ESD valve closing time 1

[MortenA]

I have often used a closing time of max. 20 seconds for ESD valves. Are there anyone here who knows a reference for this value (closing time for an ESDV?)

Best regard¨s

Morten

 

[JLSeagull]

In the US offshore industry the requirement is to close within 45 seconds including the system response time (consider in case of pneumatics). This is a rule applied by the Department of Interior Minerals Management Service is covered by API RP 14C Recommended Practice for
Analysis, Design, Installation, and Testing of Basic Surface Safety Systems for Offshore Production Platforms, Appendix C - Support Systems C.2.1.4. "The time it takes for any safety device (e.g. PSH, BSL, ESD station, etc.) to effect component or platform shutdown should not exceed 45 seconds."

 

[MortenA]

Brilliant JLSeagull

Thank you

Morten

 

[Ashereng]

I would have thought that the closing time varied, by size, application, etc.

I have seen a huge volume bottle to close a valve (I think 6", maybe 4") in little over 5 seconds.

I have seen others where 45 seconds probably is more than enough.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[JLSeagull]

Actual times are far different than the API requirements. Shutdown valves three-inch and smaller close quickly.

My casual observation is that the closing time for ball valves requires about one second per inch. As you approach the 24-inch size you should be using quick exhaust devices to meet the 45-second rule. Also, the actual process pressure impacts the closing time. A 36-inch full port ball valve may close within less than 45-seconds during commissioning then actually close in 75-seconds against 1200 psig.


API RP 14C lacks opening time criteria.

 

[stanier]

Should one consider the transient pressure results in closing the ESD in a certain time? The philosophy should be that no safety measure should create an unsafe situation. A fast closing ESD may cause a pressure transient that could rupture a pipeline.

It comes down to a risk management situation. WHat is the likelihood adn consequence of an action. Engineering design will follow from the analysis.

 

[MortenA]

I am familiar with a NFPA rule of thum that says 1-1.5 sec/"

Sometime "worst case" is a fast closing time (surge e.g.) sometime the long closing time may be a problem (overpressure vented inventory etc.).

But the ansver from JLSeagull was what I was looking for (just couldnt remember the reference).

Best regards

Morten