I'm not sure what section of the Boiler and Pressure Vessel Code you fall under (Section I or VIII). But on Section I valves installed on Boilers proper, you may find that they pop periodically - but reseat properly (I guess the same can be said about Section VIII valves). At our mill, we had a program that would require us to inspect all Section I valves on a yearly basis and all Section VIII valves on a three year basis - all uncoded valves (ie. sludge...) would be inspected on a 5 year basis. That being said, if we had an instance where an SRV was weeping, or popped on too regular an interval, we would make arrangements to inspect the valve at the next available opportunity.