Mercer Valve Pressure Relief Valve 91-12J13LA7B8

Warning: This procedure requires trained personnel!

Are two pressure gauges available 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.

Is at least one of the gauges an analog (dial) gauge that is not liquid filled?

Is a digital gauge used for the second gauge?

Digital gauges have to be used carefully because quick pressure increases are not always seen on the gauge readings.

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

The portion of the gauge used should be selected so that the tolerance of it is more stringent than the set pressure’s tolerance.

Warning: This inspection requires trained personnel with PPE!

Set pressure of the valve verified?

Enter the set pressure of the valve

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

Pressure held steady during the test?

Any leakage observed during the test?

Choose the method used for testing leakage

Zero bubbles observed for one minute in API 527 test?

For dependable performance, PRVs must be maintained regularly.

Mercer Valve Co., Inc. recommends its PRVs are inspected and tested annually.; After the valve has been in installed and a service history has been established, the testing and inspection frequency may be adjusted.

Some guidelines for testing frequencies are found in NB-23, API 576, and API 598.; Additionally, government jurisdiction should be reviewed.; When maintenance is done, qualified repair personnel should perform it.; Qualified repair personnel conducting the annual inspection and testing may alter the maintenance schedule based on the service conditions.

During the inspection, a visual inspection, a set pressure verification, and a leak check should be completed.; These tests can be performed while the PRV is installed on its system or when it’s on a testing bench.; The PRV can only be tested while on its application if there is a method and procedure to apply a controlled pressure to the PRV’s inlet without exceeding any limits of the system.

A visual inspection is used to identify if the PRV is installed properly, is correct for the application, and doesn’t have apparent problems.

Check the nameplate information to verify that the valve is installed on the proper service. A missing nameplate requires immediate addressing.

If the valve is installed on gas/vapor service, the nameplate’s capacity will indicate an air capacity at standard conditions.

If the valve is on liquid service, the nameplate will indicate a water capacity.

Check the seal wire. A broken seal wire indicates that an unqualified person has adjusted the set pressure this also removes any warranty the valve had.

Warning: This inspection requires trained personnel with PPE!

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

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

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 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/

The correct fluid for testing has to be used to achieve accurate results

For gas/vapor service, nitrogen or compressed air is used as the test fluid

Warning: Ensure the valve is not pressurized before starting the inspection

Flanged Connections in good condition

Threaded Connections in good condition

Outlet free from corrosion or debris

External Surface free from damage

Valve Tag information verified and corresponds to service conditions

Note any issues found during the visual inspection

Sign off on the visual inspection