On-Off and Control Valve Maintenance

1. Inspect and clean outside with in instrument air.
2. Record Tag No. and Mfg. date in check sheet
3. Marking bonnet and valve body
4. Disassembly bonnet and check damage parts.
5. Inspect plug and seat and check damage parts.
6. Cleaning all wet parts.
7. If plug and seat to ware out it needs to repair as follow up to repairing procedure.
8. Change damage part if necessary.
9. After cleaning finish them assembly all part and accessory.
10. Leak test and re- calibrate as follow up to test procedure.

1. Control valve install vertically at the fix condition with both flange.
2. Connect the air supply tube inlet flange.
3. Connect the PVC tube. For outlet flange with flow meter
4. Apply air pressure to inlet flange for leak test conform ANSI/FCI 70-2 standard
5. If leak correctly specification. After that re-calibration zero-span and stroke check

At 0-100% as following specification sheet

1. If  leakage over specification it need to repair as follow up to repairing procedure
2. Record data calibrate in calibration sheet

1. After inspect plug and seat then it was found to wear out should be lapping with lapping compound.
2. If plug and seat damage it need to re-machine.
3. If plug and seat cannot lapping or re-machine if need to change with spar parts.

After repair finish should be clean with water , acetone, cleaning thinner and with instrument air.

1. Assembly all part and accessory
2. Leak test pluge ,seat and valve body conform ANSI/FCI 70-2 standard as follow up to test procedure.
3. Re-calibration follows up to test procedure.