Safety Valves

Added: 17:52 15.10.2008

Is it acceptable to install an isolation valve between a pressure vessel and the Safety/Relief valve? Safe Working Pressure of the Air Receiver is 150psi.

terry-scott.thomson | Post a reply | Report this question as unsuitable

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Re: Safety Valves

Terry.

I is not illegal to install an isolation valve between a pressure vessel and the safety / relief valve.

Is it acceptable? That depends on the controls that you have in place.

Certainly an isolation valve that could be operated by anyone would be unacceptable. Removing the handle wouldn't be acceptable either, as it is more than forseeable that A.N. Other would find another handle.

The only time I have installed such a valve was with a chain and a lock, that kept it permanently open, and the lock and chain could only be removed under a Permit to Work. Plus of course all the normal signs and warnings etc.

This is about the best you can do. The Engineering Surveyor might comment, but you will need to demonstrate that you have adequate control. Breaking of a lock or a chain without a Permit to Work would be a deliberate violation.

It still introduces a degree of failure over and above if the isolating valve was absent.

Hope this helps.

Regards