IIAR 9 and the MSSE Requirement Explained: The Nuts and Bolts Of TheCompliance Obligation By January 1, 2026 | Blog 108

For facilities operating ammonia refrigeration systems, January 1, 2026, is more than a

future date on the calendar. It represents a clear line between proactive compliance and

regulatory exposure. By that date, existing ammonia refrigeration systems are expected

to have completed a Minimum System Safety Evaluation (MSSE) in accordance with

IIAR 9.

This is not a theoretical expectation or an optional safety exercise. Failing to complete

An MSSE is a compliance issue with real implications under OSHA enforcement.

including the General Duty Clause, and EPA’s Risk Management Program.

Understanding who must comply, what the MSSE is, when it applies, and why it matters

is essential for responsible system ownership.

What Is a Minimum System Safety Evaluation?

A Minimum System Safety Evaluation is a structured, engineering-based assessment of

An ammonia refrigeration system that is already operating. IIAR 9 defines the MSSE as

a systematic evaluation intended to identify safety-related deficiencies in the design,

installation, condition, and operation of an existing system (International Institute of All-

Natural Refrigeration [IIAR], 2021c).

An MSSE is not limited to reviewing drawings or operating procedures. It requires a field

verification, evaluation of system safeguards, and professional judgment to determine

whether the system presents unacceptable risks to personnel, emergency responders,

or the surrounding community.

At its core, the MSSE exists to answer a simple but critical question:

Is this system safe enough to continue operating as it is today?

When a System Becomes an “Existing System”

One of the most important concepts in IIAR 9 is when a system falls under its

guidance.

Once an ammonia refrigeration system is built, tested, and placed into service, it is

considered an existing system. From that point forward, it falls under IIAR 9 for safety

evaluation purposes.

This applies universally:

● System size does not matter.

● System age does not matter.

A system that was commissioned last year is an existing system today. A small

ammonia system is no less subject to evaluation than a large one. The act of placing

the system into operation is what triggers IIAR 9 applicability.

Who Must Perform an MSSE?

Facilities operating industrial ammonia refrigeration systems are required to address the

MSSE expectation, including:

● Facilities covered by OSHA’s Process Safety Management (PSM) standard

● Facilities not covered by PSM but regulated under OSHA’s General Duty

Clause

Using IIAR 1 definitions, industrial ammonia refrigeration systems include closed-circuit

systems using ammonia for manufacturing, processing, storage, or distribution rather

than comfort cooling (IIAR, 2020).

Facilities commonly affected include:

● Cold storage warehouses

● Food and beverage processing plants

● Meat, poultry, and seafood facilities

● Dairies and ice cream manufacturing plants

● Refrigerated distribution centers

● Ice rinks and industrial freezers using ammonia

Facilities below PSM charge thresholds are often surprised to learn they are still

exposed. OSHA has consistently treated ammonia refrigeration hazards as recognized

hazards, making IIAR standards relevant under the General Duty Clause (Occupational

Safety and Health Administration [OSHA], 2023).

Where IIAR 9 Applies

IIAR 9 applies wherever an industrial ammonia refrigeration system is installed and

operating. This includes:

● Machinery rooms, as defined by IIAR 1

● Engine rooms

● Rooftop ammonia systems

● Process cooling systems integrated into production

Adoption into local code is not the deciding factor. IIAR standards are widely recognized

as generally accepted good engineering practices, which gives them regulatory weight

regardless of jurisdiction.

IIAR 2 vs. IIAR 9: Design Versus Continued Operation

IIAR standards are often misunderstood as overlapping or interchangeable. They are

not.

IIAR 2: How the System Is Built

IIAR 2 governs the design and installation of closed-circuit ammonia refrigeration

systems (IIAR, 2021b). It applies during construction, major modifications, and

expansions.

It answers the question:

How should this system be designed and installed safely?

IIAR 9: Whether the System Is Safe to Keep Running

IIAR 9 applies after the system is placed into service. It introduces the MSSE as a

way to evaluate existing systems against current safety expectations without requiring

full redesign.

It answers a different question:

Does this operating system present an unacceptable risk?

Once a system is operational, IIAR 9—not IIAR 2—becomes the governing standard for

safety evaluation.

Why Not Completing an MSSE Is a Compliance Issue

Failing to complete an MSSE is not simply a missed best practice. It is a failure to

address recognized hazards using recognized methods, which is the foundation of

both OSHA and EPA enforcement.

OSHA Enforcement and the General Duty Clause

Under OSHA’s General Duty Clause, employers must protect workers from recognized

hazards when feasible means of abatement exist. Ammonia refrigeration hazards are

well documented, and IIAR standards define accepted industry controls.

An MSSE is one of the clearest demonstrations that a facility has identified and

evaluated those hazards. Without it, a facility has little defense against allegations that

known risks were ignored. Following an incident, OSHA routinely asks whether the

system was evaluated against current industry standards. If the answer is no, citations

often follow (OSHA, 2023).

EPA Expectations Under the Risk Management Program

EPA’s Risk Management Program requires facilities to identify hazards and prevent

accidental releases of regulated substances, including ammonia (40 CFR Part 68). An

MSSE directly supports these objectives.

When an ammonia release occurs, EPA investigators examine whether the facility

assessed system vulnerabilities and addressed known deficiencies. The absence of an

MSSE makes it difficult to demonstrate compliance with prevention requirements (U.S.

Environmental Protection Agency [EPA], 2023).

In short, not completing an MSSE leaves a compliance gap that is difficult to

defend after an incident.

Why the January 1, 2026, Deadline Matters

The January 1, 2026, date exists to give facilities time to evaluate systems and correct

deficiencies before they lead to harm. MSSE findings often result in corrective actions

that require engineering, budgeting, and scheduling.

Waiting until the deadline—or until after an incident—removes flexibility and increases

risk. Completing an MSSE early allows facilities to plan improvements thoughtfully

rather than react under regulatory pressure.

Final Thoughts

By January 1, 2026, facilities operating ammonia refrigeration systems are expected to

have completed an MSSE in accordance with IIAR 9. Once a system is built, tested,

and placed into service, it is considered an existing system under IIAR 9 guidance.

System size and age do not change this obligation.

This expectation applies to facilities covered by OSHA’s PSM standard and those

regulated under the General Duty Clause. The MSSE is not optional, and it is not

merely advisory. It is a recognized method of addressing known hazards and

demonstrating regulatory responsibility.

Taking action now is not just the safer choice. It is the compliant one.

References

International Institute of Ammonia Refrigeration. (2020). IIAR 1: Definitions and

terminology used in ammonia refrigeration. IIAR.

International Institute of Ammonia Refrigeration. (2021b). IIAR 2: Standard for safe

design of closed-circuit ammonia refrigeration systems. IIAR.

International Institute of Ammonia Refrigeration. (2021c). IIAR 9: Standard for existing

ammonia refrigeration systems. IIAR.

Occupational Safety and Health Administration. (2023). Occupational Safety and Health

Act of 1970, Section 5(a)(1): General Duty Clause. U.S. Department of Labor.

U.S. Environmental Protection Agency. (2023). Risk management programs under the

Clean Air Act (40 CFR Part 68).

Thank you for reading!

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