safety valve's gag

[morojlu]

Dear friends,

It is kindly requested to inform me some information related to application of gag in safety valves.
More over I'd like to know that the reason of gag opening due to Hydrostatic test.

Sincerely yours

 

[JimCasey]

The gag is to prevent the valve from lifting during hydro test. In a hydro, you are intentionally overpressurizing the system. The valve is there to PREVENT that. So you gag the valve down (finger-tight) so you can build the pressure well past the valve's setpoint.

 

[MarcelValve]

Hi people,

May I take the opportunity to point out that these test gags should be REMOVED and safely stored during normal operation????

I consider test gags as very dangerous, they should be red labelled and checked upon during start up procedure.

Be aware I have seen them mounted in a full operating plant, scares the hell out of me as people are not aware of their danger! The valve will not open at set pressure with a test gag mounted.

Some manufacturers of safety valves mount them standard as transport protection with the disc screwed down to the seat firmly.....

Get out there, see for yourself if you are safe!

Marcel