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Time's Advanced Tank Welding in Major Middle East Project

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Time's Advanced Tank Welding in Major Middle East Project TECHNICAL WELDING ALL TIME’S ADVANCED TANK WELDING IN MAJOR MIDDLE EAST PROJECT All Time’s automatic vertical tank welder provided more productive and efficient welding for a large tank project HONG KONG company All mean the vertical joints of the top three Time, which has a production 01 courses out of the total nine courses with facility in Shanghai, China, has 20 thicknesses ranged from 10–12.4mm years of experience in manufacturing would need to be welded by the less specialist tank welding equipment. Its productive processes unless more expertise was recently called upon by advanced welding procedures can a major Middle Eastern engineering be implemented. company, which had been awarded The EPC company evaluated a recently the engineering, procurement and developed technique, based on the construction (EPC) contract to deliver a narrow gap EGW joint design with lower network of 95 crude oil storage tanks for weld volume and smaller CO2 shielded a leading oil company. wire, that is easier to operate, with less Each of the tanks is 110 m in diameter slag and heat input. This is proven to and 22 m in height, and has a storage improve the ease of operation for EGW capacity of 200,000 m3. With only a year process on thinner shell thickness as little to complete this project, welding is a as 9 mm, with the additional benefits of fundamental facet of the construction due improved weld metal properties. This to the sheer size and number of the tanks. advanced EGW process can be referred as the narrow gap electrogas welding The storage tanks for the project are process (NG EGW), which also comes designed to be fabricated in nine courses with the options for self-shielded wire with a shell thickness of 42.3 mm, (NG EGW-SS) for better fusion and gas 41.3 mm, 30.1 mm, 26.4 mm, 21.3 mm, shielded wire (NG EGW-GS) for lower heat 20.9 mm, 12.4 mm, 11.1 mm, and 10 mm input and ease of operation. from the bottom to the top, as internal pressure from the tank contents is combination of the flux and shielding gas After a series of trials and evaluations, progressively reduced upward, and so (EGW-GS). the EPC company concluded the most the weight of the shell. Each section The joints welded with this process are effective solution is to adopt the NG EGW is 2.4 m high, it was decided that fully traditionally square edge butt welds. process with 2.4 mm self-shielded wire for automatic welding equipment should be Plates should be fitted up so the copper the first six courses of the tanks with shell implemented for all joints of the shells shoes can prevent slag spillage between thicknesses up to 42.3 mm, then switch from the outset. the plate and the shoes. to NG EGW-GS with 1.6 mm CO2 shielded wire for the last three courses with shell It is important to note that while the thickness as little as 10 mm. process of building tanks with an automated welding process is not new, AUTOMATION AND INNOVATION Once the implementation for a advancements in the implementation has Compared to the use of a conventional combination of narrow joint, self- resulted in increased productivity and flux-cored arc welding (FCAW) process, shielded, and gas-shielded wires was quality to be discussed in the following which takes more than five hours and decided, the focus of the project was sections. requires multiple weld passes, EGW shifted to the equipment that offers the permits the welding of all vertical joints required capability. in one pass up to a shell thickness of TANK VERTICAL JOINT WELDING 32 mm, taking only 1.2 hours to weld AUTOMATIC VERTICAL The electrogas welding process (EGW) a 2.4 m vertical joint. This represents WELDER FOR EGW is often used for welding vertical joints an improvement in productivity of over of high capacity flat-bottom storage 400%. However, the high productivity The demand for multiple EGW processes tanks for maximum productivity. It is process is traditionally limited for shell was long considered by All Time based similar to continuous casting as the weld thickness over 12.7 mm due to the on their experience in the design and is produced between two water-cooled difficulty to control and monitor the weld manufacturing of vertical welders for copper shoes, which progresses up the puddle with heavy slag at high travel international contractors with different joint with the molten weld pool to hold it speed. In addition, there is a concern backgrounds and requirements. As a in place until it has solidified. Oxidation for weld metal properties and distortion result, via its manufacturing programme of the weld pool is prevented by the caused by the extra heat input due to for continuous improvements, All Time flux of self-shielded wire (EGW-SS) or a the large weld volume. These limitations developed the latest version of its vertical PAGE 2 TECHNICAL WELDING EGW GS processes, where welders are 02 required to possess tailored knowledge and understanding of the advanced welding process and parameters. The EPC company and Automatic Welding Consultant (AWC), the local service agent of All Time, responded by introducing training onsite. AWC employs six engineers and technicians and dispatched them in three teams of two to support the training. CONCLUSION All parties who participated in the shell erection welding of the Strategy Tanks Project recognise the importance of investing in innovation, development and training. With this recognition in mind, we are thus enabling more productive and efficient methods of welding and construction in hopes to deliver an end tank welder, with multi-process capability, OSCILLATION result with a higher value. and a quick switch over function from For conventional EGW, the electrode is one process to another, e.g. between held in a fixed position in the centre of the EGW-SS and EGW-GS, for welding storage For more information: joint without oscillation. Such a technique tanks in different sizes and operational requires a large diameter wire (e.g. 3 mm) This article was written by All Time environments. and a wider joint with high weld volume Mechanical & Electrical Equipment The All Time EGW Vertical Welder is made to achieve sufficient fusion with adequate Co. Ltd. To learn more, email info@ up of five key components: build-up on both sides of the joint. alltimewelding.com Conversely, the narrow gap EGW process All Time Mechanical & Electrical 1. Weatherproof work platform with uses smaller wires and an oscillation Equipment Co. Ltd. To learn more, email motorised lateral travel between joints system to achieve full joint fusion. [email protected] 2. Motorised vertical welding carriage When the shell thickness exceeds www.alltimewelding.com with electric magnetic rail for quick 20 mm, oscillation is required to alignment and weld travel ensure sidewall fusion. The equipment 3. Variable speed operator lifts for safety has a mechanical oscillator built for and operator monitoring this purpose. Control of oscillation 4. Close loop arc current control (ACC) to amplitude, speed, and dwell times need 01 Electrogas welding of the storage tank with automatic vertical welder maintain a fixed wire extension relative to be preset before welding commences. to the weld puddle 02 Vertical welder interior with Optimum oscillation is a key factor to Figureelectrogas 4. Calibration welding module carriage, to supportarc current multiple EGW process variants. 5. Standard constant voltage (CV) improve weld metal properties in high heat Sincecontrol,Figure the 4 .andstart Calibration operatorof the project,module lift toa supporttotal of multiple31 sets EGWof All processTime vertical variants. welders had been set up on three different tank sites. welding power supply and automatic input EGW welds. Oscillation amplitudes 03 DoubleSince the V jointstart of on the shell project, thickness a total of 31 sets of All Time vertical welders had been set up on three different tank sites. wire feeder and position, in conjunction with the over 30mm groove profile of the copper shoes, are There are two key features of the All 04JOINT Single DETAILS V joint for shell thickness proven to have a significant impact on the underJOINT 30mm DETAILS Time vertical welder, the first is its fully The variation in joint volume has a critical impact on the EGW process in terms of operation, productivity and front and backside of the weld profiles. The variation in joint volume has a critical impact on the EGW process in terms of operation, productivity and enclosed work platform design that weld metal properties. After trials, two types of narrow gap joints for NG EGW-SS and NG EGW-GS processesweld metal have properties been .adopted After trial, sthe, two double types Vof jointnarrow (Figure gap joints 5), and for NGthe EGWsingle-SS V andjoint NG (Figure EGW -6).GS creates an indoor welding environment The oscillation speed or frequency also has processes have been adopted, the double V joint (Figure 5), and the single V joint (Figure 6). that makes gas shielded welding a significant influence on the weld metal feasible for site erection. The second is grant structure due to the stirring effect. 03 the continuous close-loop ACC with a calibration module, which can switch the EGW CONSUMABLES arc current to travel speed in relation to EGW-SS on thick plates and to EGW-GS Consumables for EGW-SS and EGW-GS for thinner plates by a dip switch. are commonly classified as AGW EG72T-1 or EG70T-2 under American Welding Since the start of the project, a total of 31 Society standard AWS 5.26.
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