Please i would like to know the allowable pressure drop and the test duration of pneumatic test with 10.5 bar test pressure of PE natural gas pipe line
Test duration time depends on the design code and operation requlations in your country. I don't know what they are in the UK.
Allowable pressure drop during a test (not due to leaks), is correlated to the temperature change over the duration of the test. If the pressure drop can be attributed to the change in temperature, it passes.
You're the engineer, you have to specify it. There is guidance out there, but it tends to be quite contradictory from source to source with extensive lists of exceptions. The test designer is obligated to weigh the information available in the codes against company policies and apply liberal quantities of "engineering judgement" (whatever that is) and pick a time.
One company that I did work for specified a 24 hour test with zero pressure drop. They hired me to help them understand why they never had line pass a test. When I questioned their test duration and pressure requirements they pulled out a policy manual that had been prepared in the 1950's with no sources cited. The first step toward sanity was to trash it and write a procedure that was consistent with today's standards and a sense of the goals of a static test.
Allowable pressure drop during a test is an even murkier subject. When I write a test procedure I always include an acceptable minimum ending pressure, and everyone accepts it, but it comes deeply from the anal-extract tables.
we take the pressure drop at the same condition , same temperature ,
i check TD3 edition 4 and transco D5.5
i didn't find test duration for 10.5 bar
please advice
thanks
§ 192.507 Test requirements for pipelines to operate at a hoop stress less than 30 percent of SMYS and at or above 100 p.s.i. (689 kPa) gage.
Except for service lines and plastic pipelines, each segment of a pipeline that is to be operated at a hoop stress less than 30 percent of SMYS and at or above 100 p.s.i. (689 kPa) gage must be tested in accordance with the following:
Here is a typical US standard: (a) The pipeline operator must use a test procedure that will ensure discovery of all potentially hazardous leaks in the segment being tested.
(b) If, during the test, the segment is to be stressed to 20 percent or more of SMYS and natural gas, inert gas, or air is the test medium—
(1) A leak test must be made at a pressure between 100 p.s.i. (689 kPa) gage and the pressure required to produce a hoop stress of 20 percent of SMYS; or
(2) The line must be walked to check for leaks while the hoop stress is held at approximately 20 percent of SMYS.
(c) The pressure must be maintained at or above the test pressure for at least 1 hour.
