4BE3.5 U3 C1 Obj 3 True and False

Pressure Relief Valve Maintenance

• Pressure relief valves must be kept in good working condition at all times and tested regularly to ensure proper functioning.

Try Lever Test

• The try lever test determines if a pressure relief valve is operating freely, but not if it will open at its set pressure.
• The test is performed:
  • Monthly on steam heating boilers
  • Every three months for hot water heating boilers
  • Every six months on power boilers operating below 2760 kPa
  • Prior to pop tests and accumulation tests
• Boiler pressure must be:
  • 35 kPa or higher for steam heating boilers
  • At least 75% of the safety valve setting for power boilers
• The test procedure:
  • Pull the try lever to the wide-open position
  • Allow steam to discharge for 5-10 seconds
  • Release the lever
  • Allow the spring to snap the valve disc to the closed position
  • If the valve simmers, operate the try lever 2-3 times to allow the disc to seat properly

Pop Test

• The pop test checks the full operation of the safety valve, including the exact pressures at which it opens and closes.
• The test procedure:
  • Increase the boiler steam pressure to the safety valve set point
  • Record the opening and reseating pressures accurately
  • Compare the opening pressure and blowdown to the ASME BPVC performance tolerances
• The pop test should be performed annually, before taking a boiler off-line for maintenance.
• Defective valves can be identified and replaced or repaired prior to the boiler re-entering service.

Repair and Adjustment

• Repair or adjustment of pressure relief valves must be done by the valve manufacturer or its authorized repair representative.
• Consult the relevant ASME BPVC sections and the local Boiler Inspector to determine who is qualified to adjust or repair PRVs in a particular jurisdiction.