In my last several Process Safety courses, I had several requests for “code requirements” surrounding Relief Valve “maintenance” (e.g., inspection, replacement, and rebuild frequencies). In general, there is the “at least every five years” interval that is ever so popular, and the vast majority of manufacturers will REQUIRE their RV(s) the be changed/rebuilt/certified “at least” every five (5) years. The path/option an employer chooses to take will be based on many factors, which I will not get into in this article. But when it comes to establishing a frequency for our RV maintenance, this frequency will be established based on the actual service the RV is in. The actual service can vastly shorten the “frequencies” that we establish!!!
We turn to the National Board Inspection Code (NB-23) Part 2 – Inspection for the best guidance, as this Recognized And Generally Accepted Good Engineering Practice (RAGAGEP) provides us with all the tools necessary to establish frequencies and to perform an analysis on those valves we have to establish our own frequencies (should be rarely done!). In this RAGAGEP, we find the “5-year” window and some surprises on other RV frequencies.