Recent Blog Posts

Ammonia Release | Relief Valve Set Pressure

September 2nd, 2025

Summary In February 2024, the installation of a relief valve with the wrong set pressure resulted in the release of a small quantity of ammonia. Release calculations were not performed since the estimated release amount was below 100 lbs of ammonia.  Incident Description Contractors were in the process of replacing relief valves throughout the system […]

PSI Explained: Relief System Design and Design Basis

June 24th, 2025

This is an update to a blog that was originally posted on 6/13/17. You can read the original blog here. Relief System Design and Design Basis is one of the most commonly inspected components of Process Safety Information (Title 8 CCR §5189(d)(3)(A)(4) and Title 29 CFR §1910.119(d)(3)(i)(D)). This documentation, when prepared correctly, will describe the […]

Relief Valve Piping System Design Scenario

May 13th, 2025

This is an update to a blog that was originally posted on 1/24/17. You can read the original blog here. One often overlooked aspect of a relief valve discharge termination piping system is the scenario that was used as the basis of the piping design. Most designers understand that termination piping must be sized so […]

Relief Valve Replacement (Dual Assembly)

April 15th, 2025

This is an update to a blog that was originally posted on 3/10/15. You can read the original blog here. Question: Do both relief valves on a dual assembly have to be replaced every five (5) years, or just the relief valve that has been subject to system pressure? Answer: Most pressure vessels in an […]

Relief Valves Discharging Back into a Refrigeration System

March 18th, 2025

This is an update to a blog that was originally posted on 4/19/16. You can read the original blog here. ANSI/IIAR 2-2021 §15.3.10 outlines the requirements for providing Hydrostatic Overpressure Protection. In situations where thermal hydrostatic expansion of trapped liquid ammonia could occur, hydrostatic protection must be provided. Per ANSI/IIAR 2-2021 §15.3.10.1, Protection against overpressure […]