Installation and Inspection of RegO® Pressure Relief Valve

PRV9400, PRV19400, PRV29400, and PRV19534

Field Topics are intended to provide useful information to the network of authorized and Anhydrous Ammonia distributors regarding the proper use of RegO® products.

In its continuing quest for safety and quality performance, RegO publishes a series of bulletins explaining the proper installation, inspection, and maintenance of various products. This document is not intended to conflict with federal, state, or local ordinances or regulations; these regulations should be observed at all times.


The purpose of this bulletin is to offer guidance for the installation and inspection of RegO Pressure Relief Valve PRV9400, PRV19400, PRV29400, and PRV19534 Series.


Use of PTFE tape as a pipe lubricant. Pipe aways and deflectors may be required by local codes, laws, and regulations depending on the installation. Fingers tighten the relief valve, and then use the proper wrench to tighten the valve to the appropriate torque settings hand-tight plus X turns”, X is dependent on the thread size.

Use only RegO adapters for RegO relief valves. Adapters not designed specifically for piping away RegO relief valves, such as those with 90° turns or reduced internal diameters, will decrease flow dramatically. These should never be used as they can cause the relief valve to chatter, shortening the life of the valve.

Liquid Phase Installations

It is recommended to use a riser tube or “candy cane” when installing a PRV in a liquid phase, cryogenic process. By designing the system in this manner, the PRV can function in the gas phase. The riser tube wall section absorbs heat from the ambient and transfers it to the liquid, causing a gas phase chamber between the line and the PRV. This allows the PRV to only be subject to the liquid phase during a relief event.

It is recommended to use a pipe away adapter in an indoor PRV installation, in which it is necessary to vent the exhaust out of the room.

Gas Phase Installations

For gas phase installation where the installation of the PRV is done directly in the pipeline, and the probability of moisture building up in the valve is high (normally outdoor installation).

It is recommended to use a PRV with a drain hole in order to avoid moisture buildup in the valve, the candy cane is the best practice for gas phase installation too.


RegO pressure relief valves are not designed to be repaired nor reconditioned. If a valve needs to be replaced, then choose one that is designed for that specific system and or operation.

According to CGA S 1.2, a visual inspection of the relief valves is recommended every 5 years to ensure that:

  • The outlet is open and free to discharge;
  • There are no signs of corrosion, cracks, or other mechanical damage;
  • The stamped set pressure is suitable for the design pressure;
  • No leaks are found; and
  • The adjacent piping is not deformed.

Note: More frequent examinations may be warranted depending upon the type of service, operating conditions.

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Field Topic Conductor :

Carlos Arevalo

Technical Manager/IG & Cryogenics Division at RegO Products

Experienced Technical Manager with a demonstrated history of working in the industrial gases, cryogenic, oil & energy industry. Skilled in Negotiation, Management, Troubleshooting, Business, and Logistics Management. Mechanical Engineer with a Diploma in Modern Management focused in Management from Universidad de Carabobo.