MANUAL VALVE PRESSURE TEST

[VanniDiCarlo]

HI ALL
I HAVE A QUESTION REGARDING THE PRESSURE TEST OF MANUAL VALVE, OUR CLIENT REQUEST BY CONTRACT TO PRESSURE TEST THE MANUAL VALVE AT SITE, EVEN IF THE VENDOR ALREADY TESTED. I REMEMBER THAT IN ASME CODE IS WRITTEN THE IS NOT ALLOWED TO PRESSURE TEST THE MATERIAL MORE THE TWICE TO AVOID THE OVER-STRESS OF THE SAME. ANYONE REMEMBER ABOUT THIS OR KNOWS SOMETHING TO AVOID TO TEST THE VALVES ONE MORE TIME AT SITE?
THANK YOU

 

[racookpe1978]

1. Please do not "shout" - Use proper capitalization.
2. What country, what code, what service and what operating pressure?
3. What type of valve, what type of pressure test, and what is the purpose of the pressure test?

A "manual valve" requires operational (leak check) tests at the normal operating pressure, and hydrostatic pressure tests. Often, the system operational testing/startup testing also checks manual and automatic valves after installation for leaks at the flange/weld, and leaks across the seat. The manual valve does not (usually) require an operational (movement) test, unlike an automatic or remote-actuated valve. But most good operators manually cycle every valve as well - you never know what happened during construction and storage and layup.

 

[LittleInch]

I agree with racoopes post.

"ASME" is an organization, not a code. They issue many hundreds of codes.

A test should not be at a level where is damages the equipment being tested or results in permanent strain / deformation.

There, in theory, the item can be tested as many times as you like.

For valves the issue is normally that the seals (in stem seals) are not rated for the test pressure and therefore, if tested a lot, you could damage some of those seals.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rconner]

I suspect what you are referring to is a difference between a test against a closed valve as a test boundary (i.e. also referred to as a "seat" test) or in effect testing through a fully or partially open valve to another test bulkhead (the latter referred in some cases as a case or "shell" test). For at least some valve designs the former is limited to the pressure rating of the valve seat e.g. say 250 psi for a 250 psi rated isolation valve, whereas a through or "shell" test might allow for higher pressure testing i.e. all the way through the valve , e.g. up to twice that value or 500 psi, as long as a closed valve (e.g. gate or disc etc) is not used as the bulkhead. The specific valve manufacturer should proably be consulted. [and of course other items, e.g. the pipeline joints or flanges or other specials, or the gaskets used in same etc might also limit the testing pressure to lower values.

 

[KevinNZ]

You will have to look up the code the valve is made to. e.g B16.34. Valves do get tested more than once e.g after overhauling.

I can see why the client wants to test valves on site. I have seen factory test certs for seat tests and the valves turned up on site with no seats installed!

 

[MickMc]

It is not unusual to field test manual valves as it is not uncommon for valves to be either damaged in transit or similar and is only noticed during testing/commissioning after installation. Many operators stipulate in their standards either a percentage or maybe by criticality/service/pressure rating or other criteria. In new projects it is not practical to field test all valves stipulated in standards and usually client and contractor come to agreement that satisfies clients requirements.