The Stroh Brewery Company, Winston-Salem - Executive Summary |
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EXECUTIVE SUMMARY The Stroh Brewery Company stores ANHYDROUS AMMONIA at the Winston-Salem brewery in an amount that exceeds the threshold established by EPA for Risk Management Planning. The Stroh Brewery Company believes that risks associated with ANHYDROUS AMMONIA storage at this facility are well managed. SOURCE AND PROCESS DESCRIPTION Refrigeration is a critical component of malt beverage production. Refrigeration is required for chilling water and beer, and for controlling air temperature in beer storage cellars. Refrigeration is provided through the evaporation of liquid anhydrous ammonia by a heat source. Evaporated ammonia gas is contained in a closed loop system where it is mechanically compressed back into a liquid state and stored for re-use on demand. Liquid ammonia is pumped from storage through piping to locations where refrigeration is needed. SUMMARY OF MAJOR HAZARDS Ammonia is a hazardous substance. As a gas, it is severely irritating to the eyes and to moist s kin and mucous membranes. As a liquid, contact can cause freezing and third degree burns. Exposure to high concentrations of ammonia gas or vapor (approximately 2,500 to 6,500 ppm) for up to two hours can induce chemical pneumonitis; burns to eyes, face, and mouth; severe local edema (fluid in lungs); and death after 30 minutes. The consequence of equipment failure or improper control of refrigeration system temperature and pressure could be a sudden release of ammonia. In the refrigeration system, ammonia is stored as a liquid under pressure, then evaporated into a low pressure gas state as it cools its intended heat source, then compressed into a high pressure gas state, and then condensed by cooling water once again into a liquefied state and returned to storage. Accidental release of ammonia could occur during any of these system processes. An accidental release of liquid ammonia under elevated pressure would create an airborne mixture of ammonia vapor and very fine liquid dr oplets that would not fall to the ground. The droplets would entrain air quickly as they tried to evaporate. Evaporation of the droplets would cool the air creating a cold mixture of air and ammonia vapor. The mixture would be denser than air forming a cloud that would tend to stay at ground level until evaporation to a gas was complete. A release of liquid ammonia inside a building would cause an initial overpressure condition due to flash vapor expansion and underpressure condition due to air cooling from droplet interaction. Instantaneous over- or under- pressure greater than 1 pound per square inch (psi) could cause explosion effects such as structural damage to windows and blowout panels; greater than 2 psi could cause explosion effects such as shattering of concrete or cinder block walls. In addition, ammonia can be explosive at concentrations between 15% and 25% by volume in air with ignition by a high intensity source. An accidental release of gaseous ammonia vapor at va rious temperature and pressure would create a buoyant ammonia jet less dense than air. The rate of release would be much less than that of liquid ammonia. CONSEQUENCES OF FAILURE TO CONTROL THE HAZARDS EPA has established a toxic endpoint value of 200 ppm as the maximum airborne concentration below which an individual could be exposed for up to one hour without experiencing serious health effects or symptoms that would impair the ability to take protective action. A worst case release scenario at the facility is defined as the release of 17,600 pounds of liquid anhydrous ammonia from a liquid storage receiver which represents the largest single container at the facility. According to a computer program (RMP Comp) an accidental release of 17,600 pounds of ammonia within a 10-minute period would reach the toxic endpoint at a distance of 1.7 miles. According to a 1991 Bureau of Census computer database (Landview III), the worst case release would affect a population of 5,000 people, residences, and commercial, office, or industrial areas within this radius. A more likely alternative release scenario at the facility is defined as a 1/2-inch diameter leak in ammonia manifold piping within a 10-minute period. Safety shutoff valves would activate in this instance as a release control. The ammonia system operating pressure is 180 psi and at this pressure the release rate would be 540 pounds per minute for a 1/2-inch diameter hole. According to a computer program (RMP Comp) a release of 540 pounds of ammonia for 10-minutes would reach the toxic endpoint at a distance of 0.4 miles. According to a 1991 Bureau of Census computer database (Landview III), the more likely alternative release would affect a population of 200 people and residences within this radius. In either release scenario, release would not affect any public receptor such as a school, hospital, prison, public recreational area or arena; or environmental receptor such as a park, forest, monument, wild life sanctuary, preserve, refuge, or Federal wilderness area. 5-YEAR ACCIDENT HISTORY There has not been any accidental release of ammonia from the refrigeration system since 1994 that caused any of the following: * on-site death, injury, or significant property damage; * known offsite death, injury, property damage, environmental damage, evacuation, or sheltering in place. EXPLANATION OF HOW RELEASES ARE PREVENTED Overall responsibility for coordination of the Ammonia Refrigeration System Risk Management Plan is assigned to the Manager of Plant Engineering. Engineering-Maintenance Supervisors, Operating Engineers, and Utilities-Mechanical Maintenance employees perform operation and maintenance of the refrigeration system. Each of these key personnel is aware of the provisions of the Ammonia Refrigeration System Risk Management Plan and has contributed to the construction of the plan, the components of which are as follows: * Maintenance Good engineering practices, equipment manuf acturer's recommendations, and operating experience determine the means for system inspection, testing, and preventive maintenance. Routine maintenance functions include: - periodic walk-throughs to find unusual or increasing vibration, incipient leaks, or other indication of potential failure that could lead to a release; - inspection of pressure vessels by State certified Factory Mutual Insurance engineers and pressure vessel inspectors; - periodic inspection and maintenance of pressure relief valves; - periodic inspection and calibration of liquid level, temperature, and pressure instruments, switches, and shut down devices that have safety implications; and, - periodic inspection of major powered equipment such as compressors, pumps, large fans, bearings, couplings, shaft seals, mountings, and such for vibration or other incipient mechanical failure. Maintenance employees are trained to perform their work. Maintenance contractors are hired based on their qualifications to perfor m work on refrigeration equipment. Spare parts are purchased from refrigeration equipment vendors. * Process Safety Information Information needed to safely operate the ammonia refrigeration system is available to personnel involved with the system including: - material safety data sheet for ammonia; - block flow diagram for the plant; - piping and instrument drawings; - a list of safety relief valves; - a list of high- and low- level, high- and low- pressure, shutdown and alarm devices; - equipment manufacturers operating instructions; - equipment drawings and specifications. * Process Hazard Analysis Potential hazards associated with the ammonia refrigeration system have been evaluated by means of a general safety review of drawings and what-if checklist on each component of the system. Plant conditions or operating procedures that could lead to an accident have been identified and improved. * Operating Procedures Written operating procedures are constructed to address the follo wing issues for normal operations, new equipment startup, equipment shutdown, emergency operation due to leaks or other foreseeable operating problems, and emergency equipment shutdown procedures: - relevant process safety information and operating experience; - changes to ammonia refrigeration equipment; - safe operating limits for temperature and pressure; - consequences for operating outside the safe operating limits; - procedures to correct errant operating conditions to return to safe operating limits. Other safe working practices also are applied to ammonia refrigeration system work such as procedures for lockout/tagout, confined space entry, opening process equipment and piping, and control of access to the facility. * Training Each employee who operates ammonia refrigeration equipment is trained to operate it safely. Training includes periodic review of operating procedures. Improvements to operating procedures are implemented based on these periodic reviews. Refresher tra ining is planned every 3-years. * Management of Change A change to ammonia refrigeration equipment or change to system operating limits starts a process to review its effect on system safety. The change review process applies both to equipment that is removed and not replaced in kind, as well as re-routing of ammonia piping and inadvertent change resulting from maintenance activities. Process hazard analysis is applied to the change. System drawings, operating procedures, and equipment specifications are revised in the Risk Management Plan as necessary. Any need to improve the design of system change for safety reasons is addressed before startup of the modified system. A secondary pre-startup review provides an independent recheck that changes are in a condition to be operated safely. * Compliance Audits A compliance audit is planned every 3-years to make sure that employees are properly performing their duties regarding the ammonia refrigeration system. Any deficiency found in an audit is corrected. * Accident Investigation A procedure is established to investigate any event that causes or comes close to causing an accidental release of ammonia. In this case, a team will be assigned to document the causes of the accident and correct deficiencies in a timely manner. * Hot Work Permits A procedure is established to issue permits for work to be performed on or near the ammonia refrigeration system that produces a spark or flame, such as welding, brazing, cutting, or grinding. The permits communicate the hazards of the work and precautions to prevent fires to those performing the hot work. * Contractors If mechanical and refrigeration contractors are used for construction, maintenance, or repair of the ammonia refrigeration system, a procedure is established to evaluate the qualifications of the contractor and inform the contractor of facility safety and worker training requirements. Safety information for any addition or change to the refrigeration syste m is incorporated into the Risk Management Plan. EMERGENCY RESPONSE PROGRAM A facility Emergency Action Plan is established to give direction to employees for safe response actions to be taken during fire and other emergencies. Potential ammonia release is addressed in the Emergency Action Plan including notification procedures, evacuation procedures, and medical assistance procedures. Engineering-Maintenance Supervisors, Operating Engineers, and Utilities-Mechanical Maintenance employees are knowledgeable about the ammonia refrigeration system and are trained in first responder awareness. These personnel identify and repair any minor ammonia gas leak. In the event of a substantial ammonia gas leak, these personnel are knowledgeable about location of emergency isolation valves on the ammonia refrigeration system. If possible, the isolation valves would be secured from an unaffected area in response to a substantial release. In the event of a major ammonia gas release, only perso nnel trained in first responder operations are allowed to enter an affected area with proper personal protective equipment to secure isolation valves. Arrangements are established with the local emergency response agency, the fire department, and local hospital. |