Mercer Valve Pressure Relief Valve 91-43G51V61I1

Warning: This procedure requires trained personnel!

Are two pressure gauges available for testing?

Are the gauges reading identical values within their respective tolerances?

Select the type of the first gauge

Select the type of the second gauge

Is the analog (dial) gauge not liquid filled?

Does the digital gauge respond to quick pressure increases?

Does each 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?

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?

Before this test is performed, the valve must have had its set pressure examined

Select the method used for testing for leakage

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!

Refer to NB-18 for set pressure definition and other valve characteristics

Use correct fluid for testing: nitrogen or compressed air for gas/vapor service, water for liquid service

Pressure increase should be slow when within 15% of set pressure, not more than 2 psi/sec

Common set pressure definitions: 'Pop', 'First Audible Sound', 'First Steady Stream'

Valve connected to test fixture?

Enter the pressure at which the valve opens

If pressure reaches more than 1.5 times the expected set pressure and hasn’t opened, valve is considered stuck closed and has failed

Valve opened at correct pressure?

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

Cap and Seal Wire in good condition

Flanged Connections in good condition

Threaded Connections in good condition

Outlet free from corrosion or debris

External Surface free from damage

Valve Tag information corresponds to service conditions

If any of the above checks fail, the valve is deemed dangerous to test and should be replaced or repaired immediately

Sign off on the visual inspection