0.27 Repeatability ±0.20 ±0.18 ±0.30 ±0.26 - * angle means the tool position against the ground unit: [mm]
3-3-4-3. Qualification test of the welding To verify the effect of the blanket location, qualification tests were performed in various postures of the bore tool. After the welding test on different posture, (1) bead appearance tests, (2) radiographic testing (RT), (3) liquid penetrate testing (PT), (4) tensile tests (No. 13 blanket), (5) macroscopic observation tests and (6) measurement of shrinkage quantity were performed for the welding qualification. (1) Appearance tests Figure 3.18 shows the bead appearance of welding penetration after the welding. Full penetration was observed on welded part in all cases. (2) Radiographic testing (RT) All test samples show the 1st grade in the RT regulation. (3) Liquid penetrant testing (PT) Figure 3.19 shows the results of the liquid penetrant testing. No crack is shown on all test samples. (4) Tensile test Tensile tests were carried out after welding. Table 3.13 shows the tensile test results. From this result, although the mechanical properties of laser welding sample in nitrogen is reduced to about 30 MPa compared with the base metal, the break part was on the base metal. In the other hand, the mechanical properties of laser welding sample in the air was very similar to the base metal's one.
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Table 3.13 Results of tensile tests in the various posture Item No. Proof stress Tensile strength Break part (MPa) (MPa) 1 277 506 base metal Base metal 2 279 493 base metal 3 281 511 base metal Ave. 279 503 - 1 230 452 base metal No.13 blanket 2 244 484 base metal (angle = 8°) 3 243 474 base metal in nitrogen Ave. 239 470 - 1 256 499 welded metal No.13 blanket 2 246 470 base metal (angle =8°) 3 250 482 base metal in air Ave. 251 484 -
(5) Macroscopic observation tests Figure 3.20, 3.21 and 3.22 show the cross section of the weld region in the various posture welding. The full penetration is observed in all cases. (6) Measurement of shrinkage quantity Table 3.14 shows the shrinkage quantity of the test samples which are not used for tensile tests. As the test results, the length of test samples was shrunken to 0.42 mm in average.
Table 3.14 Shrinkage quantity in the various posture welding Blanket Test Measurement position Ave. Shrinkage No. No. 1 2 3 4 quantity 1 65.65 65.65 65.61 65.51 65.61 0.39 No.1 2 65.68 65.56 65.47 65.46 65.54 0.46 (= 28°) 3 65.57 65.77 65.68 65.68 65.70 0.30 1 65.70 65.58 65.39 65.56 65.56 0.44 No.7 2 65.71 65.51 65.41 65.64 65.57 0.43 (= 83°) 3 65.52 65.60 65.50 65.49 65.53 0.47 Ave. ------0.42 unit: [mm]
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3-3-4-4. Qualification test of the cutting To verify the effect of the blanket location, qualification tests were performed in various postures of the bore tool. After the cutting test on different posture, (1) appearance tests and (2) macroscopic tests were performed for the cutting qualification. (1) Appearance tests Figure 3.23 shows the appearance test results after the cutting. Although the dross with dispersion was attached around the cutting surface, the similar appearance was observed in all cases. (2) Macroscopic tests Figure 3.24 shows the cross section of the cutting samples. Although the dross was attached outside of pipes, the cutting surface was smooth.
3-3-4-5. Summary of welding/'cutting test on different posture From these tests, the following results are obtained in all cases; (1) From welding test results, all test samples were obtained the 1st grade in the RT regulation.. (2) From PT results, the crack is not appeared on the welding region. (3) From tensile test results, welded parts have the tensile strength as same as base metal. (4) From cutting test results, it is found that rewelding is available because the cutting surface is smooth.
3-3-5. Repeat welding/cutting test To verify the repeatability of the laser cutting and rewelding, repeat welding/cutting tests were performed on a NC table with high positioning accuracy. In this test, the laser cutting samples were welded to new SS316L pipe with machining surface. The patterns of repeat tests are listed as Table 3.15. The maximum frequency of repeat welding is assumed 5 times. To verify the welding/cutting qualification on the different posture of the bore tool, the welding/cutting quality tests were performed on No.7 and 13 blanket positions. The location of No.7 blanket was assumed to the manifold angle of 83 degree against the ground. In the same way, No. 13 blanket was 8 degree. After the repeat welding tests, (1) 3-dimensional measurement of the pipe shape, (2) bead appearance tests and macroscopic observation, (3) radiographic testing (RT), (4) liquid penetrant testing (PT) and (5) tensile tests were performed for the welding qualification: [Welding conditions] Laser power : 1100 W Frequency : 40 Hz Duty : 50 % Welding speed : 0.5 m/min Shield gas : Nitrogen Work distance : 2 mm
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Defocus distance : 0 mm Tool posture assumed Pattern) a,b,c,d,e : No. 13 blanket (angle = 8 degree) Pattern) e : No.7 blanket (angle = 83 degree) [Cutting conditions] Laser power :1000 W Frequency :40Hz Duty :50% Welding speed : 0.8 m/min Assist gas : Nitrogen, 100 1/min Work distance : 2 mm Defocus distance : 0 mm Tool posture assumed Pattern) a,b,c,d,e : No. 13 blanket (angle = 8 degree) Pattern) e : No.7 blanket (angle = 83 degree)
Table 3.15 Repeat test patterns Pattern Procedure of test a 3D measurement -> Welding -> 3D measurement -> RT -> PT -> Appearance test -> Macroscopic test b 3D measurement -> Welding -> Cutting -> Welding -> 3D measurement -> RT -> PT -> Appearance test -> Macroscopic test c 3D measurement -> Welding -> Cutting -> Welding -> Cutting -> Welding -> 3D measurement -> RT -> PT -> Appearance test -> Macroscopic test d 3D measurement -> Welding -> Cutting -> Welding -> Cutting -> Welding -> Cutting -> Welding -> 3D measurement -> RT -> PT -> Appearance test -> Macroscopic test e 3D measurement -> Welding -> Cutting -> Welding -> Cutting -> Welding -> Cutting -> Welding -> Cutting -> Welding -> 3D measurement -> RT -> PT -> Appearance test -> Macroscopic test
3-3-5-1. Qualification tests of repeat weldingl cutting (1) 3-dimensional measurement of the pipe shape Figure 3.25 shows the 3-D measurement position of the welded branch pipe. After every welding, the shrinkage quantity of the samples was measured. From Tables 3.16 to 3.21 show the change of the branch pipe diameter every welding. The maximum deviation between "before welding" and "after welding" was 0.88 mm at 5 times welding as shown in Table 3.19.
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From Figures 3.26 to 3.30 show the relation between measurement position and shrinkage quantity. The maximum shrinkage was -0.5 mm to the direction of the radius as shown in Fig.3.30.
Table 3.16 Results of shrinkage quantity at position of blanket side : a2 Cycle Inner diameter Deviation Before welding^ After welding 1 54.50 54.33 0.17 2 54.49 54.32 0.17 3 54.50 54.36 0.14 4 54.48 54.35 0.13 5 54.49 54.34 0.15 unit: [mm]
Table 3.17 Results of shrinkage quantity at position of blanket side : b2 Cycle Inner diameter Deviation Before welding After welding 1 54.50 54.42 0.08 2 54.49 54.41 0.08 3 54.49 54.39 0.10 4 54.48 54.41 0.07 5 54.50 54.42 0.08 unit: [mm]
Table 3.18 Results of shrinkage quantity at position of blanket side : c2 Cycle Inner diameter Deviation Before welding After welding 1 54.50 54.48 0.02 2 54.49 54.48 0.01 3 54.50 54.46 0.04 4 54.48 54.46 0.02 5 54.50 54.48 0.02 unit: [mm]
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Table 3.19 Results of shrinkage quantity at position of manifold side : a1 Cycle Inner diameter Deviation Before welding After welding 1 54.47 54.24 0.23 2 54.47 54.09 0.38 3 54.47 54.02 0.45 4 54.48 53.92 0.56 5 54.48 53.60 0.88 unit : [mm]
Table 3.20 Results of shrinkage quantity at position of manifold side : b1 Cycle Inner diameter Deviation Before welding After welding 1 54.48 54.34 0.14 2 54.48 54.28 0.20 3 54.47 54.23 0.24 4 54.48 54.20 0.28 5 54.48 54.05 0.43 unit: [mm]
Table 3.21 Results of shrinkage quantity at position of manifold side : d Cycle Inner diameter Deviation Before welding After welding 1 54.47 54.43 0.04 2 54.47 54.41 0.06 3 54.48 54.39 0.09 4 54.48 54.40 0.08 5 54.47 54.36 0.11 unit: [mm]
(2) Appearance and macroscopic tests Figure 3.31 shows the results of repeat cutting from 2 to 5 times. The asperity on the weld bead was increasing as the welding times were increasing. However, there was no porosity in the welding region even 5 times welding as shown in Fig. 3.32. In the case of No.7 blanket (83°), there was no change as compared with another cases. It is shown in Fig.3.33. (3) Radiographic testing (RT)
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All test samples show the 1st grade in the RT regulation. From this result, it is found there are no defect and no bad fusion in the weld region. (4) Liquid penetrant testing (PT) Figure 3.34 shows the results of the liquid penetrant testing. In the case of No.7 blanket (83°), Fig.3.35 shows the results of the liquid penetrant testing. No crack is shown on all test samples. (5) Tensile tests Tensile tests were carried out in the cases of 3 and 5 times welding. Table 3.22 shows the tensile test results. From this result, the mechanical properties of repeat laser welding is very similar to the base metalFls one. As a result, 5 times repeat welding of the laser cutting samples can be possible.
Table 3.22 Results of tensile tests in the repeat welding Item No. Proof stress Tensile strength Break part (MPa) (MPa) 1 277 506 base metal Base metal 2 279 493 base metal 3 281 511 base metal Ave. 279 503 - 1 293 501 base metal 3 cycle 2 279 498 base metal 3 229 466 base metal Ave. 267 488 - 1 275 519 base metal 5 cycle 2 270 509 base metal 3 263 520 base metal Ave. 269 516 -
3-3-5-1. Summary of repeat weldinglcutting From these tests, the following results are obtained; (1) All test samples welded from 1 to 5 times satisfied the 1st grade in the RT regulation. (2) From PT results, the crack is not appeared on the welding region in all cases. (3) From tensile test results, welded parts show the same tensile strength as that of the base metal. (4) From 3-D measurement test results of the pipes, it is found that welding shrinkage is increased in proportion to the number of welding. As results, it is confirmed that the repeat welding is possible at least by 5 times.
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3-4. Conclusion The YAG laser type welding/cutting tool for branch pipes of module type blankets has been developed and tested under the various conditions, and the realization of the branch pipe maintenance was confirmed. In particular, this system can be moved inside a 100-A pipe with a minimum curvature of 400 mm and the welding/cutting nozzle with telescopic mechanism can be extended into a branch pipe with a diameter of 50 mm for welding/cutting. In addition, this system is designed to have 5 axes freedom so as to position the welding/cutting nozzle within the required accuracy for welding/cutting. The centering mechanisms and position sensors are also facilitated for positioning and fixation of the processing head. In parallel with this tool development, welding, cutting, rewelding and repeat welding experiments using YAG laser have been performed to clarify the optimum welding and cutting conditions including the effects of gaps and assist gas on the weldability and reweldability. From these tests, the following conclusions are obtained: 1) The optimum conditions of welding are listed below. Laser power :1100W Frequency :40 Hz Duty : 50 % Welding speed : 0.5 m/min Shield gas : Nitrogen Work distance : 2 mm Defocus distance : 0 mm 2) A maximum allowable gap for welding is to be around 0.5 mm without filler materials. 3) The optimum conditions of cutting are listed below. Laser power : 1000 W Frequency : 40 Hz Duty : 50 % Welding speed : 0.8 m/min Assist gas : Nitrogen, 100 1/min Work distance : 2 mm Defocus distance : 0 mm 4) Rewelding of the laser cutting surface can be performed with keeping similar mechanical properties to those of machining surface. 5) Welding/cutting in the various posture is available. 6) Repeat welding/cutting on the same part is available by 5 times. 7) The traveling method is stepping type such as an inchworm and the traveling speed of the tool is 0.5 m/min in the manifold with bent and curved sections.
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4. Manifold Welding/Cutting Tool
4-1. Constitution of welding/cutting tool (1) Manifold conditions The manifolds are cut, welded and inspected so as to replace the Class-3 components classified unscheduled maintenance during the machine life, such as Vacuum Vessel and super conducting magnets. The manifolds are routed from upper port to cryostat and bio-shield through the guard pipe which provides the secondary boundary of cooling water, as shown in Fig. 4.1. The blanket manifold conditions are summarized below. a) Outer diameter 114.3 mm b) Thickness 6.0 mm c) Minimum curvature R400mm d) Material SS316L e) Assumption of maximum gaps before welding 50 mm (axial direction) 10 mm (lateral direction)
(2) Constitution of the tool Figure 4.2 shows the structural design of the manifold welding/cutting tool and Figure 4.3 shows the fabricated processing head. A 4 kW YAG laser transmitted through the flexible optical fiber is adopted for this tool. The processing head is composed of two trucks fitted with a clamping mechanism to align and fix prior to welding and a processing mechanism for welding/cutting. The clamping mechanism consists of two hooks fitted to the front and rear of the trucks with air actuators. The processing head can be moved inside the cooling manifold by connecting it to the traveling trucks similar to branch pipe welding/cutting tool. The welding/cutting mechanism has three axes, head rotation (6 axis), nozzle lateral movement (R axis) and nozzle axial movement (Z axis). The manifold pulling mechanism has two axes, alignment hooks clamping (C axis) and three front alignment hooks axial movement (Zl axis). The specifications of these axes are summarized below, a) 0 axis Movement direction : rotation of the head around the axis of manifold Movement mechanism : motor and gear Stroke : ±225 degree Movement velocity : 4.75 rpm b) R axis Movement direction : lateral movement for nozzle adjustment Movement mechanism : motor and rack & pinion Stroke : 5 mm Movement velocity : 64.3 mm/sec c) Z axis Movement direction : axial movement for nozzle adjustment
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Movement mechanism : motor and ball screw Stroke : 10 mm Movement velocity : 2.71 mm/sec d)C axis Movement direction : clamping of alignment hooks Movement mechanism : air cylinder Stroke : 15 degree e)Zl axis Movement direction : axial movement of front alignment hooks Movement mechanism : motor and ball screw Stroke : 60 mm Movement velocity : 0.3 mm/sec
(3) Optical system A 4 kW YAG laser transmission is composed of an optical fiber with a core diameter of 1.0 mm, four lenses with synthetic quartz and a reflection mirror with Cu. The specifications of laser transmission are summarized below, a) Optical fiber Type : step index Core diameter : 1.0 mm Length : 10 m b) Lens Material : synthetic quartz c) Reflection mirror Material : Cu
(4) Operation procedure Figures 4.4 and 4.5 show the cutting operation procedure. The tool is positioned roughly by the optical image fiber on processing mechanism and the encoder on traveling truck. After the rough positioning, the tool is fixed by clamping hooks and the 3 mm height pre-installed projection on the inner surface of cooling manifolds. The nozzle position is decided by the monitoring of He- Ne laser transmitted through the optical image fiber. The nozzle is extended close to the inner surface of cooling manifold by R axis motor and the plunger pre-installed on nozzle keeps the constant distance between nozzle and manifold. Figures 4.4 and 4.6 show the welding operation procedure. After the rough positioning of tool, the tool pulls the cooling manifold using clamping hooks for final alignment and fixation before welding. The clamping mechanism is designed to produce clamping forces of about 500 kgf and to close the axial gaps of 50 mm and the lateral gaps of 10 mm to the final alignment required for welding with alignment cone on the outer surface of cooling manifolds.
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4-2. Performance test of welding/cutting tool The performance tests were performed in order to verify the basic functions and characteristics of the fabricated tool. Test results are summarized below. (1) Welding/cutting mechanism Three axes were tested to verify the allowable movement stroke. The results are shown in Table 4.1.
Table 4.1 Test results of welding/cutting mechanism Test item Axis name Design value Measurement result Range of movement e ±225 deg. ±225deg. R 5 mm 5.1 mm Z 10 mm 10.2 mm
(2) Clamping mechanism Two axes were tested to verify the allowable movement stroke, and Zl axis was also tested to verify the clamping force. The results are shown in Table 4.2.
Table 4.2 Test results of clamping mechanism Test item Axis name Design value Measurement result Range of movement C 15 deg. 15 deg. Z1 60 mm 60.4 mm Force Z1 467 kgf 467 kgf
4-3. Alignment characteristic test The alignment test was performed to verify the alignment characteristics of fabricated tool. Figure 4.7 shows the test stand pre-installed springs for simulation of flexibility similar to bellows and Table 4.3 shows the test results. In this test, the spring constants in axial direction and lateral direction were 4.76 kgf/mm and 3.68 kgf/mm, respectively. The allowable gaps for pipe welding are 0.8 mm in axial direction and 2.0 mm in lateral direction, as mentioned in Appendix A-3.
Table 4.3 Results of alignment test (Pipe clamping force : 467 kgf) Pipe gaps before alignment Pipe gaps after alignment Axial direction Lateral direction Axial direction Lateral direction 25 mm 10 mm 0 mm 1.0 mm 50 mm 10 mm 0 mm 0.8 mm
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4-4. Welding/cutting tests The pipe welding/cutting tests using fabricated bore tool and test stand were performed in order to clarify the welding/cutting abilities of tool. In these tests, the tool and nozzle positions inside pipe were adjusted by an operator prior to welding/cutting. (1) Cutting test This test was conducted using SS316L pipes with a thickness of 6.0 mm and an inner diameter of 102.3 mm under the optimum conditions, which had been obtained in the last basic cutting tests (Ref. Appendix A-3), as follows; Laser power : 3.0 kW (PW), Peak power of 6.0 kW Duty : 50 % Defocus : 0 mm Stand off : 1 mm Cutting speed : 0.3 m/min Shield gas : Nitrogen, 120 1/min In this test, however, the cutting speed was changed from 0.6 m/min to 0.3 m/min in order to increase the heat input into a pipe. The increase of heat input was considered to be able to obtain the good result in all cutting positions and to prevent the miss-cutting due to the change of stand off during cutting operation. The cutting time and the temperature of mirror were 64 second and maximum 140 degree, respectively. The following tests were performed for the cutting quality; a)cutting appearance and b)surface roughness. a) Cutting appearance Figure 4.8 shows the result of cutting appearance. The dross attached to a pipe is not almost observed. b) Surface roughness The result of surface roughness is max. 131 micro meters. This is twice as a value of basic cutting test result. It is why that the weld metal increases due to the increase of heat input into a pipe.
(2) Welding test This test was conducted using SS316L pipes with a thickness of 6.0 mm and an inner diameter of 102.3 mm under the optimum conditions, which had been obtained in the last basic welding tests (Ref. A-3), as follows; Laser power : 3.6 kW (CW) Defocus : -1 mm Stand off : 3 mm Welding speed : 0.3 m/min Gap quantity : 50 mm (axial direction) : 10 mm (lateral direction) Shield gas : Nitrogen, 501/min
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Butt type : I butt The pipe was aligned before welding by the tool. An image fiber on nozzle could monitor the inner surface of pipe during the alignment operation. Figure 4.9 shows the image of inner surface of pipe obtained by the image fiber. The welding time and the temperature of mirror were 64 second and 209 degree, respectively. The temperature of mirror exceeded the allowable temperature of 200 degree. In addition, the top of nozzle was melted. It was found that these troubles were caused by the decline of nozzle due to a reaction force of flexible optical fiber. The YAG laser transmitted through the declined nozzle was reflected at the inner surface of pipe and was exposed to the top of nozzle. Finally, the heat input into a nozzle melted the top of nozzle and increased the temperature of mirror by thermal conduction. The following tests were performed for the welding qualification; a) bead appearance and macroscopic test, b) radiographic test (RT) and c) tensile strength and elongation tests. a) Bead appearance and macroscopic test Figure 4.10 shows the results of bead appearance and macroscopic test. The lack of penetration bead is observed. In addition, the bead appearance by flat position welding differs from overhead position. b) Radiographic test (RT) The porosity was not observed. c) Tensile strength and elongation tests The results of tensile strength and elongation tests are 485.70 MPa (83.31 % relative strength) and 24.41 % (49.82 % relative elongation), respectively. The lack of penetration bead causes the low tensile strength and elongation. In particular, the tensile strength is not satisfied with the allowable value of 490MPa.
(3) Re-welding test The little modification of tool was performed prior to the re-welding test. In the welding tests, it was found that the nozzle declined and swayed due to a reaction force by a flexible optical fiber. For this, the optical fiber was fixed by a fiber support inside tool for the prevention of nozzle decline. In this test, the SS316L pipes which were used for the previous cutting test were welded to a new SS316L pipe, under the same conditions as welding test. In this test, as cut welding was adopted. Laser power 3.6 kW (CW) Defocus -1 mm Stand off 3 mm Welding speed 0.3 m/min Gap quantity 50 mm (axial direction) 10 mm (lateral direction) Shield gas Nitrogen, 501/min The welding time and the temperature of mirror were 64 second and 178 degree, respectively. The temperature of mirror was below the allowable temperature of 200 degree. The following tests
-32- JAERI-Tech 99-048 were performed for the re-welding qualification; a)bead appearance and macroscopic test, b) radiographic test (RT) and c) tensile strength and elongation tests. a) Bead appearance and macroscopic test Figure 4.11 shows the results of bead appearance and macroscopic test. The good penetration bead is obtained. b) Radiographic test The porosity was not observed. c) Tensile strength and elongation tests The results of tensile strength and elongation tests are 527.37 MPa (90.46 % relative strength) and 30.00 % (61.22 % relative elongation), respectively. These are higher than the welding test results because of the good penetration bead.
(4) Summary The pipe cutting/welding/re-welding tests using the fabricated tool were performed. In these tests, the characteristics and welding/cutting ability of tool were clarified. The good cutting/re- welding test results were obtained. It was found that the stand off could not be kept in a certain value during welding/cutting due to the reaction force by a flexible optical fiber. The modification of R axis which drives nozzle in lateral direction will be needed.
4-5. Conclusion The bore tool for blanket manifold welding/cutting was fabricated and verified the characteristics through the performance test, the pipe alignment test and the pipe welding/cutting tests. In addition, this system is designed to have 5 axes freedom so as to position the welding/cutting nozzle within the required accuracy for welding/cutting. The clamping mechanism is also developed and tested about the alignment between the pipes. In parallel with this tool development, welding/cutting/rewelding experiments using YAG laser have been performed to clarify the optimum welding and cutting conditions. From these tests, the following conclusions are obtained: (1) The good result of pipe alignment by fabricated tool was obtained. The tool is able to accommodate 10 mm axial gap and 50 mm lateral gap to allowable gaps for welding, respectively. (2) The optical image fiber on nozzle is able to observe inner surface of pipe. For this, the alignment procedure can be monitored by tool. In the future, the monitoring tests of welding/cutting will be performed by means of the in-process monitoring (Ref. Appendix A-2) or the direct monitoring of inner surface. (3) The welding/cutting conditions are summarized below, a) Cutting Laser power : 3.0 kW (PW), Peak power of 6.0 kW Duty : 50 % Defocus : 0 mm Stand off : 1 mm
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Cutting speed : 0.3 m/min Shield gas : Nitrogen, 1201/min b) Welding/re-welding Laser power : 3.6 kW (CW) Defocus : -1 mm Stand off : 3 mm Welding speed : 0.3 m/min Gap quantity : 50 mm (axial direction), 10 mm (lateral direction) Shield gas : Nitrogen, 50 1/min It was found that the nozzle could not be kept in a certain position during welding/cutting due to the reaction force by a flexible optical fiber. The modification of R axis will be needed in order to avoid the nozzle sway in the future.
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5. Non-Destructive Inspection Tool for The Branch Pipe
For surface crack detection of pipe welds, Electro-Magnetic Acoustic Transducer (EMAT) was selected in terms of radiation hardness, high temperature application and no couplant requirement. The EMAT, which is basically composed of a magnet and a coil to generate ultra-sonic waves, is conventionally used for the non-destructive inspection of nuclear power plants welds. The main technical issue for ITER apphcations is to increase the radiation hardness and the detectabihty of defects for pipe welds within a constrained space. The irradiation tests of EMAT units were conducted at a dose rate of about 10 kGy/hr with no significant degradation observed up to 10 MGy. To increase the detectability, a new sensor configuration, in which wave transmitter and receiver is arranged in various position, was adopted and a share horizontal (SH) wave was applied.
5-1. Sensor arrangement 5-1-1. Position of the transmitter and receiver An EMAT sensor is constructed by two elements, whose functions are to transmit and to receive the ultra-sonic waves respectively. They are usually arranged around the cracks and detect the signal to/from the cracks. To optimize the arrangement of each element, three arrangement methods of the sensor, which were transmission, tandem and reflection technique as shown in Fig. 5.1, were examined. Table 5.1 shows the EMAT's specifications for the arrangement test in the branch pipe.
Table 5.1 EMAT's specifications for arrangement tests Frequency 700 kHz Beam angle about 64.4 ° Wave mode SH ultrasonic wave Heat proof temp. 150 °C Magnet Coil - Material SmCo, 8 elements - Material polyamide based -Height 7.5 mm - Length 30 mm -width 5.0 mm - Width 12 mm
(1) Transmission technique Figure 5.2 shows the result of the transmission technique. The transmitter and receiver of EMAT are arranged at both sides of weld point. An ultrasonic wave runs along the pipe. In the case of this technique, the reflected echo level becomes small because the ultra-sonic wave is passed through the weld region. In addition, the shape is to be long in the pipe. (2) Tandem technique Figure 5.3 shows the result of the tandem technique. The transmitter and receiver of EMAT are arranged on the same straight line. The receiver which is located behind the transmitter catches an ultrasonic wave from the defect. The distance from the transmitter to the JAERI-Tech 99-048
receiver through the defect is so long that the high signal level is expected. However, the shape is to be long in the pipe as same as transmission technique. (3) Reflection technique Figure 5.4 shows the result of the reflection technique. The transmitter and receiver of EMAT are arranged such as a letter of ' V. The receiver catches the echo from the defect. The reflected signal level is low compared with other methods because the surface of magnets is flat and can not touch the surface of the pipe. The shape is compact more than other methods because of 'V shape. Table 5.2 shows the results of the sensor arrangement. The tandem and reflection techniques were better than the transmission. Though the tandem technique is required more large size to improve the sensitivity, the reflection technique has the possibility of improvement in detectability. From the test results and the space constraint in the branch pipe, the reflection technique is adapted to the non-destructive inspection method and the improvement of the sensor is expected by refabrication.
Table 5.2 The results of the arrangement test Technique Path Ultrasonic Shape Sensitivity Total estimate length noise X X A X X Transmission short exist another long little change difficult to path signal length discriminate without noise •A X A A A Tandem a little exist another long low flaw echo low sensitivity long path signal length level A A Reflection long exist echo large low flaw echo low sensitivity from weld width level shape
Figure 5.5 shows the test result of the refabricated EMAT for 50A pipe. The EMAT's surface is shaped to inner curvature of 50A pipe.
5-1-2. Angle of the transmitter and receiver To improve the detectability of EMAT, the optimum angle between a transmitter and a receiver was examined. In this test, the angle was changed from 80 to 120 degree per 10 degree and a test piece of flat plate was adapted as shown in Fig. 5.6. The specifications of EMAT is same as the arrangement test as shown in Table 5.1. Figures 5.7 and 5.8 show the wave form of the angle test results. Figure 5.9 shows the comparison result of S/N level on sensor angle. In the case of the angle of 100 degree, S/N level shows the best sensitivity on both inside and outside defect. The angle of 26 degree had been tested in the arrangement test as mentioned above. According to the comparison of 26 and 100 degree, it is
-36- JAERI-Tech 99-048 found that the sensitivity of them is obviously deferent. From these results, it is chosen that the angle of EMAT is 100 degree.
5-1-3. Lift-off of sensor An EMAT does not need a couplet for contacting an object. However, the surface of EMAT must be attached to the object in order to detect a defect. From a viewpoint of the contact between an EMAT and an object, a lift-off test was carried out. Figure 5.10 shows the result of the lift-off test. It is found that the sensitivity of sensor is increasing as the quantity of lift-off is decreasing. From this result, the EMAT must be attached to an object surface with a small compression force.
5-2. Constitution of non-destructive inspection tool To detect defects of weld region of a branch pipe, an internal pipe inspection tool has been studied and designed. The design conditions are same as the welding/cutting tool which is mentioned in the chapter 3. In the case of the welding/cutting tool, however, it is required that the optical fiber, which transmits the laser power, is positioned in the center of the tool in order to keep the precise laser processing. Thus, the welding/cutting tool was selected to the inchworm type traveling trucks. The non-destructive inspection tool has no constraint conditions to keep the enough space in the tool center. As a result, a wheel type traveling truck is adopted to move in cooling manifolds. Figure 5.11 shows the fabricated non-destructive inspection tool. The system is composed of six vehicles which are two traveling trucks, an inspection unit, a rotation unit, a distance sensor unit and a connection unit. The external diameters are below 94 mm which is considered about oblateness of the bent pipe. (1) Specification of the weld inspection sensor Figure 5.12 shows the appearance of fabricated EMAT. The specifications of EMAT are listed below; - Inspection method : EMAT (Electro-Magnetic Acoustic Transducer) - Frequency : 700 kHz - Wave mode : SH ultrasonic wave - Beam angle : about 64.4 ° - Magnet : SmCo, 7 elements - Coil : polyamide based - Arrangement : V position (reflection technique), angle of 100 ° - Dimension (EMAT is shaped inner surface of 50A pipe) • Length : 26 mm (including case) • Width : 16 mm • Height : 14 mm (2) Specification of each unit
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Figures 5.13 ~ 5.18 show the tool appearance of each unit. Table 5.3 shows the specifications of each axis movement and the centering performance is listed below. a) Inspection head and rotation unit - Centering dia. range : 86 ~ 108 mm b) Distance detection unit - Centering dia. range : 90 ~ 159 mm - Detection distance : non restriction
Table 5.3 Specifications of the tool movement Axis name Symbol Scanning range Scanning speed Insertion stroke EMAT R 27 mm 20 28 mm up &down mm/sec EMAT P ±185 deg. 90 - rotation deg./sec Tool e ±185deg. 75.9 - rotation deg./sec
5-3. Performance test of the non-destructive inspection tool In order to verify the basic functions and characteristics of the fabricated non-destructive inspection tool, the traveling trucks has been tested and the results are as follows: (1) Design conditions of traveling head - Traveling speed : > 1.0 m/min - Tractive force : movable force between the cask and the farthest branch pipe - Positioning accuracy :± 10 mm - Connection method : universal link connection, possible to increase other truck - Rescue method : possible to release the pipe pushing force (2) Specification of the traveling head The following results are obtained; - Centering dia. range : 86 ~ 108 mm - Movement distance range ; non restriction - Movement speed : max. 1.5 m/min with cable handling - Tractive force : average 40 kgf with two traveling trucks - Positioning accuracy (error) : within 3 ~ 4 % under all cases
5-4. Inspection characteristic test
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In order to verify the basic functions and characteristics of the fabricated EMAT for branch pipes, the sensor has been tested and the results are as follows: Figure 5.19 shows the appearance of EMAT for setting inspection tests and schematic view of the artificial defects. (1) Conditions of the basic performance test The prototype EMAT for pipes was arranged and tested in reference technique (V arrangement). Test conditions are listed below; Objective : SS316L pipe with thickness of 3 mm inner diameter of 54.5 mm Welding condition : YAG laser Defect shape -Depth : 0, 20, 30 % depth of pipe thickness - Inside defect size : 15 mm long (34.4°), 0.3 mm width - Outside defect size 15 mm long (30.7°), 0.3 mm width Location of defect surface and back near weld point with 1 mm (2) Test results Table 5.4 show the test results of the non-destructive inspection with EMAT and Fig.5.20 shows the example of test results.
Table 5.4 Results of the non-destructive inspection with EMAT Depth A: Base metal B : Base metal C :Across weld D : Across weld of slit (inside) (outside) (inside) (outside) 30 %* ft ft ft ft 20 %t ft ft ft X 10 %t A A X X
5-5. Conclusion The non-destructive inspection tool for the welding pipe has been successfully fabricated and the applicability to the blanket branch pipe inspection has been demonstrated. The system can be also moved inside a 100-A pipe with a minimum curvature of 400 mm and the inspection nozzle with telescopic mechanism can be extended into a branch pipe with a diameter of 50 mm for the non- destructive inspection. In this tool, the EMAT which is one of the non-destructive inspection methods was adopted and tested. The crawler type traveling trucks are adopted to this system because of no space constraint for installation of optical fiber such as the branch and manifold welding/cutting tool. In parallel with this tool development, non-destructive inspection tests using EMAT have been performed to clarify the sensitivity of the inspection ability. From these tests, the following conclusions are obtained: 1) Specifications of the weld inspection sensor are listed below; - Inspection method : EMAT
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(Electro-Magnetic Acoustic Transducer) - Frequency : 700 kHz - Wave mode : SH ultrasonic wave - Beam angle : about 64.4 ° - Magnet : SmCo, 7 elements - Coil : polyamide based - Arrangement : V position (reflection technique), angle of 100 ° - Dimension (EMAT is shaped inner surface of 50A pipe) • Length : 26 mm (including case) •Width :16 mm • Height : 14 mm 2) The EMAT can detect 10 % defect on a base metal and 20 % defect across a weld region. 3) The traveling speed of the tool is faster than l.Om/min in the manifold with bent and curved sections.
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6. Branch Pipe Leak Detection Tool
6-1. General Leak detection is essential to confirm reliability and quality of cooling pipe welding. This chapter describes leak detection methods and test results of leak detection head designed and developed. Table. 6.1 show the design conditions of leak detection tool. Table.6.2 and Fig. 6.1 summarize the leak detection sensitivity of various detection methods and typical leak detection method.
(1) Design conditions
Table 6.1 Design conditions of leak detection Atmosphere Dry N2 or inert gas Pressure 1 bar Temperature <50°C Radiation 3 x 106 Rad/hr Contamination Tritium, activated dust, beryllium Magnetic field Zero Target detectable sensitivity < 1 x 10"7 Pa • m3/sec
(2) Sensitivity of various detection methods
Table 6.2 Sensitivity of detection methods Method Detection Measureme Tracer gas or Pressure Min. detectable type nt style liquid (Pa) leak (Pa*m3/s)
lonization Detector C4Hio,H, 0.13 to 1.3 10-8 gauge CO2 x10-6 Helium leak Detector He < 1.3 x 10-2 10-11 Vacuum detector Mass Detector He, H, Ar 1.3x10-2 10-11 analyzer to 1.3x10-10 Babble Visual H2O,N2 3x106 4x10-7 Ammonia Visual NH3,Air < 2 x 106 10-8 test Compression Halogen Detector Halogen < 1.5 x 106 10-7 test Sniffer Detector He < 1 x 105 10-8
(3) Leak detection process for the ITER Figure 6.2 shows a general leak detection process for the blanket cooling pipe.
(4) Selection of leak detection method for the ITER A leak detection method for the blanket cooling pipe should be selected on the basis of the conditions mentioned above and experimental data obtained in large size tokamaks as well as
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compatibility with remote handling under severe gamma radiation. The data obtained in tokamak experience and the 1st stage tool experiment is attached to Appendix B. As a conclusion, a probe method using a nude type ionization vacuum gauge and a sniffer method using a helium leak detector were selected as the candidates of leak detection method.
6-2. Constitution of leak detection equipment In order to verify the leak detection performance, partial models of detection heads were fabricated, together with mockup of blanket cooling pipe, in accordance with the Japanese industrial Standards (JIS). The main features of the detection heads and pipe mockup are described below.
(1) Mockup of blanket cooling pipe Figure 6.3 and 6.4 show an overall structure of the fabricated mockup which is composed of two blanket manifolds, two branch pipes, vacuum pump and a movement mechanism to move a leak detection head in the axial direction. The arrangement of the cooling pipes simulates the blanket cooling pipes, including orifice to reproduce a conductance of blanket module and cooling pipes. The orifice is designed taking into account the real pipe arrangement shown in Fig.6.5. Figure 6.6 represents the analysis model to calculate the conductance. In order to simulate a leak, several variable standard leaks are installed at the positions of branch pipe welding joints.
1) Mockup of blanket cooling pipe Manifold pipe : JIS 100A sch 40 Branch pipe : JIS 50A sch 40 Orifice conductance :7.1 x 10-4m3/sec Dummy leak position : 80mm of branch pipe from manifold center
Helium leak rate : Less than 1.2 x 10-9 pa*m3/s
Ultimate pressure : 2.2 x 10-5 pa
(2) Partial model of detection head Figure 6.7 shows the fabricated detection head using probe method. This head is composed of a commercial base nude gauge and mechanical jacks to insert the head into the branch pipe. This tool can be moved along the pipe axial direction using the movement mechanism. A directional nozzle was attached to the detection head so as to increase detectability. The size of directional nozzle was specified in accordance with the tokamak experience as shown in Fig.6.8. Figure 6.9 shows the fabricated detection head using sniffer method. A sniffer tube is attached to the same head structure as the probe method, so that the sniffer tube can access to the branch pipe welding joints. The main parameters of the fabricated detection heads are listed below.
1) Ionization probe head (Probe method) Gauge size : OD26 mm, L39 mm (commercial product)
Detectable pressure : to 10-6 pa Directional nozzle size : ED9 mm, L22 mm 2) Sniffer tube head (Sniffer method) Tube size : OD0.9 mm, L25 m
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6-3. Performance test of leak detection head Before the leak detection test, function of axial and radial movement mechanism has been tested and confirmed. The results are summarized below and it has been found that all mechanism are functioned, i) Axial direction Movement Range : Max. 680 mm Movement speed : Variably (to Max. 2000 mm/min) ii) Radial direction Movement Range : Max. 50 mm Movement speed : Variably (to Max. 200 mm/min)
6-4. Leak detection performance test In case of the probe method, the detection head was moved inside the pipe after evacuation of pipe so as to detect standard leak located at the branch pipe welding joints. Table. 6.3 summarizes the testing conditions of the probe method.
Table 6.3 Test conditions of Probe method Pipe outer atmosphere Air/1 bar. Temperature RT Pipe inner pressure (Pa) order 10-4 Leak rate (Pa*m3/sec He) 1.8 x 10-7 Scanning direction Radial direction Scanning speed 25 mm/min uniformity Leak position 1A
On the other hand, in case of sniffer method, the inside of pipe was filled with nitrogen, which is used as a carrier gas (viscous flow), for detection of the standard leak, as schematically shown in Fig.6.10. In this case, the sniffer tube is not inserted into the branch pipe. Table 6.4 summarizes the testing conditions of the sniffer method.
Table 6.4 Test conditions of Sniffer method Pipe outer atmosphere Air/1 bar. Temperature RT Scanning direction Axial and Radial direction Axial direction scanning speed 200 mm/min Radial direction scanning speed 25 mm/min Leak rate (Pa*m3/sec He) 2.0x10-4,8.0x10-7 Leak position Branch pipe 1A, 1A+2A Carrier gas Dry Nitrogen Carrier gas flow rate 11 l/min Pipe inner pressure 9.3 KPa
Notes : Refer to Figs. 6.11 and 6.12 which show the schematic diagram of detection methods.
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6-5. Leak detection performance test results The results of both methods are listed in Table 6.5 and the details of the data obtained are shown in Fig. 6.13 to Fig.6.15. From this result, the probe method can detect 1.8x10-7
Pa*m3/sec He at a vacuum pressure of 10-4 pa inside the pipe. On the other hand, snifer method detects 2x10-4 ~ 8x10-4 Pa*m3/sec He depending on the number of leak location.
Table 6.5 Performance test parameter and results Detection method Probe Sniffer Branch pipe leak position 1A 1A 1A+2A Leak rate (Pa*m3/sec He) 1.8x10-7 2.0x10-4 8.0x10-4 Pipe inner pressure 10-4 Pa 9.3 kPa 9.3 kPa Carrier gas flow rate - 11 l/min 11 l/min Scanning direction Radial Axial Axial Scanning speed 25 mm/min 200 mm/min 200 mm/min
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7. Composite Fiber for YAG Laser Welding/Cutting Tool
The pipe welding/cutting has to be carried out under the severe gamma-ray conditions in a limited space inside the pipe. Therefore, no extra space is available to install monitoring equipment for welding/cutting operation. A solution of this problem is to prepare a composite fiber for laser energy and images transmission. A composite fiber whose functions are YAG laser transmission for welding/cutting and images transmission for monitoring has been developed with radiation hardness type fiber scope and optical parts. It consists of one fiber for laser transmission and a number of small fibers located around the fiber for images transmission. This section describes the construction of the composite fiber and the result of basic performance tests.
7-1. Constitution of the composite fiber The proposed composite fiber has two functions which are laser transmission and images transmission. YAG laser is transmitted through a fiber whose diameter is 0.6 or 0.7 mm. It depends on the laser power to weld or cut. For image transmission approximately 3,000 ~ 20,000 fibers with a diameter of 9 or 10 |J.m are arranged around the fiber for laser transmission. The purpose of this study is to combine two types of fibers which have a different diameter and to develop the optical parts in order to share the high power laser and the image data. Figure 7.1 shows the conceptual design of the composite fiber. The futures of this fiber are listed below; 1) One fiber for laser transmission is positioned in the center of the composite fiber to perform the precise laser focusing for welding/cutting. 2) The image fibers are installed around the laser transmission fiber for monitoring, and to collect and analyze the scattered laser light during welding/cutting in order to assure the quality. 3) Replacement from a normal laser transmission fiber to the composite fiber is easy because the total diameter of the fiber is only about 2 mm and the optical parts for focusing are the same. The test stand for the composite fiber was designed under the mentioned conditions. Figure 7.2 shows the whole of this system. It is composed of objective lenses, a focusing system, a composite fiber, a light source, a TV monitor, a CCD camera and its controller. The objective lens head which includes the optical parts imitates the branch pipe welding/cutting nozzle, as shown in Fig. 7.3. Figure 7.4 shows the focusing system. It consists of a CCD camera for observation of images, an optical coupling for sharing the reflected images and laser transmission, focusing lenses for laser and images, and so on. Figure 7.5 shows the fabricated composite fiber and test stand. Two composite fibers were fabricated to compare the difference in optical performance. Figure 7.6 shows the schematic view of the composite fiber and Table 7.1 shows the specifications of each fiber. The two fibers are basically the same structure but contain the different number of image fiber, which causes the different viewing resolution.
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Table 7.1 The specifications of composite fiber Item Type A (low resolution) Type B (high resolution) Material pure silica <— Length 1 m 10m Outer dia. of composite fiber about 1.0 mm about 2.0 mm Max. allowable bending dia. 250 mm <- Laser transmission - core diameter 0.52 mm 0.7 mm - clad diameter 0.6 mm 0.8 mm Image transmission - fiber diameter 9 (im 10 |o.m - number of fibers 3000 pixels 15000 pixels
7-2. Observation test In order to confirm the basic performance of the composite fiber and to verify the adequacy of this system, observation tests were carried out using the fabricated composite fiber and test stand. In the observation tests, the following objects were observed; (1) various lines with a different width, (2) SS pipe connection before and after welding. (1) Object: lines Figure 7.7 shows the results of observation test for the lines. The width of lines are 0.01, 0.2 and 0.3 mm. In this test, the number of image fiber is 15000 pixels. Though the quality of stationary picture is not good, each line can be recognized by the animated picture. (2) Object: SS pipe connection before and after welding Figure 7.8 shows the results of observation tests, in case of SS pipe before and after YAG laser welding. In this test, two types composite fibers are tested. Though the quality of stationary picture is not good, each picture can be recognized by the animated picture.
7-3. Conclusion The composite fiber for combing the laser and images transmission has been developed for precise positioning and monitoring so as to assure the quality of welding/cutting. The prototype fiber was fabricated to confirm the resolution and to verify the adequacy of this system. From the results of observation tests, the following results are obtained. 1) Though the further optimization is needed, the objective can be observed by the composite fiber.
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2) A focus of images from the fiber are proportional to the distance between the objective and the lenses. The characteristic of focusing can be used for positioning before welding. In this study, the function of the observation was tested using the fabricated composite fiber. In the next step, the penetration test of the high power laser is needed for the YAG laser welding/cutting. In addition, an image processing technique for the scattered laser light while welding is also required to verify the quality assurance of YAG laser welding.
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8. Conclusions
The remote bore tools for the blanket cooling pipes have been successfully developed and the advanced technologies have been demonstrated through the ITER R&D task. All tools and technique can be adopted to pipe welding, cutting and welding inspection under the ITER in-vessel environments. Each conclusion of this task is summarized bellow :
(1) Branch pipe welding/cutting tool A YAG laser type processing head and traveling trucks have been successfully fabricated and the applicability to the blanket branch pipe welding/cutting has been demonstrated. The following conclusions are obtained: 1) The optimum conditions of welding speed and laser power is 0.5 m/min for 1100 W. 2) A maximum allowable gap for welding is to be around 0.5 mm without filler materials. 3) The optimum conditions of cutting speed and laser power is 0.8 m/min for 1000 W. 4) Rewelding of the laser cutting surface can be performed with keeping similar mechanical properties to those of machining surface. 5) Welding/cutting in the various posture is available. 6) Repeat welding/cutting is possible at least by 5 times. 7) Inchworm type traveling mechanism shows the traveling speed of 0.5 m/min in the manifold with bent and curved sections.
(2) Manifold welding/cutting tool A YAG laser type processing head has been successfully fabricated and the applicability to the blanket manifold welding/cutting has been demonstrated. Though the processing head is only developed, traveling trucks which are developed for the branch pipe welding/cutting tool can be adopted to this head. The following conclusions are obtained: 1) The initial gaps of 50 mm in the axial direction and 10 mm in the lateral direction can be aligned using the clanmping mechanism for welding. 2) The allowable gaps for pipe welding without filler materials are 0.8 mm in the axial direction and 2.0 mm in the lateral direction. 3) The optimum conditions of welding speed and laser power are 0.3 m/min for 3600 W. 4) The optimum conditions of cutting speed and laser power are 0.3 m/min for 3000 W.
(3) Branch pipe inspection tool The non-destructive inspection tool for the welding pipe has been successfully fabricated and the applicability to the blanket branch pipe inspection has been demonstrated. The following conclusions are obtained: 1) The arrangement of EMAT is a letter of "V" (reflection technique) and the angle between elements is 100 degree. 2) The EMAT can detect 10 % defect on a base metal and 20 % defect across a weld region.
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3) The traveling speed of the tool is faster than l.Om/min in the manifold with bent and curved sections.
(4) Branch pipe leak detection tool The leak detection method for the branch pipes is studied and basic characteristic tests of leak detection are carried out. The results of these tests and consideration are summarized below: 1) A probe method using nude gauge with directional nozzle can detect a small leak and meet the ITER requirement. 2) Sniffer method using helium leak detector shows a low detectability compared with the probe method. However, the detectability can be improved by adopting a scanning mechanism to the sniffer tube for survey around the welding joint and by optimizing the position of the sniffer tube.
(5) Composite fiber for welding/cutting/observation The prototype composite fiber was fabricated to confirm the resolution and to verify the adequacy of this system. From the results of observation tests, the following conclusions are obtained: 1) Though the quality of image is to be improved, the welding/cutting can be monitored by the composite. 2) A focus of images from the fiber are proportional to the distance between the objective and the lenses. The characteristic of focusing can be used for positioning before welding.
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ACKNOWLEDGMENTS
The authors would like to express their sincere appreciation to Drs. M. Ohta, S. Matsuda and H. Kishimoto for their continuous encouragement on this work. The contributions by the staffs of department of ITER project and Toshiba Corp., Hitachi Corp., Mitsubishi Heavy Industry Corp., Ishikawajima Harima Heavy Industry Corp. and Fujikura Corp. are gratefully acknowledged.
REFERENCES
[1] S.Matsuda, et al: Proc. 13th Conf. on Plasma Physics and Controlled Nuclear Fusion Research, (Washington, 1990) IAEA-CN-53/G-2-2. [2] K.Shibanuma, T.Honda, K.Satoh, Y.Ohkawa, T.Terakado, et al: Remote Maintenance System Design and Component Development for Fusion Experimental Reactor, Proc. 16th Sympo. on Fusion Tech., Vol.2, pp.l317-1321(1990) [3] K.Honda, Y.Makino, M.Kondoh, K.Shibanuma: Feasibility Study of Internal-Access Pipe Welding/Cutting System for Fusion Experimental Reactor(FER), Proc.LASER'91,(1991) [4] K.Oka, S.Kakudate, M.Nakahira, et al: Critical Element Development of Standard Components
for Pipe Welding/Cutting by CO2 laser, JAERI Tech 94-033 (1994) [5] M.Nakahira, K.Oka, S.Kakudate, et al: Feasibility Study on YAG Laser System for Cooling Pipe Maintenance, ITER Emergency Task Agreement JB-RH-1 (1993) [6] K.Oka, M.Nakahira, S.Kakudate, et al: Development of Remote Bore Tools for Pipe Welding/cutting by YAG Laser, JAERI Tech 96-035 (1996)
-50- Vacuum vessel
Rail Rail mounted vehicle type manipulator
> i en o-i so
Fig.1.1 Schematic view of the blanket module maintenance Tool iinsertion n
Cooling pipes
IC w
Blanket modules 1. Cutting with the branch 2. Remove the blanket pipe welding/cutting tool module by the manipulator > m •pa en 5
I 1
/ r { Cross section J \ j of the blanket ^3
3. Rewelding after new 4. Non-destructive inspection 5. Leak detection test blanket module set
Fig.2.1 Schematic view of the procedure of the branch pipe maintenance from the inside of manifold We Id Ing/Cutting Iine
pa en Co I
Fig.2.2 Pipe layout of upper port area 1. Initial state Bio-shield 5. Manifold cutting and removal 8. Class 3 component installation 11. Cryostat and bio-shield recovery
Blanket manifold
Guard pipe 2. Top bio-shield removal 6. Lower guard pipe cutting and removal 9. Lower guard pipe installation and welding
Cryostat •.
/
>
3. Upper cryostat cover removal 7. Class 3 component removal 10. Manifold installation and welding, and upper guard pipe recovery
Support 4. Upper guard pipe cutting and removal ZLL I
\Alignment cone Fig.2.3 Schematic view of Manifold/ the procedure of the manifold replacement I en & i
•-uis—fa , | ,
Fig.2.4 A cask design for the boor tools JAERI-Tech 99-048
The cask for Laser and power source the blanket pipe maintenance
Fig.2.5 Cask layout for the blanket pipe maintenance (cross section)
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The cask for the blanket pipe maintenance Laser and power source
Fig.2.6 Cask layout for the blanket pipe maintenance (top of view)
-57- Nozzle Sleeve^ Eddy current sensor
WeSaing/Cutting head
Fixing mechanisiTij
YAG Laser Processinq Head
Slider shaft Traveling truck B Over all of the weldinq/cuttinq tool
en 00 Traveling truck A Pushing pad i Traveling trucks s 00
Nozzle
Welding / cutting nozzle
Head through bent pipe Fig.3.1 The branch pipe welding/cutting tool Main pipe Traveling truck B Traveling truck A Measurement truck Flexible tube Processing head
CJl 5 so o CO Fig.3.2 YAG laser welding/cutting system for the branch pipe A Assist gas CT 5 O I A Transmission tube Optical fiber A-A Fig.3.3 Schematic view of the transmission tube Ring ditch Z-axis positioning mechanism |«_ g Z-axis air cylinder Welding/cutting head Centering drive motor Fig.3.4 YAG laser welding/cutting head > I VIEW E -E VIEW F 2 oo Fig. 3.5 (1) Measurement truck 8 > L._. i CO i? I s I CO Fig.3.5 (2) Traveling truck JAERI-Tech 99-048 Power & measurement truck Flexible tube V n Traveling truck B Traveling truck A Processing head Confiquration of the branch pipe weldinq/cuttinq tool ^ pp Step 0. Initial position Truck [1 R— 1 L —A Step 1. Fix [A] support L Truck Step 2. Move [A] slider —B- A—b Truck Step 3. Fix [B] support —B- rv -A—^= Truck Step 4. Release [A] support 4^=-L._R—L r~A"~ Truck Step 5. Move [B] slider R I & Move [A] slider Truck Fig.3.6 Procedure of traveling -64- JAERI-Tech 99-048 3600 1GG0 t l Winding equipment Bend pipe 1 o o Flange CD Bend pipe 2 Straight pipe Straight pipe jointed branch pipe Fig.3.7 (1) Mock-up test system -65- JAERI-Tech 99-048 fcV (1) Cable winding equipment for the tool and manifolds • ; lit i ' ' I (2) Appearance of the tool set Fig.3.7 (2) Mock-up test system -66- JAERI-Tech 99-048 (3) Mock-up view of the laser processing Fig.3.7 (3) Mock-up test system -67- JAERI-Tech 99-048 Fig 3.8 Location of the blanket modules -68- > s T H 3- [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.9 (1) Results of the bead appearance test as a parameter of defocus -1.0 mm 0 mm +1.0 mm +1.5 mm i [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min oo Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.9 (2) Results of the macroscopic test as a parameter of defocus 900 W 1000W 1100W I i CO CO [Processing conditions] Welding speed : 0.5 m/min Defocus : +1 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.10 (1) Results of the bead appearance test as a parameter of laser power 900 W 1000W 1100W pa I [Processing conditions] Welding speed : 0.5 m/min Defocus : +1 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.10 (2) Results of the macroscopic test as a parameter of laser power 0.4 m/min 0.5 m/min 0.6 m/min CTi 5 s [Processing conditions] Laser power: 1000 W Defocus : +1 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.11 (1) Results of the bead appearance test as a parameter of welding speed 0.4 m/min 0.5 m/min 0.6 m/min 8 [Processing conditions] Laser power: 1000 W Defocus : +1 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.11 (2) Results of the macroscopic test as a parameter of welding speed 0 mm 0.5 mm 1.0 mm 1 H 8- [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Weld joint: butt joint Fig.3.12 Results of the bead appearance test as a parameter of gap JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Fig.3.13 (1) Results of the macroscopic test as a parameter of 0 mm gap -76- JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0.5 mm Fig.3.13 (2) Results of the macroscopic test as a parameter of 0.5 mm gap -77- JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 1.0 mm Fig.3.13 (3) Results of the macroscopic test as a parameter of 1.0 mm gap -78- JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 1.5 mm Fig.3.13 (4) Results of the macroscopic test as a parameter of 1.5 mm gap -79- -1.0 mm 0 mm +1.0 mm >m pa 00 o I sl [Processing conditions] Laser power: 1000 W Cutting speed : 0.8 m/min Frequency: 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.14 (1) Results of the appearance test as a parameter of defocus Defocus -1.0 mm 0 mm +1.0 mm Manifold side 5=0 I 00 i Blanket module side [Processing conditions] Laser power: 1000 W Cutting speed : 0.8 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.14 (2) Results of the appearance test as a parameter of defocus > i [Processing conditions] Laser power: 1000 W Cutting speed : 0.8 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.14 (3) Results of the macroscopic test as a parameter of defocus 900 W 1000 W 1100 W oo CO [Processing conditions] Cutting speed : 0.8 m/min Defocus : +1.0 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.15 (1) Results of the appearance test as a parameter of laser power Power 900 W 1000W 1100 W Manifold side M I 00 Blanket i module £ side [Processing conditions] Cutting speed : 0.8 m/min Defocus : +1.0 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.15 (2) Results of the appearance test as a parameter of laser power so oo on i [Processing conditions] Cutting speed : 0.8 m/min Defocus :+1.0 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.15 (3) Results of the macroscopic test as a parameter of laser power I 2 00 S [Processing conditions] Laser power: 1000 W Defocus : +1.0 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.16 (1) Results of the appearance test as a parameter of cutting speed Speed 0.7 m/min 0.8 m/min 0.9 m/min Manifold side I OO 5 CO Blanket co module side [Processing conditions] Laser power: 1000 W Defocus : +1.0 mm Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Fig.3.16 (2) Results of the appearance test as a parameter of cutting speed 0.7 m/min 0.8 m/min 0.9 m/min ! •••• H|HH| 00 00 i [Processing conditions] Laser power: 1000 W Defocus : +1.0 mm Frequency : 40 Hz Duty : 50 % Work distance :2 mm Fig.3.16 (3) Results of the macroscopic test as a parameter of cutting speed 00 to i (1) Bead appearance (2) Macroscopic observation I [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency: 40 Hz Duty: 50 % Work distance : 2 mm Weld joint .butt joint Defocus : 0 mm Gap : 0 mm Fig.3.17 Result of the rewelding test JAERI-Tech 99-048 (1) Setting angle of manifold : 28° (No.1 blanket) (2) Setting angle of manifold : 83° (No.7 blanket) (3) Setting angle of manifold : 8° (No.13 blanket) [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Fig.3.18 Result of the bead appearance test in the various posture welding -90- JAERI-Tech 99-048 (1) Setting angle of manifold : 28° (No.1 blanket) (2) Setting angle of manifold : 83° (No.7 blanket) (3) Setting angle of manifold : 8° (No. 13 blanket) [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Fig.3.19 Result of the liquid penetrant test in the various posture welding -91- JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Manifold angle : 28° (No.1 blanket) Fig.3.20 Result of the macroscopic test of the various posture welding at position of No.1 blanket (28°) -92- JAERI-Tech 99-048 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Manifold angle : 83° (No.7 blanket) Fig.3.21 Result of the macroscopic test of the various posture welding at position of No.7 blanket (83°) -93- JAERI-Tech 99-048 Position 1 [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap: 0 mm Manifold angle : 8° (No. 13 blanket) Fig.3.22 Result of the macroscopic test of the various posture welding at position of No. 13 blanket (8°) -94- JAERI-Tech 99-048 Setting angle Cutting appearance Blanket No.1 (28°) c HBBB^S^BoBSMM^^^™|WHM^^^BwBBwl|Bn|B iJJMSJMMMfc-MfcJ" J*-JHt>i WMJjjiljHUMMiMMWftaWManBea jaHLIJalSMMlMBSHBMMeMllllPllllll"jtlltMljM"MHlM8BIB|aMiaWWMa>iMIBMflei HHHBHH Blanket No.7 SHWHHBBii (83°) iIjiplllplilli l •H lip Blanket No.13 (8°) [Processing conditions] Laser power: 1000 W Welding speed : 0.8 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Fig.3.23 Results of the appearance test in the various posture cutting -95- JAERI-Tech 99-048 Setting angle Cross section Blanket No.1 (28°) Blanket No.7 (83°) Blanket No. 13 (8°) [Processing conditions] Laser power: 1000 W Welding speed : 0.8 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Defocus : 0 mm Gap : 0 mm Fig.3.24 Results of the macroscopic test in the various posture cutting -96- JAERI-Tech 99-048 c2 b2 a2 V I / • 4» 1 • 4 i • § is 4 * • 4 1 t • » • 4 < i ! I | (1) Measurement positions before welding cl bl al a2 b2 c2 V \_ iii • • • • • • • • • ... ! I I 8 a I ! • • » ±l ^ 37.0 ^ 34.5- 42.0 ^ 39.5 T 470 44.5 (2) Measurement positions after welding Fig.3.25 3-D measurement points of the branch pipe -97- JAERI-Tech 99-048 1.5 E 1 W •% 0.5 2 nn e 8?-0-5 o _« co ' -1.S 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (1) Manifold side 1.5 -—b2 w 0.5 (0 L. 0) M -0.5 O -1 CO ' -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (2) Blanket module side Fig.3.26 The change of the shrinkage quantity after repeat welding (1 cycle) JAERI-Tech 99-048 1.5 E 1 -—b1 (0 •-1 0.5 2 <0 § 0 rs J :r-i-*- ••-*-•. -I O --'» . —«—-•— —-»—«— 0) TO us O _1 CO 1 -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (1) Manifold side 1.S £ 1 — b2 w M 0.5 -*-c2 2 c0) c 1 0) -0.5 o -1 CO -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (2) Blanket module side Fig.3.27 The change of the shrinkage quantity after repeat welding (2 cycle) -99- JAERI-Tech 99-048 1.5 •—a1 E 1 -—b1 CO 4 0.5 2 I ° --*—*" • -•-•-•-• < —• •— —« » ..-•-••••- —«—• ' —•—•— » » o __•—•— ——«—»—— J>-0.5 c X o < CO "' -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (1) Manifold side 1.5 — a2 £ 1 -— b2 -^-c2 ^ 0.5 i o o |-0.5 c O i CO "' -1.5 0 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (2) Blanket module side Fig.3.28 The change of the shrinkage quantity after repeat welding (3 cycle) -100- JAERI-Tech 99-048 1.5 E :::: ••i 0.5 2 © i o ,-m—* — * • •—. • • « » ^"0.5 o « co ' -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (1) Manifold side 1.5 -^-a2 E — b2 =i 0.5 -*-c2 (0 C C r *~T'J: 8?-0.5 : o CO -1 -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (2) Blanket module side Fig.3.29 The change of the shrinkage quantity after repeat welding (4 cycle) -101- JAERI-Tech 99-048 1.5 -^a1 E 1 — b1 I 0.5 2 V. § o - - * - -4- -i —-»—• , —«— M AC . '• 4 • i > c o -1 -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (1) Manifold side 1.5 -^-a2 E 1 -—b2 E V) -^-c2 ••£ 0.5 2 :.4-4-..i i .r •f-T;y-=-j —^ i—: —"f= + -^ —*^i^zj ^-0.5 c -1.5 45 90 135 180 225 270 315 360 Angle of measuring position (degree) (2) Blanket module side Fig.3.30 The change of the shrinkage quantity after repeat welding (5 cycle) -102- JAERI-Tech 99-048 2 cycle 3 cycle 4 cycle 5 cycle [Processing conditions] Laser power: 1000 W Cutting speed : 0.8 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Defocus : 0 mm Fig.3.31 Results of the appearance test in the repeat cutting -103- I [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Defocus : 0 mm Fig.3.32 (1) Results of the appearance and macroscopic tests in the repeat welding (1) I I—» o I [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Defocus : 0 mm Fig.3.32 (2) Results of the appearance and macroscopic tests in the repeat welding (2) JAERI-Tech 99-048 5 cycle ;i!«lfiiiiiiHiiiiiiiiii m •; Appearance fl8B1BiBBH9B^BSB^B^^B^H^B^B^H^^«^raiCT^4 MHWlWBB^BHHHBfl)BJ^B^^BJW^WB^Oj||pCffl»sSsSjip|^^ Cross section *p •llfpSfSfflls [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Defocus : 0 mm Manifold angle : 83° (No.7 blanket) Fig.3.33 Results of the appearance and macroscopic test in the repeat welding at the position of the No.7 blanket -106- Liquid penetrant testing (PT) results o 5 co [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Defocus : 0 mm Manifold angle : 8° (No.13 blanket) Fig.3.34 Results of the penetrant testing after the repeat welding at position of the No. 13 blanket (8°) 5 cycle Liquid penetrant testing (PT) result " llf^^HffiBIllilr lit o 00 i i «! W « |SQ [Processing conditions] Laser power: 1100 W Welding speed : 0.5 m/min Frequency : 40 Hz Duty : 50 % Work distance : 2 mm Weld joint: butt joint Gap : 0 mm Defocus : 0 mm Manifold angle : 83° (No.7 blanket) Fig.3.35 Results of the penetrant testing after the repeat welding at position of the No.7 blanket (83°) itail A Rlankflt manifnIH I I—' o I I Detail A Over view Fig. 4.1 Blanket Cool ing Manifold i Guide ring (Alignment cone) Alignment hook Air cylinder > o CO CO Fiber (Dia. 1.0) 225deg (Theta axis) Mirror/ \_R axis motor\Lens\ Optical parts Theta axis motor Fig. 4.2 Structual Design of Manifold Welding/Cutting Tool >s i Tool Nozzle Fig. 4.3 Welding/Cutting Tool for Blanket Manifold Pipe Cutting Pipe Welding 1. Pipe clamping 1. Pipe clumping Projection 2. Pipe alignment 2. Pipe cutting to i I CO 3. Pipe welding Fig. 4.4 Welding/Cutting Procedure JAERI-Tech 99-048 Stepl:Travelling in the manifold Support Vacuum Vessel Bio Shield New pipe Projection Guide ring (Alignment cone) Step2Positioning of the tool and manifold cutting Step3:Traveling in the manifold Step4:Positioning of the tool and manifold cutting Step5:Traveling in the manifold Fig. 4.5 Cutting Operation Procedure -113- JAERI-Tech 99-048 Stepl:Travelling in the manifold Support Vacuum Vessel Bio Shield , Tool Projection Hew pipe .25 , Guide ring (Alignment cone) Step2-.Positioning of the tool Step3:Alignment and welding of the manifold _J Step4:Positioning of the tool Step5'.Alignment and welding of the manifold Fig. 4.6 Welding Operation Procedure -114- en I i oo Fig. 4.7 Test Stand for Pipe Alignment JAERI-Tech 99-048 Fig. 4.8 Result of cutting appearance -116- JAERI-Tech 99-048 1. Before alignment He-Ne laser Flexible pipe Fixed pipe Tool body 2. Under alignment Flexible pipe Fixed pipe 3. Completion of alignment Flexible pipe Fixed pipe Fig. 4.9 Pipe Inner Surface by Image Fiber •117- JAERI-Tech 99-048 il mm Outside of pipe Inside of pipe Bead appearance Flat position Overhead position Cross section Fig. 4.10 Results of welding bead appearance and cross section -118- JAERI-Tech 99-048 welded pipe specimen (Material: SUS316L, 100AxS( \,.,scr; 3.6kW (CW) Welding speed: 0.3m/min shielding gas: N2,5OLVmin Outside of pipe Inside of pipe Bead appearance Flat position Overhead position Cross section Fig. 4.11 Result of rewelding bead appearance and cross section -119- JAERI-Tech 99-048 Tr. EMAT Weld region Re EMAT Test piece Ultra sonic wave Defect (a) Transmission technique Re. EMAT Tr. EMAT Weld region Test piece Ultra sonic wave Defect (b) Tandem technique Defect weld region \ 7 Tr. EMAT Re. EMAT Ultra sonic wave Test piece (c) Reflection technique Fig.5.1 EMAT arrangement methods -120- no slit Inside 30%slit Inside 20%sHt .25 -O.D0 echo -.S5- -.2 -.25- -.5 c I I III II I 1 I III I I 1 1 1^ •> a 13 is ao a-i ^fl 'A at .-4u I Outside 30%slit Outside 20%slit CO I i 49mm 2 Tr. EMAT Re. EMAT V oo rr -O.ODl echo PipeT.P. t = 3mm -.25 -.25- 4 1 li IS 3B 24 £ 3t -tu Fig.5.2 The results of non-destructive inspection test using the transmission technique no slit Inside 30%slit .25- -Q.GU -Q.QD WWW echo -.25- -.25 noise . (J. 111,1 Mi.lU I I i 4 a la is la a-t ia 3£ it, 4u 5 tus] > 2 to Outside 30%slit o5 DO cr CO CD 37min 13mm Re.EMAT .25 Tr. EMAT sHt echo Pipe T.P. t = 3mm -.25 noise 4 U 12 16 3D a-t id 'Ji 3b 40 Fig.5.3 The results of non-destructive inspection test using the tandem technique noslit Inside 30%slit c£ Edge (Plate T.P.,t=4mm) VI* VSMA -O.BI noise noise -.DSl- -.«*- '3s 39 43 47 SI 555 553 663 BB7 771 75 in' • • • • I '3S 39 43 47 51 5S 59 Ej BT 71 T5 Outside 30%slit c£ Edge (Pipe T.P.,outeide,fc=3mm) 5 Tr.EMAT Re. EMAT 43 47 51 55 53 tl 67 71 5T 3S 43 47 Si 55 53 E.J 6T 7 1 PipeT.P. t = 3mm Fig.5.4 The results of non-destructive inspection test using the reflection technique slit outside slit at no weld inside slit at no weld outside slit over weld inside slit over weld 55mm 56mm 56mm test 55mm rr thickness : 3 mm direction frequency : 700 kHz V wave : 4 periods Defect Defect Defect Defect output : 15 App gain : 80 dB 30% averaging : 10 times transmission wave form 20% impossible 3 2/jS/div §- 10% impossible impossible Noise -<**»•• X rt rt ,^ i> rt , A 5S—a—rt A .'h—rt—*K~ Fig.5.5 The results of non-destructive inspection test with the prototype EMAT based on the reflection technique Specifications of EMAT Frequency : 700 kHz Magnet Coil Beam Angle : 64.4 ° - Material : SmCo - Length 30 mm Mode : SH wave - Height : 7.5 mm - Width 12 mm Temperature : 150 C° - Width : 5.0 mm - Material polyamide based - Thickness : 2.5 mm - Number : 8 elements Sensor arrangement Test piece 200 50 > Artificial defect shape CJ1 10%t slit 1.5LxO.3WxO.3Dmm 20 %t slit S 3.0Lx0.3Wx0.6Dmm oo Previous test !£? L : Length 30 %t slit 4.5LxO.3WxO.9Dmm 50 %t slit W : Width 7.5LxO.3Wx 1.5Dmm Aspect ratio : 5 defect o CO _rr This test D : Depth Fig.5.6 Angle test conditions for the reflection method disposition of sensors SOKtalit 3OKtalit 20KtaUt lOStaUt no slit tranamit-raceivs angle 26" transmit-receive angle go* braxunut-roooivo angle 90' .9 to 5 o txananrit-receivB to angle 100' transmit-receive angle no' tranamit-receiva 120* Fig.5.7 The wave form of the angle test in the case of outside defect disposition of sensors 6OStaUt 3OKtalit 20%tslit lOSt slit no slit transmit-receive angle 26* tranamit-receive angle go* tranamit-receive angle go' s- tran»mit-recoive 2 angle 100' oo transmit-receive angle no* 3 if Sf-T transmit-ieoeive angle 120' Fig.5.8 The wave form of the angle test in the case of inside defect 15- tranamit-receive angle —o— 8 0° y' ,,,, ^ 9 0° y' 10- ...-Q.... 1 0 0° y O'' ~"-A~~— 1 1 0° ---ffl------ffi--- 1 2 0° / CO 5" JAER I - * * * *-***"^i -Tec h l o - i i i 1 10 20 30 40 50 i 10 20 30 s depth of slit (%) depth of slit W oo (a) Inside defect (b) Outside defect Fig.5.9 (a) The comparison result of S/N level on sensor angle 100° .100° ...... _ 26° 26° CO 5- I•pa CD I 10 20 30 40 50 10 20 30 40 50 depth of slit depth of slit (%) (a) Inside defect (b) Outside defect Fig.5.9 (b) The comparison result of S/N level on sensor angle corner (100%t) oo 3 o liftoff (mm) Fig.5.10 The result of the lift-off test I t—' CO CO Connector Traveling truck No.2 Distance Rotation Inspection Traveling sensor part truck truck No.1 o i s OO Fig.5.11 The non-destructive inspection tool with EMAT for the branch pipe JAERI-Tech 99-048 (1) Appearance of the fabricated EMAT magnet magnet support plate casing2 flexible print coil protection panel casingl -^.support plate cable -casingl flexible print coil perspective magnet protection panel of magnet (2) Schematic view of the EMAT Fig.5.12 Appearance of the fabricated EMAT for branch pipe inspection -132- 252 3 00 o I s s oo A-A Fig.5.13 Traveling truck EMAT Stroke by motor Stroke s by cylinder Fig.5.14 Inspection truck with EMAT JAERI-Tech 99-048 252 Fig.5.15 Rotation part -135- JAERI-Tech 99-048 252 Fig.5.16 Distance sensor unit -136- JAERI-Tech 99-048 229 Fig.5.17 Connector unit -137- JAERI-Tech 99-048 AH A-A Fig.5.18 Connection part -138- JAERI-Tech 99-048 Top view h ,. * Back view Side view (1) Appearance of the EMAT sensor on the pipe C : inside, A : inside, accross weld base metal EMAT I I pipipee S D : outside, weld B : outside, accross weld region base metal (2) Position of the artificial defects Fig.5.19 Appearance of the EMAT for setting inspection tests -139- pa o I I &I 2 oo Fig.5.20 Signal wave of the inspection tests with EMAT JAERI-Tech 99-048 (1) Vacuum method Vacuum ~" Detector Permanent or temporary tracer gas supply tube Connection line (2) Probe method Vacuum Detector Permanent or temporary tracer gas supply tube Connection line Probe (Ion-gauge) (3) Sniffer method Detector Tracer gas under pressure Permanent or temporary Sniffer tube Connection line Fig.6.1 Leak localization concept of branch pipe -141- JAERI-Tech 99-048 Fig.6.2. Outline of Leak detection process NDT of pipe welding joint Leak test of blanket modules connected to a cooling manifold (When a leak is defected) Leak localization -142- He tank N2 tank Head axial driving unit V4> Vacuum pump unit H co o I Sniffer tube 0.9mm dla. Manifold (100mm dla.) length: 25 m Branch pipe A, B (50mm dta) Axial direction range 660 2500 ELD] SP Fig.6.3. Structure of Leak detection test equipment Iso I 2 oo Leak test equipment controlle Fiq.6.4 Appearance of Leak detection test equipment JAERI-Tech 99-048 Plasma side Blanch pipe Fig.6.5. Blanket module cooling channel model -145- JAERI-Tech 99-048 Fig.6.6. Blanket module cooling channel equivalent circuit -146- JAERI-Tech 99-048 .Steeping motor ,...<[._• luni/ation gauqe .-• .. _--;"ffT' ' " • * - " Probe head appearance OD=60.3 ^•Branch pipe Rod lonization gauge Probe head structure Fig.6.7. Detection head partial model of Probe method -147- JAERI-Tech 99-048 0 0 4 6 8 10 D-(mm) Fig.6.8. Directional nozzle size fixed graph Relation between L (length of the tube) and D (diameter of the tube) in order to make the value E (rate of leakage into the sensor out of whole leakage) maximum. -148- JAERI-Tech 99-048 Sniffer head appearance Orifice Sniffer tube Sniffer head structure Fig.6.9. Detection head partial model of Sniffer method -149- He leak position QLHe o i I He gas LD Signal level 0 A pipe center |Tube head position B pipe center Scan area of manif Fiq.6.10. Leak ditection concept bv Sniffer method JAERI-Tech 99-048 Fiq.6.11. Schematic diaaram of Probe method Gate valve open Vacuum Pum )mg ' Orifice r- Manifol Leak point Stroke x 1A, 2 A 50mm Probe Radial direction Fig.6.12. Schematic diaaram of Sniffer method ••• Carrier gas install Flow Gate valve closed • Orifice Rough pumping Manifol Branch pipe leak point Stroke 1A, 2A 5Qmm_i. Sniffer tube- Axial direction Max.660mm Radial direction -151- JAERI-Tech 99-048 Leak test start after 1 minuet Dammy leak point: 1A, Leak rate: Z4x10'7Pa-m3/s He Radial direction scan speed: 0.1m/min Leak point(45mm) I « 5x1 (T4 Probe t Scan start Scan end oriqin(Omma v ) Leak valve open ' end position(50mm) n. oov o. oov t Pipe Measurement time(sec) 201). Os 1X10"4 -= Leak test start after 15 minuets Dammy leak point: 1 A, Leak rate: 2.4x10"7Pa-m3/s He Radial direction scan speed: 0.1m/min Leak point(45mm) 5x10" Probe / / Scan start Scan end origin(0mm) endposition(50mm) 0.00V 0.OOV Pipe Measurement time(sec) 1X10" Fig.6.13. Results chart by Probe method -152- JAERI-Tech 99-048 Test condition Leak position: Branch pipe 1A Scanning direction: Manifold axial [Origin - End (660mm) - Origin] Scanning speed: 200 mm/min. Carrier gas (N2) flow rate: 11 l/min. Pipe inner pressure: 9.3 kPa He leak rate: 2x10'4Pa*m3/sec Time constant (delay time): 65 sec (due to 25m long tube) Fig.6.14. Results chart by Sniffer method -153- JAERI-Tech 99-048 Test condition Leak position: Branch pipe 1A + 2A Scanning direction: Manifold axial [Origin - End (660mm) - Origin] Scanning speed: 200 mm/min. Carrier gas (N2) flow rate: 11 l/min. Pipe inner pressure: 9.3 kPa He leak rate: 8x10"4Pa*m3/sec Time constant (delay time): 65 sec (due to 25m long tube) Fig.6.15. Results chart by Sniffer method -154- Fiber for image transmission en Tube for cover on i Fiber for laser transmission A-A Fig.7.1 The conceptual design of the composite fiber Composite fiber Focusing system YAG laser Objective lenses w so I en Optical fiber for light guide i Xe light source TV monitor Camera controller Fig.7.2 The test stand for the composite fiber Mirror Objective lenses Composite fiber Coliimate lenses I I—> en i i £ oo Mirror Fig.7.3 The objective lenses for the composite fiber YAG laser Mirror adjustment Fixing table mechanism Laser focusing lens Zoom lens Composite fiber CCD camera jo i I Laser mirror s Laser focusing lens CD Fig.7.4 The optical stage for focusing and sharing of laser and image transmission (b) Objective lenses en CO o5 co CO I (a) Full view of the test stand (c) Optical stage Fig.7.5 The fabricated test stand for the composite fiber JAERI-Tech 99-048 SS flexible tube Optical fiber for laser transmission Epoxy-acrilate (pure silica core) CO CD CM CD O CO Oi r Jacket tube (silica glass) Optical fiber for Image transmission (pure silica glass, 3000 pixels) (a) Composite fiber A SS flexible tube Epoxy-acrilate Optical fiber for laser transmission (pure silica core) Jacket tube (silica glass) Optical fiber for Image transmission (pure silica glass, 15000 pixels) (b) Composite fiber B Fig.7.6 The schematic view of the composite fibers -160- JAERI-Tech 99-048 Image fiber Laser fiber Line (a) Line width : 0.01 mm (b) Line width : 0.2 mm (c) Line width : 0.3 mm Fig.7.7 The results of the observation test: lines (image fiber of 15000 pixels) -161- JAERI-Tech 99-048 (1) normal view (2) SS pipe connection (a) Image fiber: 3000 pixels (1) SS pipe connection before welding (2) SS pipe connection after welding (b) Image fiber: 15000 pixels Fig.7.8 The results of the observation test: SS pipe -162- JAERI-Tech 99-048 Appendix-A YAG Laser Welding/cutting Characteristics A-l. Welding/Cutting Tests with Dual YAG laser Figure A-l. 1 shows the dual YAG laser system utilized for the tests. This system is composed of a 1.8 kW (CW) and a 1 kW (PW) laser sources, three optical fibers and an optical connector. Two optical fibers are used for the transmission of 1.8 kW and 1 kW laser, respectively. The core diameter and length of optical fiber for 1.8 kW laser are 0.6 mm and 200 m. The core diameter and length of optical fiber for 1 kW laser are 0.6 mm and 5m. These fibers are combined at the optical connector. The optical fiber with a core diameter of 1.2 mm and a length of 5m is used for the transmission of combined laser between the optical connector and welding/cutting nozzle. A-l-1. Basic Welding Test In this test, the welding conditions were surveyed using SS316L plate with a thickness of 6.0 mm as parameters of defocus, laser power, welding speed, welding position and gap, as listed below. Defocus : -1.6, -1.2, -0.8, -0.4, 0, 0.4, 0.8, 1.2, 1.6 mm Total laser power : 1400 W (856 W (CW)+544 W (PW)) 1600 W (978 W (CW)+622 W (PW)) 1800 W (1100 W (CW)+700 W (PW)) Duty : 50% (CW), 29% (PW) Welding speed : 0.2, 0.4, 1.0, 1.5 m/min Welding position : Flat position, Horizontal position Gap quantity : 0, 0.2, 0.4, 0.6 mm Shield gas : Nitrogen As an additional test, the in-process monitoring was performed to observe the welding operation state. A-l-1-1. Dependency of defocus, laser power and welding speed The dependency of defocus, laser power and welding speed on the welding quality was investigated. In this test, the butt weld without gaps was adopted. The following tests were performed for the qualification; (1 )appearance and macroscopic test and (2)radiographic test (RT). (l)Appearance and macroscopic tests Figure A-1.2 shows the results of bead appearance and macroscopic test as a parameter of defocus. The quantities of weld metal with a defocus of -0.4 mm were observed. Figure A-l.3 shows the results of bead appearance and macroscopic test as a parameter of laser power. In case of a defocus of -0.4 mm and a welding speed of 0.4 m/min, the quantities of weld metal was observed under a condition of 1800W laser power. Figure A-l.4 shows the results of bead appearance and macroscopic test as a parameter of welding speed. In the case of a laser power of 1800W and a defocus of -0.4 mm, the quantities of weld metal was observed under a condition of 0.2 m/min -163- JAERI-Tech 99-048 welding speed. The distortion of welded plate became larger in proportion to the decrease of a welding speed. (2)Radiographic test (RT) All samples satisfied the RT regulation (1st grade). A-l-1-2. Dependency of welding position The comparison of welding quality on welding position which are flat position and horizontal position, was performed. The welding test conditions are 1.8 kW laser power, 0.4 m/min welding speed and -0.4 mm defocus. In addition, the butt weld without gaps was adopted. The following tests were performed for the quality; (l)appearance and macroscopic test, and (2)radiographic test (RT). (l)Appearance and macroscopic tests Figure A-1.5 shows the results of bead appearance and macroscopic test for the horizontal position. The weld metal quantity was almost same in all samples. (2)Radiographic test (RT) All samples satisfied the RT regulation (1st grade). A-l-1-3. Dependency of gap The dependency of gap on welding quality were investigated as parameters of gaps and filler wire. The gap ranging from 0 to 0.4 mm were examined under the conditions of 1870 W laser power, 0.25 m/min welding speed and -0.4 mm defocus. The gap ranging from 0.4 to 0.6 mm were also examined using filler wire. The following tests were performed for the quality; (l)bead appearance and macroscopic test, (2)radiographic test (RT) and (3)tensile test. (l)Bead appearance and macroscopic test Figure A-l. 6 shows the results of bead appearance and macroscopic test under the conditions of 0, 0.2 and 0.4 mm gaps without filler wire. Good penetrations were obtained in all samples. However the under cut became larger in proportion to the increase of gap. Figure A-1.7 shows the results of bead appearance and macroscopic test in case of 0.4 and 0.6 mm gaps with filler wire. The under cut became smaller than the gap welding without filler wire. Good penetration in case of 0.4 mm was not obtained in spite of good penetration in case of 0.6 mm gap. (2)Radiographic test (RT) All samples except case of 0.4 mm gap welding with filler wire satisfied the RT regulation (1st grade). (3)Tensile test Table A-l. 1 shows the summaries of the tensile test results. The tensile strength of all samples were stronger than the base metal of stainless steel. -164- JAERI-Tech 99-048 Table A-1.1 Results of tensile strength tests Gap (mm) Tensile strength (MPa) 0 620, 620 0.2 607, 630 0.4 617,615 Base metal 602 A-l-1-4. Availability of in-process monitoring In this test, the availability of welding operation control by the in-process monitoring which means the observation of luminous intensity, was investigated using optical fiber. The luminous intensity changes in proportion to the changes of defocus, laser power and welding speed. The test result shows that the change of defocus, laser power and welding speed can be detected by the in-process monitoring. A-1-1-5. Summary of welding test 1) Optimum welding conditions Optimum conditions for SS316L plate with thickness of 6.0 mm using dual YAG laser are as follows: Total laser power : 1800W (1100 W (CW)+700 W (PW)) Duty : 50% (CW), 29% (PW) Welding speed : 0.4 m/min Defocus : -0.4 mm Shield gas : Nitrogen 2) Allowable gap A maximum allowable gap with filler wire is considered about 0.6 mm or more. 3) In-process monitoring The changes of defocus, laser power and welding speed can be detected by the observation of luminous intensity in the welding operation. A-l-2. Basic Cutting Test In this test, the cutting conditions were investigated using SS316L plate with a thickness of 6 mm as parameters of defocus, laser power, cutting speed and cutting position as listed below. Defocus : -1.4, -0.9, -0.4, 0, 0.1, 0.6 mm Total laser power : 1000 W, 1250 W, 1500 W Cutting speed : 0.1 to 0.4 m/min Cutting position : Flat position, Horizontal position Assist gas : Nitrogen (5 kgf/cm2) As an additional test, the in-process monitoring was performed to observe the cutting operation -165- JAERI-Tech 99-048 state. A-l-2-1. Dependency ofdefocus, laser power and cutting speed The dependency ofdefocus, laser power and cutting speed on the cutting quality were investigated. The following tests were performed for the quality; (l)cutting appearance and (2)roughness of surface. (1) Cutting appearance Figure A-1.8 shows the results of cutting appearance as a parameter of defocus. In this test, the defocus ranging from -1.4 to 0.6 mm were examined under the conditions of 1250 W laser power and 0.2 m/min cutting speed. The 6.0 mm thickness plate cutting with any defocus were possible. The attachment of dross was observed in all samples. Figure A-1.9, 10 and 11 show the results of cutting appearance as parameters of laser power and cutting speed under the condition of -0.4 mm defocus. The 6.0 mm thickness plate cutting with any laser power were possible in spite of the dross attachments on the back surface of all samples. (2) Roughness of surface Figure A-1.9, 10 and 11 show the results of surface roughness. The surface roughness became smaller in proportion to the decrease of cutting speed and the increase of laser power. A-l-2-2. Dependency of cutting position In this test, the cutting quality with two cutting positions which are flat position and horizontal position, were compared under the conditions of 1250 W laser power and 0.2 m/min cutting speed. The following tests were performed for the quality; (l)cutting appearance and (2)surface roughness. (l)Cutting appearance Figure A-1.12 shows the results of cutting appearance by horizontal position. The cutting quality by horizontal position was same as the flat position. (2)Surface roughness Figure A-1.12 shows the results of surface roughness by the horizontal position. The surface roughness was same as flat position. A-l-2-3. Availability of in-process monitoring In this test, the availability of in-process monitoring by the observation of luminous intensity was investigated. The luminous was not observed when the cutting was performed perfectly, while the luminous was observed when the plate cutting could not be performed perfectly. A-l-2-4. Summary of cutting test (l)Cutting ability The SS316L plate with a thickness of 6.0 mm can be cut under the conditions of 1000 W laser power, 0.2 m/min cutting speed and -0.4 m defocus. But the dross attachment on cutting surface can not be avoided. (2) In-process monitoring -166- JAERI-Tech 99-048 The cutting results are estimated to be detected by the observation of luminous. A-l-3. Re-welding Test The re-welding test was performed in order to clarify the re-welding ability without machining under the following conditions. In this test, the dross was removed from the cutting surface before welding. The re-welding was performed twice and the butt weld without gap was adopted. The bead appearance, macroscopic test, radiographic test (RT) and tensile strength test were performed for welding quality. l)Cutting conditions Laser power : 1250 W (650 W (CW)+600 W (PW)) Cutting speed : 0.2 m/min Defocus : -0.4 mm Assist gas : Nitrogen, 5 kgf/cm2 2)Welding conditions Laser power 1870 W (1110 W (CW)+760 W (PW)) Cutting speed 0.25 m/min Defocus -0.4 mm Shield gas Nitrogen (l)Bead appearance, macroscopic test and radiographic test Figure A-l. 13 shows the results of bead appearance and macroscopic test. All samples had good bead appearances and satisfied the RT regulation (1st grade), but the organization that differ from normal weld metal was observed at the center of bead. (2)Tensile strength test Table A -1.2 shows the results of tensile strength test. The tensile strength of weld metal became lower than the base metal due to the oxidation or nitride. Table A-1.2 Results of tensile test Gap (mm) Tensile strength (MPa) 0.4 612,615 0.6 608,617 Base metal 602 -167- JAERI-Tech 99-048 A-2. Welding/Cutting Tests with High Power YAG laser Basic welding/cutting tests using SS316L plate with a thickness of 7.6 mm were performed in order to clarify the characteristics of high power YAG laser. Figure A-2.1 shows the high power YAG laser system utilized for the tests. This system is composed of industrial 4 kW laser source and an optical fiber with a core diameter of 1.0 mm and a length of about 10 m. A-2-1. Basic Welding Test In this test, the welding conditions were investigated using SS316L plate with a thickness of 7.6 mm as parameters of defocus, laser power, welding speed and gaps, as listed below. Defocus : -3, -2, -1, 0, 1 mm Laser power : 3.4, 3.6, 3.8 kW Welding speed : 0.2, 0.3, 0.4, 0.5 m/min Gaps :0,0.4,0.8,1.2,1.4 mm Assist gas : Nitrogen, 70 1/min A-2-1-1. Dependency of defocus, laser power and welding speed In this test, the dependency of defocus, laser power and welding speed on the welding quality were investigated. The following tests were performed for the quality; (1) macroscopic test and (2)microscopic test. (l)Macroscopic test Figure A-2.2 shows the results of macroscopic test as a parameter of defocus. In this test, the defocus ranging from -3 to 1 mm were examined under the conditions of 3.8 kW laser power and 0.3 m/min welding speed. In the case of -1 or -2 mm defocus, the quantities of weld metal were observed. Figure A-2.3 shows the results of macroscopic test as parameters of laser power and welding speed under the condition of -1 mm defocus. The conditions of 3.6 kW laser power and 0.3 m/min welding speed were the optimum conditions for the welding of plate with a thickness of 7.6 mm. (2)Microscopic test Figure A-2.4 shows the results of microscopic test under the optimum conditions for welding of plate with a thickness of 7.6 mm as listed below; Laser power : 3.6 kW (CW) Welding speed : 0.3 m/min Defocus : -1 mm Assist gas : Nitrogen, 70 1/min No welding defect could be observed. A-2-1-2. Dependency of gap and mismatch In this test, the welding quality were investigated as a parameter of gaps ranging from 0 to 1.4 mm. The gap welding were examined under the optimum conditions as mentioned above. The following tests were performed for the quality; (l)bead appearance and macroscopic test and (2)tensile strength, -168- JAERI-Tech 99-048 elongation and fatigue strength. (l)Bead appearance and macroscopic test Figure A-2.5 shows the results of bead appearance and macroscopic test as a parameter of gaps. The welding of gap up to 0.8 mm were possible without using filler wire. Figure A-2.6 shows the results of bead appearance and macroscopic test as parameters of gaps and feeding rate of filler wire with a diameter of 1.2 mm. The gap welding up to 1.2 mm using filler wire were possible, but the under cut became larger in proportion to the increase of gap. Figure A-2.7 shows the results of bead appearance and macroscopic test as a parameter of gap using inter layer metal, with a thickness of 0.8 mm and a height of 9.1 mm, attached to the edge of plate. The gap welding up to 1.2 mm was possible, but the under cut was larger than one of gap welding using filler wire. Figure A-2.8 shows the results of bead appearance and macroscopic test in the case of 2 mm mismatch. In this test, the welding ability with mismatch of 2 and 3 mm were investigated. As the results, the mismatch welding up to 2 mm was possible without filler wire. (2)Tensile strength, elongation and fatigue strength Table A-2.1 shows the results of tensile strength and elongation for gap welding without filler wire. The tensile strength and elongation deteriorated in proportion to the increase of gap. Figure A- 2.9 shows the results of fatigue strength in the case of the welding without filler wire. In this figure, ASME Jaske & OiDonell Curve for stainless steel and master curve for stainless steel are shown in order to compare with the curve of YAG laser welding. The fatigue strength of YAG laser welding are estimated to be as same as one of TIG welding. Table A-2.1 Results of tensile and elongation test Gap (mm) Tensile strength (MPa) Elongation (%) 0 568, 565 51.2,50.8 0.4 560 , 564 , 550 45.8,43.8,45.2 0.8 541 , 544 , 538 35.4,36.4,36.6 1.2 515 ,522 ,528 34.4 , 34.2 , 34.0 Base metal 576 55 A-2-1-3. Summary of welding tests (l)Optimum welding conditions Optimum welding conditions for SS316L plate with a thickness of 7.6 mm using high power YAG laser are as follows. Laser power :3.6kW(CW) Welding speed : 3 m/min Defocus : -1 mm Stand off : 5 mm Assist gas : Nitrogen, 701/min (2)Allowable gap and mismatch 169- JAERI-Tech 99-048 A maximum allowable gap and mismatch without filler wire is up to 0.8 mm and 2 mm, respectively. A-2-2. Basic Cutting Test In this test, the cutting conditions have been investigated using SS316L plate with a thickness of 7.6 mm. This test was performed as parameters of laser oscillation type (continuous wave or pulse wave), laser power, cutting speed and assist gas flow rate, as listed below. Laser oscillation type : Continuous Wave (CW), Pulse Wave (PW) Laser power : 3.2, 3.6 kW (CW), 6 kW as peak power (PW) Cutting speed : 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 m/min Assist flow rate gas : Nitrogen; 125, 150, 175 1/min Defocus : 0 mm Stand off : 1 mm A-2-2-1. Dependency of laser oscillation type and laser power In this test, the dependency of laser oscillation type and laser power on the cutting quality were investigated. This test was examined as parameters of 3.2 kW continuous wave, 3.6 kW continuous wave and 6 kW peak power of pulse wave under the conditions of 0.4 m/min cutting speed and 175 1/min assist gas flow rate. The following tests were performed for cutting quality; (l)cutting surface, (2)macroscopic test, (3)surface roughness, (4)kerf width, (5)bevel angle, (6)dross quantity and (7)spatter quantity. (l)Cutting surface Figure A-2.10 shows the results of cutting surface as parameters of laser oscillation type and laser power. The oxidation was observed on cutting surface in the cases of pulse wave and 3.2 kW continuous wave. (2)Macroscopic test This test was performed under the cutting speed of 0.4 m/min. Figure A-2.11 shows the results of macroscopic test. The results of all samples were almost same and the melted metal was observed on cutting surface. (3)Surface roughness Figure A-2.12 shows the results that the cutting surface using 3.2 kW CW were rougher than PW and 3.6 kW CW. In addition, the lower part on cutting surface in all samples were rougher than upper part. (4)Kerf width This test was performed under the cutting speed of 0.4 m/min with PW, 0.6 m/min with 3.2 kW CW and 0.6 m/min with 3.6 kW CW, respectively. Figure A-2.13 shows the results that the kerf width in the case of PW was approximately 0.94 mm, and kerf width in the case of 3.6 kW CW was approximately 1.01 mm. (5)Bevel angle This test was performed under the cutting speed of 0.4 m/min with PW, 0.6 m/min with 3.2 kW 170- JAERI-Tech 99-048 CW and 0.6 m/min with 3.6 kW CW, respectively. Figure A-2.14 shows the results that the bevel angle in the case of PW was approximately 2 degree. (6)Dross quantity This test was performed under the cutting speed of 0.4 m/min with PW, 0.6 m/min with 3.2 kW CW and 0.6 m/min with 3.6 kW CW, respectively. Figure A -2.15 shows the test results. (7)Spatter quantity This test was performed under the cutting speed of 0.4 m/min with PW, 0.6 m/min with 3.2 kW CW and 0.6 m/min with 3.6 kW CW, respectively. Figure A -2.16 shows the test results. A-2-2-2. Dependency of cutting speed and assist gas flow rate In this test, the dependency of cutting speed and assist gas flow rate on the cutting quality were investigated. This test was examined as parameters of the cutting speed ranging from 0.3 to 0.8 m/min and assist gas flow rate ranging from 125 to 175 1/min using 3.6 kW (CW) laser power. The following tests were performed for cutting quality; (l)cutting surface, (2)macroscopic test, (3)surface roughness, (4)kerf width, (5)bevel angle, (6)dross quantity and (7)spatter quantity. (l)Cutting surface Figure A-2.17 shows the results of cutting surface as a parameter of cutting speed. The cutting surface became rougher in proportion to the decrease of cutting speed, and the cutting of 7.6 mm thickness plate was impossible in the cases of over 0.8 m/min cutting speed. The optimum cutting speed was approximately 0.6 to 0.7 m/min. Figure A-2.18 shows the results as a parameter of assist gas flow rate under the condition of 0.7 m/min cutting speed. The increase of dross in proportion to the decrease of flow rate was observed. (2)Macroscopic test Figure A-2.19 shows the results of macroscopic test as a parameter of cutting speed. The width of melted metal at the lower part on cutting surface became smaller in proportion to the increase of cutting speed. Figure A-2.20 shows the results as a parameter of assist gas flow rate. As mentioned above, the increase of dross in proportion to the decrease of flow rate was observed. (3)Surface roughness In this test, the surface roughness were measured. Figure A-2.21 shows the results of cutting surface as a parameter of cutting speed. In the case of 0.6 m/min cutting speed, the surface was smoothest. Figure A-2.22 shows the results as a parameter of assist gas flow rate under the condition of 0.7 m/min cutting speed. The surface at 3.5 mm depth from plate surface became smoother in proportion to the increase of flow rate. However the changes of surface roughness at 0.5 and 6.5 mm depth from plate surface were not observed in spite of the change of flow rate. (4)Kerf width Figure A-2.23 shows the results of kerf width as a parameter of cutting speed. Kerf width did not change in spite of the increase of cutting speed and it was approximately 1.0 mm. Figure A- 2.24 shows the results as a parameter of assist gas flow rate. This test was performed under the condition of 0.7 m/min. The increase of kerf width in proportion to the increase of flow rate was observed. -171- JAERI-Tech 99-048 (5)Bevel angle Figure A-2.25 shows the results of bevel angle as a parameter of cutting speed. Bevel angle did not change in spite of the increase of cutting speed. Figure A-2.26 shows the results of bevel angle as a parameter of assist gas flow rate. This test was performed under the condition of 0.7 m/min. The decrease of bevel angle in proportion to the increase of flow rate was observed. (6)Dross quantity Figure A-2.27 shows the results of dross quantity as a parameter of cutting speed. The dross quantity increased in proportion to the increase of cutting speed. Figure A-2.28 shows the results as a parameter of assist gas flow rate under the condition of 0.7 m/min cutting speed. The dross quantity decreased in proportion to the increase of gas flow rate. (7)Spatter quantity Figure A-2.29 shows the results of spatter quantity as a parameter of cutting speed. The spatter quantity decreased in proportion to the increase of cutting speed. Figure A-2.30 shows the results as a parameter of assist gas flow rate under the condition of 0.7 m/min cutting speed. The spatter quantity increased in proportion to the increase of assist gas flow rate. A-2-2-3. Summary of cutting tests (l)Optimum cutting conditions Optimum cutting conditions using SS316L plate with a thickness of 7.6 mm are as follows; Laser power : 3.6 kW Oscillation type : Continuous wave Cutting speed : 0.6 m/min Defocus : 0 mm Stand off : 1 mm Assist gas : Nitrogen, 175 1/min (2)Cutting quality Cutting quality is as follows under the optimum cutting condition, as mentioned above. Surface roughness : 0.17 mm Kerf width : 1 mm Bevel angle : 3 degree Dross quantity : 0.7E-2 g/mm Spatter quantity : 4.0E-2 g/mm A-2-3. Re-welding Test In this test, re-welding ability was investigated using high power YAG laser under the optimum cutting and welding conditions. This test was adopted butt welding without gaps and machining. The microscopic test, radiographic test (RT) and tensile strength/ elongation test were examined for the re- welding quality. l)0ptimum cutting condition Laser power : 3.6 kW -172- JAERI-Tech 99-048 Laser oscillation type : Continuous wave Cutting speed : 0.6 m/min Defocus : 0 mm Stand off : 1 mm Assist gas : Nitrogen, 175 1/min 2)Optimum welding condition Laser power : 3.6 kW Laser oscillation type : Continuous wave Welding speed : 0.3 m/min Defocus : -1 mm Assist gas : Nitrogen, 70 1/min (l)Microscopic test and radiographic test (RT) Figure A-2.31 shows the results of microscopic test. Good penetration and organization were observed, and no welding defect could be observed. (2)Tensile strength and elongation test The tensile strength and elongation test were 98.3% and 80.7% as compared with base metal. -173- JAERI-Tech 99-048 a)Laser head b)Monitor Fig.A-1.1 Dual YAG laser system -174- JAERI-Tech 99-048 Welding conditions Defocus Cross section Bead appearance (mm) Total power 800W -1.6 CW power 489W Duty 50% PW power 31IW Duty 29% Welding speed 0.4m/min -1.2 Assist gas Nitrogen Welding joint:Butt -0.8 -0.4 0 ir 0.4 0.8 • ^^^^ 1.2 1.6 Fig.A-1.2 Bead appearance and macroscopic observation as a parameter of defocus -175- Welding condition Laser power Bead appearance Macroscopic observatI on Welding speed :0.4 m/min Total:1800W Defocus :-0.4 mm CW:1100W Assist gas :Nitrogen PW:700W Welding joint :Butt Total:1600W CW:978W PW:622W 3 s Total:1400W CW:856W PW:544W Fig.A-1.3 Bead appearance and macroscopic observation as a parameter of laser po Welding conditions Welding speed Bead appearance Macroscopic (m/m i n) observation Total power :1800W 0.2 CW power :1100W Duty :50% PW power :700W Duty :29% Defocus :-0.4 mm Shield gas :Nitrogen 0.4 Welding joint :Butt 5 o CO «o 1.5 Fig.A-1.4 Bead appearance and macroscopic observation as a parameter of welding speed Welding condition Bead appearance Macroscop i c observat i on Total power :1800W CW power :1100W Duty :50% PW power :700W Duty :29% Welding speed :0.4 m/min Defocus :-0.4 mm tr Assist gas CO :Nitrogen CO Welding joint I :Butt oo Fig.A-1.5 Bead appearance and macroscopic observation with horizontal position JAERI-Tech 99-048 Q. H— o o 2 05 Q. 03 .2 DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Welding conditions Gap Bead appearance Macroscopic (mm) Front surface Back surface observation Total power M870W 0.4 CW power Duty :50% PW power :760W Duty :29% Welding speed :0.25 m/min Defocus :-0.4 mm Shield gas :N i trogen Welding joint :Butt oo 0.6 o i I si oo Fig.A-1.7 Bead appearance and macroscopic observation by gap welding with filler wire Cutting conditions Defocus Cutting surface (mm) Front surface Back surface Cross section Total power :1250W 0.6 CW power :650W Duty :50% PW power :600W Duty :29% Cutting speed:0.2 m/min 0.1 Assist gas :Nitrogen -0.4 > 18 -0.9 11 ill -1.4 Fig.A-1.8 Cutting surface as a parameter of defocus Cutting conditions Cutting speed Cutting surface Roughness (m/min) Front surface Back surface Cross section (um) Total power :1000W 0.1 7 CW power :400W Duty :50% PW power :600W Duty :29% Defocus :-0.4 mm 0.15 13 Assist gas :Nitrogen • f >'*'£$' ' 0.2 19 pa 00 i to to CO 0.25 impossible to cut I 0.3 impossible to cut Fig.A-1.9 Cutting surface and cutting roughness as parameters of laser power and cutting speed Cutting conditions Cutting speed Cutting surface Roughness (m/min) Front surface Back surface Cross section (um) Total power M250W 0.1 10 CW power :650W Duty :50% PW power :600W Duty :29% Defocus :-0.4 mm 0.15 Assist gas :Nitrogen 0.2 16 OO oo 0.3 37 I 2 Oo 0.35 impossible to cut Fig.A-1.10 Cutting surface and surface roughness as parameters of laser power and cutting speed (1) Cutting conditions Cutting speed Cutting surface Roughness (m/min) Front surface Back surface Cross section (urn) Total power :1500W 0.2 10 CW power :900W Duty :50% PW power :600W Duty :29% Defocus :-0.4 mm 0.25 12 Assist gas :Nitrogen 0.3 16 > OO I 0.35 29 2 OO 0.4 impossible to cut Fig.A-1.11 Cutting surface and surface roughness as parameters of laser power and cutting speed (2) Cutting conditions Cutting surface Roughness Front surface Back surface Cross section (um) Total power M250W 13 CW power :650W Duty :50% PW power :600W Duty :29% msmmmmmm Cutting speed :0.2 m/min SO 00 en Defocus :-0.4 mm Assist gas :Nitrogen I Welding joint :Butt Fig.A-1.12 Cutting surface and surface roughness with horizontal position Welding conditions Bead appearance Macroscopic D i stort i on Front surface Back surface observation (mm) Total power 1870W 0.54 CW power Duty :50% PW power :760W Duty :29% ^^^^^m^^ Welding speed :0.25 m/min • I- .i !| Defocus :-0.4 mm Shield gas :Nitrogen I Welding joint :Butt I—> 00 0.59 in1 ' ••!;•!, Fig.A-1.13 Bead appearance and macroscopic observation by rewelding JAERI-Tech 99-048 Optical fiber (10m) 4kW-YAG laser oscillator 6-axis robot a)Schematic diagram of equipment b)Processing equipment c)Laser head Fig.A-2.1 High power YAG laser system -187- JAERI-Tech 99-048 Welding condition Defocus Macroscopi c (mm) observation Laser power :3.8 kW 1 Welding speed :0.3 m/min Assist gas :Nitrogen Gas flow rate :70 l/min Welding joint :Butt 0 -1 -2 -3 Fig.A-2.2 Macroscopic observation as a parameter of defocus -188- Welding conditions Laser power Welding speed (m/min) (kW) 0.2 0.3 0.4 0.5 Defocus :-1 mm 3.4 Shield gas :Nitrogen Gas flow rate :70 l/min Welding joint :Butt 3.6 00 CD I £i oo 3.8 Fig.A-2.3 Macroscopic observation as a parameter of laser power and welding speed Welding conditions Microscopic observation Deta iI Laser power :3.6 kW Welding speed:0.3 m/min Assist gas :Nitrogen Gas flow rate".70 l/min Welding joint:Butt -•'•*-* :l:-^^-J^tsc-u\ Fig.A-2.4 Microscopic observation under optimum welding conditions Gap(mm) Laser welding conditions 0.4 0.8 1.2 1.4 CW laser power :3.6KW Cross section Welding speed :0.3m/min Defocus :-1.0mm Stand off :5mm Assist gas :Nitrogen Gas flow rate :0.07m3/min Welding joint :Butt Inter layer metal thickness :0.8mm Plate thickness :7.6mm Plate material :SS316LN i i—i Bead appearance CO 5 i—> o i CO to i o CO CO Fig.A-2.5 Bead appearance and macroscopic observation as a parameter of gap Gap (mm) Laser welding conditions 0.4 0.8 1.2 Feeding rate 0.2m/min LOm/min 0.6m/min CW laser power :3.6KW Cross section Welding speed :0.3m/min Defocus :-1.0mm Stand off :5mm Assist gas ."Nitrogen Gas flow rate :0.07m3/min Welding joint :Butt Wire diameter :1.2mm Plate thickness :7.6mm Plate material :SS316LN Bead appearance CO I i o CO CQ Fig.A-2.6 Bead appearance and macroscopic observation as a parameter of gap and filler wire feeding speed Gap(mm) Laser welding conditions 0.4 0.8 1.2 1.4 CW laser power :3.6KW Cross section Welding speed : 0.3m/m i n Oefocus :-1.0mm Stand off :5mm Assist gas :Nitrogen Gas flow rate :0.07mVmin Welding joint :Butt Interlayer metal thickness :0.8mm Plate thickness : 7.6mm Plate material •-SS316LN 0.8 Bead appearance 3 GO 3- I o\ Gap O CO Fig.A-2.7 Bead appearance and macroscopic observation using interlayer metal as a parameter of gap Welding conditions Bead appearance Macroscopic Front surface Back surface observation Laser power :3.6 kW Welding speed :0.3 m/min Defocus i-1 nm Assist gas :Nitrogen mmm Gas flow rate :70 l/min :Butt 2 Welding joint 5 o CO CO i Fig.A-2.8 Bead appearance and macroscopic observation with 2 mm mismatch welding JAERI-Tech 99-048 1 v i 500 AS^IE Jacke&O'Dnnell curve]for stainless steel 400 Master curve for I-butt joint of stainless steel •§ 300 200 CC 100 I I05 10s 10' Fatigue life (cycle) Fig.A-2.9 Results of fatigue strength test -195- Cutting conditions Cross section of cutting surface CW 3.6kW CW 3. 2kW PW 6kW (peak power) Cutting speed :0.4 m/min Defocus :0 mm Assist gas :Nitrogen Gas flow rate :175 l/min 'I''! Ill; 'I' a> o Fig.A-2.10 Cross section of cutting surface as parameters of laser oscillation type and laser power Cutting conditions Macroscop i c observat i on CW 3.6kW CW 3.2kW PW 6kW (peak power) Cutting speed :0.4 m/min Defocus :0 mm Assist gas :Nitrogen Gas flow rate :175 l/min > I I—» Fig.A-2-11 Macroscopic observation as parameters of laser oscillation type and laser power JAERI-Tech 99-048 400 Kisi Top 0.5mm CS 1771 Middle 3.5mm e [XXI Bottom 6.5mm Pi 300 2 j 200 i g loo — f • 1/5 Pulse CW,3.2kW, CW,3.6kW Fig.A-2.12 Results of surface roughness as parameters of laser oscillation type and laser power I. 10 05 - s 1.00 - & 0.95 : 0.90 Pulse,0.4m/min CW^.2kW,0.6m/min Fig.A-2.13 Results of kerf width as parameters of laser oscillation type and laser power 4 - 3 - 4> 2 - --__ I - Pulse,0.4m/min CW^.2kW,0.6m/min CW^.6kW,0.6m/niin Fig.A-2.14 Results of bevel angle as parameters of laser oscillation type and laser power -198- JAERI-Tech 99-048 6 | 5 O 4 3 - 0 2 - 3 GO CO mmmmm 2 o ilillill Puke,0.4m/min CW,3.6kW,0.6m/min Fig.A-2.15 Results dross quantity as parameters of laser oscillation type and laser power 1 -I 5 .1.1.1.1 . • 1 til l 03 3 1 1 1 HI .1.1.1 . cS 0 PuJse,0.4m/min CW,3.2kW,0.6m/nun CW,3.6kW,0.6m/min Fig.A-2.16 Results of spatter quantity as parameters of laser oscillation type and laser power -199- JAERI-Tech 99-048 Cutting conditions Cutting speed Cross section On/in in) Laser power :3.6 kW 0.3 Defocus :0 mm Assist gas :Nitrogen Gas flow rate :175 l/min 0.4 0.5 0.6 i!ni!iiniiii!fTiiTnffifiminiiinifntiniii|[[ 0.7 0.8 impossible to cut Fig.A-2.17 Cutting surface as a parameter of cutting speed -200- Cutting conditions Assist gas flow rate Cross section (l/min) Laser power :3.6 kW 125 Cutting speed :0.7 m/min Defocus :0 mm Assist gas :Nitrogen ,,,„,„, ,, ^[.inhninniMiMiin;)^! 150 CO o I lilillllHilHlililHIIllll'lllHiipHIIliilinilHK 175 Vr|i!!iinii;i!l!|l!;iil!!i:;ii!!l!i;;!li|!lll|l!l!|l Fig.A-2.18 Cutting surface as a parameter of assist gas flow rate JAERI-Tech 99-048 Cutting conditions Cutting speed Macroscopic (m/min) observation Laser power :3.6 kW 0.3 Defocus :0 mm Assist gas :Nitrogen Gas flow rate :175 l/min 0.4 0.5 0.6 0.7 0.8 impossible to cut Fig.A-2.19 Macroscopic observation as a parameter of cutting speed -202- Cutting conditions Assist gas flow rate Macroscopic (l/min) observat i on Laser power :3.6 kW 125 Cutting speed : 0. 7 m/m i n Defocus :0 mm Assist gas :N i trogen 150 O oo i si oo 175 Fig.A-2.20 Macroscopic observation as a parameter of assist gas flow rate JAERI-Tech 99-048 « Top 0.5mm — •-. E Middle 3.5mm •L. Bottom 6.5mm ai.. 300 - > 3D 200 - F o .1 1-"*" ,- 100 - x_" 1r*" « CO — . 0.3 0.4 0.5 0.6 0.7 0. i Cutting speed (m/min) Fig A-2.21 Results of surface roughness as a parameter of cutting speed 400 ss 3.6kW, 0 7m/min —•—Top 0.5mm E —•--Middle 3.5mm —*~— Bottom 6.5mm on> 300 - en - ¥^ I. 200 - O V u too - , -• s CO • • I20 130 140 150 160 170 110 Assisting gas flow rate (I/min) Fig.A-2.22 Results of surface roughness as a parameter of assist gas speed rate I.10 3.6kW .2kW £ I.05 3 Pulse 1.00 °-95 —-f- 0.90 0.2 0.4 0.6 0.1 Cutting speed (m/min) Fig.A-2.23 Results of kerf width as a parameter of cutting speed -204- JAERI-Tech 99-048 I.10 3.6k\V,0.7m/min g 1.05 i 1.00 •3 0.95 120 140 160 ISO Assisting gas flow rate (I/min) Fig.A-2.24 Results of kerf width as a parameter of assist gas flow rate 1 —•—3.6kW 4 - \ - \ 1 —•— jJkW us \ u / ••A- Pulse 3 - / 2 - •' • A--'"'" 0.2 0.4 0.6 0.8 Cutting speed (m/min) Fig.A-2.25 Results of bevel angle as a parameter of cutting speed 5 l6kW,0.7m/min s- •S 3 £" 2 120 140 160 180 Assisting gas flow rate (1/min) Fig.A-2.26 Results of bevel angle as a parameter of assist gas flow rate -205- JAERI-Tech 99-048 ——3.6kW 0£ SI —*- 3.2kW 2 - CO g l Q « • 0.2 0.4 0.6 0.8 Cutting speed (m/min) Fig.A-2.27 Results of dross quantity as a parameter of cutting speed 3.6kW, 0.7m/min = 5 4 - 3 - 2 - ; a1 CO CO i i s 120 140 160 180 Assisting gas flow rate (1/min) p Fig.A-2.28 Results of dross quantity as a parameter of assist gas flow rate ——3.6kW 5'ta-„x-_.._.. ^fc^__-_-__- '© --— 3.2kW CS 2 - I - C8 CO 0.2 0.4 0.6 0.8 Cutting speed (m/min) Fig.A-2.29 Results of spatter quantity as a parameter of cutting speed -206- JAERI-Tech 99-048 E $.6kW, 0.7m/min "5b 5 4 - Is 3 j, . • 2 - 120 140 160 180 Assisting gas flow rate (1/min) Fig.A-2.30 Results of spatter quantity as a parameter of assist gas flow rate -207- Welding conditions M i croscoDi c observat i on Detail Laser power :3.6 kW a Welding speed:0.3 m/min Assist gas :Nitrogen * "As- ^ Gas flow rate:70 l/min I* • Welding joint:Butt '- ^ •* - *-c-* b -Vi .1 S?; CO r [I ," o _ ;n:" Fig.A-2.31 Microscopic observation by rewelding JAERI-Tech 99-048 Appendix-B Leak Detection Methods and Tests B-l Experimental Data on Leak Detection and Localization 1. Leak detection and leak localization results obtained in tokamak experience. Refer to Fig.B-1.1 andFig.B-1.2 2. Leak detection and leak localization results using a 1st stage leak detection tool developed in this R&D (a directional nozzle wan not extended into branch pipe.) Refer to Fig.B-1.3 to Fig.B-1.13. 3. Conclusions As a results of tokamak experience and the 1st stage experiment, a nude type ionization gauge with a directional nozzle can detect 10~8 Pa*m3/sec He, so that this method is applicable to the leak detection of blanket cooling pipe. It is also expected that the localization ability will be less than 2 mm accuracy. -209- 2) Baking -power supply and control He-standard leak Simulated defect Variable leak valve Quadrupole mass spectrometer He-gas reservoir Unidirectional detector (Sensor) Vacuum vessel B-A Gauge Pirani gauge >en I Turbomolecular pump I—• O Rotary pump Manipulator He-leak detector Sensor control unit Recorder Manipulator control -unit Potentiometer T Fig.B-1.1. Leak detection systematic diagram of the facility = 700 mm/min Vz = 350 mm/min Vi = |75 mm/min 10 7 x 10 7 QU2.6X10' 10 Qk7.0XlD" QI.2.6X10" QU7.0X10" QI-7.0X10- QI.2.6 10'' 3 3 3 PaTn3/soc Ho Pa-m /s6c He Pa-m /sec He Pa-m3/sec He Pa-m /sec He QI=5.2X10"5 (PaTn3/sec He) .A/-5 •7 A 1=18 (mm) IT) ••6 Al=23 b el- X Al=33 -•5 5 Al=53 > Al=93 40 AJ-20 3 • •weo 8 I SCANNING DIRECTION (Z) -50 50 Relation between scanning speed(Vz), distance(Al) Pressure indication and intensity of signal on the sensor moved Z-direction Fig.B-1.2. Leak detection and leak localization results Reference: 9th symposium on engineering problems of fusion research (1981,Chicago) JAERI-Tech 99-048 2500 Orifice with Conductance of Blanket Module Pipes Standard leak (10-7~10-9Pa-m3/sec) Actuator (Linear Motion) View Port \ B-A gauge SS Pipe (Poloidal Manifold) Leak Test Equipment •\ 11 / Center of Leak Point Range of Leak Detection Fig.B-1.3. Leak detection equipment of Blanket cooling pipe -212- Over view of Branch pipe partial model for leak test Over view of Probe head direction device oo I I View of Vacuum pumping manifold side for Branch pipe partial model Over view of SL atached for branch pipe Fig.B-1.4. Appearance of Leak detection test equipment 0 26 Vacuum > I CD CO 5 5o CO SSRod Cable SS Pipe (Poloidal Manifold) Fig.B-1.5. Probe head construction Detection does helium flowing into vacuum exhausted pipe through dummy leak point (or inert gas), and scan along manifold inner wall with attached probe with directional nozzle, and leak localized. Standard leak I Branch pipe to 50A i Fig.B-1.6. Concept of Leak detection test JAERI-Tech 99-048 Manifold •Leak point 2A.2B 'Leak point 4A,4B I Vacuum pumping Orifice with conductance - of Blanket module o Branch pipe CO Leak point 1A.1B , Leak point 3A,3B rvv l\ 80 Probe origin point Detectio I . _. , B oint Pr be and detection stat point end point ! P ° . t Detection end point start point Blanket cooling pipe model Probe head Dummy leak position and Standard leak rate (Pa-m3/s) Measuring position Scan 1A 1B 2A 1A+3A speed (mm/min) 10-7 10-8 10-7 10-7 Origin«=>End point 500 O O Can't detect O 1000 O o - O Fig.B-1.7. Basic performance test results -216- JAERI-Tech 99-048 Dammy leak point:1 A, S.L open: after 1 min. S.L rate: 1.8x10"7Pa«m3/s, Scan speed: 0.5 m/min -3 10' 10 — • CC 1 910 1 Probe O CO - 1...... - Pipe 8 10 CO CO =3 co 710 CO D. CD CD Branch Pipe A center -Q w..... 6 10 O Origin 0(mm) Middle position 340 (mm) .,1...... 1,.,. ,,,, ,1,,,,,,,, ,1 ,,, 10' 5 10 10 20 30 40 50 60 70 Time (sec) S.L open: after 5 min. 10" 10 9 10 CC CC 8 10 •* D Probe CD 710 * CD Pipe! 3 CO 6 10 "* CO oress u CD 5 10 " ob e i Origin 0 (mm) Branch Pipe A center Middle position 340 (mm) l 10' 4 10 10 20 30 40 50 60 70 Time (sec) S.L open: after 10 min. 10 10 J - - 910 CC O CC - 8 10 I — Probe - - 710 Z3 — Pipe | CO I CO CD CO 6 10 CO Branch Pipe A center Q. CD CD - _Q O Origin 0 (mm) Middle position 340 (mm) 5 10 DL 10' .. .I i .I 10 20 30 40 50 60 70 4 10 tA50iO-l>SC Time (sec) Fig.B-1.8. Results chart 1-1 -217- JAERI-Tech 99-048 Oammy leak point:1 A, S.L open: after 1 min. S.L rate: 1.8x10"7Pa«m3/s, Scan speed: 1 m/min 10 10' 910 CO Probe cC Pipe 810 CO ri Branch Pipe A center CO co 7 10 CD co Q. CD CD X! 6 10 O Origin 0 (mm) Middle position 340 (mm) I 10" 510 10 20 30 40 50 1A7SI-1ASC Time (sec) S.L open: after 5 min. 10 10 9 10 '4 (Pa ) CO 4 Probe 8 10 " CD —i CD I — Pipe! 4 7 10- co ess i co Q. 2 6 10 "* a. 'ob e Origin 0 (mm) Branch Pipe A center Middle position 340 (mm) 10 510 10 20 30 40 50 Time (sec) S.L open: after 10 min. 10" 10 • Probe c 9 10 - Pipe| CO - 810 CO CD - 710 ZS CD CO CO CO - 610 CO * 1 i a i i 11 CL CD CD i - 5 10 o Pipe A center Origin Branch Middle position 340 (mm) 0 (mm) CL . . . I I 1 .. . 10" . . ."V 4 10 10 20 30 40 50 1A7510-&ASC Time (sec) Fig.B-1.9. Results chart 1-2 -218- JAERI-Tech 99-048 Dammy leak point: 1B, S.L open: after 1 min. S.L rate: 2.1x10"8Pa«m3/s, Scan speed: 0.5 m/min 10' Probe 910 CO --- Pipe O CC Branch Pipe A center 8 10 CD 13 CD CO 10' CO :5 710 CD co co CD CD 610 .Q O Origin 0 (mm) Middle position 340 (mm) 10' 510 10 20 30 40 50 60 70 1BS01-5.ASC Time (sec) S.L open: after 5 min 10 10" 910 CC Probe cc 810 CD Pipe| 3 CD CO 710 to CD CO CO CD CD Branch Pipe A center "mi_ 610 O Origin 0 (mm) Middle position 340 (mm) L^ til 10 I. I. ... 510 10 20 30 40 50 60 70 Time (sec) S.L open: after 10 min 10" 10 "J - 910 CO - 8 10 CC CD — Pipe - 710 13 CD CO - CO rs - CD CO - 610 CO ii-a-n Mi Q. ——" » m > m> CD T CD Branch A center • 510 Pipe O Origin 0 (mm) Middle position 340 (mm) 5 • t • i 1111 II,.,,, i ,. .1 1 ... 1 10 " ii .1 410 10L... 20 30 40 50 60 70 1B501O-1ASC Time (sec) Fig.B-1.10. Results chart 1-3 -219- Pressure (Pa) Pressure (Pa) Pressure (Pa) : O o 3. '. "S. ; o ; , ,3 : A 3 •n ro - (5" - b 3 o o -o -vj 5" o •o rr g. L o CD •a d i H l to J3 p to (D 3 o CD < CD 1 I «5 L a> CD o O § § o i Q. o CD O 3. •a en f f o I, 3' "8 * 0) u O • a _J. u>it i a P 31 ro ; o o in 5 K en i o L " B 1" 3 ' Prob e Pipe | 3 ; fr 5' 1 1 1 1 1 St. -si CO CO en 00 03 L O o o O O Probe pressure (Pa) Probe pressure (Pa) Probe pressure (Pa) JAERI-Tech 99-048 Dammy leak point:"! A&3A, S.L open: after 1 min. S.L rate: 1.8x10"^Pa«m^/s, Scan speed: 0.5 m/min 10" 10' .. , _,__ _ _ 1 Probe CC 1 - cc - Pipe| - 910 :5 03 03 "~~tm__Lr 03 810 ^ °- Branch Fipe A center CD Branch Pipe B center O Middle position 340. mm) Origin 0 (miTI) Ql r.. . i i .. . i i ,...!.... i.. 4 10" 710" 20 40 60 80 100 120 Time (sec) AA501-5-ASC s.L open: after 5 min. 10" 10 ^- -— • —.. - 910 Probe en CD Pipe| - 8 10 3 Branch Pipe A center Branch Pipe B center 03 Q in en CD 7 10" Q A III /ll vammlhm 1 JQ Ql ~tl Jflr -uLtJu •MB ill I Origin 0 (mm) Middle position 340 (mm) 2 .. i...... I., ....!.. 4 10" 1- i .... 6 10 " 20 40 60 80 100 120 Time (sec) S.L open: after 10 min. 10" 10" 9 10 CO CC Probe 8 10 CD 13 03 -4 03 7/ 11Un Q 03 O3 Branch Pipe A center Branch Pipe B center 10" iii... .! . •. • 11 • •. •.. i 5 10 20 40 60 80 100 120 AAS01O-SASC Time (sec) Fig.B-1.12. Results chart 3-1 -221- Pressure (Pa) Pressure (Pa) Pressure (Pa) ! CD i Ii n 0 (mm ) L •anc h Pi p i Tl r —9 •j, ro cp' - t' r > r m o - J J3 0 ro a j \ •] W 1 • CO '•_ I o o I O 2 3D TJ TJ osi l OO o •o Pi p cn ,5- ^ « 3 D) 3 CD t 5" o r- ut S o 3. CD 1 1 1 ; o —i CO : 1" rs j ro : _§_ • o * TJ Tl • 3 ! m I ro cr \ ro cn o o i. ^- J. i- i Probe pressure (Pa) Probe pressure (Pa) Probe pressure (Pa) ^ (SI) t 311 *5 w ft g ft =L H m • a min, h. d 10" E H * • 9 7 A kg 10" P • 2 s 'J •y 1. L 10' 7 T V. T y n T A y t 10' G 10' M V" t* y K f .+: 1- eV -e 10! • k mol u + Ig tii* ft 2 ± ft y x" 7 cd 10 h 10' -f 7J da •?- ffi ft 7 y T y rad leV=1.60218xl0-'J ft 1* ft X X 7 •y'7 y sr 1 u= 1.66054X 10"" kg io-' T •y d io-2 -fe y x c 10"3 ') m *3 >SHIft¥ft io-' -f f D u (16© SI ¥(4 10- 7" / n m « ft 2 io-' t° Z? P ffl * a '7 Hz s-' ft IS EJ io-" 7 i A 1- f 2 IO-" T a ^ - \-y N m-kg/s y ?' x - o — A A 2 ft /; , l£> /j X * ;l/ Pa N/m - y b •y 3 - IV J N-m /-' - ;u bar (It) £ * , ft W £ 7 y h W J/s *' Gal i-5i± "&. X\ S • ^i 1"J — D y C A-s + IJ - Ci 19 eV aft, MIT:, iiMf] ;u h V W/A y h f y R ufflfflli s& ^ ^ M 7 if IO A M 7 7 K F C/V 7 K rad S x\ ffi K - A n V/A U A rem .. 7 b, T-'i*, 3 y y 9 9 "y x y - > y X s A/V y 10 7 jr. Wb V-s 1 A=0.1 nm-10- m 2 B * S; ft X X 7 T Wb/m 1 b=100fm2 = 10-!'m2 •1 y 9' 9 9 y T- -X y ') - H Wb/A 3. barli. 1 bar^O.l MPa = 10sPa -b >u •> ^ x £ FS ti u y v x ft °C 1 Gal=l cm/s2 = 10-2rn/s2 it £ - y y lm cd-sr 2 ffi ft ;u 9 X lx lm/m 1 Ci=3.7xlO'°Bq 1 R = 2.58xlO-'C/kg r, bamfci 9 \s Bq s"1 ft W Bt 2 Cf »J£ W IS • 9' 'f Gy J/kg 1 rad = lcGy = 10 Gy ! y Sv 1 rem=lcSv=10" Sv m m *j « - "•=•"" J/kg 2 ! N(=10*dyn) kgf Ibf It MPa(=10bar) kgf/cm atm mmHg(Torr) lbf/in (psi) 1 0.101972 0.224809 1 10.1972 9.86923 7.50062 x 103 145.038 9.80665 1 2.20462 0.0980665 1 0.967841 735.559 14.2233 4.44822 0.453592 1 0.101325 1.03323 1 760 14.6959 1 Pa-s(N-s/m2)=10P(.t:rx')(g/(cm-s)) 1.33322 x 10-' 1.35951 x 10- 1.31579 x 103 1 1.93368 x 10- 2 2 lm /s=10'St(x h - ? x)(cm7s) 6.89476 x 1Q-3 7.03070 x 10- 6.80460 x 10- 51.7149 1 X J( = 10'erg) kgf'm kW- h cal«t»£) Btu ft • Ibf eV 1 cal = 4.18605 J(ttitffi) 1 0.101972 2.77778 x 10-' 0.238889 9.47813 x 10-' 0.737562 6.24150 x 10'8 = 4.184J U&it'f-) 1 9.80665 1 2.72407 x 10-' 2.34270 9.29487 x 10-3 7.23301 6.12082x 10" = 4.1855 J (15 X) ft: 3.6x10' 3.67098 x 10 s 1 8.59999 x 10s 3412.13 2.65522 x 10' 2.24694 x 10" = 4.1868 JC 3 4.18605 0.426858 1.16279 x 10' 1 3.96759 x 10" 3.08747 2.61272x 10" 1 PS 2 1055.06 107.586 2.93072x10 •' 252.042 1 778.172 6.58515 x 10 ' = 75 kgf-m/s 3 1.35582 0.138255 3.76616 x 10"' 0.323890 1.28506 x 10" 1 8.46233 x 10" = 735.499 W 1.60218 x 10-" 1.63377 x 10''" 4.45050 x 1Q-" 3.82743 x 10-20 1.51857x10-" 1.18171 x 10-" 1 ft Bq Ci Gy rad C/kg R Sv 2.70270 x 10" 1 100 3876 1 100 3.7 x 10" 1 0.01 1 2.58 x 10- 1 0.01 1 12 f\ 26