Mercer Valve Pressure Relief Valve 95-70P13077

Warning: This inspection requires trained personnel with PPE!

Set pressure of the valve verified?

Enter the leak test pressure (usually at 90% of the set pressure or 5 psi below the set pressure, whichever is greater)

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

Pressure held steady for a length of time without any leakage?

Choose the method used for testing leakage

Did the valve pass the leak inspection?

Describe any observed leakage or issues during the test

Sign off on the valve leak inspection

Warning: This procedure requires trained personnel with PPE!

Upload a photo of the lift checking apparatus

Enter the measurement of the movement of the disk from the closed position to the fully open position

Enter the minimum lift for certified PRVs as per NB-18 publication

Does the lift meet the minimum requirement?

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 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

During the set pressure inspection, the set pressure is verified in accordance with the ASME Boiler and Pressure Vessel Code.

For all valves set 70 psi (500 kPa) and above, the set pressure has a tolerance of ±3% of the nameplate set pressure.

For all set pressure below 70 psi (500 kPa), the tolerance is ±2 psi (±15 kPa) of the nameplate set pressure.

If the valve has a CDTP associated with it due to temperature and/ or backpressure, the test pressure is checked to the CDTP.

Even with a CDTP, the set pressure tolerance is calculated based on the actual nameplate set pressure.

The set pressure test should be performed before (if it passes the visual inspection) and after any repairs.

The set pressure is inspected to the definition listed in NB-18, a publication by the National Board of Pressure Vessel Inspectors, which is found at http://www.nationalboard.org/.

This publication lists all ASME Boiler and Pressure Vessel Code certified pressure relief valves.

It indicates the correct set pressure definition and other characteristics of a valve.