ASME B31.1 - Administrative controls such as "car seal open" or "locked open" on

[afrig]

Good morning all,

Does anyone know if an administrative control such as a car seal open or a locked open device is acceptable as per ASME B31.1 code?
ASME B31.1 - para 122.2 (A.3) states that when a valve might be closed on a blowoff or blowdown line, the whole line shall be design in accordance with the code. Could that be avoided with a LO or CSO?

So far I found in the ASME interpretations document that it is not acceptable on a PSV discharge line, but I was wondering if it applies to all valves regulated by B31.1 or only the ones on the PSV lines.


Anyone has any reference where it is explicit?


Thank you in advance!

 

[LittleInch]

No I don't believe you can use an CSO or LO to do this as the valve is there and can be closed.

If you look at what 122.2 is trying to do, it is saying that if your blowdown piping exits to atmospheric pressure then you don't need to design to the full upstream pressure. HOWEVER, if there is ANY possibility that this isn't correct then you need to design to full U/S pressure.

Putting a valve there means that potential exists. End of story. CSO or LO is merely an operational thing to reduce the potential / risk, but it doesn't eliminate it.

You won't find anything that says this explicitly because that's not how design codes work. If it was allowed then it would say so. Codes can't go around saying explicitly don't do this, don't do that. The code would be three times as thick. Hence if it doesn't say you can, then you can't. If you want an definitive answer you can write to the Code committee and wait 9 months for an answer. They like simple yes and no questions. I would bet my house on the answer - Could that be avoided with a LO or CSO? - being NO.

BTW ASME B31.1 is NOT a regulation, it's a design code. It might be called upon in an regulation as a code to be followed, but that's a different thing.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Sawsan311]

I think that ASME B31.1 would not differ from the other design code ASME SEC VIII where the use of administrative control is prohibited of the resulting pressure from the blocked overpressure scenario (due to inadvertent application of the CSO or LO) would cause immediately exceeding the corrected hydrotest pressure. Usually, we don't rely on administrative control credits in new designs and would only consider for de-bottlenecking overpressure in existing systems IF and ONLY IF we are preferably within the code allowable accumulation

regards,