Relief valve headers...incidents..

[jamesbanda]

Dear all,

In my company we have varied views on the approprate isolation required for relief valves.

Some sites require specticle blinds on the discharge of all valves in common header systems - its a site standard.

Other sites have banned these and insist that they prefer the spool system stating that the spec blind can be left in.

(sites are in different countries..!)...so has anyone witnessed or seen a safety incident that has occored while maintaining a valve with another going off?
(we are trying to get some consistancy and aggrement for new projects..)

 

[MortenA]

In practise anything can go wrong c.f. the Piper Alpha disaster:

http://en.wikipedia.org/wiki/Piper_Alpha

Best regards

Morten

 

[dcasto]

At one place I worked, they had block valves on the outlet of the PSV's that were locked in the proper place. The flare header could have some toxics so the valve in place with purge points to clear the PSV outlet to header. Another just said, if a PSV needs worked on, then the whole plant must be shutdown so that the header would not be a concern.

Even with blinds and spools, you still expose workers to an incident for the short time period of exchanging positions.

So, its all a risk management thing. A piper alpha to a small leak of a hydrocarbon during a switching of blind possition.