Steam - fire case allowable overpressure 1

[JLSeagull]

I am not looking at a fired heater or fired boiler, just a steam containing vessel application in a process unit. What percentage overpressure is allowable for a steam vessel for a fire case?

I have peaked around in API RP 520, API STD 521 and some of the ASME standards. Which standard reflects the allowable overpressure value for steam if different than hydrocarbon?

 

[CMA010]

Why do you think there is a difference?

 

[JLSeagull]

My thinking is that there is or was a limit of 10% overpressure for steam in any case compared to 21% for fire case in HC service. I don't remember why or of this may have once been the case and no longer exists. I could just be thinking wrongly.

 

[jamesbanda]

With boilers be careful their can be local codes that superceed API.. depends where you are.. so check.. !

i've found local codes often are guidelines it depends on my local engineers view !! so that can change,.

sorry dont know the actual answer though

 

[MortenA]

He said - not boiler!

Anyway: Is you steam case a wet fire case (only water in the vessel - set point below the critical pressure of water) then follow API520 section for steam. If the SP is above critical use same, but for superheated steam.

Best regards

Morten

 

[CMA010]

API 520 and 521 are not limited to vessels filled with hydrocarbons, check the scope.

 

[Petroprocess]

For fire scenarios the overpressure is always 21% even if it is a steam relief.

 

[colemanstoops]

I'll associate myself with Petroprocess' comments: that 21% overpressure is the rule for the fire case, the fluid notwithstanding.