A PSV test bench may fall under pressure vessel rule.
Check if the test bench falls under pressure vessel definition. If it does, and if you are using it, better do an inspection survey like any other pressure vessels in the plant.
Workers always work around the test bench and most often you must be using plant air for the test.
I would suggest that you perform a baseline thickness audit, figure out the reduction in wall thickness if any over the years and start from there.
Yearly re-certification is a good plan considering the risk around people.
GDD
Canada