ball valve passing

[000012345]

We performed passing test on MOV's on low pressure, we found valves passing, I would like to know if the high pressure above 60barg will seal the seat leakage.
thanks in advance

 

[JLSeagull]

No.

What type valve? Are you thinking that higher seat loading might seal the valve?

Perhaps a new API 6D ball valve with resilient seat is bubble tight at the factory. Once the testing group runs the nasty, rusty hydrostatic fluid that they call water the seat is often scratched and passes.

 

[steamdog]

Some types of ball valves have a 'floating' ball, where the upstream pressure assists the seating tightness so you will get a tighter seat on higher pressures. Others have a fixed ball but with springs in the seat itself. So it does depend on the type of valve you have.

 

[000012345]

Good morning,
I would like to know what is the maintenance boundaries between instrumentation and mechanical for controle valves and metering systems.
thanks in advance

 

[svi]

Does any one know of any case histories for Perar make ball valves. I have a couple of seat passing MOV and ESD valves. The valves are 36" ASME Class 900 Trunnion mounted metal seated with self relieving seats. Current investigations have not revealed any tell tales. The valves are on an off shore platform on a Gas line coming from a gas well. There is difficulty in removing the valve from the line because of the limited capacity of the platform crane.

 

[vpl]

000012345 -- sorry for the late reply, but the maintenance boundaries are usually whatever your maintenance shops work out. Some shops, especially if heavily unionized, may require having both an I&C and a mechanical (and, maybe even an electrical) maintenance person to work the same job. Where one discipline stops and the other begins is often defined in a Union contract. I wouldn't recommend even thinking about trying to change those (it's an exercise in frustration; beating your head against a brick wall will give you better results.) The best you can hope for is getting all the involved craft people to the job at the right time without losing too much time and without anyone sitting around waiting for their part to start.

Svi -- post a new question.

As an aside, I admit to getting a chuckle out of this thread's title, because of the euphemistic useage of "passing" to describe someone who has died. So I read "ball valve passing" as meaning "my ball valve died."

Patricia Lougheed

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