Pressure Safety Valves in Low Pressure ASME Systems
Pressure Safety Valves in Low Pressure ASME Systems
(OP)
Hello Everyone,
Problem: When working with non-ASME stamped vessels, what is the max pressure I can set a pressure safety relief valve to?
Background: My company deals with low pressure pipe work below 15 PSIG and we have always were able to slip through not having to get ASME stamped pressure vessels due to this. We have an internal debate going on about what the max pressure we can set a Pressure Safety Valve to. Can someone help point me toward the relevant code? I’m an electrical guy by trade and am no stranger to standards.
Our vessels are pressure tested to 25 PSIG but they aren’t stamped for service at that pressure. My co workers seem to think that means we can set a safety valve to 16 PSIG. However, my limited knowledge of ASME standards leads me to believe that would require us to get the vessel stamped for a higher pressure and the max pressure that vessel could see is 15 PSIG and below.
Problem: When working with non-ASME stamped vessels, what is the max pressure I can set a pressure safety relief valve to?
Background: My company deals with low pressure pipe work below 15 PSIG and we have always were able to slip through not having to get ASME stamped pressure vessels due to this. We have an internal debate going on about what the max pressure we can set a Pressure Safety Valve to. Can someone help point me toward the relevant code? I’m an electrical guy by trade and am no stranger to standards.
Our vessels are pressure tested to 25 PSIG but they aren’t stamped for service at that pressure. My co workers seem to think that means we can set a safety valve to 16 PSIG. However, my limited knowledge of ASME standards leads me to believe that would require us to get the vessel stamped for a higher pressure and the max pressure that vessel could see is 15 PSIG and below.
Talk To Other Members
RE: Pressure Safety Valves in Low Pressure ASME Systems
ASME VIII Division is forpressures up to 10,000 PSIG but there are alternative rues available in ASME VIII Division III
Pressure-relief designs are available as high 15,000 PSIG, though most are API-526 standard types limited to a Cl. 2500 inlet flange rating.
Your 16 PSIG Vessel would require the vessel and PRV to be code stamped.
Please note there is a separate forum for Safety Relief Valves (alternative name for PRV).
*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***
RE: Pressure Safety Valves in Low Pressure ASME Systems
I don't know why a pressure vessel designed for a MAWP of <15psi is being tested at 25psi. 22 would seem more like it at 1.5 times the MAWP.
So if you set the relief valve to 16psi, then this brings you into the ASME VIII system.
Different places have different regulations and sometimes volume is also used to decide if the item is a PV or not.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Pressure Safety Valves in Low Pressure ASME Systems
If necessary is there a problem with the usage of cheaper and easier to maintain rupture disks ?
Can you give us dimensions/ pictures, descriptions of materials ?
MJCronin
Sr. Process Engineer
RE: Pressure Safety Valves in Low Pressure ASME Systems
To me, it seems we would have to set our Pressure Safety Valve to 14.5 PSIG to ensure we do not exceed the 15 PSIG MAWP of the Glycol Exchanger. Because if our system did ever see more than 15 PSIG we would fall under SME VIII systems. Is that correct or am I overthinking this?
RE: Pressure Safety Valves in Low Pressure ASME Systems
If the former and your vessel has a MAWP of 15 psi then it might already fall into ASME VIII.
I don't know if anyone is going to split hairs like that but if I was you I would set your relief systems at 15 psig. Bearing in mind most simple spring reliefs have a -8% tolerance you should be fine.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Pressure Safety Valves in Low Pressure ASME Systems
*** Per ISO-4126, the generic term
'Safety Valve' is used regardless of application or design ***
*** 'Pressure-relief Valve' is the equivalent ASME/API term ***