High Pressure Clossure Test

[FIF99]

Hi,

We are facing large seat leakage over metal seated dual plate check valves during commissioning.
Valves are new and certificates show acceptable high pressure seat test hydrostatic (1,1*pd) and low pressure seat test pneumatic at 6 barg.
Valves will be installed in gas application.

At the moment I'm looking for detailed info regarding choices in selecting the test fluid, either hydrostatic or pneumatic at 1.1*pd as per API 598.

Anyone having detailed experience in assessment of pressure testing methods?

Thanks in advance.
Regards FKE

 

[gerhardl]

Is it possible to demount one or several valves to inspect visually for seat damage, particles and dirt and then test?

Best test is of course always with the valve out of pipeline and testing with blind flanges.

If this is not possible I imagine you would have to give more spesific details to get further advice.

 

[NGiLuzzu]

FKE,
may I ask how you notice the valves seat leakage?

Can you estimate the amount of leakage a little more quantitatively?

Maybe a "large leakage" is a subjective concept, also depending on the type of valve and the plan requirements... (...usually check valves are not intended to provide seat tightness as their primary function, are they?)

What is, more or less, the maximum seat leak rate your process can tolerate?


Hope this helps, 'NGL

 

[FIF99]

Hi,
Thanks for your responses.

We asked already for more details and circumstances at which the tests were performed.

At this moment I do have a lot of interest in detailed technical reports of researches done in pre-scribing the selection of the test fluids.

When you specify hydrostatic high pressure closure test or when to specify pneumatic high pressure closure test?

Can anybody help me by advising references?

Thanks in advance.

 

[monofm4m]

Dear FKE,


I read your thread and have a question, what is your preferred answer?

Any acceptable test fluid which will give you more better test result?, otherwise you are just making a question for test fluid as per API Specification 598?

I'm sorry to send a question to question, but I can not define either of above or else you're looking for.


Best regards,

 

[NGiLuzzu]

FKE,
as a general reference, I'd suggest to read EN 1779 standard about Non-destructive testing - Leak testing - Criteria for method and technique selection, and in particular paragraph 7.3.3 Nature of gas.


See also thread408-150132 within this Forum.


Hope this helps, 'NGL