Please could you help me with a dilemma over the use of check valves (non-return valves) as the relief valve on a tank. Any comments on where they could be applied and how appropriate they are would be welcome.
One instance where I have seen them used is where the equipment is normally operated under vacuum.
I have also seen them located on a storage tank kept under a low pressure nitrogen blanket.
I am concerned as to what is or isn't appropriate. Particularly if the storage tanks are rated as pressure vessels.
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Check Valve As Safety Valve
Started by Guest_storry_*, Nov 07 2003 08:46 AM
3 replies to this topic
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#1
Guest_storry_*
Posted 07 November 2003 - 08:46 AM
#2
Posted 07 November 2003 - 01:30 PM
As a secondary device a spring loaded check valve may acts as vauum relief. However by code this cannot be a primary safety device as listed in the overpressure protection report for the specific system if a storage tank is rated as Pressure vessel.
Section VIII Div 1 does not address on vacuum releif valves.
Please refer to API 2000 for Atmospheric /Low Pressure storage tanks
Hope this helps
Section VIII Div 1 does not address on vacuum releif valves.
Please refer to API 2000 for Atmospheric /Low Pressure storage tanks
Hope this helps
#3
Guest_storry_*
Posted 12 November 2003 - 05:48 AM
Thank you for the reply.
Could a check valve be used as a secondary pressure relief valve. For instance if it is set to lift a a pressure below that of the main bursting disc.
Could a check valve be used as a secondary pressure relief valve. For instance if it is set to lift a a pressure below that of the main bursting disc.
#4
Guest_Ben Thayer_*
Posted 12 November 2003 - 09:29 AM
Yes, as a "secondary device" you may have a check valve in addition to the main rupture disc or relief valve.
Most tanks have some type of "device" to allow for normal "breathing" when filling/emptying the tank. Depending on the nature of the material being stored, these devices may be pad/de-pad nitrogen regulators or conservation breather vents.
But having a regulator set to maintain 6" w.c. or having a check valve with 0.5 psi cracking pressure does not mean you don't need a relief device.
I would not characterize the check valve as a relief device but as just another piping component.
Most tanks have some type of "device" to allow for normal "breathing" when filling/emptying the tank. Depending on the nature of the material being stored, these devices may be pad/de-pad nitrogen regulators or conservation breather vents.
But having a regulator set to maintain 6" w.c. or having a check valve with 0.5 psi cracking pressure does not mean you don't need a relief device.
I would not characterize the check valve as a relief device but as just another piping component.
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