According to the complaints of a client of the finishing of double relief and gate valves, we had to disassemble the valves completely , the question is:
I should check the quality of the valves(butterfly, nonreturn check valve, gate, relief valves) after the hydrulically testing and painting stage and before the clients check it so
is there any guidance for this checking process and what defect that affects the functional of the valves and the degrees of the defect.(ex. a small fracture in the bonnet away from the holes that is covered in the painting and sometimes we exceed the tolerance of the distance between the flanges)
Relief valves are a different critter, and they have to be tested for opening pressure, lift, and seat tightness. If they are steam valves they have to be set on steam. Gas valves can be set on compressed air, and liquid valves can be set on water.  Refer to ASME section VIII for safety-relief valves or ASME section I for Safety valves (on fired pressure vessels)

MORE NEWS