[This blog series derives from a technical paper written by Eli Macha, President of Macha PSM]
Mechanical Integrity (MI) is integral to a solid ammonia refrigeration PSM program. Furthermore, the topic is expansive. For this reason, the scope of this paper is restricted from giving this important area the treatment it deserves. If you are looking to reinvigorate or establish a mechanical integrity program, there are two primary tasks: get the right people aboard and centralize the mechanical integrity records.
First, you must ensure you have the necessary manpower to implement the program. This can be completed with operators, contractors, or a combination of the two. Ensure the people on the team are properly trained and experienced in order to complete the tasks they are required to perform.
Next, facilities must have access to their mechanical integrity records. For many facilities, they may be able to locate their last 5-year mechanical integrity audit (MIA) in their PSM folder, binder, or software, but not much else. Perhaps the daily logs are in a dusty binder somewhere and have never been digitized. The annual IIAR 6 checklists are similarly completed and placed in a storage closet. Contractors have come out to complete vibration and oil analyses, but the reports are hiding away in someone’s email inbox. The PSM Coordinator must take on the uphill battle of centralizing all these documents. The reason is not solely for organization, but it is also the only way to ensure the necessary follow up actions are being taken. It is extremely common for facilities to finally locate all of their MI records only to discover they have 20+ important action items that they never followed up on.
After the right MI team is in place and records are being centrally stored, the PSM Coordinator must ensure they are checking the boxes from ANSI/IIAR 6-2019 American National Standard for Inspection, Testing, and Maintenance of Closed-Circuit Ammonia Refrigeration Systems. Failing to complete certain activities will be leaving low-hanging fruit on the tree for regulators to easily pick off. While it is not an exhaustive list, here is a cheat sheet for the most important ITM tasks:
Daily Logs[1]
Annual IIAR 6B Inspection Checklists [ANSI/IIAR 6-2019 Appendix B]
5-Year Mechanical Integrity Audit [ANSI/IIAR 6-2019 §5.4.2]
Annual E-Stop Test [ANSI/IIAR 6-2019 Table 12.2 Testing Item A]
Annual Compressor Cutouts Test [ANSI/IIAR 6-2019 Table 6.1 Testing Items A-D]
Annual High Level Float Switch Test [ANSI/IIAR 6-2019 Table 6.1 Testing Item E]
Annual Vibration Analysis/Compressor Alignment [ANSI/IIAR 6-2019 Table 6.1 Inspection Item Y]
Annual Oil Analysis or Replacement [ANSI/IIAR 6-2019 Table 6.1 Maintenance Item D]
Six-Month Ammonia Sensor Calibrations [ANSI/IIAR 6-2019 Table 12.3 Testing Item A]
Annual Ventilation System Test [ANSI/IIAR 6-2019 Table 12.1 Testing Items A-G]
Annual Exercising and Lubricating System Emergency Shut-Off Valves [ANSI/IIAR 6-2019 Table 11.1.6 Maintenance Item B]
5-Year Exercising and Lubricating Non-Emergency Shut-Off Valves [ANSI/IIAR 6-2019 Table 11.1.6 Maintenance Item C][2]
If the activities listed below are completed at the specified frequency, documented, and recommendations are being completed in a timely manner, then the PSM Coordinator can begin optimizing their MI program. There are several ways to do this. First, take the current version of IIAR 6, review the normative section in its entirety, and perform a gap analysis of your MI program. While the aforementioned list of MI activities takes care of the big rocks, there is plenty of minutiae for each facility to hammer out.
A facility may also take advantage of certain automations if they are seeking to become more efficient. As long as they are reviewing data as necessary, this may free up some time for their operators.[3] While there are differing opinions on the matter, there is much to be said for utilizing a separate contractor or consultant to perform annual inspections and the 5-year mechanical integrity audit.[4]
There are two additional ways to optimize your MI program. After implementing the program in alignment with IIAR 6 for a period of time, facilities have the flexibility to lengthen or shorten the frequency of tasks based on their operating history.[5] If your operators are checking the operation of the compressor unloaders every month, but never find any issues, they may consider extending the frequency to quarterly. Or—on the other hand—if operators are only checking the condenser fans semi-annually, and every time they do they find issues, they may increase the inspection frequency to monthly or quarterly.
Finally, IIAR 6 also allows for facilities to utilize a risk-based ITM schedule.[6] What this means is that a facility recognizes that not all equipment (or risk) is created equal. For example, while all piping is required to be inspected on an annual basis, a facility may observe the inherent risk associated with the piping pressure, the state of ammonia in the pipe, and whether or not it is insulated, in its determination of the inspection frequency. Uninsulated pipe, generally, is at less risk of corrosion since it would not be subject to corrosion under insulation (CUI). Consider the following risk-based ITM models developed by the Industrial Refrigeration Consortium:
Comparative mechanical integrity risk levels for insulated piping (high=1 & low=5)[7]
Piping Type | Paint/Coating | Operating Temperature | Risk |
Liquid piping (all pressure levels) | Unpainted/ uncoated | Below ambient dew point temperature but above 32°F (0°C) | 1 |
Two-phase (liquid & vapor) piping | |||
Liquid and two-phase piping (all pressure vessels) | Periodically cycling in temperature | ||
Vapor piping (medium & low pressure) | Unpainted/ uncoated | Below ambient dew point temperature but above 10°F (-12°C) | 2 |
Periodically cycling in temperature | |||
Liquid piping (all pressure levels) | Painted/coated | Below ambient dew point temperature but above 10°F (-12°C) | 3 |
Two-phase (liquid & vapor) piping | |||
Liquid and two-phase piping (all pressure levels) | Periodically cycling in temperature | ||
Vapor piping (medium & low pressure) | Unpainted/ uncoated | Below 10°F (-12°C) | 4 |
Two-phase (liquid & vapor) piping | |||
Liquid piping (all pressure levels) | Painted/coated or unpainted/ uncoated | Below 10°F (-12°C) | 5 |
Vapor piping (high, medium, & low pressure) | Painted/coated | ||
Two-phase (liquid & vapor) piping |
1] A lot goes into auditing daily logs, but here are some quick tips: (1) flip through and make sure the daily logs are being completed consistently, (2) verify the recorded values align with the safe upper and lower limits of equipment, (3) make sure compressors, condensers, auto-purgers, and refrigerant pumps are included in the daily log (everything else has a frequency less than daily).
[2] This list was originally published on the Macha PSM blog: https://www.machapsm.com/post/auditing-mechanical-integrity-i-m-giving-away-my-cheat-sheet-blog-no-26.
[3] ANSI/IIAR 6-2019 §5.3.4
[4] The 2021 RETA National Conference technical paper titled “IIAR 6: Should I Hire a Contractor or Keep it In-House?” gave this topic a more thorough treatment.
[5] ANSI/IIAR 6-2019 §5.2.1
[6] ANSI/IIAR 6-2019 §5.1.5
[7] Douglas T. Reindl, Principles and Practices of Mechanical Integrity Guidebook for Industrial Refrigeration Systems (Madison, WI: Industrial Refrigeration Consortium, 2016), 4-73 (Table 4-3). This chart is reproduced with the express permission of the Douglas T. Reindl of the Industrial Refrigeration Consortium.
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