Southstar Logistics, Inc. - Executive Summary |
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Executive Summary Southstar Logistics, Keller, Texas Cold Storage Warehouse Ammonia Refrigeration System The Southstar Logistics, Inc. facility located in Keller, Texas is a warehouse for both non-refrigerated and refrigerated products. Approximately 235,000 square feet of the entire facility is for the storage of refrigerated products. The refrigerated products are usually held for from a few days to a few weeks before being shipped to various Grocery stores throughout the greater Dallas Fort Worth area. The facility and the refrigeration system is specifically designed with many different rooms and temperatures to maintain the highest quality of products, and their shelve life. Storage temperatures range from +55(F to -10(F. There are also banana-ripening rooms that typically operate around 58 to 60(F. Because of its high efficiency and ease of operation, ammonia is used as the refrigerant for the refrigeration system. The system has been in operation since approximately 19 83. Although Southstar Logistics has only operated the facility for less than one year, the previous five-year history of the ammonia system is that no releases of ammonia have occurred. The Southstar Logistics management team is committed to maintaining and operating the refrigeration system in a safe and efficient manner. Safety is an important part of the operations and procedures carried out in the facility. There is a Safety person employed whose responsibility includes scheduling safety training for all employees at the facility. Between the Maintenance Manager and the Safety person, all of the refrigeration operators obtain or are scheduled for training in various operational skills, and hazardous response that specially deal with ammonia. There is also a specific Emergency Response Plan that among other things includes procedures to deal specifically with the possible ammonia release. Since the system has not had any ammonia release, tabletop drills and other non-release practice scenarios are carried out on an annual basis. This facility complies with the OSHA PSM program, and our program defines training, operating procedures, incident investigation, management of change, emergency response plan, hotwork permits, and other required items. In following with the RMP guidelines a "Worse Case" release has been analyzed. It is extremely unlikely that this type of release would occur. The Worse Case release that was analyzed was if the largest system vessel that holds ammonia had a major leak. Some of the reasons this scenario is extremely unlikely are as follows. One, this particular vessel is never filled, typically it only is 50% full which leaves more than sufficient space for any liquid expansion. Two, this vessel is never valved off. Because this vessel is a key part of the entire system it must be in operation continually. Three, if the system pressure did increase above normal there are high-pressure safety switches, which would shut down equipment to stop a pressure increase. Four, the vessel is designed to ASME standards and is protected against high-pressure build up by pressure relief valves. Five, the vessel is located in the refrigeration machine room which is a very low traffic area, and only authorized persons are allowed in this room. Six, the vessel is well painted to protect against corrosion and is presently is very good condition. Following the procedures given in the "Risk Management Program Guidance for Ammonia Refrigeration" published by EPA, and using the formulas and lookup tables included in chapter 4, the distance to the end point for the worse case release was determined to be 1.2 miles. An alternate and more realistic scenario was analyzed. The alternate scenario was if a forklift operating within the facility hit an oil drain valve located on the bottom of a surge drum drop leg. Since the piping is steel and will bend significantly without cracking, however for the scenario it was assumed t hat the 3/4" line cracks half way around the pipe. Using the simplified version of the Bernoulli Equation given in chapter 4, the distance to the end point of the release was determined to be 0.3 miles. |