Mercer Valve Pressure Relief Valve 81-16151V18G11

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 quick pressure increases?

Does the test 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!

Enter the set pressure of the valve

Enter the CDTP of the valve if applicable

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?

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

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.

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 of 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.

• Flanges Connections - The flanges should be checked for wear, such as pitting, and any reduction in width that would cause improper sealing and reduction in pressure rating.

Proper fastening should also be checked.

• Threaded Connection - The threads on the threaded connections should be checked for any damage that could potentially compromise the sealing of the threads or the strength of the connection.

• Outlet - The valve's outlet should be inspected to make sure there is not any corrosion or other debris accumulation within that could inhibit the operation of the valve.

• External Surface - The valve should be checked for any damage that has occurred that could restrict or impair the operation of the valve.

Tubing lines, bent piping, and other external attachments are commonly damaged and can cause unfitting function.