Leak test at high pressure
Leak test at high pressure
(OP)
We are going to carry out leak test for slug catcher in gas seperation plant. However pressure requirement for leak test is max. operation preassure. Slug catcher is designed to operate at 80 barg to max.120 barg.
In addition media for leak test is designated with nitrogen. I think that this requirement is unreasonable to carry-out.
If anyony has an experience such kind of leak test, pls give advice or alternate methods.
thanks,
In addition media for leak test is designated with nitrogen. I think that this requirement is unreasonable to carry-out.
If anyony has an experience such kind of leak test, pls give advice or alternate methods.
thanks,





RE: Leak test at high pressure
If it is valves then look at the requirements for the seat leakage test in API 6D. For valve seats, a low pressure leak test may be more severe especially using nitrogen.
I agree that testing at 120 bar is more a strength test than a leak test.
RE: Leak test at high pressure
RE: Leak test at high pressure
RE: Leak test at high pressure
Or any alternative you have?
RE: Leak test at high pressure
RE: Leak test at high pressure
RE: Leak test at high pressure
It is not unusual to perform a leak test after performing the hydrostatic test and just before the piping is placed into service. The purpose of the hydro test is to prove the structural integrity of the pipe. The purpose of the leak test is to prove the tightness of the piping assembly including valves and other components. Since the MAOP is 120 bar, this is a possible operating pressure and should be leak tested at that pressure. Nitrogen is a good choice for the leak test since you can achieve your test pressure with bottled N2 and there would be no need for an inert purge after the leak test. I suggest that the pressure be brought up in stages (say 10%, 20%, 30% …. of MAOP) and leak test every joint with soap water at each stage. Assuming that the product is a combustible gas, it would be a good idea to check all joints with a combustible gas indicator after the pipe is put into service.
RE: Leak test at high pressure
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RE: Leak test at high pressure
RE: Leak test at high pressure
RE: Leak test at high pressure
I would like to add more explanation on this subject.
System volume of slug ccatcher is about 4000 m3 and nitrogen source is limited. Hence I am looking for alternate method instead of high pressure leak test at 120 bars.
Now I am considering that just after finishing the hydrotest, deprassurize teat pressure and pressurize with nitrogen from nitrogen bullet,150 bars, with water which was filled for hydrotest.
If anyone has another idea or comments,pls
RE: Leak test at high pressure
1. this type of leak-tests is surely not the first ones being carried out. So there must exist somewhere within your company, or TOTAL where they describe how to Leak Test.
2. why not using Air? If N2 is mandatory, then make sure you have got enough available.
RE: Leak test at high pressure
Please be careful
RE: Leak test at high pressure
The volume was not 4000m3 like yours, but we managed to use air mixed with a certain amount of nitrogen to increase the pressure. The client requirement was pure nitrogen, but we talked him into submission.
The pressure was brought up to 60 bar with nitrogen, then use of a rental professional compressor (caterpillar) to increase up to 160 bar using air. At the end of the leak test, purged the system again with nitrogen to get the air out of the installation.
BEFORE starting to put up N2/air pressure on your system, do follow those sequencing steps :
. torque all flanges etc to their required couple.
. then tape all to be tested flanges etc on their circumference, so that the space in between two bolted flanges is covered by the flexible tape.
. then (using a fine needle) make a hole in each tape put in between the two flanges.
. mark the needle hole with a red marker to find it rapidly back during your inspection round.
. then increase your slug catcher internal pressure in steps, to 1 - 6 - 15 - 30 - 60 - 100 - 160 bar.
. in between each pressure increase, spray specialised leak testing fluids on all marked needle holes made on the tape, so that you can detect eventual leaks very rapidly. A bubble will form rapidly on the needle hole if there is a leak.
. if you discover a leak, torque check again, and if torque OK and still a leak, then change the gasket or use a better sealing arrangement, since your mechanical design is then proved NOT good.
good luck.
RE: Leak test at high pressure