Pressure Releif Valve – Pop-off valve

Pressure relief valves are installed on mud pumps in order to prevent an overpressure which could result in a serious damage of the pump and serious or fatal injury to personnel.
The discharge pressure is routed to the closer mud tank, via a 3” XXS line clamped strongly on tank side . Mud is flowing into the mud tank until line bled off, bearing in mind that minimum slope is required to avoid mud settling in pipe ( around 1 inch/meter).
Read carefully manufacturer instructions regarding setting, handling, refurbishing of such equipment.
In any cases if you don’t know/ clearly understand how to do it don’t do it, ask your supervisor. Do not start or later on , stop the job if you feel to do so .

1. Pressure relief valves are set usually to 90% of the maximum working pressure of the liners in use. Read carefully manufacturer chart for pressure setting versus size of liners.

2. The most commonly used pressure relief valve is 3” RETSCO TITAN type C , for mud pumps maximum working pressure of 5000psi

3. Prior to installing a pressure relief valve it needs to be tested on a special bench.

• With a low pressure setting, ie, 1000psi, by adjusting the top nylon self lock nut to move on the vertical scale to get the same setting than the scale.

• If the pop off pressure matches the setting, then screw to the pressure required on the mud pump (check liner chart) and test again.

When the pressure test has been successful, put a tag (if possible laminated) on the pressure relief valve, where it is mentioned:

• The date of the test.

• The pressure of the test.

• If the pressure relief valve was reconditioned. 

When/if the pressure relief valve activates due to:
Store it properly away from dust and adverse weather.( drilling store )

• Discharge line kept closed and pump started.

• Discharge pressure losses close to the maximum preset pressure.The Pressure relief valves are usually installed on a upper point of the discharge side of the mud pumps.

The pressure relief valve can be reset, if not damaged during the release of pressure. Special care should be taken if no working platform available to access the PRV.