RETA Breeze Jul-Aug 2025

original charge for their inventory for a LONG time. As I looked through their PSI, I thought there was no way it was correct.

diagrams can provide a quick reference to determine which part of the system I need to look at. Then I can “zoom” in with P&IDs. Second, block flow diagrams are a vital training tool for new operators. It should be a detailed part of a training program. It’s a great resource for new operators to trace the workings of the system and under stand the overall system flow. I often catch this as being missed in MOC’s when equipment is added, removed, or replaced. See the diagram on p. 32. PROCESS CHEMISTRY We need process chemistry to know what’s going on inside the pipes. Too many times, people say things like, “An ammonia refrigeration system acting in a Carnot cycle…” Very few people remember Sadi Carnot (except my dad). Be descriptive in your notations: ammonia is doing what, where and why. DX differs from flooded, just as flooded evaporators are different from overfeed evaporators. Add details to help the operator under stand what is going on in your process. MAXIMUM INTENDED INVENTORY There is a difference between the maximum intended inventory, and the operating charge. Maximum intended inventory is the amount of ammonia your system will hold taking into account administrative controls. This is the maximum charge level you would charge the system to. You would never charge every vessel 100% full, so don’t use 100% vessel levels in your calculation. In most systems, the only vessel that is designed to have a varying level is the high pressure receiver. Use the highest level you would charge to with the system operating normally. Why not use operating level? It changes daily. Every time your purger cycles, you drain oil, or ammonia breaks down microscopically, and your operating charge changes, though by very small amounts. Your operating charge is a snapshot in time. I’ve seen many facilities that use their initial charging record as their inventory calcula tion. There is sound thought in that until you need to top off the system. Then what do you do? Add the amounts together? No, that’s not right. Assume that you charged exactly what you lost over time? How can you justify that during an inspection? I know of a facility team that used their

(D) Safe upper and lower limits for such items as temperatures, pressures, flows or compositions; and (E) An evaluation of the conse- quences of deviations, including those affecting the safety and health of employees. (i) Information pertaining to the equipment in the process shall include: (A) Materials of construction; (B) Piping and instrument diagrams (P&IDs); (3) Information pertaining to the equipment in the process. (C) Electrical classification; (D) Relief system design and design basis; (E) Ventilation system design; (F) Design codes and standards employed; (G) Material and energy balances for processes built after May 26, 1992; and (H) Safety systems (e.g., interlocks, detection or suppression systems). HIGHLY HAZARDOUS CHEMICALS IN THE PROCESS “Toxicity information; permissible exposure limits; physical data; reactivity data; corrosivity data; thermal and chemical stability data; and hazardous effects of inadvertent mixing of different materials that could foreseeably occur.” Sounds like a Safety Data Sheet (SDS) to me. I always encourage customers of mine to include a reference to the SDS EVERYWHERE. Include it in your program or reference it from your HAZCOM program. If you want to go world class, use IIAR’s Ammonia Data Book, the definitive source for ammonia as a refrigerant. All of these, I use as references in the coversheet of SOPs, it covers it all. A BLOCK FLOW DIAGRAM OR SIMPLI FIED PROCESS FLOW DIAGRAM This type of tracking is often overlooked. I’ve had safety professionals ask, “Why do I need a block flow when I have piping and instrumentation diagrams (P&IDs)?” I have two reasons. First, block flow

Eventually, they had probably four recommendations between PHAs,

compliance audits and an EPA inspection to verify this. Turns out I was right. The facility had 4,000 pounds more than what they thought based off of controls. Then, I was able to put the “are we over the threshold or not” debate to bed. Don’t get me started on that one. So, take the time to develop a true maximum intended inventory, and maintain it utilizing your MOC program. SAFE UPPER AND LOWER LIMITS FOR TEMPERATURES, PRESSURES, FLOWS OR COMPOSITIONS This is simpler than it sounds. Most often, this is an element within our SOPs/ technical operating specifications (TOS). This is also outlined in operation and maintenance manuals. Our equipment list (IIAR-6 equipment forms) contain many elements as well. Compositions are an interesting element of this. I would suggest that you include limits for water content, glycol concentrations, brine concentrations, as well as non-con densable limits in your documentation. These are often missed until asked for by an inspector. There is an argument to be made for the inclusion of acceptable ranges for oil analysis and vibration analysis. I prefer to have this dictated by a reputable oil analysis company and a reputable vibration analysis company. AN EVALUATION OF THE CONSE QUENCES OF DEVIATIONS These are also normally included in SOP/ TOS, and manufacturer’s operation and maintenance manuals. Here is the quick check of things I look for. If the safe limits are exceeded, do my SOPs give my operators instructions on what to do? Also, do they know the consequences of being out of range? If so, you’re probably good. If not, your program needs work. MATERIALS OF CONSTRUCTION This requirement seems to cause a lot of confusion. I think most people either go

RETA.com 31