Mercer Valve Pressure Relief Valve 91-12L32TA7NA

Warning: This procedure requires trained personnel!

Are two pressure gauges used 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 pressure quickly and give accurate readings?

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

Is the portion of the gauge used 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?

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

Choose the method used for testing

Warning: This maintenance check requires qualified repair personnel!

Ensure to follow guidelines for testing frequencies as found in NB-23, API 576, and API 598.

Government jurisdiction should be reviewed.

Maintenance should be performed by qualified repair personnel.

During the inspection, a visual inspection, a set pressure verification, and a leak check should be completed.

Is the PRV correct for the application?

Does the PRV have any apparent problems?

Is the nameplate information correct?

Warning: This inspection requires trained personnel with PPE!

The set pressure is verified in accordance with the ASME BPVC

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

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