Page 16 - Temporary Isolation of Relief Devices - CCPS Safe Work Practice

Strategies and Effective Practices

to Manage and Mitigate Hazards

REMOVING THE ISOLATION VALVE AND RE-INSTATING THE PRD TO SERVICE

The reinstatement procedure for isolated PRDs on operating equipment is essentially the isolation procedure done in
reverse order.

PRD Reinstallation and Fit for Service Verification
g Verify that the proper PRD is being reinstalled by confirming its nameplate tag number, set pressure, orifice
designation or size, and relief capacity match that required per the site’s process safety information.
g Verify no temporarily installed blinds, plugs, caps, debris or any other device or materials are in the system that
would obstruct the PRD’s inlet and outlet circuits’ flow capability.
g Inspect the PRD to verify no damage is evident and that there is no indication of other problems that can restrict its
correct functionality.
g Reinstall the PRD and verify that it is properly oriented with its mechanical connections (such as mounting flanges)
properly tightened.

Pressurized Leak Test of PRD Inlet Connection

g If possible, perform a pressurized leak test of the PRD inlet mechanical connection using an inert fluid that is
compatible with the process fluid and will not damage the PRD, such as water or nitrogen.

g Follow your site’s leak test procedures.
g Drain and purge the leak test fluid as necessary to avoid affecting the PRD’s performance and process system
quality. NOTE: It is especially important to purge any incompatible material from the system before introducing the
process fluid, such as purging air from a process handling flammable fluid.

Operational Checks Before Bringing PRD in Service
g Perform Operational Checks as one last safety integrity check before bringing the PRD back in service.

g The Operational Check should be conducted by a competent Area Operator and verify that:
• PRD nameplate information is correct.

• No temporary isolation or blocking devices remain in the entire PRD circuit.
• Seal wires on pressure safety valves are intact (if used).
• Tail pieces or top works on pressure safety valves are vented properly and protected from rain, debris, insect
infiltration, and other potential blockages.
• PRD retest dates are recorded and current.

13 SAFE WORK PRACTICE, TEMPORARY ISOLATION OF RELIEF DEVICES