Microsoft Word - SOP - Hands-On Sessions

Rev. 2 - Fin al

REPLACING “SINGLE” PRESSURE RELIEF VALVES

PART A:

See Plant Safe Practices binder for Line Break procedures, Confined Space Entry and Hot Work Permits. Use the lock-out/tag-out log to document which valves or switches have been opened or closed. STEP NUMBER DESCRIPTION SAFETY AND HEALTH HAZARDS/ STEPS TO AVOID DEVIATION 1

Verify that associated equipment has been completely pumped out and there is no pressure remaining. Slowly disconnect pipe union on outlet line from relief valve to make room to unscrew the valve from the inlet pipe nipple.

Note: Verify that pressure has been removed by opening the service valve to atmosphere before removing relief valve.

2

Note: Monitor local environment for presence of NH 3 using portable detector.

3

Remove pipe nipple and half of union from outlet of old/defective relief valve.

4

Break loose threaded inlet connection to old relief valve while using back-up wrench on inlet pipe nipple. Unscrew old relief valve slowly, while wiggling to verify there is no pressure. Verify that replacement relief valve is rated for the same pressure as the vessel it is protecting and then install new relief valve and tighten using back-up wrench on inlet pipe nipple. Re-install pipe nipple and half of union in outlet of the new relief valve and tighten. Then reconnect union halves and tighten. After installation of new relief valve and prior to returning equipment to operation, crack open and close vent valve ¼ turn

Warning: Do not completely remove valve until sure that all pressure has been relieved from the equipment.

5

6

7

Note: Light sulfur stick and slowly wave burning stick around all pipe joints. A white smoke plume will indicate an ammonia leak reacting with the sulfur. Note: Record all information from new valve on the master list of relief valves.

and leak check new relief valve connections using sulfur sticks.

Procedure: Operation, Isolation and Replacement of Pressure Relief Valves Reviewed: 11/01/2023

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