Mercer Valve Pressure Relief Valve 95-85S16023

- Pressure Relief Valve In Situ Testing

Testing and inspecting in place eliminates the laborious task of removing and handling the valve.

This is especially desirable with large PRVs.

Additionally, not disturbing the existing connections reduces the chance of compromising the existing seals.

This type of testing is very useful when a system cannot be shut down for long lengths of time.

There are disadvantages to this type of testing.

The inspection process is more difficult because the accessibility of the valve is reduced.

The outlet pipe is often still attached and the internal parts are not observable for the visual inspection.

This can also make it difficult to leak check.

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

Cap and Seal Wire in good condition

Flanged Connections in good condition

Outlet free of corrosion or debris

External Surface free of damage

Valve Tag information corresponds to service conditions

Two tags present on 9500 Series valves

If the valve fails any of the above checks, do not proceed with set pressure inspection and leak inspection

Sign off on the visual inspection

Warning: Only qualified repair personnel should perform this maintenance.

Is there no pressure within the main valve or pilot valve?

Is the PRV correct for the application?

Does the PRV have any apparent problems?

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?

During the set pressure inspection, the set pressure is verified in accordance with the ASME Boiler and Pressure Vessel Code.

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

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

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 (if it passes the visual inspection) 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 Boiler and Pressure Vessel Code certified pressure relief valves.

It indicates the correct set pressure definition and other characteristics of a valve.

Warning: This inspection requires trained personnel with PPE!

Set pressure of the valve verified?

Enter the leak test pressure (90% of the set pressure or 5 psi below the set pressure, whichever is greater)

Contact Mercer Valve for proper leak pressure and specification for the valve if the valve has a CDTP.

Pressure held steady for a length of time without any leakage?

Choose the method used for testing leakage.

Did the valve pass the leak inspection?