Sybron Chemicals Inc.-Welford - Executive Summary |
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Facility Information Sybron Chemicals Inc. operates a facility in Wellford, South Carolina, which employs 110 full time employees. The Wellford Plant is a chemical manufacturing facility, where materials considered hazardous by the U.S Environmental Protection Agency are used, stored, manufactured, and packaged. Sybron Chemicals uses three regulated chemicals that are above threshold quantities specified in the Risk Management Program regulations. These chemicals are ethylenediamine, formaldehyde, and trimethlamine, which are chemical additives used in the manufacturing of textiles. Sybron Chemicals stores ethylenediamine in a storage tank at a 95% administrative capacity limit, which is approximately 71,250 pounds. Formaldehyde is stored in a storage tank at a 95% administrative volume control, which holds 31,635 pounds. The regulated trimethylamine is stored in a storage tank at an 80% administrative capacity limit, which holds 51,840 pounds. Sybron Chemicals adheres to th e appropriate government rules and industry guidelines for the storage and use of these flammable substances. Risk Management Planning Sybron Chemicals has an extensive information sharing practice with its workers and the general public regarding the chemicals used at the facility and their associated risk. Sybron Chemicals is subject to the Risk Management Program requirement under Section 112 (r) of the Clean Air Act due to its storage and process use of ethylenediamine, formaldehyde, and trimethylamine. The facility uses both passive measures and active mitigation to minimize the likelihood of releases and their potential impact on the public and on the environment. These mitigation systems include a range of various deterrents to further minimize a release. The mitigation system for the trimethylamine tank and associated reactor vessel includes: -excess flow valves that limit the possibility of excess fluid escaping - a vapor recovery system - a venting system through a s crubber - an N2 purge which suppresses the potential ignition of a fire - a water cannon to slow down the evaporation rate and squelch fire The ethylenediamine process uses: - relief vents, which redirects the chemicals into a water scrubber that vents into an emergency blow-down trap tank to prevent overpressurization of the reactor and to control the releases to the atmosphere - a N2 purge - a water cannon - a dike surrounds the tank, which is designed to contain its entire contents - the ethylenediamine process equipment has additional mitigation equipment, which includes a sprinkler system. The formaldehyde reactor uses: - a N2 purge and flame arrestor - A dike surrounds the formaldehyde storage tank, which is designed to contain its entire contents Regulated Toxic Substance Worst-Case Release Scenario The instantaneous failure of the ethylenediamine storage vessel and complete failure of both the active and passive mitigation systems is used as the Regulated Toxic Subs tance Worst-Case Scenario at the facility. The only surviving passive mitigation system is considered to be the dike, which controls the liquid in a 4, 750 sq. foot pool. This scenario results in a total release of the maximum intended inventory (95 percent by volume) of the ethylenediamine storage vessel (71,250 pounds) within ten minutes. The release rate is calculated to be 847.2 pounds/minute. Moreover, the worst-case meteorological conditions for Wellford are incorporated into the calculation for the endpoint distance for the ethylenediamine release. The conditions are: 39 oC, humidity 68%, and windspeed 1.5 m/sec. The distance to the endpoint for this toxic liquid spill and vaporization extends beyond the facility's property line. The radius of concern includes a residential population and industrial facilities. Regulated Flammable Substance Worst-Case Release Scenario In determining the amount of trimethylamine released in the Flammable Substance Worst-Case Scenario, t he instantaneous failure of the walls of the trimethylamine solution tank, complete failure of both the active and passive mitigation systems, and the administrative control on the capacity of the storage tank (80 percent by volume) is considered. Moreover, the worst-case meteorological conditions for Wellford are incorporated into the endpoint distance of the trimethylamine gas release. The conditions are assumed to be: temperature of (39oC, humidity 68%) and a windspeed 1.5 m/sec. Within ten minutes all the contents in the tank are released (51,840 pounds) and a vapor cloud explosion occurs. The distance to the endpoint for this vapor cloud explosion (i.e. one pound per square inch) extends beyond the facility's property line. The distance to endpoint includes a residential population and industrial facilities. Alternate Release Scenarios Seven alternate release scenarios are examined for the facility. The first scenario involves the failure of the formaldehyde reaction vessel, causing a liquid pool to form. Three plausible situations can occur involving the trimethylamine process: failure of the reaction vessel, causing a vapor cloud explosion; failure of the reaction vessel, causing a flash fire; and failure of the storage vessel, causing a pool fire. The fifth, sixth, and seventh scenarios all involve the ethylenediamine storage vessel. The fifth scenario involves the complete failure of the storage vessel, the sixth scenario entails a release from a 1/4" hole in the tank, and the seventh situation describes a flange release. The sixth and seventh release scenarios are situations that are more likely to occur than the other scenarios due to the facility's past history and the area's surrounding industry release incidents. Typical meteorological conditions for Wellford, South Carolina are used to determine the five alternate scenarios. The average temperature is 16 oC, humidity 68%, and windspeed 3.1 m/sec. Alternate Scenario 1: There is assumed to be a complete failure of the unmitigated formaldehyde reaction vessel, releasing 13,320 pounds of solution. This release forms an unmitigated pool of 5,861 square feet. It is assumed that a portion of the solution has evaporated since the spill may take 8 hours to clean up. The solution evaporates at a rate of 2.9 lbs./minute for 8 hours, resulting in an endpoint distance beyond the facility's property line. The radius of concern includes a residential population and industrial facilities. Alternate Scenario 2: There is assumed to be a complete failure of the trimethylamine vessel, resulting in a total release of the gas, causing a vapor cloud explosion. The endpoint (one pound per square inch) for the vapor cloud explosion of 20,520 pounds of material extends beyond the facility's property line. The radius of concern includes a residential population and industrial facilities. Alternate Scenario 3: There is assumed to be a complete failure of the trimethylamine vessel, re sulting in total release of the gas, causing a flash fraction vapor cloud explosion. The endpoint (i.e. one pound per square inch) for the flash fraction vapor cloud explosion of 20,520 pounds of trimethylamine extends beyond the facility's property line. There is no residential population or other environmental receptors within the radius of concern. Alternate Scenario 4: There is assumed to be a complete failure of the trimethylamine storage vessel, resulting in total release of the liquid, causing a pool fire. The fire's endpoint (5kWatts/m2) distance based on a release of 51,840 pounds of material extends beyond the facility's property line. The radius includes a residential population and industrial facilities. Alternate Scenario 5: There is assumed to be a complete failure of the ethylenediamine tank, resulting in a total release of the liquid (71,250 pounds) into a containment area of 4,750 sq./ feet. The release rate is calculated to be 25.4 pounds/minute and is assum ed to continue for 8 hours, at which time the spill is mitigated. The endpoint distance of ethylenediamine does not include a residential population or other environmental receptors within the radius of concern. Alternate Scenario 6: There is assumed to be a 1/4" leak in the ethylenediamine tank. The hole is located two feet above ground, resulting in a release of 8,327.1 pounds into a containment area of 4,750 sq./ feet. The release rate is calculated to be 25.4 pounds/minute and is assumed to continue for 60 minutes, at which time the spill is further mitigated. The total amount of liquid evaporated from the release is calculated to be 6,107.85 pounds. The endpoint distance of this ethylenediamine does not include a residential population or other environmental receptors within the radius of concern. Alternate Scenario 7: There is assumed to be a release from a leaking flange of the ethylenediamine tank or associated piping structure. The flange released 60 gallons of soluti on before it was stopped. The incident resulted in 3.54kg of solution to be evaporated. The release was cleaned 60 minutes after the release was stopped. The modeling results do not depict concentration levels below the endpoint distance concentration threshold of 0.49 mg/L. Therefore, there is not an endpoint distance of this ethylenediamine incident, defined as the distance to which a minimum concentration of 0.49 mg/L occurs from the vaporization of the liquid pool formed. Accident History and Safety Information Sybron Chemicals is committed to keeping preventive procedures, safety precautions, and alternatives updated. In addition, standard operating procedures are available for all pieces of equipment, which entail process descriptions, safety information, and emergency shut down instructions. Furthermore, personnel are trained to respond to minor accidental releases. The facility is continuously improving operating procedures, equipment, and several safety measures to re duce the likelihood of an incident. A five-year accident history is defined by the RMP regulations to include accidents related to regulated chemicals that result in deaths, injuries, or significant property damage on site or known offsite deaths, injuries, evacuations, sheltering in place, property damage, or environmental damage. Sybron Chemicals has not had any accidents involving a release of a regulated substance in processes within the past five years. Emergency Response Program Sybron Chemicals believes the best way to manage risk is not only to prevent accidents, but also to correctly know what to do if an accident should occur. After careful consideration of the identified release scenarios, the accident history, and a review of the latest inspection report from the Occupation Safety Health Administration (OSHA), no changes to the current systems are planned. The Emergency Response Program will continue to reduce the risk through continuous use of safety precautions and i nstruction manuals that already exist at the facility. Sybron Chemicals' Process Safety Management Procedures Manual includes such Risk Management components as: process safety information, equipment identification, operating procedures, mechanical integrity, inventory restrictions, process or facility change, and an employee participation plan. The extensive Safety, Emergency and Environmental Procedures Manual includes such Risk Management components as: injury/incident reporting and investigation, hot works permits, line breaking, head/eye/foot protection, respiratory protection, hazard communication plan, forklift safety, waste notification, and plant emergency operations. In addition, the facility has already incorporated process controls including, relief and check valves, manual and automatic shutoffs, interlocks, alarms, backup pumps, and grounding equipment, where appropriate. |