WORK METHODOLOGY – Mechanical Works Doc No: MS-0401059-H0-030-005
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SCOPE: This section applies to the Hydrostatic Testing of New Fabricated and installed SS pipe lines associated with the Rich Amine Piping Replacement project Unit 30/31, Habshan-0. REFERENCE DOCUMENT Reference document for the preparation of this method statement is DGS_1300-030_REV_1 PROCESS AND UTILITY FIELD - SHOP PRESSURE TESTING
GENERAL
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After completion of all welding, radiography and NDT requirements/ activities the pipe shall be hydro tested
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The supervisor shall obtain relevant permits to carry out Hydrostatic pressure test for the approved pipe line
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The pressure test constitutes the final examination of completed pipe work for its soundness and quality.
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SAFETY GUIDELINES / PRECAUTIONS:
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Activity Risk Assessment shall be carried out to ensure that the risk are brought to Alarp Level
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Tool box talk shall be conducted and documented
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The area must be roped- off at 10m radius around equipment being tested
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Warning signs must be placed at access routes
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The piping are spaded using rated spades/blind flanges as close as possible to the portion of piping to be tested.
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TEST PROCEDURE
Blank-off the ends of the test section with blind flange equipped with -
An outlet and stopcock at the top of the higher end to vent the air.
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An inlet and stopcock at the lower end situated in the middle or at the bottom for the pump and filling connection.
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Valves included in a pressure test shall be open 90%. Valves shall not be included in a pressure test fully open or fully close
To arrest the possibility of sideward displacement at the end of the test section due to pressure lateral anchorages may be provided
WORK METHODOLOGY – Mechanical Works Doc No: MS-0401059-H0-030-005
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To facilitate the air removal, water shall be introduced at the lowest point in the loop where the test pump shall be positioned . Vent the loop properly to be free from any entrapped air.
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De-mineralized water (DMW) shall be used for the hydro testing of the pipe lines. Chloride levels shall be within the acceptable limit
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The gauge shall be tagged with the date last calibrated. Gauges with outdated Calibration tags shall be recalibrated before use. Calibration intervals for the gauges will be 6months in line with the DGS requirement.
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Calibrated pressure gauges shall be located at the ends of the test section. Two gauges shall be installed as follows. -
One at the pump location
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One gauge shall be located at the highest point in the loop.
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The test pressure gauge shall include a chart pressure recorder to monitor the pressure continuously.
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Wait until all the air has been purged before raising the pressure
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The line shall be tested at required pressure as per line list.
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Pressure to be raised in steps of 5 bar maximum and hold for 10 minutes before proceeding to the next step
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The test pressure shall be as per requirement and the test shall be for 30 minutes minimum.
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The Pressure must be raised slowly to allow inspection of the weld joints. The pressure must not only reveal any possible defects in the weld joints but must provide a definite check on the main line for any cases of damage incurred during transport or laying.
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Keep the line under the test pressure for 30minutes and observe the pressure gauge for any drop in the pressure.
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Survey the line visually for any deformation
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Any drop in pressure during the hydro test not directly related to temperature fluctuations (as approved by GASCO inspection engineer) shall require a full re test.
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Upon successful completion of the hydro test, start dropping the pressure gradually and drain the water in the storm drain by using proper hoses.
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Obtain clearance from inspection and proceed with the painting of the weld joints as per GASCO specification.
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If any partial replacement in existing line the entire spoos shall be hydro tested (Flange to flange).
