EO

ethyleneoxide second edition User’s Guide Introduction 1.1 Purpose The purpose of this guide is to provide users of Ethylene Oxide (EO) with a summary of the essential information needed to safely handle this important chemical product. The flammable, reactive and toxic characteristics of EO, and its effects on the environment, pose risks that must be managed by all users and producers. This information is provided to the user as a resource in the development of their safe design, operation, maintenance, training and emergency response practices. It is not our intent to “recommend” any particular procedure, equipment design or practice, but rather to provide a summary of the authors’ current state of knowledge relating to EO and its use. Please note that this publication represents the level of knowledge of its authors as of the date of publication. The user should stay abreast of new developments of information about properties of EO, handling technology, and regulatory requirements that occur after publication. The appendices contain graphs and tables of physical property data and a section-bysection bibliography. Editorial Committee The following individuals were responsible for their respective companies’ contributions to the Guide: Carey Buckles — The Dow Chemical Company Pete Chipman — Shell Chemical Company Mary Cubillas — Shell Chemical Company Mike Lakin — Celanese Ltd. Dan Slezak — The Dow Chemical Company David Townsend — Celanese Ltd. Keith Vogel — Equistar Chemicals, LP Mike Wagner — Sunoco, Inc. 1.2 Organization In order to safely use EO, it is necessary to understand its properties. The guide starts with a discussion of physical and chemical properties (section 2), followed by discussions of health effects (section 3), and environmental effects (section 4). Section 5 discusses safety incidents that have occurred in industrial production, use, and transportation of EO. Sections 6, 7, 8 and 9 discuss safe design and operation of EO handling facilities. Sections 10 and 11 cover emergency response and federal regulations. Acknowledgements The editorial committee wishes to thank the following individuals for their significant contributions to this publication: Ralph Gingell — Shell Chemical Company Manuel Cano — Equilon Enterprises LLC Table of Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Introduction Properties of Ethylene Oxide Health Effects Environmental Overview of Hazards Design of Facilities Personnel Exposure Equipment Preparation and Maintenance Transportation & Unloading Operations Emergency Response Regulations Appendix A: Tables and Figures Appendix B: References This guide represents a revision of the earlier publication of the same name issued in September of 1995. It was produced through the cooperative efforts of Celanese Ltd., The Dow Chemical Company, Shell Chemical Company, Sunoco, Inc. and Equistar Chemicals, LP. Issue Date: August, 1999 The information contained herein is accurate to the best of our knowledge. We do not suggest or guarantee that any hazards listed herein are the only ones that exist. Use of this handling guide is intended for persons with skill and at their own risk. User has sole responsibility to determine the suitability of the product for any use and the manner of use contemplated. Any potential health hazards associated with this product of which these companies may be aware are described in the Material Safety Data Sheet (MSDS) for this product. Online Viewing The Guide is also available on the World Wide Web at http://www.ethyleneoxide.com. Properties of Ethylene Oxide 2.1 Introduction Figure 2.1 The Ethylene Oxide Molecule 3Å 1.4 1.09 Å 61.62° 1.46 Å .9° 16 1 EO (oxirane) is the simplest cyclic ether. It is a colorless gas or liquid and has a sweet, etheric odor. The structure of an EO molecule is shown in Figure 2.1. The C-C bond is short and the bond angles strained [1]. Note that the atomic distances are given in angstroms. EO is very reactive, because its highly strained ring can be opened easily, and it is one of the most versatile chemical intermediates. EO was first prepared in 1859 by Wurtz [2] using potassium hydroxide solution to eliminate hydrochloric acid from ethylene chlorohydrin. The chlorohydrin process developed from Wurtz’s discovery and industrial production began in 1914. The importance and commercial production of EO have steadily grown since then. The direct catalytic oxidation of ethylene, discovered in 1931 by Lefort [3], has gradually superseded the chlorohydrin process. Currently, EO is produced by direct oxidation of ethylene with air or oxygen. Annual worldwide production capacity exceeds 11 million tons, making it an important industrial chemical. Virtually all EO produced is further reacted (section 2.4). Its most important derivative is ethylene glycol, which is used for the manufacture of polyester and in automotive antifreeze. Other EO derivatives include surfactants, solvents, amines, and poly(ethylene) glycols. In addition to being a versatile and commercially important compound, EO has been involved in a number of serious incidents. It is necessary to understand the properties of EO to manage the risks of its use. 2-1 Properties of Ethylene Oxide 2.2 Physical Properties Important physical properties of EO are summarized in Table 2.1. Table 2.1 Physical Properties of Ethylene Oxide Ethylene Oxide Chemical Abstracts Name: PSUID Code: IUPAC Name: Chemical Abstracts Number: Structural Formula: Synonyms: Oxirane 1441 Oxirane 75 -21 -8 CH2OCH2 Ethylene Oxide 1,2-Epoxyethane Dihydrooxirene Oxacyclopropane Dimethylene Oxide Oxidoethane Epoxyethane Other Names: Ethene oxide; ETO; Oxane; Oxirene, Dihydro -; Oxyfume; Oxyfume 12; T-Gas; Aethylenoxid; Amprolene; Anprolene; Anproline; ENT-26263; E.O.; 1,2-Epoxyaethan; Ethox; Ethyleenoxide; Etylenu tlenek; FEMA No. 2433; Merpol; NCI- C50088; a,b- Oxidoethane; Oxiraan; Oxiran; RCRA waste number U115; Sterilizing gas ethylene oxide 100%; UN 1040; C2H4O [37]. Property Molecular Weight Critical Temperature Critical Pressure Critical Volume Critical Compression Factor Melting Point Triple Point Temperature Triple Point Pressure Normal Boiling Point at 101.325kPa(1atm) Liquid Specific Gravity 20°C/20°C Liquid Volume Coefficient of Cubical Expansion (20°C) Heat of Formation - Ideal Gas Heat of Formation - Liquid Gibbs Energy of Formation - Ideal Gas Gibbs Energy of Formation - Liquid Absolute Entropy - Ideal Gas Absolute Entropy (liq) Heat of Fusion at Melting Point Entropy of Fusion Standard Net Heat of Combustion Heat of Solution in Water Acentric Factor Radius of Gyration Dipole Moment Liquid Dielectric Constant at 0°C (32°F) Vapor Dielectric Constant at 15°C (54.5°F) Electrical Conductivity (liq) van der Waals Volume van der Waals Area Refractive Index, nD Flash Point Flammability Limits Autoignition Temp Decomposition Temp NOTES: 1. Estimated to be equal to the melting point temperature. 2. Determined at the normal boiling point. SI Units 44.053 469.15°K 7,191 kPa 0.00319 cu m/kg 0.2588 161.46°K 161.46°K 0.0078 kPa 283.6°K 0.875 0.00113 cu m/kg 0.00158/°K -1,194.8 kJ/kg -1766 kJ/kg - 300.3 kJ/kg -267 kJ/kg 5.52 kJ/kg*°K 3.494 kJ/kg*°K 117.5 kJ/kg 0.73 kJ/kg*°K -27,649 kJ/kg -142.7 kJ/kg 0.197 1.937E-10 m 6.3E- 30 C*m 14.5 1.01 4E-06 Siemens/m 5.485E-04 cu m/kg 7.492E+06 m sq/kg 1.3597 5C2H4 + 2CO2 + 2H2O But depending on the reaction conditions, the ratio of C2H4 to CO2 has been found to vary from 1.5 to 2.5. This reaction can be initiated at significantly lower temperatures than thermal decomposition. In the case of the industrial incident noted above, the reaction occurred: • On the tubes of a distillation column reboiler, • In the presence of a deposit of high surface area rust imbedded in an EO polymer matrix, and • During a period when flow through the reboiler was reduced by a process upset. It was concluded that loss of reboiler circulation allowed for rapid heat buildup in the vicinity of the iron oxide/polymer deposit, resulting in localized temperatures reaching the EO thermal decomposition temperature. The result was an explosion that destroyed the distillation column. Britton [17] has indicated that rust with very high surface areas can also initiate EO ignition at 284°F (140°C) or below with or without air present. 900 BTU per pound of EO reacted [13]. Britton [17] has reported a rust catalyzed heat of polymerization of 1102 ± 121 BTU/lb. The usual catalysts for EO reactions, such as strong alkali [18], iron oxide (rust) [19], and other metal oxides catalyze the reaction. When catalyzed by rust, it is most often a nuisance, causing line and equipment plugging and off-specification product. However, the presence of large quantities of loose rust could pose a significant safety hazard (see discussion above). Britton [17] also indicated self-polymerization at 392°F (200°C) in a closed, near-adiabatic system, and noncatalytic conditions. The condition of metal surfaces is extremely important in determining the rate of EO polymer formation. It has been reported [19] that even clean carbon steel catalyzes polymerization, although at a much slower rate than rusty steel. Other factors that affect rate of polymerization: • Metal surface to volume ratio • Temperature • Equipment residence time Stainless steel is often the best choice for materials of construction, especially when the surface to volume ratio is high. The polymerization reaction has not been found to be auto-catalytic [43]. That is, the presence of polymer does not accelerate the polymerization process. Contamination of EO with catalysts such as KOH or overheating can lead to runaway polymerization. Reference [18] has a discussion of an EO polymerization (or “Polycondensation”) incident brought about by contamination of an EO-containing cylinder with chlorine and alkali. The result was an accelerating or “runaway” reaction that ended with an explosion after about eight hours. Polymerization EO has a tendency to polymerize. For pure EO, the reaction is slow at ambient temperatures. The reaction is exothermic, releasing 2-7 Properties of Ethylene Oxide Table 2.4 Physical Properties of Pure poly(ethylene oxide) [44] Molecular Weight 200 600 1000 3400 10,000 100,000 4,000,000 Melting Temp. (°F) -85 (softening) 72 (softening) 102 131 145 150 150 Density (g/cc) 1.127 1.204 1.130 Table 2.5. Solubilities of poly(ethylene oxide) in various solvents [45]. Solubilities are given in weight percent. S signifies completely soluble. Solvent Water Methanol Acetone Trichloroethylene Heptane Mol Wt 500 – 600 T=68°F T=122°F 73 48 20 50 0.5 97 96 S 90 .01 Mol Wt 3000 -3700 T=68°F T=122°F 62 35 500 mg/L 48-h LC50 = 490, >500, 1000 mg/L Ethylene Oxide in Water Systems When spilled on water, ethylene oxide will volatilize and, at the same time, spread on the surface and mix with the water. EO EnviroTIP manuals [19] also document methodology to evaluate both spreading and mixing components of an EO release to water. Comments no effect concentration static; fresh water static; fresh water Reference [9] Fathead minnow Fathead minnow [9] [1] Goldfish Daphnia magna static; fresh water static; fresh water [21] [1] Brine shrimp static; salt water [1] Table includes multiple results from separate tests. 4 -3 Ethylene Oxide Dispersion in Air EO vapor cloud dispersion in air following a release can be evaluated using computer based dispersion models available commercially from a number of sources [24]. Dispersion estimates can also be made using nomographs in the EO EnviroTIP manual [19]. Analytical predictive models have been developed by the EPA for hazardous waste treatment, storage and disposal facilities [25], and these can be used to estimate EO emissions to air. Vapor emissions (including, but not limited to EO) from contained spills, either on land or water surfaces can also be predicted with methodology developed by Wu and Schroy [26]. 4.5 Fugitive Emissions A 1983 study, funded by the EPA, described a methodology for estimating fugitive emissions of volatile organic compounds (VOC) on the basis of numbers of valves, flanges, etc., and concentrations of VOC in equipment. The methodology included use of SOCMI (Synthetic Organic Chemical Manufacturing Industries) emission factors for estimating fugitive emissions, and was general for VOCs. The 1983 methodology was significantly refined in a 1988 study sponsored by the Chemical Manufacturers Association (CMA) in cooperation with the United States EPA. New correlation equations were developed for estimating fugitive emissions that are specific for manufacturing facilities handling EO. In general, CMA emission factors resulted in lower emissions estimates than the 1983 SOCMI emission factors. The 1993 US EPA Protocol for Equipment Leak Emission Estimates provides two methods for estimating VOC emissions. One option is updated SOCMI emission factors, which were revised from the 1983 factors based on the 1988 CMA study. These factors will yield lower estimates than either the 1983 or 1988 correlations. As with the 1983 SOCMI factors, a reduction in estimated emissions is allowed if the facility has a Leak Detection and Repair (LDAR) program. This estimation option may be used for emission inventories or permit applications. The other option in the 1993 Protocol [27] uses field leak concentration data collected for compliance with US EPA leak detection and repair (LDAR) requirements to calculate fugitive emissions. If the number of components found to be leaking is small, using the Fugitive Emissions Correlation Equations may result in even lower calculated fugitive emissions. These correlations allow calculation of an emission rate for each component (flange, pump seal, etc.) using the actual reading taken in the field. Many commercially available data bases developed to document LDAR compliance can also calculate the fugitive emissions based on the data collected. Fugitive emission rates calculated in this manner may be used for annual emissions inventory reporting, but not for permit applications. 4-4 Overview of Hazards 5.1 Introduction Over the past 50 years, there have been many incidents in both EO production plants and EO consuming plants [1] resulting in major plant damage, as well as fatalities. There have also been a significant number of EO transportation incidents. One of the best ways for the EO user to understand the hazards of EO is to become familiar with the incidents that have occurred in the past and their causes. The lessons learned will help in design of safer plants and development of procedures for safe operations, maintenance, training and emergency response. Figure 5.1 Blast center – EO tanks no longer visible after explosion 5.2 EO Contamination Incidents EO is routinely reacted with other chemicals under controlled conditions to produce commercial products in a safe manner. The fact that EO is reactive with so many other chemicals and the reactions are highly exothermic causes contamination to be one of the most significant hazards of working with EO. Contamination of pure EO with many other chemicals, including water, or with waste materials can lead to uncontrolled reactions producing large amounts of heat. Figure 5.2 Aerial view of the plant showing overall damage Contamination of EO with Aqueous Ammonia This incident occurred in 1962 at an EO production and derivatives plant. An EO storage tank containing 25 tons of EO was contaminated with aqueous ammonia due to back-flow from an ethanolamines unit. A rapid reaction in the tank between the EO and the ammonia resulted in over-pressure and rupture of the tank, followed by an EO vapor cloud explosion. (Figures 5.1, 5.2, 5.3) Ignition of the vapor cloud caused heavy structural damage in a radius of 500 feet from the blast center. The explosion resulted in one fatality, three serious injuries, and 18 less serious injuries. The EO producer’s investigation revealed that ammonia entered the EO storage tank by backflowing through the EO transfer line. The ammonia passed through several check valves and a positive displacement pump (through its relief valve) to get to the EO tank [2,3] . Figure 5.3 Plant laboratory after EO vapor cloud explosion – 300 feet away 5 -1 Railcar Explosion Due to Reaction Between Residual EO and Cleaning Water An EO railcar was sent to a contractor for cleaning. It contained a “heel” of a few thousand gallons of EO. The contractor pumped brackish water into the car and left it in a rail yard overnight. During the night it exploded, causing significant damage to other railcars in the rail yard. (Figures 5.4, 5.5, 5.6) The EO producer’s investigation revealed that a major contributing factor to this incident was the fact that the water was added slowly to the railcar. The EO and water formed two distinct layers in the railcar due to the difference in density and inadequate mixing. Due to the layering, there was an interface between a high concentration of EO and a high concentration of water. This resulted in a much higher reaction rate than would have occurred if the EO and water had been well mixed. Contaminants in the brackish water may have also contributed to the high reaction rate. The subsequent reaction generated a high temperature and pressure, resulting in rupture of the car [4]. Figure 5.4 Remnants of railcar after EO explosion caused by contamination Figure 5.5 Remnants of railcar after EO explosion caused by contamination EO Railcar Contamination with Bentonite Clay A railcar was returned to an EO producer’s plant after cleaning by a contractor. Unknown to the EO producer, the cleaning contractor had put bentonite clay (a drying agent) in the car, to reduce rust formation. When the car was received at the plant, the clay was not removed. During loading with EO, a fire occurred in the dome of the railcar. Reaction between the bentonite clay and EO caused an internal ignition and release of burning EO vapor through the car’s safety relief valve. The fire was extinguished with water, but re-flashed. It was finally extinguished with dry chemical. Figure 5.6 Damage to other railcars due to the EO railcar explosion 5 -2 Overview of Hazards Contamination of Railcar with Ammonia A European EO producer shipped an EO railcar to a customer. The railcar was delivered to the wrong plant and the workers at the receiving plant thought the car contained anhydrous ammonia. They attempted to offload the EO into an anhydrous ammonia tank. The ammonia tank was at a significantly higher pressure than the pressure on the EO railcar. During the attempt to offload the EO, a check valve leaked and allowed a small amount of ammonia to back-flow into the EO railcar. When the workers at the plant discovered that the car was delivered by mistake, the unloading operation was stopped and the car containing the contaminated EO was dispatched on to its proper destination, 300 km away. The railcar car exploded in the middle of the night on a rail siding at the edge of the plant. The explosion caused major damage over a 300-meter radius and broke windows up to 5 km away. (Figure 5.7) with river water, and then stored the EO contaminated water in a 22,500 gallon railcar. The railcar contained 8000 gallons of EO and 5200 gallons of washwater. The car was loaded at 63°F and padded with nitrogen at 35 psig. The railcar sat on a siding for 23 days, and exploded on December 27, 1973. Prior to the explosion, the tankcar’s relief valve lifted, and the immediate area was evacuated. When the car exploded, there was a large fireball and the explosion formed a crater. The adjacent epoxide plant was demolished. There were 28 people with minor injuries, but no fatalities. 5.3 Formation of Ethylene Oxide Vapor Clouds Release of EO vapors can result in vapor cloud ignition. Such incidents can be extremely destructive. Ethoxylation Plant Explosion The contents of an ethoxylation reactor were pumped to a neutralization vessel about one half-hour before completion of all the reaction steps. The neutralization vessel was located indoors. The material was pumped to the vessel at a temperature of approximately 390°F. It contained 100 to 150 lbs. of unre- Explosion of Railcar Containing EO Washwater An EO producer in the US washed an EO ship loading line and an EO storage sphere Figure 5.7 Remnants of railcar after EO explosion caused by contamination with ammonia. 5 -3 acted EO. The EO vaporized and escaped from the vessel rapidly and mixed with the air in the building. An explosion occurred when an operator entered the building to turn on the ventilation system. The explosion killed the operator that was entering the building, injured two other operators, and completely destroyed the building housing the ethoxylation reactor and the neutralization vessel. Nearby buildings sustained extensive damage. The heat caused an EO decomposition reaction to be initiated in the line. The decomposition propagated down the line and into a distillation column. The column head was torn off and thrown about 100 feet. Large and small parts of the column jacket were scattered over a 2000foot radius. Only 7 minutes elapsed between the start of the unit fire and the column explosion. 5.4 EO Decomposition Incidents One of the most hazardous properties of EO is the fact that it will decompose at a temperature around 1040° F. The incidents listed below illustrate the most common causes of EO decomposition incidents. • Pump Seal Leak Fire An EO pump seal leak is always a significant incident because of personnel exposure concerns. However, if a pump seal leak ignites, the results can be catastrophic. A European EO production plant had an EO pump seal leak that was ignited by contact with hot pump parts. The flame from the pump seal fire impinged on an uninsulated minimum flow return line, causing evaporation of the EO in that line. Continued heat input from the flame impingement resulted in a decomposition in the minimum flow line. The decomposition reaction propagated into the EO purification column reflux drum, where an explosion occurred. The reflux drum and its associated distillation column were destroyed. This incident resulted in four fatalities. The plant was heavily damaged and out of operation for four months. EO Decomposition Incidents Caused by External Fires An external fire is one of the most hazardous situations that can occur in an EO plant because of the potential for EO decomposition. Even with good water spray systems and well-insulated equipment, flame impingement from an external fire can increase piping and vessel wall temperatures to EO decomposition temperature in a short time period. If this happens, an internal explosion can occur. The following are examples of major incidents that were caused by an external fire. • Fire Around Distillation Column An EO producer in the US had a rupture of an EO compressor cylinder. This resulted in a large fire, which engulfed the EO distillation column. The resulting temperature increase on the surface of the column and in the contained EO resulted in an internal explosion and significant damage. • Flange Fire while Plant was Down A European EO producer experienced a flange leak in the EO distillation section. The plant had been shut down, but still contained an inventory of EO. The flange leak resulted in a fire and the flame impinged on a process line containing EO. 5-4 Overview of Hazards EO Decomposition Incidents Caused by Mechanical Equipment Important concerns regarding pumps and compressors in EO service are 1) the potential for high temperatures if mechanical energy is not dissipated and 2) the potential for a fire due to seal leaks. A good example of failure to remove mechanical energy is a blocked pump discharge. The two incidents described here are good examples of the results of operating an EO pump deadheaded. The pump seal leak fire described on the previous page is a good example of the potential consequences of a seal leak fire. ture in the pump to rise, vaporizing EO and causing a decomposition reaction. The decomposition propagated through the pump suction line into the reflux vessel where an explosion occurred. Shortly afterward the EO purification column exploded. This explosion resulted in four fatalities. The plant was heavily damaged and out of operation for four months [5]. • EO Decomposition in Blocked-in Pump A US EO producer used high-speed centrifugal pumps to feed EO to two ethylene glycol units. The plant had a common spare feed pump for the two glycol units. The spare pump was typically kept cleared of EO, pressured up with 200 psig nitrogen and left with the suction and double discharge valves blocked in. A small amount of EO leaked through two blocked discharge valves into the pump. An electrical system malfunction caused the high-speed centrifugal pump’s electric motor to start. The pump ran blocked in for approximately 10 minutes until the seal area of the pump reached EO decomposition temperature and the pump • Decomposition in Reflux Pump Propagates to Reflux Drum and Tower A European EO producer had been having problems with the EO purification column reflux pump over-speeding. There were also instrumentation problems with the level controller on the reflux drum, and the incident was triggered by the reflux control valve failing closed. The reflux pump operated deadheaded against the level control valve, causing tempera- Figure 5.8 High speed centrifugal pump “launched” by decompostion of 0.6 lb. of EO 5 -5 Figure 5.9 Motor landed on operating EO pump discharge line exploded. The decomposition of the 0.6 lb. of EO generated over 450,000 pounds of force and caused the failure of twelve, 3 ⁄4" stainless steel nuts and bolts. (Figure 5.8) The upper part of the vertical centrifugal pump and the motor (approximately 1000 lb.) were launched 60 feet in the air. The pump and motor landed on the discharge piping of another EO feed pump that was operating at 750 psig, pumping 80 gpm of EO. Fortunately the piping did not fail. (Figure 5.9) of EO. These reactions all produce heat, the dissipation of which is inhibited by the insulation itself. This can result in a “hot spot” on the wall of the vessel, which can trigger a decomposition reaction. Since the incidents discussed below, industry has largely converted to nonporous insulation such as cellular glass. This reduces the potential for hot spots and provides a degree of protection from overheating due to fire. See section 6.3 for a fuller discussion of insulation. EO Decomposition Incidents Caused by Leaks • Under Insulation High temperatures can develop in EO leaking under porous insulation due to reaction of EO in contact with the insulation. Types of porous insulation subject to this problem include mineral wool, asbestos, fiberglass, calcium silicate, magnesium silicate, and others. Porous insulation can soak up and retain water from the environment, thereby providing a large surface area for EO/water contact. In addition, it has also been shown that many types of insulation catalyze reactions • EO Leak at an Insulated Manway Flange Results in Tower Explosion In 1987, a European EO producer had a catastrophic explosion of their EO purification column. The damage to the plant was very extensive. Investigation after the incident revealed that a manhole flange leak under mineral wool insulation on the EO distillation column resulted in an external “hot spot” which caused an EO decomposition inside the tower. (Figure 5.10, 5.11, 5.12, 5.13) 5 -6 Overview of Hazards Figure 5.10 EO distillation column reboiler after explosion Figure 5.11 Aerial view of the site showing the extent of the damage 5 -7 Figure 5.12 Remnants of the base of the EO distillation column after the explosion. The column is gone. Figure 5.13 Piece of the EO distillation column wall that was turned inside out by the explosion 5 -8 Overview of Hazards • EO Leak Under Insulation Results in Tower Explosion In 1989, another European EO producer had a catastrophic explosion of their EO purification column. A crack developed where a pipe was attached to the wall of an EO distillation tower. The crack allowed EO to leak into mineral wool insulation. EO reacted with water in the insulation to produce polyglycols. When portions of the insulation and insulation jacketing were removed for maintenance, air flowed into and under the insulation, causing rapid oxidation of the polyglycols, producing a high temperature. The insulation prevented dissipation of the heat, and the reaction in the insulation caused the wall temperature of the EO distillation tower to reach EO decomposition temperature. The resulting internal decomposition reaction caused vessel failure. Damage to the plant was severe, requiring more than a year for rebuilding. reboiler. There was one fatality and the plant was out of service for more than one year [6]. After the incident, the EO producer’s research identified a previously unknown reaction of EO: disproportionation (see section 2.3). This reaction can be initiated at significantly lower temperatures than thermal decomposition. In the case of this incident, the reaction occurred • On the tubes of a distillation column reboiler, • In the presence of a deposit of high surface area rust imbedded in an EO polymer matrix, and • During a period when flow through the reboiler was reduced by a process upset. It was concluded that loss of reboiler circulation allowed for rapid heat buildup in the vicinity of the iron oxide/polymer deposit, resulting in localized temperatures reaching the EO thermal decomposition temperature. The result was an explosion that destroyed the distillation column. EO Decomposition Caused by Reaction in Column Reboiler • EO Re-distillation Column Explosion An EO manufacturer experienced an explosion in an EO re-distillation column. (Figure 5.14) The explosion appeared to have been initiated at the top of the Figure 5.14 Scene of EO re-distillation tower explosion. EO re-distillation tower is gone and adjacent tower is damaged and leaning. EO Decomposition Incident Caused by Catalyst Residue in the Vapor Space of an Ethoxylation Reactor An ethoxylation reactor exploded during normal operation, while EO was being fed to the reactor. During the investigation of the explosion, pieces of the reactor head were found that had a heavy buildup of potassium hydroxide catalyst on the metal. A liquid stream containing KOH was added at the top of the reactor, and a KOH residue had built up on the inside of the head. The KOH catalyzed a reaction of the EO in the vapor space of the reactor driving the temperature in localized areas of the reactor head to the decomposition temperature and the vapor space decomposed explosively. The vapor space was not inerted with nitrogen. 5 -9 5.5 EO Transportation Incidents In both of the following transportation incidents an EO railcar was punctured and a fire resulted. In one incident the emergency responders controlled the process of burning off the EO. In the other incident, injuries were prevented by evacuation. Figure 5.15 Filter case after runaway polymerization EO Railcar Fire A railcar of EO was punctured in a rail accident and the leak ignited. Three unmanned fire monitors were set up to limit the temperature increase in the car and to reduce the likelihood of a “hot spot” in the car shell. Nitrogen was fed into the car through a hose from portable nitrogen bottles to maintain of an inert atmosphere inside the car. A 1.5” firewater hose was also connected to allow flooding of the car’s interior, should it become necessary. The fire was allowed to burn until all liquid EO had been consumed. When the fire went out, the car was filled with water as rapidly as possible to cool the car and to expel unburned EO vapors. No further damage resulted. 5.6 Runaway EO Polymerization Incidents Polymerization Incidents in EO Filters In 1969, a major US EO producer had an EO filter explode due to a runaway polymerization. The filter had been left full of EO and blocked-in. (Figure 5.15) In May 1998, another US EO producer had a runaway polymerization in an EO railcarloading filter. Circulation through the loading filter, which normally provides cooling, was stopped for over two days due to maintenance on other equipment in the EO tankfarm. The filter elements had not been changed in 18 months and were highly loaded with rust. The ambient temperature at the time of the incident was 100° F. The combination of the stagnant EO, the high ambient temperature, and the rust in the filter elements initiated the polymerization. The filter case did not rupture, but the temperature in the center of the filter case exceeded 400° F. EO Railcar Explosion A derailment resulted in the puncture of an EO railcar and a fire. Water was put on the burning railcar and on an adjacent EO car that was not leaking. The fire was extinguished after about 12 hours. About five hours after the fire was out, the safety relief valve on the adjacent car lifted and vapor from the relief valve caught fire. At this point, the accident scene was cleared for a radius of 3⁄4 mile. After about 55 hours, the relief valve fire went out for a brief period and then a violent explosion occurred. A large piece of the railcar was blown 5,000 feet through the air. The explosion was attributed to flame propagation back through the safety relief valve or a “hot spot” in the metal near the relief valve that triggered a decomposition reaction. 5 -10 Overview of Hazards 5.7 Runaway Reactions in Ethoxylation Units Delayed Addition of Catalyst EO was added to an ethoxylation reactor with the circulation cooling line blocked. The circulation line was also used for addition of potassium hydroxide catalyst. In order to continue feeding EO to the reactor, the operator had to reset the high temperature EO feed shutdown. When it was discovered that the circulation line was blocked, the block valve was opened to re-establish cooling, but this action allowed a “slug” of concentrated KOH to enter the reactor and come into contact with EO. Subsequently, the reactor ruptured explosively. Metal parts and valves were propelled over a distance of approximately 2300 feet. Inadvertent Addition of Hydrogen Peroxide The reactor in a European ethoxylation unit suddenly exploded. The incident investigation revealed that hydrogen peroxide that was used to bleach the product was inadvertently added during the EO addition phase of the operation. The EO reacted with the hydrogen peroxide and caused the reactor to explode. 5.8 Explosions in EO Abatement Devices During 1997, there were explosions at three plants that use catalytic oxidizers for destruction of EO in process vents. Each of the explosions either damaged or destroyed the catalytic oxidizer. One of the incidents occurred during the startup testing of the oxidizer. In one of the incidents, there was an explosion with a fireball, and the oxidizer system and the building were destroyed. 5 -11 Design of Facilities 6.1 Introduction The design of facilities for storing, transporting and processing EO must take into account the flammability, toxicity, and reactivity characteristics of this material. This summary of EO facility design issues reflects not only consideration of its chemical and physical characteristics, but also the practical experience of industry in dealing with those characteristics. Before using this section, it is recommended that the reader review section 5, “Overview of Hazards,” since much industry design philosophy has been developed in response to the incidents summarized in that section. A significant number of industrial incidents have been caused by contamination of EO in storage and shipping containers, followed by uncontrolled reactions. Much of the design philosophy is based on prevention of contamination. Other incidents have been caused by fire impingement on EO-containing equipment or reaction of EO leaking under porous insulation. Designing to mitigate this risk involves careful selection of insulating materials to provide adequate fire protection of equipment, while minimizing the insulation’s reactivity with EO. Both causes have elevated temperatures inside equipment to the point where uncontrolled thermal decomposition occurred. Risk assessment and hazard analysis are mandated by OSHA 29 CFR 1910.119 and should be an integral part of the initial design of the facility and should precede modifications to equipment and procedures. 2, Group B (or Group C if conduit seals comply with NEC paragraph 501-5(a)). 6.3 Materials of Construction Because of the reactivity of EO, materials in contact with EO should be chosen with care. Metallic Materials Equipment for storage and handling of EO is generally fabricated from mild carbon steel or 300 series austenitic stainless steels. Stainless steels have the advantage of eliminating the potential for rust, which can catalyze EO polymerization. Austenitic stainless steels such as Type 304 and Type 316 should be used for small piping, instrumentation, and other equipment that cannot be readily cleaned of rust. They should also be considered where EO liquid or vapor is likely to remain stagnant for periods of time. Carbon steels should be chosen which retain integrity under the full range of temperatures encountered in the specific application. Iron oxide in the form of red hematite or black magnetite on internal surfaces of carbon steel equipment will lead to polymerization of the EO. The following metals should not be used with EO: • Magnesium and magnesium alloys • Mercury • Cast irons (because of low ductility) Care must be taken with externally insulated equipment to guard against corrosion under wet insulation. Wet insulation and metal surfaces can be caused either by ingress of rainwater or by condensation of atmospheric moisture on metal surfaces containing refrigerated EO. Carbon steel equipment handling EO should be protected from external corrosion by suitable coatings. The physical integrity of the coating and process equipment it protects should be monitored periodically in accordance with the plant’s mechanical integrity program. 6 -1 6.2 Plant Layout & Siting For plant layout and siting, consider using criteria developed for LPG service in NFPA [1], [2], [3] and API [4] standards. The user will have to appropriately modify these standards for EO service. Electrical equipment in areas that produce, store, use, load, or unload EO must conform to National Electrical Code, Class I, Division 1 or Design of Facilities Depending on location and process conditions, stainless steels can be subject to stress corrosion from naturally occurring atmospheric chlorides and may also require external coating. Spiral wound stainless steel gaskets filled with virgin PTFE have been successfully used to seal raised face flanges and valve bonnets in EO service. However, there have also been quite a few incidents where EO permeated into the PTFE filler, polymerized, and caused deformation or unwinding of the gasket. When spiral wound gaskets are used in EO service, they should have inner and outer retaining rings to prevent unwinding of the gasket in case EO polymer forms within the windings. Figure 6.3 Deformation of a spiral wound stainless steel-PTFE gasket due to EO permeation and polymerization Non-Metallic Materials EO rapidly attacks and degrades many of the organic polymers and elastomers that are normally used to make O-rings, packing material, and gaskets. Any polymer or elastomer should be tested thoroughly to confirm that it is compatible with EO before it is used in EO service. Asbestos and asbestos-filled materials are not durable in EO service. Figure 6.1 Degradation of compressed asbestos valve bonnet gaskets by EO Polytetrafluoroethylene (PTFE) is chemically resistant to EO at temperatures up to 400-500°F. However, virgin PTFE exhibits cold flow behavior at all temperatures and does not work well as a gasket material. In well confined applications (such as valve packing), virgin PTFE can be used successfully. Figure 6.2 PTFE gasket failures in EO service due to cold flow High purity (98%), flexible compressed graphite is the most widely used gasket and packing material in EO service. This material has no fillers or binders and is compatible with EO. High purity, flexible compressed graphite is available in flat sheet form as well as crinkled tape for valve packing. The sheet form of flexible graphite is somewhat fragile, so for gasket applications, the sheet is typically used as a filler for stainless steel spiral wound gaskets. When spiral wound gaskets are used in EO service, they should have inner and outer retaining rings. Figure 6.4 Spiral wound stainless steel – flexible compressed graphite gasket with inner and outer retaining rings 6 -2 Because of its tendency to cold flow, PTFE for gasket applications is typically filled with glass fibers or ceramic particles to increase its dimensional stability. Glass and ceramic filled PTFE will absorb EO. EO polymerizes within the PTFE-filler matrix and the resulting EO polymer causes swelling and failure of the gasket. Glass and ceramic filled PTFE gaskets are not durable in EO service. In EO service applications where spiral wound gaskets cannot be used, laminated flexible compressed graphite gaskets can be used. Several manufacturers produce gaskets from two layers of flexible compressed graphite laminated to a 0.004" tang (perforated) stainless steel sheet. Since the graphite is laminated to tang stainless steel sheet, there are no adhesives used in the lamination process. If a laminated gasket is used, it is important to specify a tang stainless steel sheet rather than flat stainless steel sheet. Tests have shown that EO will attack the adhesives that are used to bond flexible graphite to flat stainless steel sheet. Figure 6.5 Laminated gasket made of Polycarbon Sigraflex™ BTCSS flexible compressed graphite O-Rings Chemraz®1 505 Kalrez®2 2035 Parker EPDM-740-75 Parker EPDM-962-90 Parker E-515-8-EPM Spiral wound stainless steel with a high purity flexible compressed graphite filler and inner and outer retaining rings (Polycarbon Sigraflex®3 B Grade or UCAR Grafoil®4 GT™B filler) Laminated high purity flexible compressed graphite on 0.004" tang stainless steel sheet (Polycarbon Sigraflex®3 BTCSS or UCAR Grafoil®4 GH™E) Gaskets Packing Corrugated flexible compressed graphite ribbon (Polycarbon Sigraflex®3 Corrugated B Tape or UCAR Grafoil®4 GT™Z) Virgin PTFE rings or chevrons Figure 6.6 Laminated gasket made of UCAR Grafoil GH™ E flexible compressed graphite 1. Registered U.S. Trademark of Green Tweed and Company 2. Registered U.S. Trademark of E.I. DuPont De Nemours and Company 3. Registered U.S. Trademark of SGL Technic Inc., Polycarbon Division 4. Registered U.S. Trademark of UCAR Carbon Company Inc. Durability of non-metallic materials in EO service varies with the material used and with the process conditions. The user should have an inspection program to determine the durability and required change-out frequency for the materials selected for a given application. Elastomers which are most commonly used to make O-rings will often degrade in EO service. Experience within the EO industry has shown that there are a limited number of perfluoro elastomers and EPDM elastomers that will hold up well in EO service. Note that many of the Kalrez, Chemraz, and EPDM formulations will not hold up in EO service. Following is a list of materials that have been tested for compatibility with EO and have been successfully used in EO service in industrial applications. Insulation Insulation provides a degree of protection for metal walls of vessels, piping and other equipment against being heated to the initiation temperature for EO decomposition by external flames. In selecting insulating materials for EO service, the user should consider the following: • Porous insulating materials such as magnesium and calcium silicate, mineral wool, and asbestos absorb water from the environment. This can promote external corrosion under insulation. 6 -3 Design of Facilities • Porous insulating materials promote exothermic reactions such as that of EO with absorbed water [5]. • Aluminum sheathing on insulation has a relatively low melting point. Stainless steel sheeting/banding has superior durability in the event of a fire. The use of closed cell materials such as cellular glass reduces the potential for water absorption and for exothermic reactions in the event of an EO leak under insulation. EO leaks under porous insulation resulting in hot spots and internal ignition have been implicated in major industrial incidents. Two such incidents are discussed in section 5.7. As mentioned in the “Metallic Materials” section, use of appropriate coatings on carbon steel equipment that is to be insulated provides a degree of protection against corrosion under insulation. This is of special concern when the operating temperature of the equipment is below 200°F. This temperature range is too low to evaporate water that penetrates under the insulation. 6.4 Unloading Facilities A number of incidents described in section 5.2 resulted from contamination of EO railcars. Because of the seriousness of potential consequences, the user must assure that shipping containers are not contaminated from the process. A key to prevention of contamination is to provide a system totally dedicated to EO. Facilities should not be designed for direct feed from an EO railcar into a chemical process. There should be intermediate storage downstream of the offloading facility, and systems to prevent backflow from the process into EO storage. Figure 6.8 Representative layout of Ethylene Oxide unloading facilities - Pressurized transfer Relief Valves PI RV PR 3 Nitrogen (A) (B) Ethylene Oxide Storage Tank (G) (H) LI PI Nitrogen PR 1 PR 2 To Scrubber Internal Cooler Tank Car RO Process And Circulation Pump With Low Flow, Deadhead And Overheating Protection WP FI To Process Lock or carseal open UNLOADING WITH INERT GAS 1. Open liquid valves A, G 2. Open vapor valve B and apply nitrogen pressure 3. Open valve H as pressure builds up NOTE: This diagram is for illustration purposes only. Specific system design for individual applications must be done only with consultation from professional engineering services or other qualified experts. NOMENCLATURE RO – Restrictive orifice TI – Temperature indicating device PI – Pressure indicating device PR 1 – Pressure regulator - 35 psig setting min. PR 2 – Pressure regulator - 35 psig setting min. PR 3 – Pressure regulator - 60 psig setting max. RV – Safety valve set at 70 psig relieve LI – Level indicating device WP – Wash point valve FI – Flow indicator 6 -4 Figure 6.7 Ethylene Oxide unloading facilities Acceptable means of transfer from a railcar into the storage facility are pressurization with an inert gas and pumping. Typical layouts for a pressure transfer facility and a pump transfer facility are shown in Figures 6.7, 6.8 and 6.9. If pressurization is used to unload railcars, a safe means of venting off excess pressure is recommended. Shipping empty railcars at unloading pressure can result in releases from the safety relief valve in transit. Pressurized transfer by heating is not recommended. Facilities for railcar loading and unloading should be equipped with a water deluge system that can be activated manually or by combustible gas detectors or high temperature sensors. An elevated rack for access to the railcar dome is preferred. Protection against inadvertent movement of the railcar while the loading/unloading hoses are connected is required by DOT regulation. Figure 6.9 Representative layout of Ethylene Oxide unloading facilities - Pump transfer (C) Relief Valves PR 1 PR 2 PI Nitrogen (F) (A) (B) Ethylene Oxide Storage Tank FI (G) (H) LI To Scrubber (D) Tank Car (E) WP FI Internal Cooler To Process RO Transfer Pump With Low Flow, Deadhead And Overheating Protection Process And Circulation Pump With Low Flow, Deadhead And Overheating Protection Lock or carseal open UNLOADING WITH TRANSFER PUMP 1. Open liquid valves A, D, E, G 2. Close liquid valve C 3. Open vapor valves B, F NOTE: This diagram is for illustration purposes only. Specific system design for individual applications must be done only with consultation from professional engineering services or other qualified experts. NOMENCLATURE RO – Restrictive orifice TI – Temperature indicating device PI – Pressure indicating device PR 1 – Pressure regulator - 35 psig setting min. PR 2 – Pressure regulator - 35 psig setting min. LI – Level indicating device WP – Wash point valve FI – Flow indicator 6 -5 Design of Facilities 6.5 Ethylene Oxide Storage Design Considerations Design considerations for storage vessels in EO service should include: • Compliance with the current ASME Code for Unfired Pressure Vessels for the minimum design working pressure consistent with process requirements, including consideration of the blanket inert gas pressure needed to maintain a non-decomposable vapor space (see next page under “Inerting of Storage”). • Adequate capacity to accept the entire contents of the shipment container. • EO storage tanks should be located within a diked area, or one otherwise designed to contain a tank leak and to prevent other product spills from entering the EO storage area. The area should be adequately supplied with fire water deluges and/or fixed fire water monitors. Because of its hazardous nature, the user of EO should design storage facilities to minimize the working inventory of EO. Railcars should not be used for extended storage. They cannot be monitored for temperature or pressure increases as effectively as permanent storage tanks. They also offer no means of heat removal in the event of EO polymerization or reaction with a contaminant. • Installation of multiple, independent temperature measurements, and alarming on high temperatures. • Installation of multiple, independent level measurements, or an independent high level alarm. • Monitoring and alarming on rate of rise of storage temperature. Changes in the rate indicate intensification of a contamination reaction and dictate when emergency response plans should be activated. • Alarming on low pressure (low pressures indicate loss of inerting gas). Gauge glasses have potential for fitting leaks and plugging from polymer formation. Using stainless steel instrument lines for EO service reduces the likelihood of polymer formation and plugging. The use of remote diaphragm sealed differential pressure transmitters, “bubbler” dip tubes, ultrasonic, radar and nuclear level indicators can reduce the potential for erroneous level indication caused by polymer formation. The user should avoid use of mercury-containing instrument systems (e.g., manometers), as mercury is reactive with EO. Inerting of Storage Section 2.3 discusses the potential for pure EO vapor to decompose explosively in the presence of a suitable ignition source. EO vapor spaces can be rendered non-decomposable by diluting with the appropriate proportion of an inert gas. In practice, vessels are inerted with nitrogen, and are maintained in the non-decomposable region by controlling pressure. Figure 6.10 shows minimum storage pressures required to ensure that EO vapor spaces are non-decomposable, as a function of liquid storage temperature. The figure assumes use of nitrogen as the inerting gas. No margin of safety has been incorporated into this graph [6]. Inerting systems are themselves potential sources of contamination and EO users should carefully evaluate this potential. Systems in place to prevent inert gas contamination include: Instrumentation EO storage instrumentation must provide the following: • Accurate level measurement. • Assurance that the storage vessel is inerted at an adequate pressure to stay out of the explosive region. • Reliable indication of heat release from a contamination reaction. Consider the following when designing instrument systems for EO storage: 6 -6 FIGURE 6.10: Total pressure required to inert vapor above ETHYLENE OXIDE with nitrogen diluent 200 150 NON-DECOMPOSABLE 100 TOTAL PRESSURE, Psia 50 DECOMPOSABLE 0 20 40 60 80 100 120 140 160 180 Liquid Temperature, °F Based on “Prediction of decomposition limits for ethylene oxide-nitrogen mixtures”, J.L. Brockwell; Plant Operations Progress, vol 9, 98-102, April 1990 20 40 60 80 100 120 140 160 180 6 -7 Design of Facilities • Dedicated sources of inert gas (e.g., directly from a high pressure pipeline or from high pressure cylinders). • Area knockout pots on nitrogen supply lines with high liquid level alarms or interlocks. This design can prevent contamination of EO with other chemicals or contamination of other plant systems with EO. • Backflow prevention systems at each user. A single check valve should not be relied on as the sole means of preventing inert gas contamination. • Continuous analyzers (for contaminants) on inert systems. removal in the event of an exothermic reaction within the storage tank. However, internal coils can potentially contaminate the storage tank if a leak occurs. Heat transfer fluids such as water or glycols could react with the EO in the tank. External heat exchangers may also contaminate the tank contents, but the leak can be more readily isolated. In practice, storage temperatures range from 20°F to 80°F. Operating with temperatures in the lower end of the range can result in precipitation of EO polymer, especially if the EO had been previously stored or transported at higher temperatures. Refrigeration Refrigerated storage has the following benefits: • Lower temperatures decrease the rate of EO polymerization, reducing potential for product specification problems, and for problems with tank nozzle plugging, etc. However, lower temperatures reduce the solubility of EO polymer and may cause the precipitation of polymer that has already formed. • In case of contamination, refrigeration systems can remove all or part of the heat of reaction. This can allow the reaction to be controlled. At the minimum, it will allow more time to implement control or disposal measures. • Lower EO storage temperature allows a lower inert gas pressure to maintain the vapor space in the non-decomposable region. • Lower temperatures will result in a smaller fraction of EO being vaporized in the event of a leak. The hazard of a pool of EO liquid may be mitigated more successfully than that of a vapor cloud. Reference [7] contains a study of the relative risks of storing EO at moderate temperature and pressure versus low temperature and pressure. EO storage refrigeration designs can either incorporate refrigerated coils within the storage tank or an external heat exchanger and circulation pump. Internal coils can offer better heat 6 -8 Emergency Disposal of Tank Contents An EO storage facility should be designed with provisions to safely dispose of the inventory in the event of a contamination reaction. Options in current practice include: • Reacting the EO to glycols or other derivatives by feeding to downstream users. • Depressuring the vessel. This can be to a scrubber, a flare system, or to an elevated discharge point. This can be a highly effective response, since evaporation of the EO during this procedure provides an autorefrigeration effect which cools the vessel contents. • Transferring to a holding system, such as a pond, and diluting with water. EO users must carefully consider the effects of any of these actions (e.g., venting of EO) on the health and safety of their workers and communities, and on the environment. They should only be taken as part of a well defined emergency response plan. 6.6 Reaction Systems Consider the following elements in design of reaction systems: • Prevention of backflow from reactors into EO storage. • Prevention of build up of unreacted EO. • Prevention of explosive mixtures in reactor vapor space. Each of these elements is discussed below, as well as reactor instrument and control design philosophy. Reactor Design Consider designing reactor cooling systems with sufficient capacity to remove the heat generated by an incipient runaway reaction. Reactor vent capacity should similarly be sized to control upset conditions. Prevention of Backflow from Reactors Catalysts in widespread use in EO reaction systems, such as KOH, have the capability to initiate EO polymerization and accelerate other reactions if they backflow into EO storage. These reactions are exothermic, and can result in uncontrolled heat release and vessel rupture. Positive backflow prevention must be present between storage and reaction systems (see section 6.7 “Prevention of Backflow/ Contamination”). Reactor Instrumentation & Control Design Philosophy Consider designing reactor control systems to stop EO addition in the event of the following: • Excess rate of EO feed • Failure to add other reactants • Failure to add catalyst • Mixing system failure • High reactor pressure • Low reactor pressure • Reactor temperature control failure (high OR low reactor temperature) • Loss of utilities Reactor instrument systems should also be designed to give a good temperature profile for detection of localized reactions. Process analyzers can be used to continuously determine EO concentration in reactor vapor space and to stop EO addition when concentrations approach the explosive range. When process analyzers are used as part of a safety system, adequate maintenance attention must be provided to maintain high reliability. Analyzer cycle time should be considered when relying on a non-continuous analyzer to avoid unsafe conditions. Prevention of Buildup of Unreacted Ethylene Oxide Unreacted EO in a reaction system represents an inventory of highly reactive material. The rate of reaction is generally limited by the feed rate of EO. The presence of higher than design quantities of EO can result in a reaction rate and associated heat release that exceeds the capabilities of the reactor control and safety systems. An additional hazard occurs if reactor product contains significant quantities of unreacted EO. This can result in release of EO vapor from product storage. To avoid these conditions, the following must be controlled within design limits: • EO addition rate • Mixing of reactants and catalysts • Concentration of catalyst • Reaction temperature Prevention of Flammable Mixtures in Reactor Vapor Space The amount of diluent required to provide a non-flammable mixture in the reactor vapor space varies with temperature and unreacted EO concentration. The reactor pressure control system should be designed to provide adequate diluent pressure to prevent flammable mixtures over the range of reactor operation. 6.7 Piping & Pumps Piping One effective element of a safe design is dedicating all appropriate piping systems exclusively to EO service. Carbon and stainless steels are suitable materials 6 -9 Design of Facilities for piping in EO service and should meet applicable ASME and ANSI codes. Stainless steel offers the advantage of avoiding the potential of rust formation associated with carbon steel lines. EO polymerization can be a significant problem in piping because of the relatively high amount of surface area. Stagnant areas in piping systems enable polymerization to proceed over extended periods. Therefore, piping systems should be constructed to avoid low points and dead spots. Lines should be designed to be as short as possible with gravity drainage to points at which contents can be purged from the system with nitrogen. If emptying stagnant EO lines is not feasible, for example in the case of a long EO charging line to a batch reactor, a pipe loop that circulates back to the storage tank may be considered. Chilled tracing of lines that may sit idle can also reduce the polymerization potential. Centrifugal pumps with double mechanical seals are in widespread use for EO service. For double seal pumps, an important criterion in the selection of a seal fluid should be its relative non-reactivity in contact with EO. A 50% aqueous solution of ethylene glycol (EG) as well as pure diethylene glycol (DEG) have been used successfully. Magnetic drive pumps and canned motor pumps have also been successfully used in EO service. Proper specification of magnetic drive pumps is dependent on accurate determination of NPSH requirements, as these pumps are easily damaged by cavitation. If a sealless pump with a magnetic coupling is used, a strong magnetic filter on the suction side of the pump is recommended to prevent damage from metal particles entrained in the product stream. Pumps represent a potential source of ignition of flammable vapors in an EO storage and processing area, primarily due to the potential for overheating. The preferred location for pumps is in curbed areas separate from process or storage areas. In general, good design practice will include at least some of the following safeguards: • Minimum flow shutoff. • High (absolute) discharge temperature shutoff. • High temperature delta (across the pump) shutoff. • A system of detecting and alarming on pump seal leakage. • Thrust bearing displacement shutoff (magnetic drive pumps). • A deluge system, activated manually, by hydrocarbon leak detectors or by high temperature. • Power usage monitors to shutdown pumps on high or low power usage. • Automatic cooled bypass to pump suction on high discharge pressure or low flow. All lines in EO service should be clearly labeled. Piping in EO service should use welded and flanged construction. Screwed connections should be avoided. The design process should minimize the number of flanges. Each flange represents a leak potential (including fugitive emissions). Where flanges are necessary, they should be fitted with gasket materials approved for EO service. Liquid EO should not be confined in lines closed at both ends because heating (atmospheric or otherwise) can result in high liquid pressures, leading to bursting of the lines or joints. If the confining of liquids is unavoidable, lines may be equipped with relief valves with provision to capture vented EO and return it to an appropriate location in the system. Pumps As part of the effort to reduce fugitive emissions, practices in the industry are trending away from the use of packed pumps and single mechanical seals. Where packed pumps cannot be avoided, packing material should be non-reactive in contact with EO (e.g., flexible graphite). Pump bodies should be of carbon steel, stainless steel or ductile iron construction. Cast iron is not acceptable. Valves Selection of valves for EO service should consider designs that do not trap EO in the valve cavities where it can subsequently polymerize 6 -10 and render the valve inoperative. Valve selection should also consider the effectiveness of the design in controlling fugitive emissions. Experience indicates that gate valves, globe valves and high-performance butterfly valves perform well in EO service. By nature of their design, ball valves and plug valves are subject to polymerization problems. Automatic addition of steam to the relief valve outlet piping can improve dispersion and reduce flammability of the EO plume. Relief valve discharge piping routed to the atmosphere should be designed to minimize potential for human exposure. Design of relief systems in EO liquid or vapor service should consider the potential for polymer formation and plugging. EO polymer can form in the piping upstream of relief valves, reducing the valve’s capacity. Methods to protect against plugging include: • Use of stainless steel piping. • Installation of rupture disks or rupture pins underneath relief valves. • Minimization of piping distance (hence the surface area available to support polymerization) by fitting relief valves as close as possible to the equipment they are protecting. • Continuous injection of small amounts of nitrogen directly under the relief valve and directly after the relief valve if it discharges into a header system. Rupture discs or rupture pins may be useful in minimizing fugitive emissions from relief valves. However, their use as the sole means of pressure relief is generally not recommended, as they cannot reseat when the pressure excursion has ended. Prevention of Backflow & Contamination It is essential to protect against backflow from the process to storage. This is typically an instrumentation system providing tight shutoff on low pressure differential between downstream users and storage. Check valves should also be included in the system, particularly at pump discharges, but exclusive reliance on their performance is not recommended. Should a common EO source feed multiple process units, isolation and backflow protection should be provided between EO storage and each unit and between the separate units. 6.8 Handling of Vents & Effluent Relief Systems Pressure relief devices should be sized to relieve pressure developed by the controlling contingency identified for that process. A safety analysis of the process must be conducted to define the characteristics of the controlling contingency. However, it should be recognized that relief devices are unlikely to provide adequate relief for such cases as explosive decomposition of EO. Pressure relief valves for storage tanks and for piping where liquid can be trapped should be sized in accordance with practices recommended by NFPA 58: Storage and Handling of Liquefied Petroleum Gases. Industry practice is mixed with regard to the routing of relief valve discharges. Some systems are designed to vent to atmosphere; others tie into a relief header system feeding a flare or scrubber. If vented to atmosphere, discharges from pressure relief devices should be designed with adequate height and discharge velocity to prevent contact of flammable vapor clouds with ground level and potential ignition sources. Vent Scrubbers Aqueous systems for absorbing EO in process vents are in widespread use in industry. These systems can be designed for very high efficiency of EO removal. However, the designer of a scrubber system must take into consideration the fact that EO/water mixtures are highly non-ideal and use the Raoult’s Law deviation factors given in Appendix A. Vent gas is typically fed to a scrubber column filled with random packing such as pall rings. EO is absorbed by an aqueous stream running countercurrent to the vent gas. Scrubbed gas can be discharged to the atmosphere, subject to environmental restrictions. 6 -11 Design of Facilities Figure 6.11 Ethylene Oxide Vent Scrubber System To Atmosphere Sewer Systems & Waste Disposal Facilities If EO is drained (or could inadvertently be drained) to a sewer system, the user should be aware of the potential for EO emissions in the sewer system and treatment facility, and the potential for accumulation of flammable vapors in the sewers, lift stations and waste water storage tanks. Installation of online analyzers, nitrogen purges and emission control devices may warrant consideration. It has been shown that wastewater containing low concentrations (less than 1000 ppm) of EO can be disposed of in biological waste treatment facilities after proper acclimation of the system. Section 4.2 contains a discussion of biotreatment of Ethylene Oxide. The waste disposal facility must be licensed to receive EO or otherwise approved by a regulatory agency for this service. EO Vent Scrubber Reactor Heater Vent from Process Makeup Purge Cooler Disposal of absorbed EO in scrubber effluent is the major design problem. In general, the EO is reacted to glycol. Either strong base or acid is added to the absorbent stream as a reaction promoter. However, acids are more effective promoters than bases. Phosphoric acid, sulfuric acid, and caustic soda are commonly used for this purpose. Hydrochloric acid is not recommended due to the potential to form chlorohydrin. If this design practice is followed, extreme care must be exercised to prevent acid or alkali contamination of the process from the scrubber system. (Figure 6.11) 6.9 Miscellaneous Electrical Equipment Electrical area classification Class I, Division 1, Group B or Class I, Division 2, Group B (National Electrical Code [3]) should be used where atmospheres contain or may contain EO under normal or abnormal conditions. Group C may be used if conduit seals comply with NEC paragraph 501-5(a). Chapter 5 of the National Electrical Code [3] deals with hazardous atmospheres, classifications, and equipment requirements. Additional references for area classification can be found in API RP500 [4] and NFPA 497A [2]. Other equipment, such as lighting fixtures, resistors, solenoid coils, etc., must have normal operating surface temperatures that do not exceed the ignition temperature of EO. See Section 501 of the National Electrical Code [3] for further details. Flares Several EO producers and users successfully use flares to handle EO containing vents. The most important design consideration is preventing decomposition flame propagation from the flare tip back into the relief header system. The flare designer must also be aware of the fact that conventional flame arrestors have generally not been tested on EO decomposition flames and should not be assumed to be an adequate safeguard against decomposition flame propagation. Thermal Oxidizers Thermal oxidizers have been used to control EO emissions from some processes. However, there have been recent incidents in several thermal oxidizers that control EO emissions, indicating that some safety issues in these system designs may not be fully understood at this time. 6 -12 Fire Protection Systems The user should consult NFPA 58, API 2510 and 2510A in designing fire protection systems for EO storage and processing areas. Systems can include passive (insulation) and active (deluge/sprinkler) systems. Areas requiring deluge protection can be identified using process hazards analysis methods which examine the severity of the consequences of a fire scenario. An ample fire water supply should be available. The fire water supply should be sufficient to ensure enough water to adequately dilute a spill. Drainage should be designed with a capacity to retain emergency water whether used for cooling, fire fighting or dilution purposes. Storage areas should be provided with diversion walls to prevent the possibility of a pool fire underneath vessels. • Dry-disconnect tubing fittings should be considered for the connection from the sample tubing to the cylinder. • The system should prevent overfilling of the sample cylinder with liquid. Overfilling results in the potential for cylinder overpressure from liquid expansion. Typical EO sample cylinders are stainless steel, with an internal dip tube to prevent overfilling with liquid. The cylinder must be filled while positioned vertically with the dip tube at the top. The cylinders should be designed so that only the valve with the dip tube can be connected to the sample system. • Sample cylinders should be stored under refrigeration while awaiting analysis and again after analysis until disposal of any EO remaining in the cylinder. • Unused EO remaining in the cylinder should be returned to the process if possible, or disposed of in an environmentally sound manner. • Potential for personnel exposure to EO during sample preparation and analysis should be minimized by use of a laboratory hood. Leak Detection Systems Combustible gas detectors are often used in petrochemical processing plants. However, the low concentrations of allowable exposure and the low Reportable Quantity for environmental releases make more sensitive leak detection equipment desirable for EO processes. Gas Chromatograph-based leak detection systems sensitive to 1 ppm EO are in use both in process plants and laboratories where EO may be present. These systems generally have multiple fixed sample locations connected to a single analyzer. Figure 6.12 EO sampling system. Sampling Systems Following are key design issues for sampling systems: • The system should allow a representative sample to be caught without releasing EO to the environment or exposing the sample collector. • Purging the sample connection with nitrogen and depressuring the sample system to a vent collection system prior to disconnecting the sample cylinder is recommended. 6 -13 Personnel Exposure 7.1 OSHA Ethylene Oxide Standard The EO standard was published in the Federal Register on June 22, 1984 and amended on April 6, 1988. The following is a summary of its major provisions. The regulation, 29 CFR 1910.1047, should be consulted for specific requirements. Regulated Areas Regulated areas must be established wherever occupational exposure may exceed the PEL or EL. Those areas must be marked and access limited. Warning signs must be posted around regulated areas stating: DANGER ETHYLENE OXIDE CANCER HAZARD AND REPRODUCTIVE HAZARD; AUTHORIZED PERSONNEL ONLY; RESPIRATORS AND PROTECTIVE CLOTHING MAY BE REQUIRED TO BE WORN IN THIS AREA. Coverage The standard applies to all occupational exposures to EO. The only exception to this coverage is the processing, use, or handling of products containing EO where objective data demonstrate that the product is not capable of releasing EO in air above the action level or excursion level under expected conditions of processing, use or handling. Records of the objective data must be maintained if the exemption is used. Methods of Compliance EO exposure must be limited through engineering and work practice controls whenever feasible. Where the PEL is exceeded, a written program must be established and implemented to reduce employee exposure. OSHA recognizes that engineering controls are generally not feasible for certain activities, including loading and unloading of railcars, vessel cleaning, and maintenance and repair activities. In cases where engineering controls are not feasible to prevent exposure above the PEL, NIOSH approved respirators must be worn. Exposure Limits OSHA’s Permissible Exposure Limits or PELs, are the following: • 1 ppm in air as an 8 hour time weighted average (TWA) concentration • 5 ppm 15 minute excursion limit (EL) There is also an action level (AL) at 0.5 ppm as an 8 hour TWA, which triggers certain compliance activities such as exposure monitoring, medical surveillance and training. Medical Surveillance Program The employer must institute a medical surveillance program for employees who are potentially exposed to EO at or above the action level (without regard to use of respirators). Specific requirements for surveillance and medical record retention are included in the standard. Exposure Monitoring Initial monitoring is required to determine air concentration. If concentrations are above the action level, periodic monitoring is also required. Additional monitoring may be required if process changes occur and employees must be notified of monitoring results. Training Information and training must be provided to any personnel who are potentially exposed to EO at or above the PELs. Topics for training are specified in the standard. Product Exemptions Products made from EO or containing EO are exempt from the standard if objective data shows they will not release EO at or above the action level during normal handling or use. 7-1 Written Emergency Plan An emergency plan must be developed for each workplace where there is a possibility of an emergency. The employer must have a means of promptly alerting affected employees of an emergency occurrence. Protective Clothing Many materials in common use are permeable to or attacked by EO. Any materials proposed for use in protective equipment that are not known to be EO resistant, should first be tested to establish their suitability. EO permeation data for clothing and glove materials are provided in Tables 7.1 and 7.2. Permeation test data showed the following equipment provides adequate protection in EO service: Suit: Kappler ®1 Responder and Responder Plus, DuPont Barricade, TYCHEM 9400 and 10,000. In cases where there is concern of a flash fire, consider using a Kappler ®1 Responder with aluminized fiberglass or PBI/Kevlar overcover. Safety 4-H North B-131 Butyl Rubber Silver Shield® Pioneer A-15 nitrile rubber Butyl Rubber Chlorinated Polyethylene Recordkeeping The standard contains requirements for retention of medical and exposure records. Other provisions of the standard also contain recordkeeping requirements. 7.2 Measuring Exposure A number of methods are available for monitoring exposure to EO. Many of these involve the use of charcoal tubes and sampling pumps, followed by analysis of the samples by gas chromatography. Sensidyne and Draeger market hand pumps and indicator tube systems, which do not require subsequent analysis, with detection limits in the low ppm range. Portable electrochemical EO detector/alarms are available from Interscan and Draeger. Dupont and 3M market passive badge-type monitors for EO exposure. OSHA has an extensive discussion of available methods for monitoring exposure to EO (29 CFR 1910.1047), including an OSHAdeveloped method. Gloves: Boots: 7.3 Personal Protective Equipment Eye Protection All personnel in areas where EO is handled must carry chemical goggles. Goggles should be worn at all times in those areas in which there is a risk of splashes from liquid EO. Face shields (visors) provide additional protection when performing any activity which has a liquid exposure risk. Contact lenses should not be worn where contact with EO can occur. In the case of visor materials, the best EO resistance is provided by fluorinated ethylenepropylene (FEP) - polycarbonate composite. FEP and PVC provide adequate resistance. 1. Registered U.S. Trademark of Kappler Europe Ltd. Previously, Chemrel Max was a recommended suit. However, it is no longer manufactured. Other factors to consider in the selection of protective clothing are durability, dexterity, heat/cold resistance and whether disposable or reusable clothing is preferred. If there is potential for a flash fire, this factor should be considered in the selection process. Either a flash oversuit or an EO resistant suit incorporating flash protection should be considered. PVC, nitrile rubber, neoprene, and Viton are permeated rapidly on contact with EO. EO and aqueous mixtures permeate leather. Clothing subjected to EO contamination 7-2 Personnel Exposure must either be discarded or decontaminated before re-using. Clothing must be discarded if it has been degraded or has absorbed EO. Leatherwear contaminated with liquid EO must be discarded because decontamination is not practical. Respiratory Protection If the presence of EO in excess of exposure limits is expected or detected, respiratory protection consisting of a NIOSH approved respirator must be used. OSHA regulation 29 CFR 1910.1047 provides the following minimum standards for respiratory protection for airborne EO: Airborne EO (PPM) Less than or equal to 50 ppm Less than or equal to 2,000 ppm Minimum Required Respirator Type (A) Full facepiece with EO approved canister, front or back mounted. (A) Positive-pressure supplied air equipped with full facepiece, hood or helmet, or (B) Continuous-flow supplied air (positive pressure) equipped with hood, helmet or suit. (A) Positive-pressure self contained breathing apparatus (SCBA), equipped with full facepiece, or (B) Positive-pressure full facepiece supplied air respirator equipped with an auxiliary positive-pressure self-contained breathing apparatus. Positive-pressure selfcontained breathing apparatus (SCBA), equipped with full facepiece. Any respirator described above. Potential for EO exposure When there is potential for exposure to EO vapors or liquid, it is important to use the proper protective clothing. EO can be trapped against the skin and can cause severe chemical blistering and burns, which take a long time to heal. When released, EO liquid will quickly change to vapor. If protective clothing with open sleeves and legs is worn, this vapor can readily get underneath the clothing, resulting in burns. EO can also penetrate protective clothing seams so it is important to consider suit construction as well. Even dilute EO solutions can result in severe chemical burns if the skin remains exposed to the solution. Figure 7.1 is a chemical burn resulting from 1.5 hours exposure to dilute EOwater mixture absorbed into leather shoes. Figure 7.1 Chemical burn resulting from low concentration of EO in water. Above 2,000 ppm or unknown (e.g., emergencies) Firefighting Escape 7-3 Table 7.1 EO Permeation Test Data for Clothing CLOTHING MATERIAL ChemFab Challenger 5100 ChemFab Challenger 5200 DuPont Barricade DuPont Barricade DuPont Saranex R-23 DuPont TYCHEM 10,000 DuPont TYCHEM 10,000 DuPont TYCHEM 7500 DuPont TYCHEM 9400 DuPont TYCHEM 9400 DuPont TYCHEM SL DuPont TYVEK QC DuPont TYVEK-Polyethylene coated Fairprene Neoprene ILC Dover Cloropel CPE ILC Dover Polyurethane Kappler CPE Kappler CPF-3 Kappler CPF-4 Kappler Life-Guard Butyl Kappler Responder Kappler Responder Kappler Responder Plus Kappler Responder Plus Mar-Mac Ultra-Pro Commander MSA BETEX Butyl/Neoprene Pioneer N-44 Neoprene Wheeler Acid King Butyl Wheeler Acid King PVC Wheeler Acid King Teflon * NS - Not specified in test data. NOTE: Breakthrough times are reported from data found in vendor and other databases. Some materials have been tested more than once as indicated by multiple results. Formulation of clothing materials may change, impacting break through times. Contact the supplier for specific product information or current information on the testing of their products. VAPOR/LIQUID NS* NS Liquid Vapor NS Liquid Vapor Liquid Liquid Vapor Vapor Vapor NS NS NS NS Vapor Vapor Vapor NS Liquid Vapor Liquid Vapor Vapor NS NS NS NS NS BREAKTHROUGH TIME, minutes >950 31, 44, 64, 66 >480 >480 55, 6, 121, >400 >480 >480 53 >480 >480 immediate immediate 480 >480 44, 48, 52 >180 >480 >180 >480 >180 165 31 55, 85, 400 44, 13, 31 71 7-4 Personnel Exposure Table 7.2 EO Permeation Test Data for Gloves GLOVE MATERIAL Ansell-Edmont 4H Best 65NFW Natural Rubber Best 6780 Neoprene Best 878 Butyl Best 890 Viton Best Hustler 725R PVC Best Nitri-Solve 727 Nitrile Best Ultraflex 22R Nitrile Best Ultraflex 32 Neoprene Dayton Natural Rubber Surgical North B-131 Butyl North Silver Shield Pioneer A-14 Nitrile Pioneer A-15 Nitrile Pioneer N-44 Neoprene * NS - Not specified in test data. NOTE: Breakthrough times are reported from data found in vendor and other databases. Some materials have been tested more than once as indicated by multiple results. Formulation of glove materials may change, impacting break through times. Contact the supplier for specific product information or current information on the testing of their products. VAPOR/LIQUID Vapor Vapor Vapor Vapor Vapor Vapor Vapor Vapor Vapor NS* Vapor Vapor NS NS NS BREAKTHROUGH TIME, minutes >240 1 21 189 48 1 17 12 7 3, 5 >480 >480 32 195, >315 31 7-5 Equipment Preparation and Maintenance 8.1 Preparation for Inspection or Maintenance General When equipment in EO service must be opened for testing, inspection, or repairs, all precautions applicable to equipment handling of flammable liquids and gases must be observed. All EO must be removed from the system and disposed of in accordance with federal, state and local regulations. Contaminants such as oxygen, water, and cleaning chemicals must be completely eliminated before equipment is placed in or returned to EO service. Persons entering equipment, vessels or any confined space which has been in EO service must be equipped with appropriate respiratory protection (see section 7.3), unless it is demonstrated that the atmosphere inside the equipment, vessel or confined space is without hazard and will remain so during the time people are inside. from the process and from any potential hazard source. Equipment atmosphere must be tested for EO and proven safe to enter. Special Problems with Ethylene Oxide Polymer In systems storing pure EO, it is common for polymer to form and to accumulate gradually, especially where the EO is relatively stagnant. Polymer can retain EO after washing, which it can gradually release even after the equipment initially tests free of EO. After the initial purging and rinsing steps, good practice is to wait several hours and retest prior to opening up to the atmosphere. Low molecular weight polymer can generally be removed by steaming or washing with hot water. Because hot water and steam would be reactive with EO, the user must assure that free EO has been removed before using hot water or steam on equipment. High molecular weight polymer must generally be removed by physical means, such as high pressure water blasting. If polymer is present and time limitations or other circumstances prevent warm water cleanup, appropriate protection must be provided for personnel engaged in opening or entering the vessel. Polymer residues are both flammable and a health hazard. They must be completely removed and the equipment certified as being free from all flammable residues and safe for the intended work before undertaking hot work. Preparations for Entry The user should follow the requirements of the OSHA confined space standard (29 CFR 1910.146). Equipment should be cleaned and purged of EO before beginning any maintenance work. If it is impractical to reduce airborne concentrations in and around the equipment below 1 ppm, appropriate personal protective equipment should be worn. All maintenance work on EO equipment should incorporate a safe work plan to ensure that all personnel understand the hazards involved, that proper personal protective equipment is utilized, that applicable safety precautions are observed in each work task and that other measures appropriate to working with EO are observed. Equipment being worked on must be thoroughly drained and blown free of liquid EO with nitrogen. The equipment is then washed with cool water and drained. Care should be taken that hydrates are not formed during this process, since the melting points of such materials can be as high as 52°F (see Table 2.2, in section 2). Rinse water should be disposed of in a safe and environmentally responsible manner. It should be noted that even dilute solutions of EO in rinse water have caused severe chemical burns (see section 7). Steam purging or hot water washing may be further required to remove EO polymer. Prior to entry, the equipment must be isolated Mothballing Equipment which has been in EO service, but is being removed from service should be decon8 -1 Equipment Preparation and Maintenance taminated by washing or steam cleaning to less than 1 ppm of EO. Such equipment should be maintained under a nitrogen blanket and disconnected or blinded from “live” equipment. Caution: It is extremely important to remove all residues of cleaning chemicals, as EO may react violently with them when the equipment is put in EO service. 8.2 Preparation of Internal Surfaces Foreign material on internal surfaces causes slow self-polymerization of EO with an attendant buildup of the polymerized material on those surfaces. This self-polymerization can be minimized by removing foreign matter such as welding slag, loose debris and rust on internal surfaces prior to putting them in service. Cleaning can be accomplished by shot or grit blasting, or by chemical methods. Shot blasting creates dust and debris which must be removed. Where equipment surfaces, such as pipework, are inaccessible to blast cleaning, chemical methods may be required. Chemical cleaning involves the use of hazardous materials and can cause damage to equipment if not properly specified and performed. The use of a qualified contractor is advisable. A variety of chemical cleaning processes are available for preparing metal surfaces for EO service depending on what surface contaminants are present, including: • Alkaline or detergent degreasing, followed by thorough rinsing. • Acid cleaning, if the metal is carbon steel. If both carbon and stainless steel are present, engineering advice should be obtained before acid cleaning. Rinse thoroughly afterwards. Common acid cleaning uses EDTA or citric acid. It may or may not be preceded by a degreasing step. If the system contains mild steel, a neutralization and passivation should be performed. Sodium nitrite is typically used for passivation. The system must be flushed clean and dried by blowing with dry, hot nitrogen. Equipment should be left under nitrogen pressure until ready to receive EO. Failure to adequately passivate or to keep material under nitrogen blanket will result in significant rust formation. 8-2 The effectiveness of a given chemical cleaning procedure or the possibility of problems should be evaluated using a test sample of the same metal as the surfaces to be cleaned. 8.3 Leak Repair Clamps Clamp-on or bolt-on, split body style leak repair clamps have been used for temporary mitigation of small ethylene oxide leaks from piping, valves and vessels. These leak repair clamps can be either purchased as “off-the-shelf” clamps or engineered to fit, depending on the application. The user must evaluate the risk of using clamps. Many common sealants are not suitable for use in EO service, and all sealants should be tested for material compatibility and durability prior to use. As with any moving stem valve, valves in ethylene oxide service may experience fugitive emissions leaks. Ethylene oxide valve packing glands should not be on-line repaired using the drill-and-inject method due to the localized frictional heat generated during the drilling on the valve body. 8.4 Preventive Maintenance Equipment containing ethylene oxide should be on a routine preventive maintenance program to insure proper operability. Internal inspections should focus on monitoring equipment integrity and detecting polymer formation. No flow or low flow zones in a piping network and small bore instrumentation tubing have the potential for polymer buildup and should be included in the inspection program. Nozzles for instrumentation and inlets to pressure relief valves are areas that should also be inspected on a routine frequency. Special considerations should be made for purging spare and offline piping and equipment to prevent polymer formation. Transportation & Unloading Operations Figure 9.1 DOT 105-J railcar for transporting Ethylene Oxide 4" Glass Wool Insulation Compressed to 31/2" and 0.65" (Ceramic Fiber) Thermal Protection 1/ " 2 Gauging Device, Safety Valve, 3/4" Thermometer Well 3 - 2" Angle Valves & 1/4" Sample Line Angle Value Jacket Head 9 " /16 9 " /16 Tank Head Tank A–End 116" Inside Dia. Center Line of Angle Valve 13' - 11" 13' - 11/4" Top of Grating B–End 2' - 101/2" 40' - 11" Truck Centers 51' - 10" Over Strikers 54' - 5 1/2" Coupled Length 9.1 Regulations EO is classified by the United States Department of Transportation (DOT) as a primary poison gas hazard with a subsidiary hazard of being a flammable gas, and must be placarded accordingly. Further, it carries the materials poisonous by inhalation (PIH) designation by the DOT. All persons offering a loaded or empty railcar for transportation must meet the general awareness and familiarization as well as function specific training requirements, as specified in 49 CFR 172.704. Special attention must be paid to the pressurization of empty railcars for return to the shipper. The objective is to maintain a nonflammable vapor phase, as specified by DOT Regulation CFR 49, Section 173.323(f), even if the car heats up to 105°F. Reference should be made to the special railcar pressurization criteria supplied by the shipper. For a given unloading temperature, these criteria allow for the extra nitrogen that is required for safety over the entire range up to 105°F. See also section 11, “Regulations Applicable to Ethylene Oxide”. / 15'- 4 15 16" B-End 10'- 5" Over Grabs 9.2 Railcars Design EO tank cars are designed to make the transportation and handling of the material safe and easy. The DOT requires that EO be transported in DOT class 105-J tank cars. All tank cars used in EO service must have a tank test pressure 9-1 Transportation & Unloading Operations Figure 9.2 Dome arrangement of a class DOT 105-J railcar for Ethylene Oxide service Magnetic Gauging Device Safety Valve Liquid Valve Liquid Valve Vapor Valve Thermowell of at least 300 psi by July 1, 2006 at the latest. Most EO tank cars in service already meet this requirement. DOT also requires EO tank cars have a reclosing pressure relief device set to function at 75 psig. These requirements are specified in 49 CFR 173.323. DOT class 105-J tank cars meeting the required 300 psi tank test pressure are constructed from fusion welded carbon steel with 9 ⁄16" minimum plate thickness, and must have an approved thermal protection system. A typical thermal protection system consists of 0.65" of ceramic fiber surrounding the tank shell, with 4" of glasswool fiberglass insulation compressed to 31⁄2" by an outer metal jacket. The outer metal jacket is 11 gauge (about 1⁄8") 9-2 carbon steel, except at the ends of the car where tank puncture protection is provided by 1 ⁄2" head shields. An EO tank car is designed for loading and unloading from the top only with no bottom fittings. The potential for leakage from damaged tank fittings is greatly reduced in a transportation incident when protected top fittings and no bottom fittings are used. EO in a tank car must always be kept under an atmosphere of an inert oxygen free gas. Dry nitrogen is typically used. No air should be allowed to enter tank cars in EO service. Excess Flow Check Valves EO tanks are equipped with float type excess flow check valves below the liquid load/ unload valves and the vapor valves. This is a safety precaution as the excess flow check valves are designed to shut off the flow of liquid or vapor if these valves are sheared off in a derailment. can get stuck closed if there is EO polymer present in the vent line. Nitrogen pressure may have to be supplied on the down stream side to force the valve back down. In all cases, problems such as malfunctioning equipment, running gear or loading appliances should be reported to the EO supplier. Other than emergencies, repairs should only be done with supplier approval, to ensure material quality, equipment function and design requirements are maintained. Emergency repairs should be reported to the supplier before putting the car in transportation. Caution: Carbon dioxide is more than ten times as soluble in EO as nitrogen and is not suitable for blanketing or purging railcars or other equipment containing EO. 9.3 Preparation for Unloading An EO railcar (Type DOT 105-J) is equipped with two eduction pipes/unloading connections, one vent for loading or vapor connection, a gauging device, a reclosing pressure relief device (safety valve), and a thermometer well (thermowell). If a liquid or vapor valve is opened too rapidly, the excess flow check valve immediately closes, cutting off the flow of liquid or vapor. If the liquid excess flow check valve should happen to close while unloading at less than 120 gpm, there may be a restriction such as polymer in the line creating a higher than design pressure differential. If the excess flow check valve closes, the pressure needs to be equalized to drop the float back down. Equalizing the pressure can be done by closing the load/unload valve on the liquid line. Be aware that the vapor line excess flow check valve can close if the car is depressurizing too rapidly. If the excess flow check valve closes, a false reading of railcar pressure can occur, as pressure is measured in the line downstream of the car loading/unloading valve. The railcar could be mistakenly over-pressured and lift the pressure relief device set at 75 psig. Again, by closing the load/unload valve the pressure can equalize on both sides of the excess flow check valve and gravity should drop the float back into position. In extremely unusual circumstances, the float • The user should develop and provide to unloading personnel a detailed procedure and checklist specifying each step of the unloading operation and the precautions to be observed. • An operator unloading log should be kept to record key information (temperature, pressure, etc.). • The receiver of EO railcars should monitor temperature. The presence of higher than normal temperature may indicate the presence of contamination and the potential for reaction in the railcar. Section 5.2 discusses hazards of contamination. Section 10 discusses emergency response. • Railcar numbers and the seal numbers on the dome of each car should be recorded in the log. • The DOT car specification number on the car must be 105-J100W or 105J300W. “Ethylene Oxide” and “Inhalation Hazard” must be stenciled on opposing sides of the railcar. • Check the dome to assure that the seal is intact. If it is not intact, contact the railroad and the EO supplier. 9-3 Transportation & Unloading Operations • Before breaking the dome seal or initiating any testing or unloading action the following precautions are suggested: – Keep in mind that EO is highly reactive. – The unloading area should be wellventilated and free of sources of ignition. – OSHA requires that exposures not exceed either 1 ppm averaged for an 8 hour period or 5 ppm over a 15 minute period (excursion level). – Use appropriate respiratory protection (Section 7.3) when making/breaking connections, and during EO product sampling. – Know where safety showers and eye wash facilities are located in the railcar unloading area. – Know the location, in the unloading area, of fire fighting equipment (extinguishers, fire monitors, hose reels, deluge systems) and know how to use it. Figure 9.3 Steps in preparation for unloading Ethylene Oxide • The DOT requires placement of blue signs that read “Stop – Tank Car Connected” or “Stop – Men at Work” at appropriate spots. 9- 4 • Lock out switches and install a • Set the hand brake. derail mechanism to prevent collisions with other cars. • Chock the car front and back of at least one wheel. 9-5 Transportation & Unloading Operations • Ground the railcar on its bolster or on the top working area. • Break the railcar seal. 9-6 • Raise the dome cover. Inspect the area under the dome carefully. Use caution as valves and devices under the dome could leak. • Measure and record the temperature of the EO in the railcar by lowering a thermocouple or thermometer into the thermowell. Allow several minutes for the temperature measurement to stabilize. 9-7 Transportation & Unloading Operations • Measure and record the outage level using the car’s magnetic gauge rod. Figure 9.4 Canister mask with EO specific canister Figure 9.5 Positive pressure, “hoseline” type respirator • Experience has shown that it is difficult to meet the 1 ppm exposure limit when hooking up or disconnecting EO railcars. Operators should wear respiratory protection equipment when making or breaking connections on EO railcars. 9-8 9.4 Unloading Figure 9.6 Steps for unloading Ethylene Oxide • Remove plugs in both vapor and liquid lines. • Pipe extensions should be inserted into the valves so that connections can be made outside the dome of the car. Be sure that pipe extensions do not interfere with the proper operation at the valve operating mechanism. 9-9 Transportation & Unloading Operations • Attach the unloading line to the liquid valve extension. • Off-loading can be accomplished by either pressuring or pumping EO from the railcar. In either case, nitrogen is needed to replace the liquid and to maintain tank pressure. • Check for leaks on hose connections prior to introducing EO. • Nitrogen should be attached to the vaporline to allow maintenance of the 9-10 railcar nitrogen pad. • Purge lines with nitrogen. • Install a pressure gauge on the vapor line. Measure and record pressure. • Monitor temperature and pressure throughout the unloading process. • Refer to Figure 6.4 in section 6 (Design of Facilities) for proper nitrogen pressure to maintain a non-explosive EO vapor content. Minimum pressures should be set at 35 PSIG and maximum pressures at 60 PSIG. • Carefully open the vent and liquid valves. Maintain railcar pressure in non-explosive region during unloading by adding nitrogen. 9-11 Transportation & Unloading Operations • If sampling is part of your procedure, sample and obtain laboratory verifi- cation before unloading the railcar. The sample cylinder should be grounded to prevent static sparks. Polymer has a tendency to build up in the railcar sampling line in cars equipped with a sampling valve. Sampling from the offloading line reduces potential for plugging. • The excess flow check device consists of a float that becomes buoyant at high flow. Once closed, the excess flow check valve will not reopen until the pressure differential on both sides of the valve is equalized. Remember that the car pressure monitor is downstream of the vapor check valve and therefore will not read car pressure if the check valve is closed. It is important to note that emptying a tank or a shipping container of liquid EO does not remove the danger of vapor decomposition. In fact, an empty vessel can be more dangerous than one filled with liquid. As long as EO vapor remains in a vessel, full inert gas storage pressure must be maintained. • • • • • 9-12 When all EO is unloaded, blow the lines to storage until the tank indicates nitrogen flow. Use nitrogen to raise the car pressure to the level required for a non-combustible atmosphere as recommended by your EO supplier. Close the liquid and vapor valves. Log the final temperature and pressure in the railcar. Nitrogen in the unloading lines should be vented in a safe and environmentally sound manner. Disconnect all lines and remove valve extensions. • Replace all plugs. Magnetic gauge and thermowell caps should be hand tightened. Others should be wrench-tight to prevent leaks. Close the dome cover and install and secure the locking pin. • If placards are faded or torn, replace. • Disconnect ground wires. • Remove chocks, derails, and signs. • 9.6 Transportation Emergencies In case of an emergency involving an EO railcar, contact the emergency assistance numbers provided in the shipper’s Material Safety Data Sheet (MSDS). For additional assistance or information call: CHEMTREC at (800)424-9300 or (202)483-7616. 9.5 Shipping Data Density (lb/gal) 20OF 40OF 60OF 80OF 100OF 105OF 7.59 7.47 7.34 7.21 7.08 7.05 Vapor Pressure (psia) 7.1 11.6 18.0 26.9 39.1 42.7 9-13 Emergency Response 10.1 Overview Every emergency situation will be different, and it is not the intent of this publication to provide recommendations for every situation. This section will cover the unique hazards of EO as they apply to emergency situations and for specific emergency situations such as fire, air release, etc. When preparing your emergency procedures for handling EO, the MSDS provided by your EO supplier should be reviewed thoroughly. Emergency responders must be properly trained and equipped per OSHA standards on emergency response and emergency fire protection (29 CFR 1910.38, 1910.120 and Subpart L). The first priority in responding to an emergency situation is the safety of the emergency responders, employees, and people in the surrounding community. The second priority is to determine the incident’s impact on the surrounding equipment, environment and property, and to set a strategy to stabilize the situation and minimize the impact. The third priority is the conservation or protection of property and the environment. Downwind evacuation should be considered if EO is leaking but not on fire. For large spills, DOT recommends evacuating in all directions at least 400 ft. DOT further recommends evacuation of downwind areas to at least 0.2 miles (day) and 0.6 miles (night). In case of small spills, evacuation of downwind areas to at least 0.1 miles (day) and 0.2 miles (night) is recommended. If a tank or rail car is involved in a fire consider initial evacuation for one mile in all directions. If the fire is prolonged or uncontrollable, or if a container is exposed to direct flame, evacuation for one mile in all directions for protection from flying debris if the container should rupture violently. (1996 North American Emergency Response Guidebook) — Are extremely irritating to skin and eyes — Can cause blistering and severe damage — Easily penetrate cloth, leather and some types of rubber. Leather cannot be decontaminated. • EO vapor can be absorbed by wet or sweaty skin, with potential for serious chemical burns. • Odor thresholds are much greater than permissible exposure limits; overexposure occurs before the odor can be detected. • Inhalation of EO vapors — Causes irritation of exposed surfaces (eyes, nose, throat, and lungs) — Potential effects on central nervous system include drowsiness, nausea, convulsions and limb weakness • IARC (International Agency for Research on Cancer) classifies EO as class 1 – carcinogenic to humans (IARC 1994). • Water contaminated with EO evolves EO vapor and can be a source of exposure. See also section 3, “Health Effects of Ethylene Oxide”, and section 7, “Personnel Exposure”. Fire Hazards • Volatile flammable liquid with heavier than air vapors that may travel considerable distance to a source of ignition. • Lower Flammable Limit: 2.6%. Upper Flammable Limit: 100% • Fire impingement on EO-containing equipment can result in container failure and/or explosive decomposition. • Combustion products are irritating and considered hazardous. 10.2 Potential Hazards Health Hazards • Liquid EO and EO/water solutions 10 -1 • Water/EO mixtures can support combustion if water/EO ratio is less than 22:1 (open areas). • In closed systems such as sewers, water/ EO mixtures can potentially flash at dilution ratios up to 100:1. See also section 2, “Properties of EO”. • Withdraw immediately in case of venting safety device or discoloration of tank. • Keep fire-exposed containers and nearby equipment cooled using water spray. Minimum 500 gpm/point of flame impingement. • The addition of warm (above 51°F) water to pools of liquid ethylene oxide may temporarily increase vapor evolution. If there is potential for container rupture, runaway internal reaction, or heat impingement causing explosive decomposition, consider evacuation for one mile according to DOT recommendations. Hazards of Contamination • Reacts with water, evolving heat. In closed containers, reaction may be self accelerating, resulting in container rupture. • Contamination with acidic or basic materials accelerates reactions with water. • Contamination of pure EO with acidic, or basic materials; metal oxides, metal chlorides, or active catalyst surfaces may cause explosive polymerization. • May polymerize violently in container if exposed to heat. Should a Fire be Extinguished? Fire impingement on EO-containing equipment can result in explosive decomposition. Because of this, a responder should strongly consider extinguishing a fire if there is potential for flame impingement on EO-containing equipment, even if the source of hydrocarbon feeding the fire has not been stopped. 10.3 Fire Response 10.4 Spill Response Extinguishing Materials General Information • Carbon dioxide – small fires only • Proceed with caution. • Dry chemical – small fires only • Restrict access to spill area. • Alcohol foam • Water spray • Keep unprotected personnel upwind of spill. • Avoid contact with spilled product. • Wear SCBA and a full chemical protective suit. • Eliminate ignition sources. • Wear self-contained breathing apparatus (SCBA) and appropriate protective clothing. Wear full chemical protective suit if contact with material is anticipated. • For a large fire in a storage area, use unmanned hose holders or monitor nozzles. • Prevent liquid EO and contaminated runoff water from entering sewers and confined spaces. • Notify proper authorities as required by regulations. 10 -2 Extinguishing Techniques • Stay upwind. • Avoid physical contact. Emergency Response • If spill has the potential of entering a waterway, notify downstream users of potentially contaminated water. • Prevent intake of contaminated water into boilers or industrial process equipment. • Use only equipment approved for flammable atmosphere in the vicinity of an EO spill. • Be cognizant of the extremely volatile, flammable, and heavier than air nature of EO while planning the response. • Slow temperature rise by removing heat such as with a sprinkler system, cooling coils or water deluge. Evacuate area if rate of temperature increase is rapid or uncontrolled. 10.6 Use of Water in Emergencies In considering the use of water in emergency response, the user should be aware of the following: • Water can be useful for extinguishing EO fires and cooling equipment subject to fire impingement. • EO and water are completely soluble in each other, and a water spray can be useful in knocking down EO vapors. However, a water spray directed on a pool of liquid EO will increase evolution of EO vapors until significant mixing and dilution of the liquid EO have occurred. • Water/EO mixtures of less than 22:1 ratio can support combustion in open areas. In closed systems such as sewers, water/EO dilution ratios up to 100:1 are required to eliminate combustion potential. From the above it can be concluded that the maximum amount of water available should be applied to an EO release. EO also reacts with water. At ambient conditions, the EO/water reaction occurs over days and months. The responder should not hesitate to apply water in situations where EO has been released to the environment, since the hazard of fire and personal exposure is far more significant than the potential for an EO/ water reaction. In a closed container, however, the heat release from the EO/water reaction can build up the temperature, leading to an accelerating or “runaway” reaction and loss of containment. This potential exists unless the EO in the container can be rapidly purged out or diluted to a few percent weight. Air Release Techniques for responding to releases to the atmosphere include: • Evacuate local and downwind areas as conditions warrant to prevent exposure of personnel and to allow vapor to dissipate. • Knock down vapor with water fog or spray. Water fog or spray applied to EO vapors or fumes will absorb a substantial amount of EO. • Alcohol foam applied to the surface of liquid pools may slow the release of EO vapors into the atmosphere. • When using water spray, small quantities are likely to make conditions worse because of acceleration of vaporization. Large quantities of water are necessary to effectively knock down EO vapor and dilute spills. 10.5 Contamination Response • Dispose of contaminated material as quickly as possible by feeding to downstream users. • Reduce reaction rate by venting to a safe location (venting results in auto-refrigeration of the contained EO). • Drain contaminated material to a holding pond or tank and dilute with water. 10 -3 Regulations 11.1 Summary The following federal regulations are directed towards users and producers of EO and were found by doing a scan of the Index to Chemical Regulations. The scan was done by specifically looking for federal regulations that mentioned or referenced ethylene oxide. This list is not represented as inclusive of all federal regulations that apply to manufacturing and handling EO. The list specifically does not include: • Federal regulations promulgated after the date of the scan. • State and local regulations. The reader is also advised that there are numerous regulations that may impact EO operations that do not specifically mention EO and may not have been picked up by the scan. (A) of operating procedures; training; contractor relations; pre-startup safety reviews; mechanical integrity; permit systems; management of change; incident investigation; emergency planning and response and compliance audits. .178 — Prohibits use of powered industrial trucks in hazardous atmospheres; practically requires a permit system covering use of these vehicles in an EO plant; ((c) (2) OSHA 31:6505) industrial trucks in atmospheres containing hazardous concentrations. .1000 — Removes EO exposure scenarios from this general section on air contaminants and references them to 1910.1047. .1047 — Specific regulation covering all exposure scenarios to EO except those below the action level (still requires retention of objective data for exempted operations). Establishes action level of 0.5 ppm, 8 hour time weighted average. Establishes permissible exposure limits of 1 ppm, 8 hour time weighted average and 5 ppm excursion limit (15 minute average). Requirements for exposure monitoring including initial, periodic and termination samples; periodic sampling required every 3 or 6 months depending on exposure levels. Also includes monitoring accuracy and notification of employee requirements. Requires establishment of regulated areas where EO concentrations exceed 8 hour TWA or excursion limit. 11 -1 11.2 Regulations — Numerical with Subject Listed Commerce (Foreign Trade) 15 CFR 799 Commodity control list for foreign trade (polymers). (B) Labor – OSHA 29 CFR 1910 EO-specific regulations for worker and workplace safety. .19 — Applies exposure section; ((h) OSHA 31:3110 and 31:4303) to exposure limit, permissible; (.1047) to ship repair, ship building, ship breaking, longshore and marine terminal activities and construction work. .119 — Applies process safety to facilities with EO in excess of the threshold planning quantity (5,000 lbs.). Elements of PSM program include employee participation; generation of process safety information; process hazards analysis; generation, review and update (C) (D) (E) Regulations (F) Delineates methods of compliance with exposure requirements including engineering controls (preferred) and personal protective equipment. Also requires a written compliance program, emergency plan, leak detection surveys with annual review and updates. (G) Outlines approved respiratory protection, protective clothing and equipment. (H) Requires written emergency response plan and employee alerting procedures. (I) Outlines mandated medical surveillance plan; required for all employees exposed at or above the action level (0.5 ppm) for 30 days or more per year, without regard to respiratory protection and any employees exposed during an emergency event. Exams must be done prior to assignment to the work area, annually, at termination or reassignment, after an emergency exposure, where symptoms of overexposure exist or when the employee requests medical advice concerning the effects of current or past exposure on reproductive capabilities. (J) EO hazards communication program requirements including signs at demarcation zone, labels on containers, MSDS on site and employee training programs (annual). (K) Recordkeeping requirements including objective data to support exempted operations, exposure measurements (30 year retention) and medical surveillance records (duration of employment plus 30 years retention). (L) Permits employee or designated representative observation of 11 -2 monitoring activities. Appendices A, B, C and D cover non-mandatory samples of MSDS, substance technical guidelines, medical surveillance guidelines and sampling and analytical methods, respectively. 29 CFR 1926 Construction Standards .55 — Gases, vapors, fumes dusts and mists. Refer to 1926.1147 for ethylene oxide parameters. .64 — Process safety management of highly hazardous chemicals. This regulation is similar to 1910.119 but applies to the construction industry. .1147 — This is similar to 29 CFR 1910.1047. Again, it applies to the construction industry. Appendices A, B, C and D. Transportation – U.S. Coast Guard (Ports) 33 CFR 126 USCG — Handling of explosives or other dangerous cargoes within or contiguous to waterfront facilities. .10 — Designates EO as a “cargo of particular hazard”. Requires authorization of waterfront facility to engage in transfer operations. May be waived by USCG. Authorization includes minimum requirements for guards, smoking prohibitions, hot work controls, vehicle controls, electrical installations, on-site emergency equipment, storage requirements and operating procedures. 33 CFR 127 USCG — Hazardous materials Transportation Final Regulation .1209 — Respiratory protection. Each waterfront facility handling LNG must provide equipment for respiratory pro- 33 CFR 154 33 CFR 160 tection for each employee of the facility in the marine transfer area for LNG during the transfer of one or more of the following toxic LNG’s; anhydrous ammonia, chlorine, dimethylamine, ethylene oxide, methyl bromide, sulfur dioxide, or vinyl chloride. The equipment must protect the wearer from LNG’s vapor for at least 5 minutes USCG — Facilities transferring oil or hazardous materials in bulk. .0 — Requirements for facilities including operations manual and procedures, equipment specifications, vapor control systems, standard specifications for tank vent flame arrestors and detonation flame arrestors. USCG — Ports and Waterways Safety .203(E) — Requires notification of USCG for arrivals, departures, dock shifts and hazardous conditions of vessels carrying EO. May be waived by USCG. 40 CFR 60 Environmental Protection Agency 42 USC 7412 Clean Air Act Section 112 — National Emission Standards for Hazardous Air Pollutants list of pollutants section 112b lists EO. 40 CFR 52 Illinois state implementation plan (additional requirements). .741 App. A — Required control strategies for Cook, DuPage, Kane, Lake, McHenry and Will counties. Covers EO as “miscellaneous organic chemical manufacturing process”. Mandates additional control strategies, record keeping, report40 CFR 61 40 CFR 63 ing, leak detection and repair. Emission capture and control techniques must be > 81%. May be additional controls where EO is part of other processes covered elsewhere in SIP. Standards of performance for new stationary sources covering VOC emissions from SOCMI air oxidation processes, equipment leaks, distillation operations. .489 Subpart VV (SOCMI equipment leaks) — Required inspection program, corrective action, QA/QC Programs reporting and recordkeeping for leaks associated with pumps, compressors, relief devices, sampling connections and valves. .617 Subpart III (SOCMI Air Oxidation Unit Processes) — required control strategies, emissions limitations, monitoring, reporting and record keeping. .667 Subpart NNN (SOCMI Distillation Operations) — required control strategies, emissions limitations, monitoring, reporting and recordkeeping. National emissions standards for hazardous air pollutants (NESHAP). .340 — Producers that manufacture EO by cracking hydrocarbons are subject to this bezene-in-wastewater NESHAP because benzene is a by-product of the process and appears in certain wastewaters. Control requirements are specified for drains, conveyances, and treatment steps. Maximum Achievable Control Technology (MACT) 11 -3 Regulations for certain listed Hazardous Air Pollutants (HAP) including EO and other HAP that are present in EO manufacturing facilities. .100 — Compliance with this regulation began October 1994 for certain parts of the plants and will be complete after April 1999 for all regulated plant elements. List of regulated toxic substances and threshold quantities for accidental release prevention. .130 Table 1 lists EO with a threshold quantity of 10,000 pounds based on the following: a) Mandated by congress; b) On EHS list, vapor pressure 10mm Hg or greater. Pesticide residue tolerances on agricultural commodities. Pesticide residue tolerances in food products. Identification as hazardous waste/inclusion on hazardous constituents list. .33(F) — Classifies as a hazardous/toxic waste any discarded commercial chemical product off-spec species, spill or container residues. Does not apply to process waste streams (although SOCMI HON would). EO is designated as “U115” (U list waste). App. VIII — Hazardous constituents list (relates to 261.33 above). Management of specific hazardous wastes including where burned for energy recovery and burned in boilers and industrial furnaces. App. V — Risk specific dosages. App. VII — Health based limits/residue concentration limits = 3 x 10-4 mg/kg. Land disposal restrictions including technology based treatment standards and maximum allowable constituent concentrations in waste residue .42 — Establishes technology based treatment standards for U115 waste (EO) as follows: (1) Wastewaters — wet air oxidation or chemical/electrolytic oxidation followed by carbon absorption or incineration (2) Non-wastewaters — chemical/electrolytic oxidation or incineration. .43 — Establishes maximum constituent concentrations in treated waste residue which will permit land disposal. Wastewaters = .12 mg/l. 40 CFR 302 Designations, reportable quantities and notification requirements for CERCLA hazardous substances. .4 — Designates EO as hazardous substance under CERCLA section 102(A) with a final reportable quantity of 10 lb. 40 CFR 355 Requirements for emergency planning and notification under CERCLA. .0 — Establishes threshold planning quantity of 1000 lb. for EO. Excess of this amount triggers more stringent emergency planning with local/ state response groups and notification requirements. App. A and B — Superfund, extremely hazardous and threshold planning quantity. 40 CFR 372 Toxic chemical release reporting .0 — Community right to know program components applicable to EO plants. Requires certain recordkeeping, reporting thresholds and schedules and notification to 40 CFR 268 40 CFR 68 40 CFR 180 40 CFR 185 40 CFR 261 40 CFR 266 11 -4 buyer of EO of product information and hazards. .65 — Superfund, emergency planning. 40 CFR 414 Effluent guidelines and standards for organic chemicals, plastics and synthetic fibers. .60(A) — Regulates effluent from EO plants under Subpart F (commodity organic chemicals). Requires use of BPC (best practical control technology) and mandates maximum effluent levels for BOD (biological oxygen demand), TSS (total suspended solids) and pH for existing and new plants. 46 CFR 153 46 CFR 154 Transportation – U.S. Coast Guard (Shipping) 46 CFR 40 USCG — Special carriage requirements for EO transport on vessels. .05 — EO specific requirements for bulk shipment. Subchapter 0 — Certain bulk dangerous cargoes — Compatibility of cargoes. .0 — Mandates certain construction, ventilation, equipment and operating requirements. Tables I and II, Compatibility of cargo on tank vessels. Subchapter 0 — Certain bulk dangerous cargoes. Barges carrying bulk liquid hazardous material cargoes. .0 — Includes requirements for construction, ventilation, equipment, operations, cargo segregation, tank types, transfer operations procedures, emergency equipment, special requirements, environmental controls, electrical installation and inspection periods. 46 CFR 150 .05 — Bulk shipment minimum requirements. Subchapter 0 — Certain bulk dangerous cargoes — Ships carrying bulk liquid/liquefied gas or compressed gas hazardous materials. .0 — Includes requirements for construction, ventilation, equipment, operations, cargo segregation, tank types, transfer operations procedures, emergency equipment, special requirements, environmental controls, electrical installation and inspection periods. Subchapter 0 — Certain bulk dangerous cargoes safety standards for self-propelled vessels carrying bulk liquefied gases. .0 — Additional requirements covering hull structure, stability, tank arrangements, cargo containment systems, tank types, cargo piping systems, hoses, pressure and temperature controls, electrical systems, firefighting systems, ventilation, instrumentation and operating procedures. 46 CFR 151 11 -5 Regulations Transportation – Research and Special Programs Administration 49 CFR 172 DOT/RSPA Hazardous materials table .0 — Table providing chemical specific requirements for hazards class, identification numbers, packaging groups, labeling, special requirements, quantity limitations and stowage requirements. Also covers EO/CO2 mixture and EO/ propylene oxide mixture. Subpart with HAZMAT training requirements. References CERCLA RQ = 10 lb. .101 — Subpart B Hazardous Materials Table. This table provides information concerning the proper shipping name, hazard class or division, identification numbers, packing group, label requirements, special provisions, packaging authorizations, quantity limitations and vessel stowage requirements for hazardous materials. .101 (Appendix A) — List of hazardous substances reportable quantities (RQ). This Appendix lists materials and their corresponding reportable quantities (RQs) which are listed or designated as “Hazardous Substances” under 101(14) of the comprehensive environmental response, compensation and liability act (CERCLA). DOT/RSPA Shippers — General requirements for shipments and packaging. .304 — Requirements for charging of cylinders with liquefied compressed gas. .323 — Chemical-specific requirements for packaging portable containers, tanks and tank cars. Note: 49 CFR is the same as BOE 6000-M 11.3 Shipper’s Requirements Any person who offers EO (or any hazardous material) for transportation must comply with the following subparts of: 49 CFR 172 Subpart C (Shipping Papers) Subpart D (Marking) Subpart E (Labeling) Subpart F (Placarding) 49 CFR 173 (Shippers) — General requirements for shipments and packaging. Subpart G (Gases, preparation and packaging). .323 — (Ethylene Oxide). 49 CFR 179 (Specifications for tank cars) Subpart C (Specifications for pressure tank car tanks, class DOT-105). .105-7(C) — (Ethylene Oxide). 49 CFR 173 11 -6 Appendix A: Tables and Figures Figure 1 – EO Liquid Density Figure 2 – EO Vapor Pressure Figure 3 – EO Liquid Heat Capacity Figure 4 – EO Liquid Viscosity Figure 5 – EO Liquid Thermal Conductivity Figure 6 – EO Heat of Vaporization Figure 7 – EO Vapor Heat Capacity Figure 8 – EO Vapor Viscosity Figure 9 – EO Vapor Thermal Conductivity Figure 10 – Freezing Points of EO/Water Mixtures Figure 11 – Saturated EO Vapor Cp/Cv Ratio Figure 12 – EO Vapor Density Figure 13 – EO Coefficient of Cubic Expansion Figures 14, 15 – Raoult’s Law deviation factors for EO/water mixtures Table 1 – Physical Property Equations Table 2 – Conversion Factors Table 3 – Henry’s Law Constants (Atm/Mole Fraction) Table 4 – Henry’s Law Constants (MPa/Mole Fraction) A-1 3 Lbs/Ft A-2 Appendix A: FIGURE 1: FIGURE 1: Ethylene Oxide Liquid Density 60 55 50 45 40 40 80 120 160 200 240 0 Temperature, ° F FIGURE 2: Ethylene Oxide Vapor Pressure 1000 100 Psia 10 1 0 40 80 120 160 200 240 Temperature, ° F A-3 Appendix A: BTU/Lb*°F A- 4 FIGURE 3: FIGURE 3: Ethylene Oxide Liquid Heat Capacity 0.56 0.52 0.48 0.44 0.40 40 80 120 160 200 240 0 Temperature, ° F FIGURE 4: FIGURE 4: Ethylene Oxide Liquid Viscosity 0.40 0.35 0.30 Centipoise 0.25 0.20 0.15 0.10 40 80 120 160 200 240 0 Temperature, ° F A-5 Appendix A: BTU/Ft*Hr*°F A-6 FIGURE 5: FIGURE 5: Ethylene Oxide Liquid Thermal Conductivity 0.10 0.09 0.08 0.07 0.06 0 40 80 120 160 200 240 Temperature, ° F FIGURE 6: FIGURE 6: Ethylene Oxide Heat of Vaporization 275 250 BTU/Lb 225 200 175 40 80 120 160 200 240 0 Temperature, ° F A-7 Appendix A: BTU/Lb*°F A-8 FIGURE 7: Ethylene Oxide Vapor Heat Capacity FIGURE 7: 0.4 IDEAL GAS SATURATED EO VAPOR 0.3 0.2 0 40 80 120 160 200 240 Temperature, ° F FIGURE 8: FIGURE 8: Ethylene Oxide Vapor Viscosity 0.013 0.012 0.011 Centipoise 0.010 0.009 0.008 0 40 80 120 160 200 240 Temperature, ° F A-9 Appendix A: BTU/Ft*Hr*°F A-10 FIGURE 9: FIGURE 9: Ethylene Oxide Vapor Thermal Conductivity 0.014 0.013 0.012 0.011 0.010 0.009 0.008 0.007 0.006 0.005 0.004 0 40 80 120 160 200 240 Temperature, ° F FIGURE 10: FIGURE 10: Freezing Points Ethylene Oxide/Water Mixtures 52 48 Pure EO Freezing point – 170 °F 44 40 Freezing Point, °F 36 32 28 24 20 40 60 80 100 0 Ethylene Oxide in Water, wt% A-11 Appendix A: Cp/Cv Ratio A-12 FIGURE11: FIGURE 11: Cp /Cv For Saturated Ethylene Oxide Vapor 1.32 1.31 1.30 1.29 1.28 1.27 1.26 1.25 1.24 1.23 1.22 50 100 150 200 250 300 0 Temperature, ° F FIGURE 12: FIGURE 12: Ethylene Oxide Vapor Density 2.5 2.0 Lbs/Ft 3 1.5 1.0 0.5 0.0 40 80 120 160 200 240 0 Temperature, ° F A-13 Appendix A: Coefficient of Cubic Expansion per °F A-14 FIGURE 13: FIGURE 13: Ethylene Oxide Coefficient of Cubic Expansion 0.0017 0.0015 0.0013 0.0011 0.0009 0.0007 0 40 80 120 160 200 240 Temperature, ° F This page blank intentionally. A-15 Appendix A: FIGURE 14: Raoult’s Law Deviation Factors for Ethylene Oxide/Water Mixtures Terminal Regions are Expanded in the Next Figure 10 psia 9 8 7 17 35 45 55 65 Where: yi = mol fraction (EO or water) in gas phase xi = mol fraction (EO or water) in liquid phase Di = Raoult's Law Deviation Factors from Figures 14 and 15 (no units) (vp)i = pure component vapor pressure at system temperature Pt = total system pressure *** 6 5 Di = yi Pt xi (vp)i 4 Di 3 2 psia 65 35 Water Ethylene Oxide 1 0 0.2 0.4 0.6 Mole Fraction Ethylene Oxide in Water 0.8 1.0 *** Any pressure units can be used, so long as the units for vapor pressure and total pressure are the same. A-16 FIGURE 15: Raoult’s Law Deviation Factors for Ethylene Oxide/Water Mixtures 0.94 Mole Fraction Ethylene Oxide in Water 0.96 0.98 1.00 14 Where: yi = mol fraction (EO or water) in gas phase xi = mol fraction (EO or water) in liquid phase Di = Raoult's Law Deviation Factors from Figures 14 and 15 (no units) (vp)i = pure component vapor pressure at system temperature Pt = total system pressure *** 12 DH2O 10 35 8 yi Pt xi (vp)i 0.10 psia 65 Di = 8 psia 17 7 35 45 55 65 6 DEO 5 4 0 0.02 0.04 0.06 0.08 Mole Fraction Ethylene Oxide in Water *** Any pressure units can be used, so long as the units for vapor pressure and total pressure are the same. A-17 Appendix A: Table 1 Physical Property Equations EQUATION COEFFICIENTS (ALL PROPERTIES IN SI UNITS) PROPERTY Solid Density Liquid Density Coeff of Expansion Vapor Density Vapor Pressure Heat of Vaporization Solid Heat Capacity Liquid Heat Capacity Ideal Gas Heat Capacity Second Virial Coefficient Liquid Viscosity Vapor Viscosity Liquid Thermal Conductivity Vapor Thermal Conductivity Surface Tension UNITS KgMOL/M3 KgMOL/M3 per °K KgMOL/M3 Pa J/KgMOL J/KgMOL*°K J/KgMOL*°K J/KgMOL*°K M3/KgMOL Kg/M*S Kg/M*S W/M*°K W/M*°K N/M 3.3904E+00 9.1944E+01 3.6652E+07 –2.1143E+04 1.4471E+05 3.3460E+04 6.0016E-02 –8.5210E+00 2.9540E-06 2.6957E-01 –3.7880E-04 7.4730E-02 A 2.75E+01 1.8360E+00 2.6024E-01 2.6024E-01 –5.0556E-02 –5.2934E+03 3.7878E-01 1.4903E+03 –7.5887E+02 1.2116E+05 –5.2057E+01 6.3420E+02 4.1720E-01 –3.9840E-04 1.1150E+00 1.1410E+00 –5.6410E+03 –1.1881E+01 2.8261E+00 1.6084E+03 –1.8056E+07 –3.3140E-01 7.8740E+02 –2.3580E+04 3.8745E-02 –3.0640E-03 8.2410E+04 6.9368E+19 4.6915E+02 4.6915E+02 2.9010E-04 –1.1682E+01 2.6960E-01 2.6960E-01 -7.6743E-07 1.4902E-02 B C D Note: The symbol * denotes multiplication. The symbol ^ denotes exponentiation. T is temperature, deg Kelvin. Tr is reduced temperature, T/T critical. Table 2 Conversion Factors To Convert From KgMOL/M3 Pascals J/KgMOL J/KgMOL*°K Kg/M*S W/M* K O To Lb/Gal Lbf/sq in BTU/Lb BTU/Lb* F O Multiply By 0.3676 1.45E–04 9.758E–06 5.422E–06 1E+03 O Notes 1 1 1 Centipoise BTU/Ft*Hr* F Lb f/ft 0.578 6.852E–02 N/M Notes: 1. Only valid for Ethylene Oxide. A-18 E USABLE RANGE MIN MAX °K °K 161 161 161 469 469 383 469 469 161 284 1500 1500 284 1000 284 1000 469 EQUATIONS Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4) Y = A/(B^(1 + (1 - T/C)^D)) Y=(-D/C)*LN(B)*((1-T/C)^(D-1)) Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4) Y = exp (A + (B/T) + (C*lnT) + (D*T^E)) Y = A*((1 - Tr)^(B + (C*Tr) + (D*Tr^2) + (E*Tr^3))) Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4) Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4) Y = A + B*((C/T)/SINH(C/T))^2 + D*((E/T)/COSH(E/T))^2 Y = A + (B/T) + (C/T^3) + (D/T^8) + (E/T^9) Y = exp (A + (B/T) + (C*lnT) + (D*T^E)) Y = (A*T^B) / (1 + (C/T) + (D/T^2)) Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4) Y = (A*T^B) / (1 + (C/T) + (D/T^2)) Y = A*((1 - Tr)^(B + (C*Tr) + (D*Tr^2) + (E*Tr^3))) 7.9840E-10 1.0000E+00 233 161 161 25 161 7.3730E+02 –1.7212E+22 50 235 161 161 161 273 161 Table 3 Henry’s Law Constants (Atm/mole fraction) T(°F) 32 77 122 Nitrogen 2800 2180 1820 Argon 1670 1420 1270 Methane 613 614 595 Ethane 84.3 109 129 Table 4 Henry’s Law Constants (MPa/mole fraction) T(°C) 0 25 50 Nitrogen 284 221 184 Argon 169 144 129 Methane 62.1 62.2 60.3 Ethane 8.5 11.0 13.1 Henry’s Law Constants can be used with the following equation to determine solubility of these gases: t Xi= YiP Hi Where: Xi = mol fraction of gas (N2, Ar, Methane, or Ethane) in liquid EO Yi = mol fraction of gas in vapor space above liquid EO Pt = total pressure, Atm Hi = Henry’s Law Constant for gas, Atm A-19 Appendix B: References Section 2 - Physical Properties [1] [2] [3] C. 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