When Does a Relief Valve’s Clock Start?
While it is well known that good engineering practice requires that relief valves be replaced every five years, industry literature does not clearly state when the five-year timer starts its countdown. Is it when the valve is manufactured? Taken out of the box? Installed? Exposed to ammonia?
Due to the lack of clarification on this topic, the International Institute of Ammonia Refrigeration (IIAR) Standards Committee answered this exact question on March 10, 2017. The full text of their response is available on their website and included below for quick reference:
Interpretation IIAR SC 2016-01
Question: Does the 5-year replacement interval begin upon: a) Installation of equipment b) Charging the system with refrigerant or c) Start-up of the system?
Answer: The IIAR Standards Committee has considered the topic of shelf life. The committee’s conclusion was that the replacement interval shall start on the day that the SRV is installed onto the system, regardless of how long it has been stored.
It is incumbent upon the installer to visually inspect SRVs before installation. Any visual deterioration (such as surface rust) would be cause to reject the SRV. Facilities should have a procedure in place such that a visual inspection is made before installing SRVs. Further, if it is the practice of facilities to stockpile SRVs, their procedures should indicate that they are stored in an appropriate area, with appropriate protection.
It is important to note that the inspection and storage recommendations are not part of this interpretation.