Mercer Valve Pressure Relief Valve 95-75Q14056

Warning: This procedure requires trained personnel!

Are two pressure gauges used for testing?

Are the gauges reading identical values within their respective tolerances?

If the gauges are not reading identical values, both should be checked for calibration.

Does the test gauge have at least 0.25% accuracy over their full scale?

Is the portion of the gauge used more stringent than the set pressure’s tolerance?

For analog gauges, is only the middle 1/3 or less of the gauge used?

Is each gauge calibrated using a dead weight tester?

Sign off on the monthly gauge calibration

Warning: This procedure requires trained personnel with PPE!

Upload a photo of the valve in closed position

Enter the initial position of the disk

Upload a photo of the valve in fully open position

Enter the final position of the disk

Enter the lift measurement (difference between initial and final position)

Refer to NB-18 publication for minimum lift for certified PRVs

Does the lift meet the minimum requirement?

Sign off on the valve lift check

- Pressure Relief Valve In Situ Testing

Testing and inspecting in place eliminates the laborious task of removing and handling the valve.

This is especially desirable with large PRVs.

Additionally, not disturbing the existing connections reduces the chance of compromising the existing seals.

This type of testing is very useful when a system cannot be shut down for long lengths of time.

There are disadvantages to this type of testing.

The inspection process is more difficult because the accessibility of the valve is reduced.

The outlet pipe is often still attached and the internal parts are not observable for the visual inspection.

This can also make it difficult to leak check.

For dependable performance, PRVs must be maintained regularly.

Mercer Valve recommends its PRVs are inspected and tested annually.

After the valve has been installed and a service history has been established, the testing and inspection frequency may be adjusted.

Some guidelines for testing frequencies can be found in NB-23, API 576, and API 598.

Additionally, government jurisdiction should be reviewed.

When maintenance is performed, only qualified repair personnel should complete it.

Qualified repair personnel conducting the annual inspection and testing may alter the maintenance schedule based on the service conditions.

Before performing maintenance, it should be ensured there is no pressure within the main valve or pilot valve.

All 6x8 and larger gas modulating pilots will have a check valve on the pilot inlet line to help with dome loading.

Warning: This inspection requires trained personnel with PPE!

Set pressure of the valve verified?

Note: Leak test pressure should be 90% of the set pressure or 5 psi below the set pressure, whichever is greater.

If the valve has a CDTP, the leak test pressure will be below the CDTP in lieu of the set pressure.

Contact Mercer Valve for proper leak pressure and specification for the valve.

Pressure held steady during the test?

Any leakage observed during the test?

There are several methods used in testing for leakage. Choose the one applicable.