Relief Requirements for Low Pressure Coded Vessel 1

[joeycranston]

I have the following question for use of a pressure vessel in a code state: For a code-stamped, pressure vessel, if the intent of use of the vessel is at atmospheric pressure, is a relief device mandatory if the code-stamp is removed and documentation generated to say the vessel is considered a non-code vessel? In other words, does the requirement of a relief device apply to a vessel operated or potentially operated (emergency situation) at pressures above 15 psig or does it apply to a vessel constructed to withstand pressure above 15 psig, regardless of the application?

 

[moltenmetal]

Relief pressure matters. As long as design pressure is ABOVE relief pressure, everybody's happy. And as long as relief pressure is below 15 psig, ASME VIII does not apply.

If the intention is atmospheric operation, then the relief device will be a piece of pipe connected to atmosphere, perhaps through a trap or other device. That's a perfectly valid relief device.

A vessel entirely without relief device, which in a credible emergency scenario may exceed 15 psig, needs that credible scenario dealt with somehow. If it's dealt with by design, i.e by giving an MAWP above 15 psig to account for the calculated max pressure the scenario can produce, then it's ASME and you're forced to have some sort of relief device on there.

 

[trottiey]

I would say that if the code stamp is removed, the name plate is destroyed, and there is nothing that could mislead someone to believe this is a pressure vessel, that means you now have a funny-shaped bucket. It is legal to put a tight-fitting lid on your bucket, even though a little bit of pressure might build up because of leftover garbage fermenting inside.

Of course, this is not a justification for amateur lawyers to evade common sense, which I think is the point that moltenmetal was getting at.

 

[joeycranston]

Moltenmetal, Thanks for the response. That makes sense. I didn't want to assume that the ASME code made sense because sometimes they do not.

Trottiey, If my situation lacks common sense, I believe you gave the perfect answer.