Is Backseat test required for new valve?

[corntozes]

Hi

According to ASME B16.34, only two type of tests specified, i.e. shell test and closure/seat test. But API STD 598 has one additional testing which is "backseat test". If the valve the we are receiving without the backseat test, is it acceptable? Which code should govern, ASME B16.34 or API 598 requirement?

I have personally never seen any backseat test being performed, what is their purpose and is it critical to ensure integrity of valve?

tq

 

[valvit]

API 598 and API 6D both state that if a valve is equipped with a backseat, it must be tested. ASME B16.34 does not address the topic.

Backseat test is a test on the valve stem...and has nothing to do with the seat test.

If you ordered the valve to be tested in accordance with API 598, and it has a backseat, and it arrives with no backseat test having been performed, then no, that is not acceptable.

If the valve does not have a backseat function, then yes, the valve is acceptable.

The purpose of the backseat (located at the bottom of the stem) is to provide isolation from the process media in the event of a packing leak, or for packing maintenance, adjustment or replacement.

API 600 has some guidance on backseat design and requirements.

 

[Roberto1956]

You need to have in mind all necessary tests to assure you no fail during the life of the valve.
Backseat, internal relief pressure device, fire test, torque to close and torque to open, NDT and so on.
Some of them are on type approval test, others are default and others you have to ask.