Refrigeration Insights Series. Season 3: The IIAR Standards, Installment 6 of 10.
How often should an ammonia compressor be inspected? What records should be kept of each intervention? Is the manufacturer's manual enough? For years, every plant answered these questions its own way. ANSI/IIAR 6 exists so that the answer does not depend on each facility's habits, and its 2025 edition has just been published.
What Is IIAR 6
The standard specifies the minimum requirements for the inspection, testing and maintenance (ITM) of closed-circuit ammonia refrigeration systems. Its scope includes the ITM tasks themselves and something just as important: the recordkeeping of those tasks, for both the system and the auxiliary equipment.
Two applicability limits that organize the family of standards: IIAR 6 does not apply to commissioning and startup (that is IIAR 5) or to decommissioning (IIAR 8). And a clarification from the text itself that is worth quoting in full: the standard is neither an exhaustive technical inspection manual nor does it constitute written mechanical integrity procedures. It defines the floor; your procedures implement it.
How It Is Organized
The core of the document is remarkably practical. Chapter 5 sets out the general provisions: the ITM program requirements, the frequencies and the recordkeeping requirements. From there on, one chapter per type of equipment: compressors, refrigerant pumps, condensers, evaporators, pressure vessels, piping, valves and the rest of the system components.
For each piece of equipment, the standard lists the inspection, testing and maintenance tasks with their frequency. It is, in practice, the skeleton of an auditable maintenance plan: you take the chapters that apply to your plant, cross-reference them with your manufacturers' manuals, and you have a program you can defend in any audit.
The Appendices That Are Worth a Course
The 2025 edition includes informative appendices that are small technical treatises:
Appendix B: water contamination in ammonia systems. Readers of this series already know the subject: water raises the evaporating temperature, degrades efficiency and accelerates corrosion. That the maintenance standard devotes an appendix to it confirms its status as the number one silent enemy.
Appendix C: how to prevent component failure due to abnormal pressures or shocks. Water hammer and its relatives, which we covered in depth last season.
Appendix D: risk-based ITM. The gateway to modern maintenance programs, where inspection frequency is adjusted according to each piece of equipment's criticality and condition.
Records: Half the Job
A common thread runs through the entire standard: without a record, the task does not exist. The ITM program requires documenting what was done, when, by whom and with what result. In an inspection by the authorities or an insurance claim, the maintenance log is worth as much as the maintenance itself.
Practical advice
Download the index of IIAR 6-2025 and use it as a gap checklist: for each equipment chapter that applies to your plant, ask yourself whether you have a task, a frequency and a record defined. Wherever one of the three is missing, there is your work plan for the next quarter. And if your program is still based on the 2019 edition, it is time to update the reference.
Next week: IIAR 7-2025, operating procedures, or how to write the routine that keeps the system alive.
Source: ANSI/IIAR 6-2025, Standard for Inspection, Testing, and Maintenance of Closed-Circuit Ammonia Refrigeration Systems, International Institute of Ammonia Refrigeration. Thermomac is a corporate member of the IIAR.
