Mercer Valve Pressure Relief Valve 81-12151V18G21

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?

Is the digital gauge used carefully for quick pressure increases?

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?

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?

Select the method used for testing leakage

Zero bubbles observed for one minute in case of soft seated valves?

Any growth of bubbles observed in soap film test?

Warning: This maintenance check requires qualified repair personnel!

Is the PRV correct for the application?

Are there any apparent problems with the PRV?

Is the nameplate information correct?

Is there any damage to the valve?

Are there any issues that would keep the valve from opening or inhibit flow?

Are there any problems found during the visual inspection?

During the set pressure inspection, the set pressure is verified in accordance with the ASME BPVC.

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

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

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/.

This publication lists all ASME BPVC certified pressure relief valves.

It indicates the correct set pressure definition and other characteristics of a valve.; The set pressure has been defined to achieve a particular operational characteristics.; If the wrong set pressure definition is used in the inspection test, the valve's set pressure will not be accurate and it may not operate appropriately.

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, while for liquid service, water is used.; If the incorrect fluid is used during the testing, the test's results will be inaccurate.; Depending on the size of the valve and its set pressure, the set pressure discrepancy can vary outside of ASME tolerances.

Setting procedures should be in accordance with ASME PTC 25.; The rate of the system pressure increase should be slow when the pressure is within 15% of the set pressure. Within this range, the rate should never be more than 2psi/sec (15kPa/sec).; Ideally each pressure increment on the pressure gauge should be clearly read as the pressure is increased. Slow pressure increase helps to accurately read the pressure gauge.

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

Cap and Seal Wire in good condition

Security seal on the seal wire intact

Flanges Connections in good condition

Threaded Connection in good condition

Outlet free from corrosion or debris accumulation

External Surface free from damage

Valve Tag information corresponds to the service conditions

Set pressure, CDTP, and capacity in appropriate unit of measure for the service fluid verified