It was only a few years ago that ammonia refrigeration was considered a dangerous field of endeavor. Available training was little or nonexistent and was mainly performed by operators and others who had little or no formal training in the technology. This led to bad habits that were passed on to younger operators, who, in turn, added their own spin and bad habits. Operating procedures existed only in the operator’s head.
The Frick compressor shown in Figure 1 was a state-of-the-art unit in its day when refrigeration-system maintenance was a hit-or-miss proposition. Some systems were extremely well maintained. Others were held together with bailing wire and bubble gum; they presented serious hazards to workers and the environment. Nevertheless, many of these older ammonia compressors are still in use.
The lack of standardized operating procedures and training, combined with spotty maintenance, led to many injuries and accidents. The old adage, ”Garbage in, garbage out,” certainly applied. Unexpected releases of toxic, reactive or flammable liquids and gases have been reported for many years. Incidents continue to occur in various industries that use highly hazardous chemicals, such as anhydrous ammonia, which can be toxic, reactive, flammable, explosive, or a combination of these hazards (Figure 2).
History tells us that regardless of the industry using these chemicals, there’s a potential for an accidental release any time they’re not properly controlled. This, in turn, creates the possibility of disaster. Major disasters include the 1984 Bhopal incident resulting in more than 2,000 deaths; the October 1989 Phillips Petroleum Co. incident resulting in 23 deaths and 132 injuries in Pasadena, Texas; the July 1990 BASF incident resulting in two deaths in Cincinnati, Ohio; and the May 1991 IMC, Sterlington, La., incident resulting in eight deaths and 128 injuries.
Although these disasters focused national attention on major catastrophes, the public record is replete with many other less notable chemical releases. Chemical releases continue to pose a significant threat to employees and provide impetus, internationally and nationally, for legislation and regulations to eliminate or minimize the potential for such events.
Something needed to be done to address the industry’s safety issues. After several large disasters and an equal number of fatalities, our government stepped in. OSHA promulgated the Process Safety Management (PSM) program (29 CFR 1910.119) and the EPA promulgated 40 CFR Part 68, the Risk Management Program (RMP).
Employers and workers need to understand the OSHA definition of the word “process” in PSM and its requirements. The regulations define process as the using, storing, manufacturing, handling or moving of highly hazardous chemicals, as separate activities or in combination. Additionally, any group of interconnected vessels, as well as separate vessels that could be involved in a potential release of highly hazardous chemicals, are considered to be a process.
PSM applies to any ammonia refrigeration facility using a charge of 10,000 lbs. or more. Each facility must use the prescriptive 14 elements of PSM to develop its own program suitable for an ammonia refrigeration system. This requires a certain amount of higher-level expertise, which is sometimes supplied by outside consulting firms.
The ammonia refrigeration industry still suffers accidents from time to time. The fact is they occur less often and typically don’t involve fatalities, largely because of the PSM program and the EPA’s Risk-Management Program.
Process hazard analysis
A key provision of PSM is the process hazard analysis (PHA). It’s a careful review of what could go wrong in your plant and what safeguards you must implement to prevent an ammonia release. Plants must identify those ammonia processes that pose the greatest risks and begin evaluating them first. After completing the process hazard analysis, you must update and revalidate it at least every five years to ensure that it remains consistent with the current ammonia operations.
The human factor
One current trend seems to be one of addressing PSM requirements by automating old systems as must as possible and by designing new systems that require less operator intervention. However, nothing can replace humans when it comes to visual checks and observations. The quality of the training and knowledge you provide to workers goes a long way in having someone on staff who knows what to look for, or by simply walking through the plant and discovering a potential problem.
Newer, more efficient equipment design has continued to improve the ammonia industry’s image. Equipment manufacturers also have learned from our mistakes and offer much safer ammonia handling equipment. As equipment becomes more sophisticated, so does the education and training required to service and repair these systems.
The unfortunate truth is that the industry doesn’t attract enough people seeking to hone their refrigeration skills. It’s not at the top of anyone’s list of top ten fields of interesting work. Consequently, most are promoted and reassigned from within and it’s not always a well-received job change to be made a new operator. In many cases, it’s a matter of a manager saying, “You’re it.”
Working with ammonia refrigeration systems every day has revealed to us the truth about this still-growing industry. A well-qualified ammonia refrigeration technician can make a good income. Well-trained operators are in high demand, as are technicians and design engineers. Industry has improved its safety and training levels and offers a more organized trade format to include state-of-the-art computer control systems and safer, more dependable valves and safety devices.
Process safety management requires that each employee operating an ammonia refrigeration system must receive a process overview and be trained in its specific operating procedures. Employers must provide refresher training at least every three years -- more, if necessary -- to ensure workers understand and adhere to the current operating procedures.
Furthermore, you must determine whether workers who operate an ammonia process have received and understood the PSM-mandated training. You’ll need to keep a record of employees, the dates of their training and the measures you took to verify that they understood the training.
Being trained using up-to-date course materials is of concern to everyone who teaches operators, technicians, engineers and others how to operate ammonia refrigeration systems safely. Many good sources exist and are known within the industry.
The control and operation of ammonia refrigeration systems has changed extensively during the past few years. The information requirements, improved training programs, enhanced maintenance and integrity checks, along with analysis of the potential vulnerabilities, have led to safer, more reliable systems. A large contributor to these changes has been increased awareness resulting from OSHA’s Process Safety Management program.
With halocarbon-based refrigerants being phased out, ammonia is rising to the top as the most popular refrigerant for large applications. We keep our finger on the pulse of the ammonia industry and work in it daily in all of its many aspects. So from someone with a positive view on the current status of our trade, things are looking up and there is most definitely a silver lining.
Maybe some of the refrigeration technicians seeking to advance their careers should take another look at ammonia refrigeration. We hope to meet you out there learning and practicing our beloved craft.
Richard M. Dumais and Chris Harmon are instructors and consultants at the Ammonia Refrigeration Technicians Association, Danville, Ind. contact them at firstname.lastname@example.org and (317) 272-7336.