Mercer Valve Pressure Relief Valve 81-12151P18G21

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

Details of the security seal on the seal wire

Flanges Connections in good condition

Threaded Connection in good condition

Outlet free from corrosion or debris

External Surface free from damage

Details of any external attachments

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: This inspection requires trained personnel with PPE!

Enter the set pressure of the valve

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

Did the pressure hold steady during the test?

Select the method used for testing leakage

Did the valve pass the leak inspection?

If the valve did not pass the leak inspection, it should be removed for further testing.

Warning: This inspection requires trained personnel with PPE!

Inspect the seat for cuts and abrasions

Measure the diameter Ds of the nozzle

Select the orifice size and corresponding nozzle diameter

Condition of the spherical surface

Select the orifice size and corresponding nozzle diameter

Warning: This procedure requires trained personnel with PPE!

Enter the pressure losses to the gauges