USS POSCO Industries - Executive Summary |
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File attached. EXECUTIVE SUMMARY THE ACCIDENTAL RELEASE PREVENTION AND EMERGENCY RESPONSE POLICIES AT THE USS-POSCO INDUSTRIES PLANT USS-POSCO Industries (UPI) has a long-standing commitment to business principles which promote the safe, ethical operation of its steel manufacturing facilities in Pittsburg, California. These principles have resulted in clear UPI business strategies that call for continual improvement of safety, quality, customer satisfaction, protection and preservation of the environment, and community responsibility. Implementation of, and adherence to, these business strategies requires the full commitment of all UPI employees. UPI policy dictates that each division continuously identify methods to reduce the use of hazardous materials and to reduce the risk to the community and environment through implementation of inherently safer technology and procedures. This commitment to safe and environmentally sound operations is documented in the facility policy statements and the manual "Principles of Accident Prevention", which are available to all employees. UPI stresses safe and environmentally sound operations in employee training programs, and in written materials (such as safety and health bulletins) periodically provided to all employees. UPI safety and environmental programs include monthly safety meetings for all employees and a joint worker/company safety committee. UPI supervisory and management personnel conduct both regularly scheduled and unscheduled (surprise) audits of internal safety, housekeeping and environmental compliance and practices. A DESCRIPTION OF THE USS-POSCO PLANT AND THE REGULATED SUBSTANCES HANDLED Description of Stationary Source USS-POSCO Industries (UPI) is located at 900 Loveridge Road in the city of Pittsburg, approximately 1/2 mile north of Highway 4. The UPI property occupies approximately 490 acres. It is bordered by the New York Slough of the San Joaquin/Sacramento River on t he north and by open space and industrial facilities in all other directions. The nearest residences are located approximately 3/4 miles to the southwest of any facilities handling chemicals regulated under the RMP Rule. The plant employs approximately 1000 people. The major divisions within the UPI facility include: the Rolling Division, the Tin Products Division, the Sheet Products Division, and the Technology Services Division. The Rolling Division is responsible for the initial steel processing operations of the facility. It typically operates continuously, 24 hours per day, seven days per week, with management supervision continuously present. The Tin Products Division is responsible for the subsequent steel processes that result in the production of tinplate products. The processing facilities include two Electrolytic Tinning Lines (ETLs), where sulfuric acid is utilized for pickling and chrome recovery, and a continuous annealing line. As in the Rolling Divis ion, operation and supervisory coverage are continuous. The Sheet Products Division is responsible for subsequent processes that result in the production of sheet products, cold rolled sheets, and galvanized sheets. The facilities include a Kawasaki Multipurpose Continuous Annealing Line (KMCAL), where ammonia is utilized for reducing NOx (nitrogen oxide compounds) emissions from the furnace exhaust stack. The annealing furnaces operated by the Tin Products and Sheet Products Divisions require internal atmospheres consisting of hydrogen diluted in nitrogen (concentrations ranging from 5 to 30 volume percent hydrogen). These reducing atmospheres are required to exclude moisture and air from the furnaces to prevent oxidation of the steel at the high furnace temperatures. The Technology Services Division provides engineering services and maintenance support for the facility. This Division also operates the facility utility systems including a Demineralization Unit, where s ulfuric acid is used for both reverse osmosis and demineralized water purification systems. Hydrogen and anhydrous ammonia are the only two state or federally regulated substances present at UPI. The sulfuric acid solutions used at UPI are at concentration of 93 weight percent or less and, thus, fall below the concentration threshold established under the RMP Rule. Description of the Ammonia Process Anhydrous ammonia is used at UPI for reducing NOx (nitrogen oxide compounds) emissions from the KMCAL furnace exhaust stack. NOx compounds in the atmosphere are one of the significant precursors to photochemical smog. The ammonia, in the presence of a catalyst, decomposes NOx compounds into nitrogen (N2) and water (H2O). Anhydrous ammonia is stored in liquid form in an outdoor 12,000-gallon supply vessel. The vessel sits on a concrete pad that is surrounded by a locked fence. The amount of ammonia stored in the supply vessel is limited to 85% of the vessel capacity, w hich is 10,200 gallons (52,500 pounds at 60oF). Instrumentation on the vessel includes a low and low-low level switch, a level indicator, a pressure gage, and a temperature indicator. The ammonia supply vessel has a design pressure of 265 psig and is protected by two 1-1/4- inch relief valve manifolds, each with two separate relief valves that vent to the atmosphere (one relief valve on each manifold is valved into service at any time). Ammonia is withdrawn from the vapor space of the supply vessel via a 3/4- inch line. The line feeds into a pressure-reducing valve, also on the concrete pad. The pressure is reduced to approximately 30 psig, at which point the line expands to 1-inch diameter. The 1-inch line runs supported and above ground into the Sheet and Tin Mill Building. Inside the Sheet and Tin Mill Building, it runs through an underground trench and an overhead pipeway to a fenced-in flow control station. The flow control station consists of a pressure regulato r, a temperature transmitter, a pressure transmitter, a flow transmitter, a nitrogen purge line, a flow control valve, and a solenoid shut-off valve. The flow control station regulates the ammonia vapor flow to the furnace stack as a function of the flue gas flow rate. The solenoid valve shuts off the ammonia supply in the event of a furnace upset, such as low temperature in the furnace stack. This precaution is necessary since ammonia entering the flue gas at a temperature of less than 392oF can form the explosive compound ammonium nitrate (NH4NO3). The 1/2-inch diameter ammonia vapor supply line exits the flow control station and travels up a structural steel column to the flue gas injection point. An air blower mixes air with the ammonia stream, and the mix enters the furnace stack through a manifold. The pressure in the ammonia supply vessel varies with the ambient temperature. A vaporizer is provided to ensure that sufficient ammonia vapor is available during cold ambient conditions. The vaporizer heats the liquid as necessary to maintain a vessel pressure above 80 psig (vapor pressure of ammonia at approximately 53oF). The vaporizer switches off when the vessel pressure exceeds 100 psig (approximately 64oF). A high- high pressure switch will also shut down the vaporizer at 200 psig (approximately 101oF). An independent high temperature switch set at 100oF (corresponding to a vapor pressure of approximately 197 psig) will also shut down the vaporizer. Ammonia is received in tank trucks and is transferred into the storage tank through a two inch liquid fill line. Vapors displaced from the storage tank return to the tank truck via a 1-inch pressure equalizing line. The pressure equalizing line, which connects the vapor space of the supply vessel to the vapor space of the tanker truck, is opened to equalize any pressure differences between the systems prior to loading. The liquid fill line enters the top of the tank and t he liquid ammonia is discharged into the tank vapor space. Characteristics and Hazards of Ammonia Ammonia is a colorless gas with a very irritating odor, and is highly soluble in water. When ammonia is released to the atmosphere, it creates a dense, white fog because it reacts with water in the atmosphere. At normal temperatures and pressures, anhydrous ammonia is a gas. It is easily liquefied by pressurizing in a container and is commonly transported and stored as a liquid. At atmospheric pressure, the liquid density of ammonia is approximately 2/3 that of water, and ammonia gas is lighter than air. Physiological Effects Ammonia in the ambient air has an intense, acute effect upon the mucous membranes of the eyes, nose, throat, and lungs. Exposure to a high concentration of ammonia can produce corrosive action on these tissues, which can lead to impairment of the respiratory system and, possibly, death. Ammonia is a regulated substance under the RMP Rule due to th is acute toxicity. A more detailed description of the health effects of ammonia is presented in the offsite consequence analysis section of this document. Description of the Hydrogen Process Liquid hydrogen is stored in two double-walled stainless steel pressure vessels (one 9000-gallon, one 18,000 gallon). Administrative controls limit the contents of the larger tank to no more than 9500 lbs of liquid hydrogen. The hydrogen is delivered, and unloaded by the supplier, who also has responsibility for the operation, inspection and maintenance of the hydrogen storage system. The hydrogen is stored at a pressure of approximately 40 psig; an economizer that circulates vaporized hydrogen to the tank headspace maintains hydrogen storage pressure. The storage vessels are pressure protected by primary relief valves, installed spare relief valves, and rupture discs. The relief valves are set to open at 150 psig. Both the relief valves and the rupture discs discharge to atmosphe re. Liquid hydrogen is passed through ambient temperature vaporizers. The vaporized hydrogen is then transferred to mixers and furnaces through a series of pressure reducing stations. The first, immediately downstream of the vaporizers, drops the hydrogen pressure to approximately 15 psig. An additional pressure reducing station further drops the pure vaporized hydrogen system pressure to 12 psig. The vaporized hydrogen is split into two separate process streams. One stream goes directly to two of the four annealing furnaces through an additional pressure reducing station, set at approximately 5 psig. The remaining pure vaporized hydrogen is piped to nitrogen mixing stations in the West Gas Room and in the KMCAL Gas Room. There are three parallel mixing systems in the West Gas Room and a single system in the KMCAL Gas Room. Each mixing system includes a mixer, a dryer, and treating equipment. In the mixing systems, hydrogen is mixed with nitrogen to produce a 5% hydrogen, 95% nitrogen mixture (identified as HN). This HN mixture is used for producing a reducing atmosphere in the annealing furnaces to prevent oxidation of the steel at high temperatures. The pure hydrogen and the HN flows are adjusted to control the HN concentration in the furnaces to the appropriate value for efficient annealing. In addition to supplying HN to the furnaces for annealing, HN is stored in a purge gas storage system. The purge system consists of three purge tanks, two having a capacity of 2500 cubic feet, and one having a capacity of 1650 cubic feet. The purge tanks provide an emergency deluge of 5% HN to the two galvanizing furnaces that uses a 30% hydrogen atmosphere. This dilute HN addition is intended to lower the hydrogen concentration in the furnaces in the event that a potentially explosive atmosphere should develop. The entire hydrogen system, including the HN system, is provided with analyzers, alarms, and shutdown safety interlocks des igned to detect, prevent, and counteract, the causes and effects of explosive atmospheres in the furnaces. Specifically, if conditions are detected that could lead to a potentially explosive condition within the furnace, the safety systems: o Stop all hydrogen flows to the furnaces o Activate the emergency purge system o Isolate HN and shutdown furnaces upon loss of nitrogen flow or supply, or upon detection of high oxygen concentrations in the system. Characteristics and Hazards of Hydrogen Liquefied hydrogen is transparent and is only 1/14 as dense as water and its vapor is only about 1/14 as dense as air. Hydrogen burns readily in air with an almost invisible flame which rapidly propagates through the mixture. At atmospheric pressure its flammable range is approximately 4 percent to 74 percent by volume of hydrogen in air. Hydrogen is a regulated substance under the RMP Rule because to its flammability. Physiological Effects Hydrogen is nontoxic but can cause asp hyxiation when it displaces the oxygen in a confined space without adequate ventilation. Hydrogen is colorless, odorless, and tasteless and, thus, offers no discernible warning properties. OFF-SITE CONSEQUENCE ASSESSMENT METHODOLOGIES The approaches used in determining possible release rates and durations were unique to the various scenarios and are discussed in the scenario-specific paragraphs. All scenarios were modeled as toxic gas releases. In other words, all of the liquid released was assumed to either vaporize or to be entrained as aerosol droplets in the cloud; i.e., there was no rainout of liquid droplets to form a liquid pool that would subsequently vaporize. This is a conservative assumption with respect to the estimation of the effect distance. However, it is a reasonable assumption based upon current knowledge of how flashing liquid releases behave. The effect zone for toxics is determined to estimate how far potentially hazardous concentrations o f the toxic will extend downwind. Since it is typically not possible to predict or exclude particular wind directions, the potential effect zone is defined as a circle, centered at the point of release, with a radius equal to the downwind distance to the threshold concentration of concern. The concentration of concern, as specific in the RMP Rule, is the ERPG-2 concentration which, for ammonia, is 200 ppm (0.14 mg/l). Potential effect distances were determined using the EPA's RMP Offsite Consequence Analysis Guidelines and the associated software tool, RMP*Comp, assuming the EPA-recommended "typical" meteorological conditions of D atmospheric stability and a wind speed of 3 m/second. Urban terrain was assumed. Residential population estimates within the potential effect zone were determined using Landview III software (produced by the US Census Bureau). This tool is based upon the 1990 census database, which provides population figures aggregated by census count ing block. Non-residential public receptors were identified using a number of approaches: o Some schools, parks, public buildings, shopping centers, etc., can be identified from USGS survey maps; o The Delorme. Phone Search USA. software (Ver. 4.0, 1998) was searched by SIC code to identify day care centers, nursing homes, etc. within a three-mile radius of the UPI site; o An internet "yellow pages" utility http://SanFrancisco.sidewalk.msn.com) was used to search the 94509 and 94565 zip codes for terms such as "child care", "adult care", "hospitals", "long-term care centers", and "nursing homes". Note that the greatest potential effect distance does not extend beyond the two zip codes that were searched. o For schools, searches were of the school district websites, followed up by phone conversations with district office personnel, as necessary. Environmental receptors were identified from the appropriate USGA survey maps. THE WORST-CASE RELEASE SC ENARIOS Well-documented offsite consequence analyses are essential to the adequate communication of potential hazards at UPI. Consistent with the requirements of the RMP Rule, and EPA's guidance, UPI has conducted offsite consequence analyses (OCA) for both the ammonia and hydrogen systems, using the EPA's RMP Offsite Consequence Analysis Guidelines for the Worst-Case Scenarios (WCS). Following are the results from the WCS OCA. Ammonia Worst Case Release Scenario The Worst-Case Scenario (WCS) for toxic substances at UPI is the release of the total contents of the anhydrous ammonia (NH3) vessel. The vessel is assumed to contain a maximum of 52,500 lbs of NH3 which is assumed to be released over a period of 10 minutes. Although there are installed control measures that would prevent or mitigate an actual release event, no credit for mitigation measures was taken into account for this scenario. The results for the WCS were generated from the EPA's RMP Offsite Consequenc e Analysis Guidelines. The maximum distance to the toxic endpoint of 200 ppm (the ERPG-2 for NH3) for this WCS is 2.6 miles. Using census data from LandView III, the estimated population within the worst-case scenario circle is 52,000. Sixteen schools are within the WCS ERPG-2 circle, as well as three child day care facilities and six senior and long-term care facilities. Since this WCS reaches off-site receptors, the ammonia process falls under Program Level 3 of the RMP Rule. There is only a single process containing NH3 and there are no other regulated toxics at UPI. Hydrogen Worst Case Release Scenario The Worst-Case Scenario (WCS) for flammable substances at UPI is the release of the total contents of the larger liquid hydrogen (H2) vessel. The vessel is assumed to contain a maximum of 9500 lbs of H2 which is assumed to be released immediately, leading to a vapor cloud explosion. Although there are installed control measures that would prevent or mitigate an act ual release event, no credit for mitigation measures was taken into account for this scenario. The results for the WCS were generated from the EPA's RMP Offsite Consequence Analysis Guidelines. The maximum distance to the explosion overpressure endpoint of 1 psig for this WCS is 0.2 miles. Since this WCS does not extend beyond the UPI facility perimeter, no residences or other off-site receptors are impacted by the WCS. As will be shown, the hydrogen process meets all additional requirements as a Program 1 process. There are no other processes at UPI containing greater than the threshold quantity of flammables. THE ALTERNATIVE RELEASE SCENARIOS Offsite consequence analysis is also a useful tool in helping UPI to coordinate with the CCCHSD Incident Response Team in emergency response planning. To do this, UPI modeled a series of three potential alternative release scenarios (ARS) to establish a reasonable "outer bound" for emergency response planning and to provide for explaining potential hazards to the community. Ammonia Alternative Release Scenarios 1. Failure of unloading hose. This ARS assumes that the 2" flexible line from the tank truck to the rigid UPI piping is severed, resulting in a twenty- minute release at a rate of approximately 1200 lb/min of ammonia. The release rate is limited by the excess flow valve at the tank truck connection. Twenty minutes was the time determined for the release to be detected, for response personnel to don the required protective equipment, and to shut the isolation valves on the tank truck and the UPI piping to stop the leak. The actual release duration may be appreciably shorter, since the unloading process is continuously attended by the truck driver and there are two remote shut-off controls located at different points on the tank truck. These shut-offs are intended to be used to close the tank outlet valve prior to the driver evacuating from the vicinity of the truck. Using the E PA-recommended meteorological conditions, the maximum distance to the toxic endpoint of 200 ppm (ERPG-2) is only 0.3 miles. There are no residential populations or public receptors, other than industrial facilities, within this radius. 2. Relief valve discharge. As previously described, the emergency pressure relief requirements for the storage tank are based upon the assumption of an external fire heating the tank, boiling the liquid ammonia, resulting in an internal overpressure that must be relieved. The required venting capacity was previously determined in accordance with the requirements of ANSI standard K 61.1. At any time, there are two relief valves in service on the tank. Each relief valve individually has the required venting capacity. (There are actually two pairs of relief valves on the tank, manifolded so that one valve in each pair can be valved into service while the other is isolated for repair.) This ARS assumes that a single vessel relief valve open s resulting in a twenty-minute release at a rate of approximately 350 lb/min of ammonia (the actual, full flow capacity of the relief valve). Twenty minutes was the time determined for the release to be detected, for response personnel to don the required protective equipment, and to stop the release. This actual release rate and duration could be appreciably less. The ammonia tank is readily visible from the continuously-manned security guard station ensuring prompt detection. An actual fire exposure would most likely ignite and consume the ammonia discharging from the relief valve. Using the EPA-recommended meteorological conditions, the maximum distance to the toxic endpoint of 200 ppm (ERPG-2) is only 0.2 miles. There are no residential populations or public receptors, other than industrial facilities, within this radius. 3. Failure of a 3/4 inch diameter liquid line from vessel. This ARS assumes that the 3/4" liquid line from the vessel to the vaporizer is severed , resulting in a twenty-minute release at a rate of approximately 250 lb/min of ammonia. The release rate is limited by the excess flow valve at the tank outlet connection. Twenty minutes was the time determined for the release to be detected, for response personnel to don the required protective equipment, and to shut the isolation valves necessary to stop the leak. Using the EPA-recommended meteorological conditions, the maximum distance to the toxic endpoint of 200 ppm (ERPG-2) is only 0.1 miles. There are no residential populations or any other public receptors within this radius. Other smaller liquid releases and various vapor releases are possible, but their effects would be markedly less severe than those discussed above. A number of mitigation systems serve to: make releases less likely to occur; to reduce the rate or duration of a release should it occur; or to reduce the consequences of the leak should it occur. These mitigation systems, including those dis cussed above, include: o NH3 detection systems with alarms at the tank and at the control station within the building; o Remote isolation of the tank truck unloading valve; o Excess flow valves on storage tank and tank car liquid and vapor transfer lines (exception: there are no excess flow valves in the relief valve lines); o Ammonia storage vessel was designed and built in accordance with the ASME Code for Pressure Vessels, Section VIII, Division 1; o Ammonia storage vessel, relief valves, and other safety systems inspected on a periodic basis; o Fire hose with fog nozzle located adjacent to storage facility, to be used in "knocking down" the water-soluble ammonia vapors that would result from a release; o Redundant relief valve protection on the storage vessel, and an additional relief valve on the vaporizer; o High temperature and high pressure interlocks on the vaporizer; o Robust barricades to prevent vehicles from impacting the ammonia- bearing equipment; o Locked, chain link enclosure surrounding the storage vessel, the vaporizer, and the primary pressure reducing station and the flow control station inside the Sheet and Tin Mill Building is similarly enclosed; o The majority of the ammonia transfer lines are routed either on elevated pipe racks or in an underground trench, to limit the potential for impact damage; o The majority of the piping connections are socket-welded to minimize leaks; o The pad under the tank is sloped to a liquid drain that would divert any ammonia spilled on the ground to the facility waste water treatment plant, minimizing the amount of ammonia vaporized; o The ammonia storage vessel is within a direct line of sight of the nearby security gate, which is manned 24 hours a day, 7 days a week. Hydrogen Alternative Release Scenarios Since the liquid hydrogen process qualifies for Program Level 1, no ARS are required for hydrogen. THE ACCIDENTAL RELEASE PREVENTION PROGRAM Note that the anhydrous ammonia process is the only Program level 2 or 3 process and, therefore, is the only process requiring a RMP prevention program. The following information is specific to the anhydrous ammonia process. Management System UPI has developed a formal management system for planning, organizing, implementing and controlling the risk management program elements. This management system is consistent with the recommendations contained in CCPS Plant Guidelines for Technical Management of Chemical Process Safety. This management system satisfies the requirements of ' 68.15 of the RMP Rule, and ensures that the risk management program elements are developed, implemented, and continually improved. The management system activities are further discussed below. o Planning - UPI has an overall risk management program policy that clearly identifies the goals and objectives of the risk management program. o Organizing - Individuals responsible for each risk management pr ogram element have been designated. The designated individuals are responsible for developing and maintaining policies and procedures for each risk management program element that meet program goals and objectives. o Implementing - Detailed responsibilities for program implementation may be delegated to other individuals. Such individuals are trained on their responsibilities, and the corresponding procedures, before they are allowed to perform their responsibilities. Strict adherence to procedures is emphasized. Refresher training is provided on an as-needed basis. o Controlling - Members of management and the individuals responsible for each risk management prevention program element periodically conduct internal reviews or audits against the goals and objectives of the element. All records associated with the prevention program elements are retained for a minimum of five years unless otherwise specified in the RMP Rule, to permit periodic , comprehensive audits. Weaknesses in program elements, or in their implementation, that may be discovered during internal audits or reviews are corrected. Prevention Program: The prevention program elements described in the following section represent an integrated system of administrative controls intended to ensure the safety of workers, the public, and the environment. Many of these prevention program elements (e.g., PHAs, compliance audits, incident investigation) result in the development and implementation of additional safeguards (i.e., administrative and engineering controls). Those recommendations that are planned for implementation at UPI will be discussed in "Planned Changes to Improve Safety". Those applicable safeguards that have already been implemented or that were part of the original design are described below. These safeguards prevent, detect, or mitigate the effects of accidental releases of regulated substances. PROCESS SAFETY INFORMAT ION: Process safety information (PSI) development, dissemination, and use is vital to the effective operation of a stationary source. Personnel use information regarding chemical hazards, equipment specifications, and operating limits in daily and strategic decision making. Accurate and complete information that is readily accessible enables personnel to identify and understand the hazards posed by those processes involving anhydrous ammonia and is, therefore, a basic component of the prevention program. Requisite PSI, satisfying the regulatory requirements of ' 68.65 of the RMP Rule, was compiled prior to the original process hazard analysis (PHA) conducted in 1995. Implementation of the management of change (MOC) and pre-startup safety review (PSSR) elements ensures that the PSI is maintained current and accurate. Personnel have 24-hour access to the PSI required by their responsibilities. The following PSI is particularly important to the prevention program: o Information pertaining to the hazards of the regulated substances in the process - The following information is available in the material safety data sheet (MSDS) maintained for anhydrous ammonia: toxicity information, permissible exposure limits, physical data, reactivity data, corrosivity data, and thermal and chemical stability data; o Information pertaining to the technology of the process - The following information is available in the facility operating procedures and/or the original RMPP documentation for the facility: a process flow diagram for the ammonia process, a description of the process chemistry, safe upper and lower parameter limits (e.g., temperature, pressure), and an evaluation of the consequences of deviations from those parameter limits. o Information pertaining to the equipment in the process - The following information is maintained: accurate or redlined piping and instrumentation diagrams (P&IDs), a listing of the vari ous safety systems (e.g., alarms, interlocks, shutdowns, suppressions systems, relief systems), and specifications of materials of construction for the process equipment. PROCESS HAZARDS ANALYSIS: By systematically examining each process and identifying hazards associated with the operation of a covered process, UPI has been able to plan and take appropriate action to improve the safety of employees, the community, and the environment. UPI performed a Process Hazard Analysis (PHA) on the ammonia storage process with the objectives of: identifying hazards; identifying credible human errors and/or equipment failures that could lead to an accidental release; evaluating the likelihood and/or consequence of various scenarios; determining if existing prevention steps/controls were sufficient; and, where existing controls were judged insufficient, identifying additional steps that could be taken to control the hazard. The PHA for the process was previously conducted to comply with the RMPP regulation. This methodology was chosen due to the relatively complex design of the ammonia storage and transfer system, as well as UPI's belief that a HAZOP would provide a high level detail for analysis of this system. The following objectives were addressed by the PHA: o Identify the hazards of the substance and of the process; o Identify the applicable external events (including seismic events) that could lead to a release; o Identify possible equipment failures or human errors that could lead to a release; o Evaluate the consequences and likelihood of the accident scenarios; o Evaluate safeguards used to prevent or mitigate failures or errors; o Consider steps needed to mitigate the risks, including changes needed to equipment design, operating procedures, process conditions, etc.; and o Propose recommendations/action items to mitigate the hazard. The PHA was conducted by a multi-disciplinary team that systematically identified haz ards and operability problems by searching for deviations from the design intent of each portion of the process. The team considered the causes and effects of these deviations to identify hazardous conditions and their consequences, listed existing safeguards, and made recommendations for changes where appropriate. The PHA team was composed of qualified personnel including a team leader with 15 years of professional safety and engineering experience; the team leader had training and experience in conducting PHAs using techniques such as the HAZOP, What If and Checklist methodologies. The team identified and evaluated hazards of the process as well as accident prevention and mitigation measures, and made suggestions for additional prevention and/or mitigation measures when they deemed such measures are necessary. The PHA was documented on worksheets containing a description of each process node and its design intent, a list of possible deviations, causes of deviation s, consequences, safeguards, and required action items/investigations/questions for further study. This documentation will be maintained for the life of the facility. The study was conducted primarily using the HAZOP Study deviation guideword technique. The guidewords, in conjunction with key process parameters, prompt the HAZOP Study team to brainstorm possible causes and potential consequences of deviations from design operation. For example, the deviation "NO FLOW" would prompt the leader to ask the team, "What could cause no flow in this section or line segmento" The "Possible Cause" and "Potential Consequence" scenarios are documented in the study worksheets. The "Existing Systems and Procedures" (safeguards) that reduce the risk associated with the specific cause/consequence scenario are then discussed and documented. For scenarios involving significant risk, "Recommendations" that the team believes may further reduce risk or improve the operability of the facility are also documented. Wrap-up Discussions The HAZOP Study technique was used to analyze line-by-line the ammonia handling systems at UPI. However, the HAZOP Study technique may not document all the general issues affecting the health and safety of the workplace employee or identify all potential ammonia releases that could have off-site impact. In addition to the line-by-line discussions that were documented in the section worksheets, "Wrap-up Discussions" were held at the end of the HAZOP Study to ensure that these general topics were covered. The "Wrap-up Discussions" topics covered in this study included: o Safety/Fire Protection o Emergency Response o Procedures o Loss of Utilities o Siting/Control Room Location o Previous Incidents o Human Factors o Testing and Inspection o Maintenance o External Events o Other Hazards Analysis Studies The HAZOP Study team members used a risk matrix to qualitatively assess the risk associated with each cause/consequ ence scenario that was developed during the study. The matrix used for this HAZOP Study is based on the information provided in the Contra Costa County Health Services Department (CCCHSD) RMPP Guidelines (March 1993), page 30. Seismic Evaluation A seismic evaluation was performed in accordance with the Proposed Guidance for RMPP Seismic Assessments, June 1992, prepared for the RMPP Sub-Committee of the Southern California Fire Chiefs Association. The scope of work included a visual walkdown review of equipment and piping identified as containing AHMs, a quantitative evaluation of selected structures where warranted, and recommendations for reducing the risk of a potential ammonia release. The seismic evaluation is intended to provide reasonable assurance that a major earthquake will not result in a release of acutely hazardous materials having potential off-site consequences. The key feature of the evaluation methodology was an on-site walkdown review of the existing facility. This was primarily a systematic visual review that considered the physical condition of the installation. The engineer performing the review investigated for potential seismic vulnerabilities, focusing on proven failure modes from past earthquake experience and engineering judgment. The walkdown review also emphasized the primary- seismic-load resisting elements and the potential areas of weakness due to design, construction, or modification practices. Special emphasis was placed on details that may have been designed without consideration of seismic loads. Where necessary, specific items could be selected for analytical investigation. These analytical reviews typically focus on items that have unusual designs, "weak links," or other attributes that may indicate insufficient capacity to resist the seismic loads from a large earthquake. No such analytical evaluations were required for the UPI evaluation. Potential seismic vulnerabilities were read ily evaluated using engineering judgment and experience. The seismic review was performed by a registered professional engineer (civil) with more than 10 years of experience performing seismic evaluations of structures and equipment in industrial and power facilities. The engineer had performed several RMPP evaluations in Contra Costa County, and had also participated in post-earthquake reconnaissance investigations after several major earthquakes, focusing on equipment and structural damage in industrial and power facilities The primary deficiencies identified with the ammonia system included a possible interaction hazard with the abandoned, unanchored tanks just west of the ammonia storage tank, interaction with a 3-inch diameter line in the Sheet Mill Building, lack of restraint on the lines at the injection point, and excess displacement of the exhaust duct. Any one of these deficiencies could have resulted in a release of gaseous ammonia. Resolution of PHA Findings The team findings for the PHA and seismic assessment were forwarded to site management for resolution. Implementation of recommendations/action items in response to PHA findings was based on a relative risk ranking assigned by the PHA team. This ranking helped ensure that potential accident scenarios assigned the highest risk receive greatest attention. All approved recommendations/action items pending implementation were tracked by the Manager of Environmental Control until completed. The final resolution of each finding was documented and such documentation will be retained for the life of the facility. PHA Revalidation The PHA will be revalidated every five years, or more often as required by significant process changes, using a team with qualifications similar to that of the original PHA. OPERATING PROCEDURES: Current, clearly written standard operating procedures and safe work practices ensure that employees (including contract employees) per form their duties in a safe, consistent, and prescribed manner. UPI has developed written operating procedures satisfying the requirements of ' 68.69 of the RMP Rule. These procedures were prepared with the input of plant employees; they will be reviewed periodically and annually certified as being reflective of current plant practice. The operating procedures are intended to be available to employees for all aspects of operations. Copies of the operating manual are maintained at the following locations: o KMCAL Exit Pulpit o Sheet Maintenance Office o Environmental Office o Plant System Repair Office Some key considerations in the safe operation of the ammonia system include: a. The addition of ammonia to the furnace-fired exhaust stack of the KMCAL Line is performed under automatic flow control. Alarms are routed to an annunciator panel in the continuously staffed exit pulpit. In addition, operators regularly drive by the ammonia supply vessel to check local fie ld indicators. b. It is operating practice to only store 10,200 gallons of ammonia at the supply vessel, which is 85% of the tank's capacity. c. Safe Job Procedure (SJP KM-122) "Anhydrous Ammonia Work Procedure For Leak Or Spill (General)" outlines steps for Operations and Maintenance personnel to follow when responding to ammonia leaks or spills (both vapor and liquid). The SJP explains requirements and location of correct apparel and spill response equipment. In addition, it lists the hazards of exposure. d. The ammonia supplier's loading procedure includes the following practices: o The hoses are visually inspected for any signs of wear and tear prior to each use. The supplier replaces the hoses every 5 years (or sooner as needed). The hoses are rated for 7 years use. o The wheels of the tanker truck are chocked to prevent unwanted movement while the truck and supply vessel are connected. o The supplier stays within 25 feet of the tanker truck at all t imes during the loading operation, to ensure an immediate response to any upset condition. o There are two emergency isolation switch stations located on the tanker truck, allowing the supplier to shut down the loading operation in the event of a release. e. Ammonia is only loaded during normal business hours, Monday through Friday, when more experienced personnel are in attendance to respond to any upset condition. f. Operating practice calls for the operator to check the bill of lading prior to allowing the loading operation to commence. TRAINING: UPI believes that employees who clearly understand how to safely operate a process can significantly decrease the number and severity of incidents, and increase efficiency. Therefore, a thorough training program focused on specific operating procedures and safe work practices is a key element of an effective prevention program. Employees involved with operating the process receive training on the hazards associat ed with the process, how to operate the process within safe operating limits, and how to handle potential emergencies. The training program satisfies the requirements of ' 68.71 of the RMP Rule and is comprised of the following: o Initial employee training o Training provided in response to equipment or process changes, as identified under the MOC program; o Periodic refresher training; and o Training documentation. All operators receive initial training in safe work practices and basic operating principles prior to assignment. The operators receive training specific to the operations of the process once they are assigned. Various means are used to verify competency, but primary emphasis is placed on on- the-job observation by supervisors. Documentation of the training is forwarded to the Learning Center for filing and tracking. In addition to on-the-job training, UPI personnel are trained in basic safety courses on an ongoing basis. All operating division employe es and all building wardens in non-industrial areas of the plant are designated potential first responders. Courses they take include: "Principles of Accident Prevention", "CPR", "First Aid", and "First Responder Training." Operating division employees also regularly attend Safety Committee meetings to discuss safety issues. MECHANICAL INTEGRITY: A well-established mechanical integrity program ensures that equipment critical to process safety is fabricated to meet process specifications, is installed correctly, and is maintained in a safe operating condition. It also allows maintenance employees to preemptively identify and correct equipment deficiencies to avoid associated incidents and down time. UPI has therefore developed a mechanical integrity program, satisfying the requirements of ' 68.73 of the RMP Rule. The mechanical integrity program applies to the ammonia storage tank, piping systems, relief systems, emergency shutdown systems, controls and any addit ional equipment (e.g., heat exchangers) deemed by operating and maintenance personnel to be important to safety. Procedures for ensuring quality assurance - Site procurement procedures ensure that equipment: o meets or exceeds all design specifications; o is properly constructed; o is suitable for its application; o is designed in accordance with good engineering practice; and o will meet the requirements for safety, reliability, and product quality. After installation, appropriate checks and inspections ensure that the equipment has been installed properly and is consistent with the design specifications and the manufacturer's instructions. These elements of the quality assurance program are often performed in conjunction with the management of change (MOC) program and the pre-startup safety review (PSSR) program. Additionally, purchasing documents for spare parts include adequate technical and engineering data to ensure that maintenance materials and spare parts ar e suitable for the process application. Written maintenance procedures for process equipment - Written procedures (including step-by-step instructions, applicable warnings or hazards, manufacturer's recommendations, and required personal protective equipment) were developed for maintaining process equipment. These procedures are reviewed annually by appropriate members of management for thoroughness and accuracy. Hard copies of these procedures are available in the Maintenance Supervisor's office. The regularly scheduled maintenance (preventive maintenance) requests are distributed to maintenance employees by the maintenance department. Non-preventive maintenance activities are performed through the work order system (i.e., operators and engineers submit work order requests to the Maintenance Supervisor who then distributes them to appropriate maintenance employees). The maintenance employee completes the preventive maintenance or work order documentation and submi ts it to the Maintenance Department for review and filing. Maintenance employee training - UPI carefully assesses each applicant for employment and only hires maintenance personnel with appropriate skills and knowledge pertinent to their required job tasks. Additional skills training is subsequently provided on an as-needed basis. The UPI Learning Center maintains documentation of skills training for maintenance employees. Maintenance employees are provided with an overview of the process, the hazards associated with the process, and safe work practices during initial employee training and annual refresher training. The UPI Learning Center maintains initial and annual training records including documentation of the content of the training, the identity of the instructor, and the means used to verify competency for maintenance employees. Inspection and testing procedures for critical equipment - Inspection and testing procedures and the required testing frequency fo r each piece of critical equipment were developed and documented by appropriate members of the maintenance and operating departments. The procedures and frequency are based upon the manufacturer's recommendations, good engineering practice, and operating history. The inspection and testing requests are distributed to maintenance employees at the established frequency. Completed inspection and test documentation including maintenance employee signature, date of the inspection or test, serial number of the equipment, inspection and test procedures, and the results of the inspection or test are returned to the Manager of the Maintenance Department for review and filing. The results of each inspection or test are reviewed to determine if the frequency of the inspections or tests should be increased or decreased, to ascertain whether the equipment is within the acceptable limits, and to project the remaining useful life of the equipment. Equipment outside of the acceptable limits is removed or replaced unless interim protective measures can be implemented to ensure continued safe operation. The ammonia leak detectors are calibrated at least every 6 months. The detectors are two-point calibrated, at 100 and 200 ppm. Relief valves are replaced every five years and the ammonia vessel is inspected every five years. Additionally, a visual inspection of the vessel, piping, and related equipment is made at least quarterly. MANAGEMENT OF CHANGE: Changes in the process, procedures, or prevention program elements are sometimes necessary to address safety, environmental, or operational concerns. A change made in one area may have unintended effects on other parts of the process, or on other prevention program elements. Such changes are therefore appropriately scrutinized before they are made to ensure the changes do not compromise the safety and integrity of the process and to avoid adverse effects to worker and public safety, and to the en vironment. UPI has developed a written management of change (MOC) procedure, including a change authorization form, that satisfies the requirements of ' 68.75 of the RMP Rule. This procedure ensures that all changes to the following are properly managed: o Process chemicals (e.g., raw materials); o Technology (e.g., operating parameters, rates); o Equipment (e.g., materials of construction, equipment specifications); o Procedures (e.g., emergency response, preventive maintenance, operating); and o Other processes and/or equipment that could affect the covered process. This procedure does not apply to a "replacement in kind" which is defined as a replacement that satisfies the original design specifications. Personnel (e.g., operations and safety) assess the potential impact of the proposed change on safety and health through a safety checklist for minor changes or a process hazard analysis (PHA) for major changes. The following steps are taken, as necessary, prio r to startup of the modified facility to ensure proper implementation of the change: o Process safety information (PSI) is updated; o Operating procedures are updated; and o Employees (e.g., operations, maintenance, contract) whose job tasks are affected by the change, are trained on the change and its potential impact on their job responsibilities. The MOC records and recommendations are tracked according to the assigned tracking number. The MOC records and documentation of completion of the recommendations are maintained for five years. PRE-STARTUP SAFETY REVIEW: UPI has developed a written pre-startup safety review (PSSR) procedure and checklist, for use in evaluating significant facility modifications prior to operation. Significant modifications requiring this review are those which require that the process safety information (PSI) be updated. The PSSR procedure satisfies the requirements of ' 68.77 of the RMP Rule, by confirming the following prior to startup: o The installation is in accordance with design specifications; o Safety, operating, maintenance, and emergency procedures are in place and are adequate; o For new facilities, a process hazard analysis (PHA) has been performed and recommendations have been resolved or implemented; o For modified facilities, the requirements contained in the written management of change (MOC) program have been met; and o Training of each employee involved in operating the modified facility has been completed. The PSSR records and documentation are tracked according to the assigned tracking number that corresponds to the MOC tracking number. PSSR records and documentation of completion of the recommendations are maintained for a minimum of five years. COMPLIANCE AUDITS: UPI recognizes the importance of periodic self-audits for ensuring that the prevention program elements are functioning properly (i.e., that they are complete, current, and applied in compliance with co mpany policy, regulations, and good process safety practices). Personnel perform internal compliance audits at least every three years to review and evaluate the written documentation/records and implementation of the prevention program. Potential areas that can be improved within the prevention program elements are identified and recommendations are formulated and implemented to ensure an effective and improved overall prevention program. The developed compliance audit program satisfies the regulatory requirements of ' 68.79 of the RMP Rule. INCIDENT INVESTIGATION: UPI believes incident investigation to be a vital component in the overall prevention program, and has developed an incident investigation procedure satisfying the requirements of ' 68.81 of the RMP Rule. The procedure requires the investigation of each incident which resulted in, or could reasonably have resulted in, a release of ammonia causing personnel injury or major property or environmental damage . The intent of the investigation is to identify underlying cause(s) and to develop and implement corrective actions necessary to prevent reoccurrence of the incident, or similar incidents. Trained management personnel assume the position of incident investigation team leader, when an incident occurs. The number and experience of the other team members is dependent upon the severity and complexity of the incident. Typically, the incident investigation team is comprised of a team leader, an expert in the process, and other employees (including contract employees) knowledgeable in the operation, design, and maintenance of the process. The incident investigation team leader is responsible for initiating the investigation as soon as possible but definitely within 48 hours of the time of the incident or "near miss". The incident investigation involves four stages: o Gathering evidence (e.g., interviewing witnesses, taking photographs, collecting evidence and records , and obtaining samples); o Analyzing the evidence; o Developing conclusions; and o Formulating recommendations. The incident investigation team prepares a written report at the conclusion of the investigation that includes: o Date and time of the incident or "near miss"; o Date and time the investigation was initiated; o Team members and their expertise; o Description of the incident or "near miss"; o Factors that contributed to the incident or "near miss"; and o Recommendations formulated as a result of the investigation. The written report is forwarded to the appropriate members of management for review. Management addresses each recommendation to identify the most appropriate resolution and to establish a schedule for completion of each accepted recommendation. The team leader or designee tracks the recommendation status until the recommendation is resolved. The investigation results, including the disposition of all recommendations, are reviewed with employees ( including contract employees) whose job tasks are relevant to the findings. The Manager of Safety & Health retains copies of the investigation reports for a minimum of five years to be used during subsequent process hazard analysis (PHA) revalidations. EMPLOYEE PARTICIPATION: UPI recognizes the contributions to safety and operations that are made by employees (including hourly and contract employees when appropriate) at all levels and in all disciplines. UPI consults with employees to ensure consideration of their knowledge and experience in all applicable areas of the prevention program. Accordingly, UPI has developed a written plan of action regarding employee participation in the prevention program elements, the hazard assessment, and emergency response program, satisfying the requirements of ' 68.83 of the RMP Rule. The written employee participation plan ensures that: o Employees and their representatives are consulted on the conduct and development of p rocess hazard analyses (PHAs) conducted to comply with ' 68.67 of the RMP Rule. UPI requires participation by plant operators and maintenance personnel as members of the PHA team. Other employees with responsibilities relating to specific processes are consulted prior to and during the PHA; o Employees and their representatives are consulted on the development of all elements of the prevention program in accordance of ' 68.65 to 68.87 of the RMP Rule, and the emergency response program developed in accordance with ' 68.95 of the RMP Rule. Examples of participation include operations and maintenance employees being: - actively involved in the development of procedures; - integral members of the established incident investigation teams; and - consulted with regarding the appropriate type and frequency of training. o Employees and their representatives are provided access to PHAs and to all other information required to be developed under the RMP Rule (e.g., hazard assessment, emergency response program). HOT WORK PERMIT: Control of ignition sources is a vital component of UPI's release prevention program. Therefore, it is critical that pertinent personnel are notified when hot work (i.e., any spark-producing operation including use of power tools, grinding, burning, welding, brazing) is to be performed in the facility and that appropriate safety precautions are taken prior to initiation of the work. UPI has developed a hot work permit program, satisfying the requirements of ' 68.85 of the RMP Rule, which requires that employees complete permits certifying that the applicable portions of the fire prevention and protection requirements are implemented prior to beginning hot work operations. These requirements are contained in the fire prevention and suppression procedure and hot work permit, Title 8 California Code of Regulations (T8 CCR) '4848 and '6777 respectively. The Operations department is sues hot work permits for all grinding, burning, welding, and brazing performed in areas not otherwise approved for cutting and welding. The hot work permit is terminated when continued use of the ignition source could be hazardous, when the conditions under which it was issued change, or when the permitted hot work has been inactive for more than 2 hours (unless tests show that conditions are still non-hazardous). The hot work permit contains the following information: o The effective date and time; o The authorized duration of the permit; o The specific location or piece of equipment where the source of ignition will be used; and o Any special precautions or limitations to be observed before, during, or after the use of the source of ignition, including the need for a fire watch and fire hoses or extinguishers. Personnel in the control room are notified prior to initiation of the hot work to make them aware of the ignition source. This awareness allows perso nnel in the control room to quickly contact the fire watch and personnel performing hot work when continued use of the source of ignition becomes hazardous. CONTRACTORS: UPI relies on contractors to supplement the existing workforce primarily during maintenance outages and when specialized expertise is required. UPI and all contract owners are jointly responsible for safety and must ensure that contract employees are trained in and understand the following: o Work practices necessary to perform job responsibilities; o Hazards associated with the process; o Applicable sections of the emergency response procedure; and o Applicable safe work practices. UPI has developed a contractor program, satisfying the requirements of ' 68.87 of the RMP Rule, to ensure that safety issues are addressed during contractor selection and that UPI and contractor owners share responsibility for the safety of all employees (including contractors). UPI requires that potential contract owne rs provide information regarding their safety programs and past safety performance to the Safety & Health Department for review. The Safety & Health Department may also request that the contract owner submit additional documentation (e.g., the written safety program) or safety training records/logs. Contractors are selected, in part, based upon the completeness and maturity of their safety program, their past safety performance, and their ability to complete the required work. Contractor employees are required to receive training before being allowed on-site. The training consists of a safety video describing emergency procedures and facility- wide practices (e.g., contractor and employee access). The training also addresses safe work practices and process-specific hazards. The content and duration of the training is dependent upon the contractor's responsibilities. Contract employees are allowed on-site only after demonstrating adequate comprehension of the trainin g program content. The Safety & Health Department audits each contractor owner periodically. The frequency of the audits is adjusted according to safety performance/history, and the type of service being provided. The Safety & Health Department ensures that proper training is provided and that documentation is maintained for each contractor. The Safety & Health Department also monitors contractor performance (e.g., compliance with safe work practices, knowledge of types of work and the hazards involved). Documentation of the audits and on site evaluations is maintained for a minimum of five years. THE FIVE-YEAR ACCIDENT HISTORY A review of facility incident investigation reports has shown that there have been no incidents involving ammonia or other hazardous substances, for which the onsite or offsite consequences exceeded the reporting requirements of ' 68.42 of the RMP Rule. THE EMERGENCY RESPONSE PROGRAM Overall safety at UPI is governed not only by the ability to prevent accidental releases of anhydrous ammonia from occurring, but also by the ability to mitigate any accidental release that might occur. UPI therefore has developed an emergency response program to minimize the effects of accidental releases of anhydrous ammonia to employees, the public, and the environment. UPI has formed emergency response teams (ERTs) to respond to onsite releases of ammonia; approximately 10% of the plant staff is so trained. An emergency response program was developed which addresses: o the emergency action plan (EAP) requirements of Title 8 California Code of Regulations (T8 CCR'3220); o an emergency response plan (ERP), satisfying the requirements of the Hazardous Waste Operations and Emergency Response (HAZWOPER) regulation, T8 CCR '51921; o coordination with local emergency response personnel and officials, satisfying the requirements of ' 68.95(c) of the RMP Rule. The EAP portion of the response program addresses tho se employees who are not responsible for responding to the release of anhydrous ammonia. This plan provides for employee evacuation routes, (or, alternatively, for "sheltering-in-place" where circumstances warrant), personnel accountability procedures, and EAP training for employees. The EAP portion also includes a call list which provides the telephone numbers of agencies and individuals to contact in the event of one of several pre-identified emergencies (e.g., fire, employee injury, employee fatality). The agencies and individuals on this call list represent local emergency responders (e.g., Fire Department), public notification and regulatory reporting requirements (e.g., CCCHSD), adjacent industrial facilities, as well as UPI personnel requiring notification (e.g., Plant Manager, Emergency Control Group personnel). UPI ERT personnel are trained in fire suppression techniques and are able to fight incipient, non-structural fires. All other fire suppression requi res the assistance of the local Contra Costa Fire Protection District (CCFPD). UPI works closely with the CCFPD to prevent fires from occurring and to quickly mitigate fires. UPI conducts drills with local fire and police departments, and participates in similar drills conducted by the neighboring industrial facilities. Such drills ensure that members of the fire department are familiar with the facility, the hazards of the anhydrous ammonia, and the locations of resources available at UPI. UPI has developed and implemented an ERP to respond to releases of anhydrous ammonia. The ERP identifies the emergency response team (ERT) training requirements, qualifications, and responsibilities within the incident command system. The ERT is comprised of individuals from the Operations, Maintenance, and Technology groups. In addition to the ERT, the UPI Security force has properly trained, and properly equipped employees to administer first aid and emergency medical treatment until outside ambulance services and associated EMT personnel arrive. Chemical-specific emergency response procedures for releases of ammonia are contained in Safe Job Procedure SJP KM-122, "Anhydrous Ammonia Work Procedure for Leak or Spill (General)". This procedure identifies the personal protective equipment (PPE) required for responding to ammonia releases, describes the safety hazards associated with ammonia, and describes mitigation measures to control the release. UPI maintains emergency response equipment and personal protective equipment (PPE) for use by the emergency response team and the Fire Department. The emergency response equipment is included in the mechanical integrity program, requiring that testing and inspection frequencies be developed and preventive-maintenance activities be conducted. Examples of PPE maintained at UPI include air-purifying respirators and self-contained breathing apparatus, as well as the appropriate chemical-resistant cloth ing. UPI also works closely with Contra Costa County Health Services (CCCHSD) for any necessary response to hazardous material releases, to assist in determining any downwind air monitoring, and to alert the public of the accidental release of ammonia. The emergency response program, including the EAP and the ERP, is reviewed annually to ensure that it remains accurate and current. Employees are trained on the emergency response program when initially hired, when the emergency response plan is revised, and when employees' responsibilities are changed. PLANNED CHANGES TO IMPROVE SAFETY At the present time, UPI plans one improvement to the pressure relief provided for the ammonia storage vessel; the intent is to capture smaller relief valve discharges in a scrubber, thereby reducing the release of ammonia to the atmosphere. As described previously, the ammonia storage tank is provided with two relief valve manifolds. Each manifold has two relief valves, bu t only one relief valve on each manifold is valved into service at any time. The relief valves are sized to safely relieve the internal pressure that would result from an external fire engulfing the vessel, and boiling its contents. Calculations have shown that a single relief valve is adequate to protect against this design basis scenario; thus, redundant protection is provided. The relief valves are sized and installed in accordance with the requirements of ANSI standard K 61.1, which requires that these relief valves discharge directly to atmosphere. In other words, the connection of any release mitigation equipment to the discharge of the relief valves is prohibited. It is recognized that the fire exposure scenario, while the most severe scenario, is not the only circumstance that could lead to vessel overpressurization, requiring that a relief valve open to protect the vessel. Accordingly, UPI proposes to provide an additional, smaller capacity relief valve on the ammonia storage vessel. The discharge from this will be piped below the surface in a water-filled scrubber tank. Smaller, more likely, ammonia releases would be absorbed in the water, reducing the amount of ammonia discharged to the atmosphere. This safety enhancement would be achieved without degrading the required protection provided by the fire exposure relief valves. |