Re-Calibration of Pressure Relief Valves & Vacuum Breakers

[JIPMKWA]

Good morning,

We have 4 - 67,000 gallon Aqueous Ammonia storage tanks with a 1" inlet - 150# raised face flange, 2" outlet RFFL pressure relief valve. It is set for 30 psi to vent to a safe location.

My question is besides initial calibration by the manufacturer , how often will the plant need to re-calibrate a valve like this ? Everything I have found in ASME Sec. VII , Div. 1 has talked about the manufacturer's requirements but I can't find anything about maintenance.

The same question applies to the vaccum breakers - It is an OCECO 2" inlet 150# RFFL - set at -0.2 psig.


Thank you for your time.

 

[Duwe6]

You'll NEVER find maintain & run info in Sect VIII - it is a design & build Code {only]. National Board and API recommend a maximum 5-year interval for PRV's between each Test & Reset. API further suggests that 10-years, based on the Test & Reset history of PRV's in benign service may be acceptable. Ammonia is not considered benign, unless the discharge is captured in a flare/vent header.

Your OCECO is probably a Vacuum Conservation Vent, with a pallet that rises to give the venting. It's an API device, but there is no Reset, just an internal Inspx for debris, bad gaskets, etc. And ensure that the necessary pallet weights [if any] have not been changed.