Recent Blog Posts

Ammonia Release | Stress Cracking

April 29th, 2025

Summary In August 2016, the sudden breaking of a valve on an ammonia pump resulted in a release of 34-284 lbs of ammonia. The root cause was determined to be a stress crack that formed at the threads of a valve, ultimately leading to the top of the valve shearing off.  Incident Description The ammonia […]

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 […]

Ammonia Release | Service Valve Hole

April 1st, 2025

Summary In June 2016, a hole developed in the nipple of a ½” service valve, resulting in a release of 1,224 lbs of ammonia. The service valve, installed on a liquid transfer vessel, began leaking liquid ammonia into the machinery room. Incident Description Long-term, chronic corrosion caused a 1.5 mm hole to develop in the […]

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 […]

Ammonia Release | Roof Collapse

March 4th, 2025

Summary In December 2016, a roof collapse resulted in a release of approximately 24,000 lbs of ammonia. Two (2) ceiling-suspended evaporators were hung from the roof and fell to the ground when the structure collapsed.  Incident Description During a heavy rainstorm, the roof over a cold storage room collapsed. Two (2) ceiling-suspended evaporator coils fell […]