Ammonia (R-717) has been a longtime, popular refrigerant choice in industrial facilities, such as cold storage warehouses, food processing plants, and chemical manufacturing plants. Now with increased regulatory activity on fluorocarbon refrigerants (i.e., HCFCs and HFCs), even more interest has grown with ammonia as a refrigerant.
The caveat, however, with this refrigerant is that it is a high health hazard, and releases of it pose a significant threat to personnel. Therefore, it needs to be properly managed. In fact, certain practices must be followed during the operation and maintenance of ammonia refrigeration systems.
While there are many safety and environmental laws on ammonia, in this article, we will focus on OSHA’s Process Safety Management (PSM) Standard (29 CFR 1910.119) and its requirements. Compliance with the PSM standard helps ensure that personnel are kept safe. Let’s get started.
How Does OSHA Define Process?
First, to understand this standard and its requirements, one must consider how OSHA uses the term “process” in PSM.
Process means “any activity involving a highly hazardous chemical including any use, storage, manufacturing, handling, or the on-site movement of such chemicals, or combination of these activities. For purposes of this definition, any group of vessels which are interconnected and separate vessels which are located such that a highly hazardous chemical could be involved in a potential release shall be considered a single process.”
Keeping this in mind, let’s move on to when a facility is covered by OSHA PSM.
When Is an Ammonia Refrigeration System Covered by OSHA PSM?
Ammonia refrigeration systems that have 10,000 pounds of ammonia (approximately 2,000 gallons) or more are subject to OSHA’s process safety management requirements. Specifically, this PSM standard is applicable to ammonia manufacturers and facilities with large ammonia refrigeration systems; it does not apply to retail facilities.
|Chemical||Threshold Quantity||Typical Uses / Sources|
|Anhydrous Ammonia||10,000 lbs||Industrial refrigeration|
Regardless of whether your refrigeration is covered by this standard, the requirements are recommended practices and thus those a part of industrial ammonia refrigeration applications should be familiar.
What Must a Covered Facility Do?
While there are many elements of the PSM standard (14 in total), we will focus on the ones that are particularly relevant to the hazards associated with industrial ammonia refrigeration systems:
- Process Safety Information (PSI)
- Process Hazards Analysis (PHA)
- Operating Procedures
- Mechanical Integrity (MI)
- Compliance Audits
Process Safety Information
An employer must complete a compilation of written process safety information (PSI) before conducting any process hazard analysis (PHA) required by the PSM standard.
Per 29 CFR 1910.119, the compilation of written process safety information is to enable personnel involved in operating the process to identify and understand the hazards posed by, in this case, ammonia.
The process safety information must include information pertaining to the hazards of the ammonia refrigerant used, information pertaining to the technology of the process, and information pertaining to the equipment in the process.
PSI is the information necessary for all other elements of PSM. Compilation of PSA provides the foundation for identifying and understanding the hazards of a process and is necessary in developing a process hazards analysis (PHA), which we will discuss next:
Process Hazard Analysis
A process hazard analysis must be performed on processes covered by the PSM standard. Such analysis must identify, evaluate, and control the hazards involved in the process.
An employer must conduct an initial process hazard analysis and, at least every five years thereafter, the process hazard analysis must be updated and revalidated by a qualified team to assure that the process hazard analysis is consistent with the current process.
One or more of the following methods must be used to determine and evaluate the hazards of the process being analyzed:
- Hazard and operability study (HAZOP);
- Failure mode and effects analysis (FMEA);
- Fault tree analysis; or
- An appropriate equivalent methodology.
Whichever method(s) are used, the process hazard analysis must address the following:
- The hazards of the process;
- The identification of any previous incident that had a potential for catastrophic consequences in the workplace;
- Engineering and administrative controls applicable to the hazards and their interrelationships, such as appropriate application of detection methodologies to provide early warning of releases. (Acceptable detection methods might include process monitoring and control instrumentation with alarms, and detection hardware.);
- Consequences of failure of engineering and administrative controls;
- Facility siting;
- Human factors; and
- A qualitative evaluation of a range of the possible safety and health effects on employees in the workplace if there is a failure of controls.
The process hazard analysis is the key provision of this standard. It should be performed by a team with expertise in engineering and process operations, and such team should include at least one employee who has experience with and knowledge of the process being evaluated. Also, one member of the team must be knowledgeable in the specific process hazard analysis methodology being used.
A facility must establish a system to promptly address the team’s findings and recommendations; assure that the recommendations are resolved in a timely manner and that the resolution is documented; document what actions are to be taken; complete actions as soon as possible; develop a written schedule of when these actions are to be completed; communicate the actions to operating, maintenance and other employees whose work assignments are in the process and who may be affected by the recommendations or actions.
Process hazard analyses and updates or revalidation for each process covered by PSM, as well as the documented resolution of recommendations, must be kept on file for the life of the process.
An employer shall develop and implement written operating procedures that provide clear instructions for safely conducting activities involved in each covered process consistent with the process safety information and must address the steps for each operating phase; operating limits; safety and health considerations; and safety systems and their functions. (See 29 CFR 1910.119(f) for full details on these elements.)
Mechanical Integrity (MI)
It is a priority of the PSM standard to maintain the mechanical integrity (MI) of critical process equipment to ensure it is designed and installed correctly and operates properly. Such MI requirements apply to the following equipment:
- Pressure vessels and storage tanks;
- Piping systems (including piping components such as valves);
- Relief and vent systems and devices;
- Emergency shutdown systems;
- Controls (including monitoring devices and sensors, alarms and interlocks) and;
Of particular interest to us here at Bacharach is the “controls” part of the Mechanical Integrity section, which is clarified as “including monitoring devices and sensors, alarms and interlocks” (29 CFR 1910.119(j)(v)). This is because our ammonia refrigerant detectors and monitors, like the MGS-400 Gas Detection Series, are applicable.
Engineered for use in cold storage facilities, MGS-400 gas detectors feature ammonia-specific sensors and are flush mounted in the enclosure to optimize the response time. For instance, when ammonia is detected, the leak detectors integrated audio/visual alarms alert personnel to the leak.
Now, to get back to the point, an employer must establish and implement written procedures to maintain the ongoing integrity of process equipment. Inspection and testing must be performed on process equipment, following recognized and generally accepted good engineering practices.
An employer must certify that they have evaluated compliance at least every three years to verify that the procedures and practices developed under the standard are adequate and are being followed.
It is important to determine and document an appropriate response to each of the findings of the compliance audit, and document that deficiencies have been corrected.
The two most recent compliance audit reports should be on-hand.
How Long Must I Follow These Requirements?
The PSM Standard is not a one-time occurrence; rather, it is a continuous program that should be sustained as long as a facility is operating a covered industrial ammonia refrigeration system.
|PSM Element||On-going Requirement||Frequency|
|Employee Participation||Employees involved||Continuous|
|Process Hazard Analysis||Update and re-validate||5 Years|
|Operating Procedures||Certified current||Annually|
|Training||Refresher training||3 Years|
|Contractors||Evaluate contractor performance||Periodically|
|Mechanical Integrity||Inspections and tests||Periodically|
|Management of Change||Update program during plant changes||As-needed|
|Incident Investigation||Investigate and develop recommendations||As-needed|
|Compliance Audit||Audit PSM program||3 Years|
Therefore, the question should not be framed as how long but how best.
Ensure Proper Maintenance and Safe Operating Procedures for Compliance
In sum, we’ve highlighted a few important elements from OSHA PSM for industrial ammonia refrigeration systems, but keep in mind that there are 14 elements in total that one should be familiar.
Importantly, throughout the PSM Standard, ammonia refrigerant detection plays an important role, and that’s where Bacharach is here to help. In fact, check out our range of refrigerant detectors and monitors for ammonia via our handy Gas Selector Tool.
Ultimately, performing proper maintenance and ensuring safe operating procedures with industrial ammonia refrigeration systems is the key to OSHA PSM compliance and ammonia refrigerant leak prevention. ∎
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How does your facility best ensure compliance with ammonia PSM requirements? Let us know in the comments below or by emailing us at email@example.com.