Mercer Valve Pressure Relief Valve 91-12K22VA7U6

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?

If leakage observed, report the issue to the maintenance team and stop the procedure

Leak inspection per API 527 passed?

Warning: This maintenance check requires qualified repair personnel!

Is the PRV correct for the application?

Are there any apparent problems with the PRV?

Describe any problems found during visual inspection

Is the nameplate information correct?

Is there any damage to the valve?

Describe any damage found on the valve

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

Set pressure discrepancy can vary outside of ASME tolerances if incorrect fluid is used

Rate of system pressure increase should be slow when pressure is within 15% of the set pressure

Set pressure testing procedures are as follows:

Check the set pressure definition from NB-18

For Mercer 9100 Series valves, a crisp “pop” is the definition of set pressure for both gas/vapor and liquid valves

Rigidly connect the valve to a test fixture

During the visual inspection, the pressure relief valve is checked for any potential issues that may restrict the operation of the valve

This inspection will be performed with the valve still assembled but the valve should not be pressurized for the safety of the person performing the inspection

Corrosion and damage to the valve are some of the common problems found in the visual inspection

Some of the items that should be checked in the visual inspection are as follows

Cap and Seal Wire - The valve cap and seal wire should be checked first on all inspections

These parts prevent adjustment tampering

On the seal wire, there is a pressed security seal that has an impression on it to indicate the certified company that last adjusted the set point the valve

When this seal wire is cut or removed, it indicates that someone may have adjusted the set point or altered the valve

This voids any warranty the valve had