Only important points or summery of points for pressure Safety Valves in-service inspection and should not be assumed as pressure safety valve inspection procedure.

You may use following content as summery of points for in-service inspection of pressure safety valve only.

1. Determination pressure safety valve inspection interval based API STD 510 and API RP 576 requirements

2. Inspection of inlet and outlet piping after pressure safety valve removal for any fouling

3. Inspection of pressure safety valve charge and discharge nozzles for possible deposit and corrosion products

4. Taking care for proper handling of pressure safety valves from unit to the valve shop. The detail of handling and transportation instruction is provided in API RP 576.

5. Controlling of seals for being intact when the valves arrived to the valve shop

6. Making as received POP test and recording the relieving pressure

7. If the POP pressure is higher than the set pressure the test need to be repeated and if in the second effort it was near to the set pressure it is because of deposit.

8. If in the second effort it was not opened near to the set pressure either it was set wrongly or it was changed during the operation

9. If the pressure safety valve was not opened in 150% of set pressure it should be considered as stuck shut.

10. If the pressure safety valve was opened below the set pressure the spring is weakened

11. Making external visual inspection on pressure safety valve after POP test. The test need contain following item as minimum;

? The flanges for pitting and roughness

? The spring and bellows for corrosion and cracking

? The external surface for any corrosion and mechanicaldamage

? Making body wall thickness measurement

12. Dismantling of pressure Safety Valves if the result of as received POP test was not satisfactory

13. Making detail and comprehensive visual and dimensional inspection on the dismantled valve parts (after cleaning)

14. Making special attention to the dismantled valves seating surfaces inspection e.g. disk and seat for roughness, wear and damage which might cause valve leakage in service

15. Replacing the damaged parts in dismantled valves based manufacture recommendation and API RP 576 requirements

16. Making precise setting of the pressure safety valve after reassembly based manufacture recommendation or NB-18 requirements
Pressure Safety Valves Inspection

17. Making at least two POP test after setting and making sure the deviation from set pressure is not more than 2 psi for valves with set pressure equal or less than 70 psi or 3% for valves with set pressure higher than 70 psi

18. Making valve tightness test for leakage purpose after approval of the setting pressure and POP tests. The test method and acceptance criteria must be according to the API RP 576.

The API RP 527 also can be used for pressure safety valve tightness test.

19. Recording and maintaining the inspection and testing results.