TERASEN PIPELINES (TRANS MOUNTAIN) INC. ENGINEERING STANDARDS AND PRACTICES
MAIN LINE HYDROSTATIC TEST PROCEDURE
MP4121, Revision 2, July 1999
TERASEN PIPELINES (TRANS MOUNTAIN) INC. ENGINEERING STANDARDS AND PRACTICES
MP4121 Revision 2 July 16, 1999 Page 1 of 23 Title: MAIN LINE HYDROSTATIC TEST PROCEDURE
TABLE OF CONTENTS
1.0 SCOPE...... 4 2.0 REFERENCE PUBLICATIONS ...... 4 3.0 DEFINITIONS ...... 4 3.1 Fabricated Assemblies...... 4 3.2 Hydrostatic Testing ...... 4 3.3 km ...... 4 3.4 Main Line Piping ...... 5 3.5 MOP...... 5 3.6 NPS ...... 5 3.7 PN...... 5 3.8 Station Piping ...... 5 3.9 SMYS ...... 5 4.0 TEST REQUIREMENTS ...... 5 4.1 General...... 5 4.1.1 Test Supervision...... 5 4.1.2 Application ...... 6 4.1.3 Safety ...... 6 4.2 Test Medium ...... 6 4.2.1 General ...... 6 4.2.2 Additives ...... 7 4.2.3 Hydrocarbons...... 7 4.2.4 Volatile Liquids ...... 7 4.3 Test Duration...... 7 4.3.1 Buried Piping During Testing...... 7 4.3.2 Piping Exposed During Testing ...... 7 4.3.3 Pre-Testing Main Line Piping ...... 7 4.3.4 Fabricated Assemblies ...... 7 4.4 Test Pressure...... 7 4.4.1 Strength Test Pressure, Piping ...... 7 4.4.2 Strength Test Pressure, Fabricated Assemblies...... 8 4.4.3 Strength Test Pressure, Maximum...... 8 4.4.4 Strength Test Pressure, Minimum...... 8 4.4.5 Leak Test Pressure...... 8 4.5 Test Equipment...... 9 4.5.1 Equipment Required ...... 9 4.5.2 Equipment Calibration ...... 9
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4.5.3 Certification ...... 9 4.5.4 Instrumentation Arrangements ...... 9 4.5.5 Test Head Assemblies...... 9 5.0 TEST PREPARATION...... 12 5.1 Test Plan...... 12 5.1.1 Test Organization ...... 12 5.1.2 Test Medium ...... 12 5.1.3 Test Temperature ...... 12 5.1.4 Test Pressure, New Construction...... 13 5.1.5 Test Pressure, Existing Pipeline Systems...... 13 5.1.6 Drawings ...... 13 5.1.7 Safety ...... 14 5.1.8 Public and Environment...... 14 5.1.9 Notification ...... 14 5.1.10 Failures...... 14 5.2 Cleaning ...... 15 5.2.1 New Construction ...... 15 5.2.2 Retesting Main Line ...... 15 5.3 Pre-Test Logistics...... 15 5.3.1 Insulation...... 15 5.3.2 Shelters...... 15 5.3.3 Temperature Recorders ...... 15 5.3.4 Fill Connections (Injection of Test Medium)...... 16 5.3.5 Pre-Test Organization ...... 16 5.3.6 Valve Integrity ...... 16 6.0 TEST PROCEDURES...... 17 6.1 General...... 17 6.2 Filling ...... 17 6.2.1 Fill Pigging ...... 17 6.2.2 Fill Suction ...... 18 6.3 Temperature Stabilization...... 18 6.4 Pressurization ...... 18 6.4.1 Pressure-Volume Plots...... 18 6.4.2 Pressurizing ...... 19 6.4.3 Leaks...... 19 6.5 Strength Test...... 19 6.5.1 Relief of Test Medium...... 19 6.6 Leak Test ...... 19 6.6.1 Piping Buried During Testing...... 19
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6.6.2 Piping Exposed During Testing ...... 19 6.7 Depressurizing and De-Watering...... 20 6.7.1 Depressurizing...... 20 6.7.2 De-watering...... 20 6.7.3 Freezing Protection...... 20 7.0 ACCEPTANCE CRITERIA ...... 21 7.1 Maximum Test Pressure ...... 21 7.2 Minimum Test Pressure ...... 21 7.3 Reconciliations...... 21 7.4 Leaks...... 21 8.0 RECORDING AND DOCUMENTATION...... 22 8.1 Test Data logging ...... 22 8.2 Hydrostatic Test Record...... 22 8.3 Hydrostatic Test File ...... 23
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1.0 SCOPE This standard covers the mandatory hydrostatic test requirements for main line piping systems. This standard shall be limited to systems transporting liquid hydrocarbons including: crude oil, condensate and liquid petroleum products. This standard shall be further limited to the testing of Low Vapour Pressure (LVP) systems intended for Category I service. The scope of this standard includes all pressure pipe, fittings and fabricated assemblies used in Main Line piping systems. This standard excludes pneumatic testing and hydrostatic testing of valves or station piping systems.
2.0 REFERENCE PUBLICATIONS Some reference publications are supplemented or qualified, or both, by specific requirements in this standard; reference publications should therefore be applied only in the context of this standard. CSA Z662-99 Oil & Gas Pipeline Systems National Energy Board Act SOR/99-294 Onshore Pipeline Regulations, 1999
3.0 DEFINITIONS
3.1 Fabricated Assemblies The term fabricated assemblies, as used in this specification, shall include prefabricated components such as: piping spools; scraper traps; and main line block valves with end extensions and associated by-pass piping. The term excludes such manufactured components as: valves; strainers; and pump casings.
3.2 Hydrostatic Testing Hydrostatic testing is defined as the application of internal pressure above the normal or maximum operating pressure to a segment of piping or pressure containing component. This pressure is applied under no flow conditions (in the case of a pipeline) for a fixed period of time, utilizing a liquid test medium.
3.3 km km, the abbreviation for kilometers, denotes location according to Terasen Pipelines (Trans Mountain) Inc. (TMPL) Profile, drawing number GS1000. The station piping will be referred to by station name.
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3.4 Main Line Piping Main line piping includes those items through which oil industry fluids are conveyed, which includes pipe, components, and any appurtenances attached thereto, up to and including the isolating valves used at pump stations and other facilities.
3.5 MOP MOP means Maximum Operating Pressure expressed in kPa. The MOP shall be the lesser of the design pressure and 80% of the strength test pressure.
3.6 NPS NPS means Nominal Pipe Size, and the NPS system of nominal size designation is contained in standards prepared by the American Society of Mechanical Engineers.
3.7 PN PN means Pressure Nominal and the PN system of nominal pressure class designation is contained in standards prepared by the International Organization for Standardization (ISO). The numerical part of the designation approximates the maximum cold working pressure rating in bars (100 kPa).
3.8 Station Piping Station piping includes all pipe, components and any appurtenances at Pump Stations, Tank Farms and Terminals downstream from the first station isolating valve or sectionalizing valve within the station.
3.9 SMYS SMYS means Specified Minimum Yield Strength. This is the minimum yield strength prescribed by the specification or standard under which the material is purchased.
4.0 TEST REQUIREMENTS
4.1 General
4.1.1 Test Supervision All testing shall be performed under the direct supervision of Trans Mountain or an appointed agent. The agent shall be independent of
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any contractor who carries out the pressure testing and any contractor who constructed the pipeline or any component intended for use in the pipeline. This agent shall date and sign all test records.
4.1.2 Application The following information shall be filed with the National Energy Board, or other regulating authority, prior to hydrostatic testing: a) diagram of test section showing physical parameters of piping and components and test conditions; b) proposed date of test; c) confirmation that all water use and disposal permits are in place.
4.1.3 Safety Piping under hydrostatic test contains considerable stored energy. If the piping ruptures in a ductile manner, it releases this energy rapidly. The resulting jet of water can cause serious injury to personnel in the immediate area. If the piping fails in a brittle manner, which may occur at cooler temperatures, pieces of steel may become projectiles. Therefore, the following safety precautions shall be adhered to during hydrostatic testing. a) Only personnel directly involved in the test shall be allowed in the test area, all other personnel shall remain outside the test area; b) All equipment which must be attended by personnel during the test shall be located behind a protective structure such as an earthen berm or be located a minimum of 15 m away from the test section during the strength test; c) Visual inspection of the test section shall not be conducted while the test pressure exceeds 115% of MOP (Note: visual inspection shall take place during the leak test. These inspections shall be conducted in accordance with subsection 6.6).
4.2 Test Medium
4.2.1 General The preferred test medium is water without additives. All practical steps shall be taken to use water as a test medium before considering other test media. (note: the reconciliation computations included in Appendix A are valid for pure water only)
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4.2.2 Additives All necessary disposal arrangements and/or permits must be in place prior to introduction of glycol or methanol additives to hydrotest water.
4.2.3 Hydrocarbons Use of hydrocarbons such as diesel or kerosene will be considered as a last resort. All necessary environmental precautions must be used and in place prior to start of test.
4.2.4 Volatile Liquids Volatile liquids such as gasoline or crude oil shall not be used as a test medium.
4.3 Test Duration
4.3.1 Buried Piping During Testing Buried piping shall undergo a sequential strength and leak test. The strength test shall be at least four (4) hours in duration, immediately followed by a leak test of at least four (4) hours duration.
4.3.2 Piping Exposed During Testing A leak test is not required for fully exposed piping where a complete visual inspection to detect leaks is conducted. The test duration in this case shall be at least one (1) hour.
4.3.3 Pre-Testing Main Line Piping As in 4.3.2, a leak test is not required for the pre-testing of main line pipe, provided that a visual inspection is conducted to detect leaks. The test duration in this case shall be at least one (1) hour.
4.3.4 Fabricated Assemblies As in 4.3.2, a leak test is not required for the testing of fabricated assemblies provided that a visual inspection is conducted to detect leaks. The test duration in this case shall be at least one (1) hour.
4.4 Test Pressure
4.4.1 Strength Test Pressure, Piping The strength test pressure for buried or exposed piping shall be that pressure at the point of maximum stress which normally produces a
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hoop stress corresponding to 100% of the SMYS of the pipe. The maximum test pressure shall be computed as shown in Appendix A. (Note: retesting of existing pipelines may require a lower test pressure)
4.4.2 Strength Test Pressure, Fabricated Assemblies The minimum strength test pressure for fabricated assemblies, whose MOP is governed by component pressure class, shall be as indicated in Table 4.4.A.
4.4.3 Strength Test Pressure, Maximum Notwithstanding the requirements of 4.4.1 and 4.4.2, the strength test pressure shall not exceed 15,275 kPa (102.5% of PN 100 flange rating).
4.4.4 Strength Test Pressure, Minimum The minimum test pressure for piping shall not be less than 97.5% of the required test pressure.
4.4.5 Leak Test Pressure The leak test pressure shall be at least 110% of the MOP.
Note: The point of maximum stress generally occurs at the point of lowest elevation, but this can vary depending on variations in pipe wall thickness within the test section.
TABLE 4.4.A TEST REQUIREMENTS FOR MAIN LINE PIPING
Test Configuration Test Test Pressure (kPa) Duration (hr)
Buried Strength Test 4 97.5% of PStrength £ P £ 102.5% of PStrength Piping Leak Test 4 110% of MOP £ P < 115% of MOP
Exposed Piping 1 97.5% of PStrength £ P £ 102.5% of PStrength Fabricated PN 50 (300 ANSI) 1 P ³ 6,210 Assemblies PN 100 (600 ANSI) 1 P ³ 12,415
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4.5 Test Equipment
4.5.1 Equipment Required The numbers of recorders, gauges, pumps, and other necessary equipment are a function of the scope of a hydrostatic test. The equipment listed in Table 4.5.1.A is the minimum required for either a main line test or a test of prefabricated piping in a shop or yard.
TABLE 4.5.1.A -- MINIMUM EQUIPMENT REQUIREMENTS Equipment Mainline Shop/Yard Plunger type squeeze pump with or without 1 2 revolution counter as required (pump only) Pressure recorder 4 1 Temperature recorder to record pipe, ground, and per test 2* ambient temperatures schematic Dead weight tester 2 1 Pressure gauge 1 1 Thermometer 1 1 Calibrated liquid measure to ± 10 ml 1 1
* pipe and ambient temperatures only
4.5.2 Equipment Calibration All recorders and gauges shall be calibrated in accordance with EI Procedure VII.A.1, Main Line Testing.
4.5.3 Certification Dead weight testers and calibrated thermometers shall be certified to a government standard every three years.
4.5.4 Instrumentation Arrangements Refer to Figures 4.5.A and 4.5.B for typical instrumentation arrangements.
4.5.5 Test Head Assemblies Test head assemblies shall not be pressurized to a stress exceeding 75% of the SMYS of the test head material. The ancillary piping shall not be pressurized to a stress exceeding 50% of the SMYS of the piping.
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FIGURE 4.5.A -- HYDROSTATIC TEST SET -UP, BURIED PIPING
TEST SECTION
PIPE PIPE PIPE SOIL PIPE PIPE PIPE AMB SOIL PIPE PIPE PIPE TR TR TR TR TR TR TR TR TR TR TR TR
M/L BLOCK M/L BLOCK M/L BLOCK GEL GEL VALVE 10m VALVE PLUG (TYP) PLUG VALVE
PR PR
DWT
DWT
PR NPS 2
PR
SPECTACLE PI BLINDS NPS 4 TEST TRAILER PI
VENT NPS 2
NPS 4
NPS 4 WATER NPS 2 TANK NPS 1 TURB. METER
NPS 2 NPS 2 NPS 2 NPS 2 TURB. METER Y-STRAINER NPS 4 NPS 4 (TYP.2)
HYDROTEST SKID
D S D S LEGEND: SPARE MAIN PUMP PUMP PI PRESSURE INDICATOR (GASO) (GASO)
TR TEMPERATURE RECORDER NOTE: PR PRESSURE RECORDER FLANGED AND THREADED CONNECTIONS ARE NOT IDENTIFIED ON THIS DRAWING ALL CONNECTIONS TO THE HYDROTEST DWT DEAD WEIGHT TESTER SKID ARE PN100 (ANSI Class 600) FLANGED
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FIGURE 4.5.B -- HYDROSTATIC TEST SET -UP, FULLY EXPOSED PIPING
Squeeze Pump
Vent
TEST SECTION
Pipe TR
DWT
TR Ambient
PR
PI
LEGEND: TR Temperature Recorder PR Pressure Recorder PI Pressure Gauge DWT Dead Weight Tester * Locate in shade
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5.0 TEST PREPARATION
5.1 Test Plan Prior to the commencement of main line test, a written test plan shall be developed. The following information shall be included in the test plan:
5.1.1 Test Organization The test plan shall clearly delineate the responsibilities of various personnel involved in the test, especially those who prepare the documentation.
5.1.2 Test Medium The source and volume of the test medium shall be identified in the test plan. The fill volume should be sufficient to fill and pressurize the test section (including allowance for retesting in case of line rupture). In addition to this requirement, the following information should also be included: a) Identification of any permits for use and/or disposal of the test water; (Note: These permits should be obtained well in advance of the test date as they can take in excess of 4 weeks to process) b) Listing of any terms or restrictions on the water use/disposal permit covering water quality requirements, total quantity of water allowed to be taken, the rate of taking and discharge, and discharge location.
5.1.3 Test Temperature The anticipated test temperatures and any freezing precautions (if required) shall be listed in the test plan. These temperatures should include that of the test medium, atmosphere and ground. The test plan should indicate how these values might affect the anticipated temperature stabilization period of the test medium. Because of the problems associated with reconciliation calculations, hydrotests with pure water should be avoided at test temperatures below 5oC (Note: as water starts to drop below 4oC it starts to expand prior to freezing).
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5.1.4 Test Pressure, New Construction The proposed test pressure and governing point of maximum stress shall be identified in the test plan (strength and leak test pressures). The test pressure is the pressure measured at the location of the dead weight tester used to monitor the test. As indicated in 4.4.1, the strength test pressure is that pressure at the point of maximum stress which normally produces a hoop stress corresponding to 100% of the SMYS of the pipe. The test pressure may be below that corresponding to 100% of the SMYS because the location of the point of maximum stress and the point where the test pressure is monitored may not coincide. In determining the test pressure, the following should be reviewed to locate the point of maximum stress: a) Location of the pipe and pipe components in the test segment. Pipe and piping components should be identified by their size, wall thickness, grade and elevation. b) The shell pressure and flange rating and location of all pipeline valves, equipment and other connections to the segment that will be exposed to the test pressure (Note: the maximum pressure differential that a mainline valve is certified for is 10920 kPa).
5.1.5 Test Pressure, Existing Pipeline Systems When testing existing pipeline systems, determination of the maximum strength test pressure must take into account the metallurgical history of the pipe. In particular the following shall be considered: a) prior test history (and potential for pressure reversals); b) pipe type and method of manufacture; c) pipe manufacturer; d) mill test and inspection records; and e) field inspection and test records.
5.1.6 Drawings The test plan should include copies of the test section profile and associated alignment drawings. The profile drawing should indicate the fill and discharge locations, point of maximum stress, and the test pressure monitoring station.
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5.1.7 Safety The test plan shall list the safety precautions and procedures for personnel who perform the test. These safety precautions shall also apply to the fill lines, instrument lines and compression equipment. These precautions should include the appropriate provisions of subsection 4.1.3 of this standard.
5.1.8 Public and Environment The test plan shall list the precautions and procedures to minimize risk to the public and the environment. When retesting sections of the main line, there exists the potential for the loss of contaminated water or hydrocarbons at a main line rupture. To minimize this potential, main line block valves shall be utilized to segregate the test section from the other contents of the main line and limit the resultant static head at the potential leak site. Finally, plans should be made to position spill containment equipment at the appropriate locations.
5.1.9 Notification In addition to the National Energy Board, the following provincial authorities and individuals (as applicable) should be kept informed of any testing of main line piping outside of Terasen Pipelines (Trans Mountain) Inc.'s terminals and pump stations: a) Ministry of Environment; b) Ministry of Highways; c) Fish and Wildlife Branch; d) R.C.M.P. and municipal police forces; e) affected landowners.
5.1.10 Failures The test plan should include all procedures and provisions for dealing with a failure. This procedure should include methods for preserving failed specimens for analysis.
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5.2 Cleaning
5.2.1 New Construction Welding slag, sand and construction debris shall be removed from the test section prior to commencement of the test. New pipelines shall be cleared with a construction cleaning pig. The cleaning pig shall be run during daylight hours and shall be driven by compressed air. If the pig becomes lodged in the line, attempts shall be made to move it by increasing pressure. The pressure shall not normally be increased beyond 150 kPa.
5.2.2 Retesting Main Line When retesting sections of the main line, flush required sectionalizing valves prior to the movement of the test batch into place. Check and tighten bonnet flange bolts, valve flange bolts, and packing of all valves in test section. Remove and plug any bonnet relief valves which may be vented to atmosphere. Check all plugged connections. (Note: the maximum pressure differential that a mainline valve is certified for is 10,920 kPa).
5.3 Pre-Test Logistics After all necessary permits are in place, the appropriate notifications have been made and the line has been cleared of any debris, the final step is installation of test equipment and pre-test organization.
5.3.1 Insulation For new construction, the length of bare pipe shall be minimized prior to the commencement of main line testing operations. Any bare piping should be backfilled, insulated and/or covered and heated such that ambient conditions (eg. wind, rain, sunlight) will not have adverse effects on the test results.
5.3.2 Shelters Adequate facilities to protect test personnel and instruments from inclement weather conditions should be provided. The shelter should include adequate lighting and heating and shall be located in accordance with the requirements of section 4.1.3 of this standard.
5.3.3 Temperature Recorders All test equipment shall be installed prior to filling the line with water. For main line testing, pipe wall temperature recorders shall be installed with the temperature bulb attached to the pipe, insulated
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from the surrounding soil and backfilled. Soil temperature recorders shall be installed to record the ground temperature 15 m from the pipe and at the same depth as the pipe. As indicated on Figure 4.5.A, a typical test section will have five (5) pipe wall temperature recorders (two end point and three intermediate) and two (2) soil temperature recorders (note: ground temperature recorders are not required for the testing of exposed piping).
5.3.4 Fill Connections (Injection of Test Medium) The temporary fill piping shall include a meter and a recording pressure gauge. These shall be installed in the fill line to enable the rate of fill and total volume of water which enters the test section to be determined and recorded. This piping shall also include a filter which will remove all solids exceeding 6.4 mm in diameter. A check valve shall be installed at the point where the fill piping is tied into the pipeline.
5.3.5 Pre-Test Organization The communication system and equipment used to monitor the test section shall be thoroughly checked out prior to test. Adequate numbers of personnel to identify leak locations shall be deployed prior to the start of the test. Any necessary safety barricades and warning signs should be posted on the right-of-way. All affected sectionalizing valves should be closed and check valves should be blocked open.
5.3.6 Valve Integrity Where valve sealing ability of a mainline block valve is in question, consideration should be given to installing a blind flange or using a gel plug to ensure a tight seal.
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6.0 TEST PROCEDURES
6.1 General The test procedure covers six distinct phases. These phases include: filling, temperature stabilization, pressurization, strength test, leak test and depressurization. These phases are illustrated in Figure 6.1.A.
FIGURE 6.1.A -- HYDROSTATIC TEST PHASES
Strength Test Leak Test Pressurization Depressurization Filling Temperature Stabilization
100% 110% of MOP
60% 0f Test Pressure
Nominal Pressure Profile
Daylight Daylight
6.2 Filling
6.2.1 Fill Pigging New lines should be filled with water using a new urethane unidirectional pig ahead of the fill water. When filling with a pig, consideration shall be given to maintaining some back pressure to prevent the pig from running away from the water when the pig is travelling down hill. This can be achieved by controlling the rate at which air leaves the opposite end of the test section. The rate of fill shall not exceed that stated in the water permit. If water is moved into test section through the pipeline, urethane pigs on either side of the water batch are required to separate oil and water.
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6.2.2 Fill Suction If test water is taken from lakes, ponds, or streams, the water intake shall be screened and located to eliminate entrained air. The intake shall be such that the fill water is free of organic or particulate matter.
6.3 Temperature Stabilization After the majority of free air as has been removed using high point vents and/or pigs, the test section shall be pressurized to 60% of the final test pressure and held until the temperature stabilizes (above ground test sections should be sloped so that air will migrate to high points). The temperature stabilization period shall last until the pipe time-temperature plot is sufficiently asymptotic to the ground temperature. Pressures shall be recorded on an hourly basis for buried piping and the stabilization period should last a minimum of twelve (12) hours. Pressurization shall not proceed until the temperature remains stable for at least two (2) hours.
6.4 Pressurization Pressurizing to test pressure and associated pressure-volume plotting shall be conducted during daylight hours. Pressurization shall start early enough to allow sufficient time prior to nightfall to discover a any leaks. All hydrostatic tests shall commence on the hour or the half hour. All personnel should be located in accordance with the requirements of subsection 4.1.3 of this standard until completion of the strength test.
6.4.1 Pressure-Volume Plots If the pressure at any location in the test section will result in a stress greater than 100% of SMYS, a pressure-volume (PV) plot is required. The PV plot must be maintained for the duration of the pressurization phase and points should be plotted at every 50 kPa increment in pressure so that any deviation from the straight-line portion of the plot can be detected. The PV plot shall start at 60% of the final test pressure. (Note: If two or more pumps are used in parallel to pressure up the line to 60% of test pressure, only one pump should be used for pressurization while PV plotting. This is recommended to facilitate recording of volumes pumped as required by the PV plot.)
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6.4.2 Pressurizing On main line tests, upon completion of the temperature stabilization period, the pressure shall be raised at a rate not to exceed 50 kPa per minute (this restriction does not apply to tests that do not require PV Plotting). Pumping shall be conducted in such a manner to prevent surges and vibrations that could damage the pipeline. Pumping shall continue until the pressure-volume plot reaches the 0.2% offset line, or the maximum test pressure is reached.
6.4.3 Leaks Prior to attempting any repairs to leaks, the pressure shall be reduced to the lower of 80% of the maximum pressure achieved at the location of the leak, or a pressure that produces a hoop stress equivalent to 60% of SMYS at the point of maximum stress.
6.5 Strength Test Upon reaching the specified test pressure, the test section shall be isolated. This may include disconnecting of the pump. After transient pressure conditions in the test section have dissipated, the four (4) hour strength test shall begin. (Note: Positive isolation using plugs, blind flanges or a double block and bleed isolating arrangement is recommended to confirm no leakage occurs through fill pipe fittings.)
6.5.1 Relief of Test Medium Test medium shall be withdrawn prior to the pressure exceeding 102.5% of the strength test pressure. If relief of the test medium is required, this volume may be re-injected later should the pressure decrease. All interim withdrawals shall be logged and reconciled.
6.6 Leak Test
6.6.1 Piping Buried During Testing Upon successful completion of the strength test, the pressure shall be bled down to a maximum of 115% of the MOP. After transient pressure conditions in the pipe have dissipated, the leak test shall start. The pressure shall not fall below 110% of the MOP for the balance of the test.
6.6.2 Piping Exposed During Testing Where the test section consists entirely of exposed piping, the leak test is not required, provided that a complete visual inspection has confirmed the absence of leaks. This inspection shall be completed
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immediately after the strength test at the pressures specified in 6.6.1 above. No visual inspection shall be conducted while the test pressure exceeds 115% of MOP.
6.7 Depressurizing and De-Watering
6.7.1 Depressurizing After successful completion of the strength test (and leak test if required) the pressure shall be bled down only to the hydrostatic head at the bleed off point. The rate of depressurization shall not exceed 150 kPa per minute. The bleed off point should be the highest of the two ends in the test section to bleed excess pressure while preventing air from entering the pipeline. Depressurizing should be carried out slowly to prevent hydraulic surges and avoid excessive pipe vibration. All test media must be disposed of in the manner specified in permits.
6.7.2 De-watering If water is moved into the test section through the pipeline, the test water shall be retained for disposal at the appropriate location. For new construction in excess of 300 m, de-watering shall be carried out by propelling with compressed air, two (2) spheres or a bi-directional pig (normally in the reverse travel to that used during filling). The air pressure should be reduced, as the run nears completion, to minimize stored energy in the system. De-watering lines shall be of sufficient strength and be securely supported and tied down at the discharge end to prevent whipping during this operation. The area at the outlet for disposal of test water should be protected from erosion or scouring by means of an energy absorbing diffuser or armouring of the outlet area.
6.7.3 Freezing Protection Dead legs, low points, and drain connections shall be emptied of water or alternately displaced of water by methanol if freezing temperatures may occur prior to placing the test section in service.
TERASEN PIPELINES (TRANS MOUNTAIN) INC. ENGINEERING STANDARDS AND PRACTICES
MP4121 Revision 2 July 16, 1999 Page 21 of 23 Title: MAIN LINE HYDROSTATIC TEST PROCEDURE
7.0 ACCEPTANCE CRITERIA The hydrostatic test will be considered acceptable if the conditions listed in subsections 7.1 through 7.4 are maintained during the test period.
7.1 Maximum Test Pressure The hydrostatic pressure in the test section does not exceed 102.5% of the strength test pressure (note: to minimize the potential for pressure reversals, the pressure should be kept to a maximum of 115% of MOP during the leak test).
7.2 Minimum Test Pressure The hydrostatic pressure in the test section does not fall below: a) 97.5% of the strength test pressure during the strength test; and b) 110% of MOP during the leak test.
7.3 Reconciliations The following circumstances shall be reconciled with the test data within the accuracy limits of the instrumentation. a) the recorded pressure losses with the recorded temperature changes; b) the additions and withdrawals of test medium that are required to maintain the test pressure.
7.4 Leaks Leaks which appear during the test shall be cause for the test to be restarted after repair of the leakage source (see subsection 6.4.2).
Note: A copy of the reconciliation computations are required for leave to open applications.
TERASEN PIPELINES (TRANS MOUNTAIN) INC. ENGINEERING STANDARDS AND PRACTICES
MP4121 Revision 2 July 16, 1999 Page 22 of 23 Title: MAIN LINE HYDROSTATIC TEST PROCEDURE
8.0 RECORDING AND DOCUMENTATION
8.1 Test Data logging The following data shall be recorded every fifteen (15) minutes during the first hour of the strength test, and every thirty (30) minutes there after for the balance of the strength and leak tests (remote data can be recorded hourly). a) time that the reading is taken; b) the ambient temperature indicated by the recorder; c) the ambient temperature indicated by a mercury thermometer; d) the pipe temperatures indicated by the two recorders; e) the soil temperatures indicated by the two recorders; f) the test pressure indicated by the deadweight tester; g) the test pressure indicated by the recorder; h) any remarks, such as weather conditions, phase of testing and volume additions and withdrawals.
8.2 Hydrostatic Test Record In addition to the test data log, all main line hydrostatic tests shall be documented with a Test Record certificate. This test record shall include: a) the time and date of the test; b) pipe standards or specification for the section tested; c) location of the test section and test points; d) the test medium used; e) the test duration; f) record of the test equipment used; g) location and cause of leaks or failures and the description of the repair action taken.
TERASEN PIPELINES (TRANS MOUNTAIN) INC. ENGINEERING STANDARDS AND PRACTICES
MP4121 Revision 2 July 16, 1999 Page 23 of 23 Title: MAIN LINE HYDROSTATIC TEST PROCEDURE
8.3 Hydrostatic Test File The following information shall be compiled and filed with engineering: a) the test data logs; b) the hydrostatic test record; c) the elevation profile; d) the pressure and temperature recording logs; and e) the pressure-volume plot (if required).
HYDROSTATIC TEST PRESSURE-UP Page: DATA SHEET
Test Section:
Test Trailer Location:
Pump #1: Unit #: Maximum Pressure Increase Rate: 50 kPa/min.
Pump #2: Unit #:
Meter #1: Unit #: Range: K Factor:
Meter #2: Unit #: Range: K Factor: Dead Weight Tester: Serial #:
(Optional) (Optional) AVERAGE AVERAGE READING INTERVAL TIME PRESSURE * TOTAL PUMP TOTAL VOLUME STROKE RATE VOLUME RATE REMARKS NUMBER (sec.) (kPa) STROKES (I) (str./min.) (l/min.) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 * Note: See Master Sheet for Test Equipment Information
Recorded By: Signature: Date: Terasen Supervisor/Technician (Print Name)
Recorded By: Signature: Date: Terasen Supervisor/Technician (Print Name)