Ammonia refrigeration facilities under 10,000 lbs often assume they’re “not regulated.” because they fall below the formal PSM/RMP thresholds. But under the General Duty Clause (GDC), the EPA still expects these facilities to identify hazards, maintain a safe system, and prevent accidental releases. While GDC sites are less likely to receive random “lottery” inspections, they will be thoroughly inspected if a release occurs. If you have onsite or offsite consequences, your fa

As the January 1 federal requirement approaches, ammonia refrigeration facilities are working to complete the required Minimum System Safety Evaluations (MSSEs) as part of their overall safety and compliance programs. MSSEs provide a structured approach for evaluating the equipment, components, and systems that are essential to maintaining safe ammonia refrigeration operations. An MSSE covers a wide range of system elements, including vessels, piping, valves, compressors, con

An ammonia refrigeration system operates in two main sections, the high side and the low side. Understanding where one begins and where one ends is key to understanding P&IDs, troubleshooting, and maintaining the system. The primary difference between the two sides is energy and pressure. The high side contains ammonia at higher pressure and higher temperature, as the name suggests, while the low side operates at lower pressure and temperature. The High Side The high side sta

As the saying goes, hindsight is 20/20.  Very often, when an ammonia release occurs, we find that the incident is not addressed in our “what-if” PHA studies.   We perform our incident investigation and realize that the root cause of the release was there all along and was something that could (or should) have been easy to foresee.  But why was it not so obvious when we were conducting our PHA? What did we miss?  Why do we not see the obvious? The following are some tips and s

Last week, our team at Macha PSM had the privilege of attending the 2025 RETA Conference — one of the most energizing and informative events in the ammonia refrigeration and process safety community. It’s always inspiring to gather with professionals who share the same goal we do: keeping people safe, facilities efficient, and programs strong. From the moment we arrived, it was clear that this year’s conference was all about connection and learning from one another, exchangin

When most people think about Process Safety Management, the first things that come to mind are inspections, training, and compliance deadlines. But one of the biggest and most overlooked challenges is poor documentation. Missing or outdated records may seem like a minor issue, but over time, they can lead to significant problems, including delays, audit findings, and unnecessary expenses. 1. The Real Cost of Missing Information In ammonia refrigeration and other industrial sy

In this article, I will explain the basic principles of Postweld Heat Treatment (PWHT), why it is used in the fabrication of pressure vessels, and how to use this information in pressure vessel inspections.  The rules for PWHT are found in the ASME pressure vessel code, and I caution you that this article is basic information and in no way comprehensive .  If you have a question about a particular vessel, seek advice from the original manufacturer or a repair/alteration organ

Last week, we shared a breakdown of the U.S. Chemical Safety Board’s (CSB) final report on the hazardous ammonia release at Cuisine...

The Chemical Safety Board (CSB) recently released its final report on the hazardous ammonia release at Cuisine Solutions, a food...

Graduating in May 2025, I found myself wondering what industry my first engineering job would be in and whether I would even enjoy it...

At Macha PSM, we work with facilities across the country to help them manage process safety for ammonia refrigeration systems. While much...

A site map is a scaled drawing that shows the layout of a facility. It includes buildings, process areas, storage locations, and access...

Are refrigeration materials of construction interchangeable?  Can you replace carbon steel that is installed in an area prone to...

Lockout/Tagout/Tryout (LOTOTO) is a critical safety practice, especially in ammonia refrigeration systems, to prevent accidental release...

A block flow diagram (BFD) is a high-level process diagram used to represent the major steps in a chemical or industrial process. As the...

[This is three of three in a "Now What?" blog series by Chris Foster, a Macha PSM Consultant] If you missed our previous instalment of...

I’m only 19 years old. I’ve been in the PSM and ammonia refrigeration industry for about a year and a half. In that short time, I’ve...

When we think of inspecting pipe supports , we go immediately to damage or deterioration, and we should.  Far less often do we consider...

[DISCLAIMER: This blog series is not a comprehensive Safety Data Sheet. You MUST refer to the appropriate SDS for your facility’s Ammonia...

[DISCLAIMER: This blog series is not a comprehensive Safety Data Sheet. You MUST refer to the appropriate SDS for your facility’s Ammonia...