EO

User’s GuideIntroduction

1.1 Purpose

The purpose of this guide is to provide users ofEthylene Oxide (EO) with a summary of theessential information needed to safely handlethis important chemical product. The flam-mable, reactive and toxic characteristics ofEO, and its effects on the environment, poserisks that must be managed by all users andproducers.

This information is provided to the user as aresource in the development of their safedesign, operation, maintenance, training andemergency response practices. It is not ourintent to “recommend” any particular proce-dure, equipment design or practice, but ratherto provide a summary of the authors’ currentstate of knowledge relating to EO and its use.

Please note that this publication representsthe level of knowledge of its authors as of thedate of publication. The user should stayabreast of new developments of informationabout properties of EO, handling technology,and regulatory requirements that occur afterpublication.

1.2 Organization

In order to safely use EO, it is necessary tounderstand its properties. The guide startswith a discussion of physical and chemicalproperties (section 2), followed by discussionsof health effects (section 3), and environmen-tal effects (section 4). Section 5 discussessafety incidents that have occurred in indus-trial production, use, and transportation of EO.

Sections 6, 7, 8 and 9 discuss safe design andoperation of EO handling facilities. Sections10 and 11 cover emergency response and fed-eral regulations.

The appendices contain graphs and tables ofphysical property data and a section-by-section bibliography.

Editorial Committee

The following individuals were responsible fortheir respective companies’ contributions tothe Guide:

Carey Buckles — The Dow ChemicalCompany

Pete Chipman — Shell ChemicalCompany

Mary Cubillas — Shell ChemicalCompany

Mike Lakin — Celanese Ltd.

Dan Slezak — The Dow ChemicalCompany

David Townsend — Celanese Ltd.

Keith Vogel — Equistar Chemicals, LP

Mike Wagner — Sunoco, Inc.

Acknowledgements

The editorial committee wishes to thank thefollowing individuals for their significant con-tributions to this publication:

Ralph Gingell — Shell ChemicalCompany

Manuel Cano — Equilon Enterprises LLC

ethyleneoxidesecond edition

This guide represents a revision of the earlier publication of the same name issued inSeptember of 1995. It was produced through the cooperative efforts of Celanese Ltd.,The Dow Chemical Company, Shell Chemical Company, Sunoco, Inc. andEquistar Chemicals, LP.

Issue Date: August, 1999

Table of Contents1. Introduction

2. Properties of Ethylene Oxide

3. Health Effects

4. Environmental

5. Overview of Hazards

6. Design of Facilities

7. Personnel Exposure

8. Equipment Preparation and Maintenance

9. Transportation & Unloading Operations

10. Emergency Response

11. Regulations

Appendix A: Tables and Figures

Appendix B: References

The information contained herein is accurate to the best of our knowledge. We do not suggestor guarantee that any hazards listed herein are the only ones that exist. Use of this handlingguide is intended for persons with skill and at their own risk. User has sole responsibility todetermine the suitability of the product for any use and the manner of use contemplated. Anypotential health hazards associated with this product of which these companies may be awareare described in the Material Safety Data Sheet (MSDS) for this product.

Online ViewingThe Guide is also available on the World Wide Web at http://www.ethyleneoxide.com.

2.1 Introduction

Properties of Ethylene Oxide

2-1

61.62°

1.46 Å

1.09 Å1.43 Å

116.9°

Figure 2.1 The Ethylene Oxide Molecule

EO (oxirane) is the simplest cyclic ether. It isa colorless gas or liquid and has a sweet,etheric odor. The structure of an EO mole-cule is shown in Figure 2.1. The C-C bond isshort and the bond angles strained [1]. Notethat the atomic distances are given inangstroms.

EO is very reactive, because its highly strainedring can be opened easily, and it is one of themost versatile chemical intermediates. EOwas first prepared in 1859 by Wurtz [2] usingpotassium hydroxide solution to eliminatehydrochloric acid from ethylene chlorohydrin.The chlorohydrin process developed fromWurtz’s discovery and industrial productionbegan in 1914. The importance and commer-cial production of EO have steadily grownsince then.

The direct catalytic oxidation of ethylene, dis-covered in 1931 by Lefort [3], has graduallysuperseded the chlorohydrin process.Currently, EO is produced by direct oxidationof ethylene with air or oxygen. Annual

worldwide production capacity exceeds 11million tons, making it an important indus-trial chemical. Virtually all EO produced isfurther reacted (section 2.4). Its most impor-tant derivative is ethylene glycol, which isused for the manufacture of polyester and inautomotive antifreeze. Other EO derivativesinclude surfactants, solvents, amines, andpoly(ethylene) glycols.

In addition to being a versatile and commer-cially important compound, EO has beeninvolved in a number of serious incidents. Itis necessary to understand the properties ofEO to manage the risks of its use.

Important physical properties of EO are summarized in Table 2.1.2.2 Physical Properties

2-2

Ethylene OxideChemical Abstracts Name: OxiranePSUID Code: 1441IUPAC Name: OxiraneChemical Abstracts Number: 75-21-8Structural Formula: CH2OCH2Synonyms: Ethylene Oxide 1,2-Epoxyethane

Dihydrooxirene OxacyclopropaneDimethylene Oxide OxidoethaneEpoxyethane

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 SI Units Engineering Units NoteMolecular Weight 44.053 44.053Critical Temperature 469.15°K 384.8°FCritical Pressure 7,191 kPa 1,043 psiaCritical Volume 0.00319 cu m/kg 0.051 cu ft/lbCritical Compression Factor 0.2588 0.2588Melting Point 161.46°K -169.1°FTriple Point Temperature 161.46°K -169.1°F 1Triple Point Pressure 0.0078 kPa 0.00113 psiaNormal Boiling Point 283.6°K 50.8 °Fat 101.325kPa(1atm)Liquid Specific Gravity 20°C/20°C 0.875 0.875Liquid Volume 0.00113 cu m/kg 0.018 cu ft/lb 2Coefficient of Cubical Expansion (20°C) 0.00158/°K 0.00880/°FHeat of Formation - Ideal Gas -1,194.8 kJ/kg -513.8 BTU/lbHeat of Formation - Liquid -1766 kJ/kg -759 BTU/lb 3Gibbs Energy of Formation - Ideal Gas -300.3 kJ/kg -129.15 BTU/lb 4Gibbs Energy of Formation - Liquid -267 kJ/kg -115 BTU/lb 3Absolute Entropy - Ideal Gas 5.52 kJ/kg*°K 1.319 BTU/lb*°FAbsolute Entropy (liq) 3.494 kJ/kg*°K 0.835 BTU/lb*°F 3Heat of Fusion at Melting Point 117.5 kJ/kg 50.52 BTU/lbEntropy of Fusion 0.73 kJ/kg*°K 0.175 BTU/lb*°F [36]Standard Net Heat of Combustion -27,649 kJ/kg -11,889 BTU/lbHeat of Solution in Water -142.7 kJ/kg -61.35 BTU/lbAcentric Factor 0.197 0.197Radius of Gyration 1.937E-10 m 6.355E-10 ftDipole Moment 6.3E-30 C*m 1.889 DebyeLiquid Dielectric Constant 14.5 14.5at 0°C (32°F)Vapor Dielectric Constant 1.01 1.01 [10]at 15°C (54.5°F)Electrical Conductivity (liq) 4E-06 Siemens/m 4E-08 mhos/cmvan der Waals Volume 5.485E-04 cu m/kg 0.008785 cu ft/lbvan der Waals Area 7.492E+06 m sq/kg 3.658E+07 ft sq/lbRefractive Index, nD 1.3597 1.3597 5Flash Point <255.16°K <0°FFlammability Limits 2.6 -100 vol.% 2.6 -100 vol.%Autoignition Temp 702°K 804°FDecomposition Temp 833.2°K 1040°F 6

Table 2.1 Physical Properties of Ethylene Oxide

Graphs and tables of selected temperature dependent properties of EO are provided in Appendix A.

NOTES: 1. Estimated to be equal to the melting point temperature.2. Determined at the normal boiling point.

3. Estimated from CRC 1994 Handbook ofThermophysical and Thermochemical Data.

4. Calculated from the enthalpy of formation and theabsolute entropy.

5. Determined at 280 °K.6. Decomposition temperature has been reported as low as

723.2°K(842°F)

WARNING: FLAMMABILITY LIMITS ARE DETERMINED AT 298°K AND 1 ATMOSPHERE. HIGHER TEMPERATURES AND/OR HIGHER PRESSURES WILLLOWER THE LOWER LIMIT.


2-3

Table 2.2 Physical Properties of Aqueous Ethylene Oxide Solutions [9,10]

Ethylene Oxide Melting Point Bubble Point Specific Gravity at Flash PointContent, wt% °F °C °F °C 50/50°F °F °C

10/10°C

0 32 0 212 100 1.00000.5 107 41.51 31.3 -0.4 88 312 37 33 29.7 -1.35 29.1 -1.6 136.4 58 0.9977 28 -2

10 42.1 5.6 108.5 42.5 0.994420 50.7 10.4 89.6 32 0.9816 -6 -2130 52 11.1 80.6 27 0.9658 -18 -2840 50.7 10.4 69.8 21 0.9500 -31 -35 60 46 7.8 60.8 16 0.9227 -49 -4580 38.7 3.7 55.4 13 0.9005 -63 -53

100 -169 -111.7 50.7 10.4 0.8828 -71 -57

Ethylene Oxide Water Mixtures

Table 2.2 shows some of the properties ofaqueous EO solutions. Of particular note arethe relatively high melting points, which aredue to hydrate formation [4]. Hydrates consistof organic molecules enclosed in a cage struc-ture. The highest melting point observed is52°F (11.1°C) and corresponds to a hydratecomposition of C2H4O • 6.89 H2O [5].

Liquid EO and water are completely misciblein each other in all proportions.

EO/water mixtures are highly non-ideal anddo not follow Raoult’s Law. Raoult’s Lawdeviation factors for EO/water mixtures areshown in figures 14 and 15 in Appendix A.

Solubility of Ethylene Oxide Gas

The solubility of ethylene oxide gas in variouscompounds has been measured and reportedat atmospheric pressure and 22-23°C byChaigneau [41]. These compounds includewater, alcohols, hydrocarbons, oils, chloro-compounds, esters, and waxes.

Solubility of Gases in Ethylene Oxide

The solubilities of gases in liquid EO vary,increasing in the order nitrogen, argon,

methane, ethane. Earlier data [6] have beenrevised [7]. Increasing temperature tends toincrease the solubility. The Henry’s LawConstants for these gases in EO at differenttemperatures are given in Appendix A.

2.3 Reactive and CombustiveProperties

Understanding the reactivity and combustionproperties of EO is important in managing therisks of its use. As outlined in chapter 5, it hasbeen involved in serious incidents.

Table 2.3 Heat of reaction of variousEthylene Oxide Reactions at 25°C

kJ/kg BTU/lb

Combustion -27,649 -11,889

Decomposition -3,051 -1,312

Isomerization -2,621 -1,127

Polymerization -2,093 -900

Hydrolysis -2,081 -895 (a)

Hydrolysis -1,996 -858 (b)

(a) Calculated from heat of formation values in CRCHandbook of Thermophysical andThermochemical Data, CRC Press 1994.

(b) Reference [9]

2-4

Combustion

EO is a flammable, explosible chemical. Itsfire and explosion characteristics are systemdependent. Some of these characteristics forEO/air mixtures are as follows:

• The minimum value cited for the lowerflammable limit of EO air mixtures is2.6% [20].

• The upper flammable limit is typicallystated to be 100%, since pure EO candecompose in the absence of air oroxygen.

• The flammable range of EO-air mixtures isaccordingly 2.6-100%.

• The autoignition temperature of EO in airat 14.7 psia is 804°F (429°C) [21].

Figures 2.2 and 2.3 illustrate the flammablelimits for the EO, air and either nitrogen orcarbon dioxide ternary mixtures at atmos-pheric pressure, i.e., 14.7 psia (101.325kPa)[39]. The literature also indicates some vari-ability in the boundary concentrationdemarcation separating the flammable andnon-flammable regions; e.g. [38, 39]. Also, itis important to recognize that mixture pres-sure affects the flammability characteristicstoo. Figure 2.4 illustrates the effects ofpressure on the flammability region forEO/Nitrogen/Air. Thus, more or less inertdilution may be required depending onwhether the pressure is greater or less thanatmospheric.

The flammable limits of other mixtures of EOwith inert gases and air can be found in theliterature, e.g., EO with H2O [22]; N2 [23],[22]; N2-H2O [24]; CO2-H2O [24]; CH4 [15];CO2 [6], [22], [25]; C3H6 [26]; C4H9 [26];


FIGURE 2.2: Flammable Region of Ethylene Oxide/Nitrogen/Air Mixtures

Initial Conditions:Temperature: 20°CPressure: 1 atm.

20 40 60 80 1000

0

20

40

60

80

100 0

20

40

60

80

100

Nitr

ogen

Con

cent

ratio

n (%

Vol

)

EO Concentration (% Vol)

Air Concentration (% Vol)

Flammable Region

Flammable Region

20 40 60 80 1000

0

20

40

60

80

100 0

20

40

60

80

100

Initial Conditions:Temperature: 20°CPressure: 1 atm.

FIGURE 2.3: Flammable Region of Ethylene Oxide/Carbon Dioxide/Air Mixtures

Carb

on D

ioxi

de C

once

ntra

tion

(% V

ol)



2-5

N2-air [6]; CH4-air [6]; CO2-air [20]; CF2Cl2-air [27], [28]; CO2-air, N2-air, R12-air,R134a-air [39]; CO2-air, N2-air, Steam-air[24]; MeBr-air [24].

Flammability of Ethylene Oxide &Water Mixtures

In closed systems such as sewers, 100 to 1water to EO dilution ratios (vol/vol) may berequired to produce a mixture that will notsupport combustion. In open systems, such asaround an atmospheric spill, water/EO mix-tures can support combustion if the water/EOratio is less than 22 to 1.

Decomposition

Pure EO vapor or EO vapor mixed with air orinert gases can decompose explosively. Thedecomposition reaction is expressed by thefollowing equation:

EO —> CO + CH4 + 1312 BTU/lb

The reaction can also produce ethane, ethylene,hydrogen, carbon and acetaldehyde [10,17].

At atmospheric pressure, thermal decomposi-tion of pure EO vapor occurs at 1040°F(560°C). This is the number most frequentlycited as the decomposition temperature.However, lower gaseous EO decompositiontemperatures have been reported – indicatingthat decomposition temperature is affected bypressure, surface characteristics, volume, andgeometry. EO can also ignite and decomposeexplosively at pressures below atmospheric,down to a pressure of around 4.8-5.8 psia, butat greater than 1040°F (560°C).

Once the decomposition reaction has beeninitiated, it can be propagated from theignition source through the gas phase as aflame and, under certain conditions, may beexplosive. It is important to understand thatthis reaction can occur in the absence of airor oxygen.

High pressure can be generated by decomposi-tion of EO. The maximum theoreticalexplosive pressure is about 10 times the initialpressure, but can increase to 20 times theinitial pressure if liquid EO is present. Thisphenomenon occurs because liquid EO evapo-rates and participates in the decompositionreactions which take place in the vaporphase [15].

Mixtures of EO with nitrogen, carbon dioxideand methane will not decompose over certainconcentration ranges. Thus, vapor decomposi-tion can be prevented by dilution with asuitable inert gas. Nitrogen is usually the gasof choice, but methane and other diluentshave been used. The dilution quantity dependson temperature, pressure, and the expectedignition source and duration [9]. The mostthorough discussion of the EO decompositionprocess is presented in [17]. The minimumtotal pressure for inert blanketing is important[9,10], and section 6.5 presents informationrelevant to the inerting of EO in storage and

handling systems. For inerting of vapor spacesof reactors using EO as feeds or reagents, thesystem is quite complex and beyond the scopeof this publication.

EO liquid mists will decompose explosivelysimilarly to the vapor. The decomposition ofthis two-phase mixture yields greater pressuresand rates of pressure rise than the vapor alone[17]. Liquid EO can participate in a decompo-sition that starts in the vapor phase. Explosionof liquid EO, initiated by a strong ignitionsource within the liquid, was first described in1980. It is thought that the ignition sourcevaporizes liquid EO, and the decompositionreaction takes place in the gas phase.


2-6

0

20

40

60

80

100

Flammable Region

1/2 atm

3 atm

FIGURE 2.4: Effects of Pressure on Flammable Region of Ethylene Oxide/Nitrogen/Air Mixtures

Nitr

ogen

Con

cent

ratio

n (%

Vol

)



10060 8020 400

100

80

40

60

0

20

Exothermic Reactions with Rust

Following a major industrial incident, it wasdiscovered that EO vapor in contact with highsurface area metal oxides, such as the gammaform of iron oxide, can undergo exothermicreactions (“disproportionation”) that can raiselocal temperatures above the decompositiontemperature of EO [42].

The disproportionation reaction has been rep-resented by the following equation:

6 EO => 5C2H4 + 2CO2 + 2H2O

But depending on the reaction conditions, theratio of C2H4 to CO2 has been found to varyfrom 1.5 to 2.5.

This reaction can be initiated at significantlylower temperatures than thermal decomposi-tion. In the case of the industrial incidentnoted above, the reaction occurred:

• On the tubes of a distillation columnreboiler,

• In the presence of a deposit of highsurface area rust imbedded in an EOpolymer matrix, and

• During a period when flow through thereboiler was reduced by a process upset.

It was concluded that loss of reboiler circula-tion allowed for rapid heat buildup in thevicinity of the iron oxide/polymer deposit,resulting in localized temperatures reachingthe EO thermal decomposition temperature.The result was an explosion that destroyed thedistillation column.

Britton [17] has indicated that rust with veryhigh surface areas can also initiate EO ignitionat 284°F (140°C) or below with or withoutair present.

Polymerization

EO has a tendency to polymerize. For pureEO, the reaction is slow at ambient tempera-tures. The reaction is exothermic, releasing

900 BTU per pound of EO reacted [13].Britton [17] has reported a rust catalyzed heatof polymerization of 1102 ± 121 BTU/lb.

The usual catalysts for EO reactions, such asstrong alkali [18], iron oxide (rust) [19], andother metal oxides catalyze the reaction.When catalyzed by rust, it is most often anuisance, causing line and equipment plug-ging and off-specification product. However,the presence of large quantities of loose rustcould pose a significant safety hazard (see dis-cussion above). Britton [17] also indicatedself-polymerization at 392°F (200°C) in aclosed, near-adiabatic system, and non-catalytic conditions.

The condition of metal surfaces is extremelyimportant in determining the rate of EO poly-mer formation. It has been reported [19] thateven clean carbon steel catalyzes polymeriza-tion, although at a much slower rate thanrusty steel. Other factors that affect rate ofpolymerization:

• Metal surface to volume ratio

• Temperature

• Equipment residence time

Stainless steel is often the best choice formaterials of construction, especially when thesurface to volume ratio is high. The polymer-ization reaction has not been found to beauto-catalytic [43]. That is, the presence ofpolymer does not accelerate the polymeriza-tion process.

Contamination of EO with catalysts such asKOH or overheating can lead to runawaypolymerization. Reference [18] has a discus-sion of an EO polymerization (or “Poly-condensation”) incident brought about bycontamination of an EO-containing cylinderwith chlorine and alkali. The result was anaccelerating or “runaway” reaction that endedwith an explosion after about eight hours.

2-7

Table 2.5. Solubilities of poly(ethylene oxide) in various solvents [45]. Solubilities are given inweight percent. S signifies completely soluble.

Mol Wt 500 – 600 Mol Wt 3000 -3700Solvent T=68°F T=122°F T=68°F T=122°F

Water 73 97 62 84Methanol 48 96 35 SAcetone 20 S <1 STrichloroethylene 50 90 30 80Heptane 0.5 .01 <.01 <.01

Properties of EO Polymer

Pure EO polymers have been characterized[44] as clear viscous liquids (molecular weightless than 600) and as opaque white solids(higher molecular weight). However, inindustrial settings EO polymer is often darkbrown or black, due to the presence of mag-netite iron oxide inside the polymer matrix.

Note that the density is significantly higherthan that of EO. This means that polymerthat precipitates inside a storage containerwill tend to collect on the bottom.

Solubility of EO polymer in various solvents,including EO, is a function of molecularweight of the polymer and temperature. Ingeneral, higher molecular weight polymer isharder to dissolve. Solubilities of low molecu-lar weight EO polymer in various solvents aregiven above.

Of note is the extremely low solubility in thenon-polar solvent heptane.

Polymer samples from EO processing andstorage equipment have had molecular weights

ranging from a few thousand to over onemillion. At the upper end of this range, thepolymer is quite insoluble in solvents and hotwater, and must be removed by physical means.

Static Electricity

Liquid EO is an electrically conductive fluidand static electricity charges cannot accumu-late in metal containers using proper bondingand grounding techniques (see NFPA 77Static Electricity Guide). Bottom filling isnot required unless there are isolated internalareas that might accumulate a charge. Staticcharge can accumulate in liquid mist producedas a result of splashing and spraying, andexcessive fill velocities should be avoided tominimize this effect. {See Eichel [32] for a dis-cussion of electrostatic calculations.}

Pure EO vapor minimum ignition energy(MIE) is about 1000 mJ [9]. A typical indi-vidual can initiate static discharge energy inthe range of 1-50 mJ, and the energy fromordinary spark plugs is ca. 20-30 mJ [31].Thus, static energy discharge, in the absenceof air, is not a significant hazard under normalhandling and storage conditions.


2-8

Table 2.4 Physical Properties of Pure poly(ethylene oxide) [44]

Molecular Weight Melting Temp. (°F) Density (g/cc)

200 -85 (softening) 1.127600 72 (softening)1000 1023400 131 1.20410,000 145100,000 150 1.1304,000,000 150

The presence of even small amounts of airwith EO vapor makes it more sensitive toignition. The MIE for EO with air is reducedto a much lower level (0.06 mJ [9]) and is sub-ject to ignition by static sparking ignition orother common ignition sources. {For compar-ison the MIE for hydrogen is 0.01-0.02 mJ andthat for ethylene is 0.07-0.12 mJ [33].}

2.4 Commercial Chemistry

EO is a very versatile compound, storing con-siderable energy in its ring structure. Itsreactions proceed mainly via ring opening andare highly exothermic. Only a few of thelarge number of possible reactions are brieflydiscussed here. More detailed informationcan be found in [8]-[14].

Addition to Compounds with aReactive Hydrogen Atom

EO reacts with compounds containing a reactivehydrogen atom to form a product containing ahydroxyethyl group:

Examples of XH are: HOH, H2NH, HRNH,R2NH, RCOOH, RCONH2, HSH, RSH,ROH, N=CH, and B2H6 (R= alkyl or aryl).The reaction is accelerated by acids and bases.All common acids and Lewis acids as well aszeolites, ion exchangers [29] and aluminumoxide are effective catalysts. A detaileddiscussion of reaction mechanisms and chem-istry can be found in [12] and [30].

Since the end product of the above reactioncontains at least one hydroxyl group, it canreact successively with additional EO to pro-duce long chain polyether polymers which aresometimes called poly-oxyethylene-glycols.The molecular weight distribution of thepolymers depends on the reaction conditions,catalysts employed and the ratio of reactants.

Commercially, the most important of this typeof reaction is the reaction with water to pro-duce ethylene glycols. Over half the total EOproduction is used in ethylene glycol produc-tion. The production of poly(ethylene)glycols by this route is also of commercialimportance.

When used with starting materials other thanwater (e.g., phenols, ammonia, fatty amines,fatty alcohols, and fatty acids), this reaction,often referred to as ethoxylation, is used toproduce the bulk of the other commerciallyimportant EO derivatives.

Addition to Double Bonds

EO can add to compounds with double bonds,e.g., carbon dioxide, to form cyclic products:

EO also adds to other double bond systems,e.g., to R2C=O, SC=S, O2S=O, RN=CO, andOS=O.

Catalytic Isomerization toAcetaldehyde

Aluminum oxide (Al2O3), phosphoric acidand phosphates, iron oxides, and, under cer-tain conditions, silver, catalyze theisomerization of EO to acetaldehyde.

XH + H2C – CH2 XCH2CH2OH

O

EO

O=C=O + H2C – CH2 H2C – CH2

O

C

O

O O

CO2 EO

=

Ethylene Carbonate

H2C – CH2 CH3 – CH

O

EO

O

=

Acetaldehyde

2-9

Properties of Ethylene OxideOther Reactions

A highly reactive compound, EO reacts withmany other compounds including: hydrogen(catalytic reduction to ethanol); hydrogen sul-fide and mercaptans; Grignard reagents;halides; hydrogen cyanide; dimethyl ether;compounds with active methylene or methyne; etc.

2.5 Uses

Products derived from EO have many differentuses. They include:

• Monoethylene Glycol: Antifreeze forengines, production of polyethyleneterephthalate (polyester fibers, film, andbottles), and heat transfer liquids.

• Diethylene Glycol: Polyurethanes, poly-esters, softeners (cork, glue, casein, andpaper), plasticizers, gas drying, solvents,and de-icing of aircraft and runways.

• Triethylene Glycol: Lacquers, solvents,plasticizers, gas drying, and humectants(moisture-retaining agents).

• Poly(ethylene) Glycols: Cosmetics,ointments, pharmaceutical preparations,lubricants (finishing of textiles, ceramics),solvents (paints and drugs), and plasticizers(adhesives and printing inks).

• Ethylene Glycol Ethers: Brake fluids,detergents, solvents (paints and lacquers),and extractants for SO2, H2S, CO2, andmercaptans from natural gas and refinerygas.

• Ethanolamine: Chemicals for textile fin-ishing, cosmetics, soaps, detergents andnatural gas purification.

• Ethoxylation products of fatty alcohols,fatty amines, alkyl phenols, cellulose, andpoly(propylene glycol): Detergents andsurfactants (nonionic), biodegradabledetergents, emulsifiers, and dispersants.

2-10

Health Effects of Ethylene Oxide3.1 Overview

A handler of EO should be familiar with theOccupational Safety and Hygiene Act [1]standards contained in 29 CFR 1910.1047,which defines the personnel exposure limitsgiven below.

EO is regulated by OSHA as a cancer andreproductive hazard. OSHA had the follow-ing comment about EO toxicology:

“Clinical evidence of adverse effects associatedwith the exposure to EtO [Ethylene Oxide] is pre-sent in the form of increased incidence of cancer inlaboratory animals (leukemia, stomach, brain),mutation in offspring in animals, and resorptionsand spontaneous abortions in animals and humanpopulations respectively. Findings in human andexperimental animals exposed to airborne concen-trations of EtO also indicate damage to the geneticmaterial (DNA).”

The International Agency for Research onCancer (IARC), an agency of the WorldHealth Organization, classifies EO as Class 1 –carcinogenic to humans [2]. Section 7 hasadditional information on the OSHA standard.

3.2 Short Term Exposure toEthylene Oxide

Skin Contact

EO is reactive, and direct contact should beavoided. Liquid EO can cause freezing of theskin by evaporative cooling. It is also highlyirritating to the eyes and skin, and even dilutesolutions can cause blistering or severe dam-age to the skin or eyes. EO easily penetratescloth, leather, and some types of rubber, andcan produce blistering if clothing or footwearcontaminated with EO is not removed. SeeFigure 7.1 in section 7.3.

Inhalation

EO has a high odor threshold (>250 ppm),and sense of smell does not provide adequateprotection against its toxic effects. The effectsof exposure are concentration and timedependent. Concentrations of several hun-dred ppm may be tolerated for a few minuteswithout significant immediate health effects.Similar concentrations may cause severeinjury, especially if inhaled for longer periods.The rat LC50 (concentration to kill 50% ofanimals) was 5000 ppm for a 1 hr exposure,and about 1460 ppm for a 4 hr exposure [3].Overexposure of animals and humans to EOvapor will cause irritation of exposed surfaces,including eyes, skin, nose, throat and lungs. Ifthe lungs are affected, secondary infectionsmay lead to pneumonia. Short-term overex-posures may also affect the central nervoussystem, leading to symptoms such as drowsi-ness, disorientation, nausea, and vomiting.Convulsions and limb weakness may alsooccur. These symptoms may be expected toreverse within a few days after cessation ofacute exposure. The exposure levels thatcould cause such effects are believed to be farabove current occupational standards.

IDLH

The National Institute for OccupationalSafety and Health has quantified exposures toapproximately 400 toxic chemicals whichcould be “Immediately Dangerous to Life andHealth” (IDLH). The IDLH exposure valuefor EO is 800 ppm.

The official definition of IDLH is given in 30CFR 11.3. The IDLH concentration repre-sents an estimate of the maximum concen-tration of a substance in air from whichhealthy workers can escape without loss of lifeor irreversible health effects under conditionsof a maximum 30 minute exposure time.

For more discussion of IDLH, see reference [4].

Exposure Limits

Action Level 0.5 ppm (8hr. TWA*)

PermissibleExposure Limit 1 ppm (8hr. TWA)

Excursion Limit 5 ppm*Time Weighted Average

3-1

ERPG

The American Industrial HygieneAssociation (AIHA) has recommendedEmergency Response Planning Guidelines(ERPGs). AIHA has recommended anERPG-3 of 500 ppm, which is “the maximumairborne concentration below which it isbelieved nearly all individuals could be exposedfor up to one hour without experiencing ordeveloping life threatening health effects”.

The ERPG-2 of 50 ppm is “the maximum air-borne concentration below which it isbelieved nearly all individuals could beexposed for up to one hour without experienc-ing or developing serious health effects orsymptoms that could impair an individual’sability to take protective action”.

There is no specified ERPG-1, the “maximumconcentration below which it is believednearly all individuals could be exposed for upto one hour without experiencing other thanmild, transient effects or without perceiving aclearly defined objectionable odor”.

3.3 Long Term Exposure toEthylene Oxide

General

Long term overexposure is generally associ-ated with lower air concentrations than thoseassociated with the acute effects noted insection 3.2.

Repeated dermal exposure to EO, or materialstreated with EO, may lead to skin sensitiza-tion (allergic) reactions. Repeated exposure tohigh inhalation concentrations may result inrespiratory sensitization (asthmatic) symptoms.

There are several other important effects toconsider in the case of repeated exposures.These relate to the central nervous system,reproduction, genetic effects, and cancer.There is also a possible association withcataract formation [3].

Neurological Effects

The neurological effects of long-term overex-posure are similar to those of acute short-termexposure in humans. Many of the effects maybe non-specific, including headaches, nausea,lethargy, numbness, and memory loss. Theremay also be a reduced sense of smell and/ortaste, and muscle weakness, particularly in thelegs. If these symptoms occur it is likely theywould have been caused by exposures muchhigher than the permissible exposure limit(PEL). The effects of EO on the nervous sys-tem are regarded as reversible. No neurotoxiceffects were reported in rats or monkeysexposed to high inhalation concentrationsof EO [5].

Reproductive Effects

Experimental studies have shown reproductiveeffects in rodents exposed to EO. Male andfemale rats were exposed by inhalation to EOat 10, 33, or 100 ppm for 10 weeks and thenmated. A decrease in the number and weightof offspring were noted at the highest two con-centrations. There was no apparent effect onthe mothers or the development of the pupsduring lactation [6]. In other studies in mice,repeated exposure of the male alone to EOconcentrations of 150 ppm and above resultedin a decrease number of live offspring, suggest-ing a mutagenic effect on sperm [7][8].

The effects of EO on fetal development havebeen examined in the offspring of rats exposedto 10, 33, or 100 ppm during pregnancy [9].The only reported effect on the mother or off-spring was decreased weight of the pups at thehighest concentration. There were no malfor-mations or other indication that EO was adevelopmental toxicant.

Repeated exposures of pregnant rats to higherconcentrations for shorter times, intended tomimic EO exposure during sterilizer use, didnot enhance the effect of decreased pupweight, nor produce malformations [10].

There have been a few epidemiological reportsof increased spontaneous abortions in pregnanthospital or dental sterilizer workers exposed for

Health Effects of Ethylene Oxide

3-2

short times to relatively high EO concentrations[1]. However, methodological questions haveraised doubts about the conclusions drawn inthese studies [12].

Genetic Effects

Because EO is reactive, it is capable of directlycombining with proteins and DNA when it isabsorbed into the body. Since EO reactsdirectly with DNA, it can be anticipated tocause genetic effects when the exposure is suf-ficiently high [13].

The genetic effects of EO have been examinedin both normal body cells (i.e., cells notinvolved in reproduction) and reproductivetissue. The effects of EO on white blood cellshave been studied and evaluations made onboth laboratory animals and exposed workers.White blood cells were used because of ease ofobtaining and culturing samples. It has beenconcluded from these studies that geneticchanges (sister chromatid exchanges) mayoccur in workers exposed long-term to concen-trations of 10 ppm or higher. It should benoted that these effects have not been associ-ated with any specific disease, but are oftenused as an indication of exposure to EO.

The impact of EO on male and female repro-ductive cells has been the subject of muchresearch. In experiments on mice, it has beenshown that exposure of males to high levels ofEO causes mutations in the reproductive cellsinvolved in the development of spermatozoa.These mutations are transmitted to offspringand may result in failure of fetuses to developto term (dominant lethal effect). This studyand others, primarily on mice, have been usedto evaluate the genetic risk for exposedhumans [14]. At the current occupationalexposure limits (PELs), the risk of heritableeffects is considered to be very low [15].

Carcinogenic Effects

The ability of EO to cause cancer has beenassessed in three animal inhalation studies, andin many studies of occupationally exposedworkers. Based primarily on animal data andon cytogenetic changes in exposed workers, the

International Agency for Research in Cancerrecently classified EO as a known humancarcinogen [2].

Two animal inhalation studies were conductedin rats, and one in mice. In each study therewas a dose-related increase in the type andnumber of tumors, although it is uncertain ifthese findings can predict quantitative risk ofcancer in man [16].

The epidemiological studies of EO-inducedcancer in workers has been recently reviewed[17]. About 30,000 workers were reviewed inthis study. The authors concluded that“although the current data do not provide con-sistent and convincing evidence that EOcauses leukemia or non-Hodgkin’s lymphoma,the issues are not resolved and await furtherstudies of exposed populations”. No associationof EO exposure with any other tumor sites wasindicated in this review. Follow-up studies arecurrently being funded by the Ethylene OxideIndustry Council of the ChemicalManufacturers Association. To date, mortalityfrom cancer among workers exposed to EO hasbeen studied in 12 distinct groups that includeover 33,000 individuals. An objective conclu-sion from these studies is that EO does notcause an increased risk in mortality, of canceroverall, or cancer of the brain, stomach orpancreas that was reported in some animal orisolated human studies. The evidence relatingto added risk from leukemias and lymphomas isinconclusive, although workers in the epidemi-ologic studies were exposed at concentrationsfar higher than prevailing occupational exposures.

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4.1 Summary

Ethylene oxide is not persistent in the envi-ronment because it is reactive and degrades bybiotic and abiotic processes. It has been con-cluded that between biochemical oxidation,reactivity, volatilization, and dilution, toxiclevels of ethylene oxide are unlikely to be pre-sent except in a very localized incident area[1]. Ethylene oxide has been shown to havelow to moderate aquatic toxicity, and as aresult, does not present a significant risk to theenvironment.

4.2 Properties of Ethylene Oxidein the Environment

Since it is reactive, EO does not persist indefi-nitely in the environment. The processes ofhydrolysis, photolysis, volatilization, andbiodegradation all result in its removal. Inaddition, ethylene oxide does not readilyabsorb into sediments or soils and does notbioconcentrate. A summary of environmen-tally relevant physical properties is given inTable 4.1.

Hydrolysis

Chemical hydrolysis is a major removalprocess. An impression exists that EO inwater is quickly converted to ethylene glycol.However, conversion to glycols at ambienttemperatures requires weeks for completion.Figure 4.1: “Ethylene Oxide Hydrolysis”,shows conversion data for EO in fresh water(half-life of 14 days) [1]. In 3% salt water,

hydrolysis is somewhat faster (half-life of 9days) [1]. The rate of EO hydrolysis is bothpH and temperature dependent. Acidic con-ditions can have a large positive effect onhydrolysis rates [7]. The data for ethyleneoxide indicates that water temperature willprobably have a greater effect on half-life thanexpected pH differences in natural waters [1].The hydrolysis product, ethylene glycol, isbiodegraded rapidly in the aquaticenvironment [8].

Volatilization

Because of its volatility, ethylene oxide has atendency to transfer from water or soil to theair. The Henry’s Law Constant is 1.4 x 10-4

atm-m3/mole [1]. It has been shown that thetransfer rate of ethylene oxide from naturalwaters is about 0.36 times that of oxygenunder the same conditions [1]. A 4-hour aera-tion test resulted in 100% removal from water[9], and the volatilization half-lives forremoval from a model river and model lakeare 5.9 hours and 3.8 days, respectively [10].

Persistence in Air

Earlier studies suggested that EO is notpersistent in air due to washout by rain [1] anddegradation by chemical processes [11].However, more recent work has indicated thatEO was not readily deposited by rain [12],[13], and the dominant chemical removalprocess is the reaction with the hydroxyl radi-cal. In a study of the reactivity/volatilityclassification of organic chemicals, ethylene

Environmental

Table 4.1: Environmentally relevant parameters.

Parameter Units Value ReferenceWater solubility mg/L miscible [2]Vapor pressure at 20°C mm Hg 1095 [2]Henry’s Law Constant at 20 °C atm-m3/mol 1.4 x 10-4 [1]Octanol-water partition -- -0.30 [3]coefficient (log KOW)

Soil-sediment partition -- -0.56 [4][5]coefficient (KOC)(a)

Bioconcentration factor (BCF)(b) -- 0.35 [4][5]Theoretical oxygen demand (ThOD) g O2/g EO 1.82 [6]

(a) Calculated using log KOC = 0.544 log KOW+ 1.377 ([4], [5])(b) Calculated using log BCF = 0.76 log KOW – 0.23 ([4], [5])

4-1

Table 4.2: Ethylene oxide biological degradation data.

Process Results Comments Referenceaerobic 5-d BOD = 20% standard BOD test [9]

10 -d BOD = 62%20-d BOD = 70%

aerobic 5-d BOD = 3% standard BOD test [20]aerobic 20 -d BOD = 52% lightly seeded BOD test [1]

99% conversion

half-life

Tim

e, H

ours

0.1

1

10

100

1000

10000

100000

FIGURE 4.1:

Temperature, F°

0 120 200 24016040 80

Ethylene Oxide Hydrolysis of Dilute, Neutral Solutions

4-2

oxide was classified as a Class I chemical, i.e.,sufficiently unreactive in the atmosphere sothat it may not participate in photochemicalsmog formation [14]. The atmospheric half-life is estimated to be approximately 200-300days from OH reaction rate [13], while otherreports have indicated atmospheric half-livesranging from 38 to 380 days without account-ing for other removal mechanisms [15], [16].

Biodegradation

A series of biodegradation experiments (bio-logical oxygen demand (BOD) tests) havebeen conducted and are summarized in Table4.2. These results indicate the ethylene oxideis rapidly and extensively biodegraded underaerobic conditions. More rapid biodegrada-tion is expected in acclimated systems [17],

[18]. Thus, ethylene oxide will biodegrade inaerobic systems such as rivers, lakes, andactivated sludge units. However, high con-centrations of EO may cause inhibition ofbacterial respiration in activated sludge units.The IC50 (concentration that inhibitedbacterial growth by 50%) in an activatedsludge test (non-acclimated) was in the rangeof 10-100 mg/L [1]. It should be noted thatEO is commonly used as a sterilizing agentbecause of its bactericidal activity [19].

In testing of a full-scale chemical plant acti-vated sludge unit, ethylene oxide was shownto rapidly biodegrade to non-detectable levels[18]. Measured ethylene oxide biodegradationkinetics were determined in this study andwere successfully used to predict the measuredactivated sludge unit EO emissions [18].

4.3 Ecotoxicological Effects

Ethylene oxide aquatic toxicity studies havebeen conducted using fish and crustaceans.The results indicate that ethylene oxide haslow to moderate aquatic toxicity (Table 4.3),with toxicity measurements (LC50 in acutetests) ranging from 57 to 274 mg/L for fish and137 to 1000 mg/L for crustaceans.

The effect of ethylene oxide on the growthand development of plants has also beeninvestigated. Heck and Pires [22] reportedthat atmospheric concentrations of 10 ppmshowed no effects on plants after seven days ofexposure but concentrations as high as 1000ppm in air caused death for all of the fiveplant species tested. Ethylene oxide is alsoreported to affect germination of seeds andshow mutagenic activity in plants [19].

4.4 Evaluation of Ethylene OxideSpills

Ethylene Oxide in Soil

Should EO come in contact with soil, muchof the material will be lost to evaporation andthe balance will infiltrate the ground. Down-ward penetration of liquid toward thegroundwater table may cause environmental

concerns as hydrolysis to ethylene glycol isrelatively slow (see above). However, theethylene glycol formed from hydrolysis biode-grades rapidly (0.2 to 0.9 day half-life) [23].

After a spill, evaporation will continue withinthe soil, but at a reduced rate. Dilution of anEO release with water will increase the viscos-ity of the resulting mixture and will have thenet effect of reducing the speed of downwardmovement in the soil. If the soil surface is sat-urated with moisture at the time of therelease, as might be the case after a rain, theEO will tend to run off or pond and eventu-ally evaporate. Calculation methodology(with examples) for evaluation of subsurfacebehavior of EO in several types of soils hasbeen documented in the EO EnviroTIPmanuals developed by the CanadianEnvironmental Protection Service [19].

Ethylene Oxide in Water Systems

When spilled on water, ethylene oxide willvolatilize and, at the same time, spread on thesurface and mix with the water. EOEnviroTIP manuals [19] also documentmethodology to evaluate both spreading andmixing components of an EO release to water.

Environmental

Species Results Comments ReferenceFathead minnow Maximum safe no effect [9]

concentration (96 -h) concentration= 41 mg/L

Fathead minnow 96 -h LC50 = 57 mg/L static; fresh water [9]Fathead minnow 24-h LC50 = 86, 90, static; fresh water [1]

274 mg/L48-h LC50 = 89 mg/L96 -h LC50 = 84 mg/L

Goldfish 24-h LC50 = 90 mg/L static; fresh water [21]Daphnia magna 24-h LC50 = 260, static; fresh water [1]

270, >300 mg/L48-h LC50 = 137,200, 300 mg/L

Brine shrimp 24-h LC50 = 350, static; salt water [1]570, >500 mg/L48-h LC50 = 490,>500, 1000 mg/L

Table includes multiple results from separate tests.

Table 4.3: Ethylene oxide aquatic toxicity data.

4-3

Ethylene Oxide Dispersion in Air

EO vapor cloud dispersion in air following arelease can be evaluated using computer baseddispersion models available commerciallyfrom a number of sources [24]. Dispersionestimates can also be made using nomographsin the EO EnviroTIP manual [19]. Analyticalpredictive models have been developed by theEPA for hazardous waste treatment, storageand disposal facilities [25], and these can beused to estimate EO emissions to air. Vaporemissions (including, but not limited to EO)from contained spills, either on land or watersurfaces can also be predicted with methodol-ogy developed by Wu and Schroy [26].

4.5 Fugitive Emissions

A 1983 study, funded by the EPA, described amethodology for estimating fugitive emissionsof volatile organic compounds (VOC) on thebasis of numbers of valves, flanges, etc., andconcentrations of VOC in equipment. Themethodology included use of SOCMI(Synthetic Organic Chemical ManufacturingIndustries) emission factors for estimatingfugitive emissions, and was general for VOCs.The 1983 methodology was significantlyrefined in a 1988 study sponsored by theChemical Manufacturers Association (CMA)in cooperation with the United States EPA.New correlation equations were developed forestimating fugitive emissions that are specificfor manufacturing facilities handling EO. Ingeneral, CMA emission factors resulted inlower emissions estimates than the 1983SOCMI emission factors.

The 1993 US EPA Protocol for EquipmentLeak Emission Estimates provides two meth-ods for estimating VOC emissions. Oneoption is updated SOCMI emission factors,which were revised from the 1983 factorsbased on the 1988 CMA study. These factorswill yield lower estimates than either the 1983or 1988 correlations. As with the 1983SOCMI factors, a reduction in estimatedemissions is allowed if the facility has a LeakDetection and Repair (LDAR) program. Thisestimation option may be used for emissioninventories or permit applications.

The other option in the 1993 Protocol [27]uses field leak concentration data collected forcompliance with US EPA leak detection andrepair (LDAR) requirements to calculate fugi-tive emissions. If the number of componentsfound to be leaking is small, using the FugitiveEmissions Correlation Equations may result ineven lower calculated fugitive emissions.These correlations allow calculation of anemission rate for each component (flange,pump seal, etc.) using the actual reading takenin the field. Many commercially availabledata bases developed to document LDARcompliance can also calculate the fugitiveemissions based on the data collected.Fugitive emission rates calculated in this man-ner may be used for annual emissionsinventory reporting, but not for permitapplications.

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Overview of Hazards5.1 Introduction

Over the past 50 years, there have been manyincidents in both EO production plants andEO consuming plants [1] resulting in majorplant damage, as well as fatalities. There havealso been a significant number of EO trans-portation incidents.

One of the best ways for the EO user to under-stand the hazards of EO is to become familiarwith the incidents that have occurred in thepast and their causes. The lessons learned willhelp in design of safer plants and developmentof procedures for safe operations, mainte-nance, training and emergency response.

5.2 EO Contamination Incidents

EO is routinely reacted with other chemicalsunder controlled conditions to produce com-mercial products in a safe manner. The factthat EO is reactive with so many other chemi-cals and the reactions are highly exothermiccauses contamination to be one of the mostsignificant hazards of working with EO.Contamination of pure EO with many otherchemicals, including water, or with wastematerials can lead to uncontrolled reactionsproducing large amounts of heat.

Contamination of EO with AqueousAmmonia

This incident occurred in 1962 at an EO pro-duction and derivatives plant. An EO storagetank containing 25 tons of EO was contami-nated with aqueous ammonia due to back-flowfrom an ethanolamines unit. A rapid reactionin the tank between the EO and the ammoniaresulted in over-pressure and rupture of thetank, followed by an EO vapor cloud explo-sion. (Figures 5.1, 5.2, 5.3) Ignition of thevapor cloud caused heavy structural damage ina radius of 500 feet from the blast center. Theexplosion resulted in one fatality, three seriousinjuries, and 18 less serious injuries. The EOproducer’s investigation revealed that ammo-nia entered the EO storage tank by back-flowing through the EO transfer line. Theammonia passed through several check valvesand a positive displacement pump (through itsrelief valve) to get to the EO tank [2,3] .5-1

Figure 5.1 Blast center – EO tanks nolonger visible after explosion

Figure 5.2 Aerial view of the plant showingoverall damage

Figure 5.3 Plant laboratory after EO vaporcloud explosion – 300 feet away

Railcar Explosion Due to ReactionBetween Residual EO and CleaningWater

An EO railcar was sent to a contractor forcleaning. It contained a “heel” of a few thou-sand gallons of EO. The contractor pumpedbrackish water into the car and left it in a railyard overnight. During the night it exploded,causing significant damage to other railcars inthe rail yard. (Figures 5.4, 5.5, 5.6) The EOproducer’s investigation revealed that a majorcontributing factor to this incident was thefact that the water was added slowly to therailcar. The EO and water formed two dis-tinct layers in the railcar due to the differencein density and inadequate mixing. Due to thelayering, there was an interface between ahigh concentration of EO and a high concen-tration of water. This resulted in a muchhigher reaction rate than would have occurredif the EO and water had been well mixed.Contaminants in the brackish water may havealso contributed to the high reaction rate.The subsequent reaction generated a hightemperature and pressure, resulting in ruptureof the car [4].

EO Railcar Contamination withBentonite Clay

A railcar was returned to an EO producer’splant after cleaning by a contractor.Unknown to the EO producer, the cleaningcontractor had put bentonite clay (a dryingagent) in the car, to reduce rust formation.When the car was received at the plant, theclay was not removed. During loading withEO, a fire occurred in the dome of the railcar.Reaction between the bentonite clay and EOcaused an internal ignition and release ofburning EO vapor through the car’s safetyrelief valve. The fire was extinguished withwater, but re-flashed. It was finally extin-guished with dry chemical.

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Figure 5.4 Remnants of railcar after EOexplosion caused by contamination

Figure 5.5 Remnants of railcar after EOexplosion caused by contamination

Figure 5.6 Damage to other railcars due tothe EO railcar explosion

Contamination of Railcar withAmmonia

A European EO producer shipped an EO rail-car to a customer. The railcar was delivered tothe wrong plant and the workers at the receiv-ing plant thought the car containedanhydrous ammonia. They attempted to off-load the EO into an anhydrous ammoniatank. The ammonia tank was at a signifi-cantly higher pressure than the pressure onthe EO railcar. During the attempt to offloadthe EO, a check valve leaked and allowed asmall amount of ammonia to back-flow intothe EO railcar. When the workers at theplant discovered that the car was delivered bymistake, the unloading operation was stoppedand the car containing the contaminated EOwas dispatched on to its proper destination,300 km away. The railcar car exploded in themiddle of the night on a rail siding at the edgeof the plant. The explosion caused majordamage over a 300-meter radius and brokewindows up to 5 km away. (Figure 5.7)

Explosion of Railcar Containing EOWashwater

An EO producer in the US washed an EOship loading line and an EO storage sphere

with river water, and then stored the EO con-taminated water in a 22,500 gallon railcar.The railcar contained 8000 gallons of EO and5200 gallons of washwater. The car wasloaded at 63°F and padded with nitrogen at 35psig. The railcar sat on a siding for 23 days,and exploded on December 27, 1973. Prior tothe explosion, the tankcar’s relief valve lifted,and the immediate area was evacuated. Whenthe car exploded, there was a large fireball andthe explosion formed a crater. The adjacentepoxide plant was demolished. There were 28people with minor injuries, but no fatalities.

5.3 Formation of Ethylene OxideVapor Clouds

Release of EO vapors can result in vapor cloudignition. Such incidents can be extremelydestructive.

Ethoxylation Plant Explosion

The contents of an ethoxylation reactor werepumped to a neutralization vessel about onehalf-hour before completion of all the reac-tion steps. The neutralization vessel waslocated indoors. The material was pumped tothe vessel at a temperature of approximately390°F. It contained 100 to 150 lbs. of unre-

Overview of Hazards

5-3

Figure 5.7 Remnants of railcar after EO explosion caused by contamination with ammonia.

acted EO. The EO vaporized and escapedfrom the vessel rapidly and mixed with the airin the building. An explosion occurred whenan operator entered the building to turn onthe ventilation system. The explosion killedthe operator that was entering the building,injured two other operators, and completelydestroyed the building housing the ethoxyla-tion reactor and the neutralization vessel.Nearby buildings sustained extensive damage.

5.4 EO Decomposition Incidents

One of the most hazardous properties of EO isthe fact that it will decompose at a tempera-ture around 1040° F. The incidents listedbelow illustrate the most common causes ofEO decomposition incidents.

EO Decomposition Incidents Causedby External Fires

An external fire is one of the most hazardoussituations that can occur in an EO plantbecause of the potential for EO decomposi-tion. Even with good water spray systems andwell-insulated equipment, flame impingementfrom an external fire can increase piping andvessel wall temperatures to EO decompositiontemperature in a short time period. If thishappens, an internal explosion can occur.The following are examples of major incidentsthat were caused by an external fire.

• Fire Around Distillation Column

An EO producer in the US had a ruptureof an EO compressor cylinder. Thisresulted in a large fire, which engulfed theEO distillation column. The resultingtemperature increase on the surface of thecolumn and in the contained EO resultedin an internal explosion and significantdamage.

• Flange Fire while Plant was Down

A European EO producer experienced aflange leak in the EO distillation section.The plant had been shut down, but stillcontained an inventory of EO. The flangeleak resulted in a fire and the flameimpinged on a process line containing EO.

The heat caused an EO decompositionreaction to be initiated in the line. Thedecomposition propagated down the lineand into a distillation column. The col-umn head was torn off and thrown about100 feet. Large and small parts of thecolumn jacket were scattered over a 2000-foot radius. Only 7 minutes elapsedbetween the start of the unit fire and thecolumn explosion.

• Pump Seal Leak Fire

An EO pump seal leak is always a signifi-cant incident because of personnelexposure concerns. However, if a pumpseal leak ignites, the results can be cata-strophic. A European EO productionplant had an EO pump seal leak that wasignited by contact with hot pump parts.The flame from the pump seal fireimpinged on an uninsulated minimumflow return line, causing evaporation ofthe EO in that line. Continued heatinput from the flame impingementresulted in a decomposition in the mini-mum flow line. The decompositionreaction propagated into the EO purifica-tion column reflux drum, where anexplosion occurred. The reflux drum andits associated distillation column weredestroyed. This incident resulted in fourfatalities. The plant was heavily damagedand out of operation for four months.

5-4

EO Decomposition Incidents Causedby Mechanical Equipment

Important concerns regarding pumps andcompressors in EO service are 1) the potentialfor high temperatures if mechanical energy isnot dissipated and 2) the potential for a firedue to seal leaks. A good example of failure toremove mechanical energy is a blocked pumpdischarge. The two incidents described hereare good examples of the results of operatingan EO pump deadheaded. The pump sealleak fire described on the previous page is agood example of the potential consequencesof a seal leak fire.

• Decomposition in Reflux PumpPropagates to Reflux Drum andTower

A European EO producer had been hav-ing problems with the EO purificationcolumn reflux pump over-speeding. Therewere also instrumentation problems withthe level controller on the reflux drum,and the incident was triggered by thereflux control valve failing closed. Thereflux pump operated deadheaded againstthe level control valve, causing tempera-

ture in the pump to rise, vaporizing EOand causing a decomposition reaction.The decomposition propagated throughthe pump suction line into the reflux ves-sel where an explosion occurred. Shortlyafterward the EO purification columnexploded. This explosion resulted in fourfatalities. The plant was heavily damagedand out of operation for four months [5].

• EO Decomposition in Blocked-inPump

A US EO producer used high-speed cen-trifugal pumps to feed EO to two ethyleneglycol units. The plant had a commonspare feed pump for the two glycol units.The spare pump was typically kept clearedof EO, pressured up with 200 psig nitrogenand left with the suction and double dis-charge valves blocked in. A small amountof EO leaked through two blocked dis-charge valves into the pump. Anelectrical system malfunction caused thehigh-speed centrifugal pump’s electricmotor to start. The pump ran blocked infor approximately 10 minutes until theseal area of the pump reached EO decom-position temperature and the pump

Overview of Hazards

Figure 5.8 High speed centrifugal pump “launched” by decompostion of 0.6 lb. of EO

5-5

exploded. The decomposition of the 0.6lb. of EO generated over 450,000 poundsof force and caused the failure of twelve,3⁄4" stainless steel nuts and bolts. (Figure5.8) The upper part of the vertical cen-trifugal pump and the motor (approxi-mately 1000 lb.) were launched 60 feet inthe air. The pump and motor landed onthe discharge piping of another EO feedpump that was operating at 750 psig,pumping 80 gpm of EO. Fortunately thepiping did not fail. (Figure 5.9)

EO Decomposition Incidents Causedby Leaks

• Under Insulation

High temperatures can develop in EOleaking under porous insulation due toreaction of EO in contact with the insula-tion. Types of porous insulation subject tothis problem include mineral wool,asbestos, fiberglass, calcium silicate,magnesium silicate, and others. Porousinsulation can soak up and retain waterfrom the environment, thereby providinga large surface area for EO/water contact.In addition, it has also been shown thatmany types of insulation catalyze reactions

of EO. These reactions all produce heat,the dissipation of which is inhibited bythe insulation itself. This can result in a“hot spot” on the wall of the vessel, whichcan trigger a decomposition reaction.Since the incidents discussed below,industry has largely converted to non-porous insulation such as cellular glass.This reduces the potential for hot spotsand provides a degree of protection fromoverheating due to fire. See section 6.3for a fuller discussion of insulation.

• EO Leak at an Insulated ManwayFlange Results in Tower Explosion

In 1987, a European EO producer had acatastrophic explosion of their EO purifi-cation column. The damage to the plantwas very extensive. Investigation after theincident revealed that a manhole flangeleak under mineral wool insulation on theEO distillation column resulted in anexternal “hot spot” which caused an EOdecomposition inside the tower. (Figure5.10, 5.11, 5.12, 5.13)

Figure 5.9 Motor landed on operating EO pump discharge line

5-6

5-7

Figure 5.10 EO distillation column reboiler after explosion

Overview of Hazards

Figure 5.11 Aerial view of the site showing the extent of the damage

5-8

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 bythe explosion

• EO Leak Under Insulation Results inTower Explosion

In 1989, another European EO producerhad a catastrophic explosion of their EOpurification column. A crack developedwhere a pipe was attached to the wall ofan EO distillation tower. The crackallowed EO to leak into mineral woolinsulation. EO reacted with water in theinsulation to produce polyglycols. Whenportions of the insulation and insulationjacketing were removed for maintenance,air flowed into and under the insulation,causing rapid oxidation of the polyglycols,producing a high temperature. The insula-tion prevented dissipation of the heat, andthe reaction in the insulation caused thewall temperature of the EO distillationtower to reach EO decompositiontemperature. The resulting internaldecomposition reaction caused vessel fail-ure. Damage to the plant was severe,requiring more than a year for rebuilding.

EO Decomposition Caused by Reactionin Column Reboiler

• EO Re-distillation Column Explosion

An EO manufacturer experienced anexplosion in an EO re-distillation column.(Figure 5.14) The explosion appeared tohave been initiated at the top of the

reboiler. There was one fatality and theplant was out of service for more than oneyear [6].

After the incident, the EO producer’sresearch identified a previously unknownreaction of EO: disproportionation (seesection 2.3). This reaction can be initi-ated at significantly lower temperaturesthan thermal decomposition. In the caseof this incident, the reaction occurred

• On the tubes of a distillation columnreboiler,

• In the presence of a deposit of highsurface area rust imbedded in an EOpolymer matrix, and

• During a period when flow throughthe reboiler was reduced by a processupset.

It was concluded that loss of reboiler cir-culation allowed for rapid heat buildup inthe vicinity of the iron oxide/polymerdeposit, resulting in localized temperaturesreaching the EO thermal decompositiontemperature. The result was an explosionthat destroyed the distillation column.

EO Decomposition Incident Causedby Catalyst Residue in the VaporSpace of an Ethoxylation Reactor

An ethoxylation reactor exploded during nor-mal operation, while EO was being fed to thereactor. During the investigation of theexplosion, pieces of the reactor head werefound that had a heavy buildup of potassiumhydroxide catalyst on the metal. A liquidstream containing KOH was added at the topof the reactor, and a KOH residue had built upon the inside of the head. The KOH cat-alyzed a reaction of the EO in the vapor spaceof the reactor driving the temperature inlocalized areas of the reactor head to thedecomposition temperature and the vaporspace decomposed explosively. The vaporspace was not inerted with nitrogen.

Overview of Hazards

Figure 5.14 Scene of EO re-distillation towerexplosion. EO re-distillation tower is gone andadjacent tower is damaged and leaning.

5-9

5.5 EO Transportation Incidents

In both of the following transportation inci-dents an EO railcar was punctured and a fireresulted. In one incident the emergencyresponders controlled the process of burningoff the EO. In the other incident, injurieswere prevented by evacuation.

EO Railcar Fire

A railcar of EO was punctured in a rail acci-dent and the leak ignited. Three unmannedfire monitors were set up to limit the temper-ature increase in the car and to reduce thelikelihood of a “hot spot” in the car shell.Nitrogen was fed into the car through a hosefrom portable nitrogen bottles to maintain ofan inert atmosphere inside the car. A 1.5”firewater hose was also connected to allowflooding of the car’s interior, should itbecome necessary. The fire was allowed toburn until all liquid EO had been consumed.When the fire went out, the car was filledwith water as rapidly as possible to cool thecar and to expel unburned EO vapors. Nofurther damage resulted.

EO Railcar Explosion

A derailment resulted in the puncture of anEO railcar and a fire. Water was put on theburning railcar and on an adjacent EO carthat was not leaking. The fire was extin-guished after about 12 hours. About fivehours after the fire was out, the safety reliefvalve on the adjacent car lifted and vaporfrom the relief valve caught fire. At thispoint, the accident scene was cleared for aradius of 3⁄4 mile. After about 55 hours, therelief valve fire went out for a brief periodand then a violent explosion occurred. Alarge piece of the railcar was blown 5,000feet through the air. The explosion wasattributed to flame propagation back throughthe safety relief valve or a “hot spot” in themetal near the relief valve that triggered adecomposition reaction.

5.6 Runaway EO PolymerizationIncidents

Polymerization Incidents in EOFilters

In 1969, a major US EO producer had anEO filter explode due to a runaway polymer-ization. The filter had been left full of EOand blocked-in. (Figure 5.15)

In May 1998, another US EO producer hada runaway polymerization in an EO railcar-loading filter. Circulation through theloading filter, which normally provides cool-ing, was stopped for over two days due tomaintenance on other equipment in the EOtankfarm. The filter elements had not beenchanged in 18 months and were highlyloaded with rust. The ambient temperatureat the time of the incident was 100° F. Thecombination of the stagnant EO, the highambient temperature, and the rust in the fil-ter elements initiated the polymerization.The filter case did not rupture, but the tem-perature in the center of the filter caseexceeded 400° F.

5-10

Figure 5.15 Filter case after runawaypolymerization

Overview of Hazards

5-11

5.7 Runaway Reactions inEthoxylation Units

Delayed Addition of Catalyst

EO was added to an ethoxylation reactor withthe circulation cooling line blocked. The cir-culation line was also used for addition ofpotassium hydroxide catalyst. In order to con-tinue feeding EO to the reactor, the operatorhad to reset the high temperature EO feedshutdown. When it was discovered that thecirculation line was blocked, the block valvewas opened to re-establish cooling, but thisaction allowed a “slug” of concentrated KOHto enter the reactor and come into contactwith EO. Subsequently, the reactor rupturedexplosively. Metal parts and valves werepropelled over a distance of approximately2300 feet.

Inadvertent Addition of HydrogenPeroxide

The reactor in a European ethoxylation unitsuddenly exploded. The incident investiga-tion revealed that hydrogen peroxide that wasused to bleach the product was inadvertentlyadded during the EO addition phase of theoperation. The EO reacted with the hydrogenperoxide and caused the reactor to explode.

5.8 Explosions in EO AbatementDevices

During 1997, there were explosions at threeplants that use catalytic oxidizers for destruc-tion of EO in process vents. Each of theexplosions either damaged or destroyed thecatalytic oxidizer. One of the incidentsoccurred during the startup testing of the oxi-dizer. In one of the incidents, there was anexplosion with a fireball, and the oxidizer sys-tem and the building were destroyed.

6.1 Introduction

The design of facilities for storing, transportingand processing EO must take into account theflammability, toxicity, and reactivity characteris-tics of this material. This summary of EO facilitydesign issues reflects not only consideration ofits chemical and physical characteristics, butalso the practical experience of industry in deal-ing with those characteristics. Before using thissection, it is recommended that the readerreview section 5, “Overview of Hazards,” sincemuch industry design philosophy has beendeveloped in response to the incidents summa-rized in that section.

A significant number of industrial incidentshave been caused by contamination of EO instorage and shipping containers, followed byuncontrolled reactions. Much of the design phi-losophy is based on prevention ofcontamination.

Other incidents have been caused by fireimpingement on EO-containing equipment orreaction of EO leaking under porous insulation.Designing to mitigate this risk involves carefulselection of insulating materials to provide ade-quate fire protection of equipment, whileminimizing the insulation’s reactivity with EO.

Both causes have elevated temperatures insideequipment to the point where uncontrolledthermal decomposition occurred.

Risk assessment and hazard analysis are man-dated by OSHA 29 CFR 1910.119 and shouldbe an integral part of the initial design of thefacility and should precede modifications toequipment and procedures.

6.2 Plant Layout & Siting

For plant layout and siting, consider using crite-ria developed for LPG service in NFPA [1], [2],[3] and API [4] standards. The user will have toappropriately modify these standards for EOservice.

Electrical equipment in areas that produce,store, use, load, or unload EO must conform toNational Electrical Code, Class I, Division 1 or

2, Group B (or Group C if conduit seals complywith NEC paragraph 501-5(a)).

6.3 Materials of Construction

Because of the reactivity of EO, materials incontact with EO should be chosen with care.

Metallic Materials

Equipment for storage and handling of EO isgenerally fabricated from mild carbon steel or300 series austenitic stainless steels. Stainlesssteels have the advantage of eliminating thepotential for rust, which can catalyze EO poly-merization.

Austenitic stainless steels such as Type 304 andType 316 should be used for small piping, instru-mentation, and other equipment that cannot bereadily cleaned of rust. They should also be con-sidered where EO liquid or vapor is likely toremain stagnant for periods of time.

Carbon steels should be chosen which retainintegrity under the full range of temperaturesencountered in the specific application. Ironoxide in the form of red hematite or black mag-netite on internal surfaces of carbon steelequipment will lead to polymerization ofthe EO.

The following metals should not be usedwith EO:

• Magnesium and magnesium alloys

• Mercury

• Cast irons (because of low ductility)

Care must be taken with externally insulatedequipment to guard against corrosion under wetinsulation. Wet insulation and metal surfacescan be caused either by ingress of rainwater or bycondensation of atmospheric moisture on metalsurfaces containing refrigerated EO. Carbonsteel equipment handling EO should be pro-tected from external corrosion by suitablecoatings. The physical integrity of the coatingand process equipment it protects should bemonitored periodically in accordance with theplant’s mechanical integrity program.

6 -1

Design of Facilities

Depending on location and process conditions,stainless steels can be subject to stress corrosionfrom naturally occurring atmospheric chloridesand may also require external coating.

Non-Metallic Materials

EO rapidly attacks and degrades many of theorganic polymers and elastomers that are nor-mally used to make O-rings, packing material,and gaskets. Any polymer or elastomer shouldbe tested thoroughly to confirm that it is com-patible with EO before it is used in EO service.

Asbestos and asbestos-filled materials are notdurable in EO service.

Polytetrafluoroethylene (PTFE) is chemicallyresistant to EO at temperatures up to 400-500°F.However, virgin PTFE exhibits cold flow behav-ior at all temperatures and does not work well asa gasket material. In well confined applications(such as valve packing), virgin PTFE can be usedsuccessfully.

Because of its tendency to cold flow, PTFE forgasket applications is typically filled with glassfibers or ceramic particles to increase its dimen-sional stability. Glass and ceramic filled PTFEwill absorb EO. EO polymerizes within thePTFE-filler matrix and the resulting EO polymercauses swelling and failure of the gasket. Glassand ceramic filled PTFE gaskets are not durablein EO service.

Spiral wound stainless steel gaskets filled withvirgin PTFE have been successfully used to sealraised face flanges and valve bonnets in EO ser-vice. However, there have also been quite a fewincidents where EO permeated into the PTFEfiller, polymerized, and caused deformation orunwinding of the gasket. When spiral woundgaskets are used in EO service, they should haveinner and outer retaining rings to preventunwinding of the gasket in case EO polymerforms within the windings.

High purity (98%), flexible compressedgraphite is the most widely used gasket and pack-ing material in EO service. This material has nofillers or binders and is compatible with EO.High purity, flexible compressed graphite isavailable in flat sheet form as well as crinkledtape for valve packing. The sheet form of flexi-ble graphite is somewhat fragile, so for gasketapplications, the sheet is typically used as a fillerfor stainless steel spiral wound gaskets. Whenspiral wound gaskets are used in EO service, theyshould have inner and outer retaining rings.

In EO service applications where spiral woundgaskets cannot be used, laminated flexible com-pressed graphite gaskets can be used. Severalmanufacturers produce gaskets from two layers of


6-2

Figure 6.1 Degradation of compressedasbestos valve bonnet gaskets by EO

Figure 6.3 Deformation of a spiral woundstainless steel-PTFE gasket due to EO perme-ation and polymerization

Figure 6.4 Spiral wound stainless steel –flexible compressed graphite gasket withinner and outer retaining rings

Figure 6.2 PTFE gasket failures in EOservice due to cold flow

flexible compressed graphite laminated to a0.004" tang (perforated) stainless steel sheet.Since the graphite is laminated to tang stainlesssteel sheet, there are no adhesives used in thelamination process. If a laminated gasket isused, it is important to specify a tang stainlesssteel sheet rather than flat stainless steel sheet.Tests have shown that EO will attack the adhe-sives that are used to bond flexible graphite toflat stainless steel sheet.

Elastomers which are most commonly used tomake O-rings will often degrade in EO service.Experience within the EO industry has shownthat there are a limited number of perfluoroelastomers and EPDM elastomers that will holdup well in EO service. Note that many of theKalrez, Chemraz, and EPDM formulations willnot hold up in EO service.

Following is a list of materials that have beentested for compatibility with EO and have beensuccessfully used in EO service in industrialapplications.

O-Rings Chemraz®1 505Kalrez®2 2035Parker EPDM-740-75Parker EPDM-962-90Parker E-515-8-EPM

Gaskets Spiral wound stainless steelwith a high purity flexible com-pressed graphite filler and innerand outer retaining rings(Polycarbon Sigraflex®3 B Grade orUCAR Grafoil®4 GT™B filler)

Laminated high purity flexiblecompressed graphite on 0.004"tang stainless steel sheet(Polycarbon Sigraflex®3 BTCSS orUCAR Grafoil®4 GH™E)

Packing Corrugated flexible compressedgraphite ribbon (PolycarbonSigraflex®3 Corrugated B Tape orUCAR Grafoil®4 GT™Z)

Virgin PTFE rings or chevrons 1. Registered U.S. Trademark of Green Tweed and Company2. Registered U.S. Trademark of E.I. DuPont De Nemours and Company3. Registered U.S. Trademark of SGL Technic Inc., Polycarbon Division4. Registered U.S. Trademark of UCAR Carbon Company Inc.

Durability of non-metallic materials in EO ser-vice varies with the material used and with theprocess conditions. The user should have aninspection program to determine the durabil-ity and required change-out frequency for thematerials selected for a given application.

Insulation

Insulation provides a degree of protection formetal walls of vessels, piping and otherequipment against being heated to the initia-tion temperature for EO decomposition byexternal flames.

In selecting insulating materials for EO service,the user should consider the following:

• Porous insulating materials such as magne-sium and calcium silicate, mineral wool,and asbestos absorb water from the envi-ronment. This can promote externalcorrosion under insulation.

6 -3

Figure 6.5 Laminated gasket made ofPolycarbon Sigraflex™ BTCSS flexiblecompressed graphite

Figure 6.6 Laminated gasket made ofUCAR Grafoil GH™ E flexible compressedgraphite

• Porous insulating materials promote exother-mic reactions such as that of EO withabsorbed water [5].

• Aluminum sheathing on insulation has a rel-atively low melting point. Stainless steelsheeting/banding has superior durability inthe event of a fire.

The use of closed cell materials such as cellularglass reduces the potential for water absorptionand for exothermic reactions in the event of anEO leak under insulation. EO leaks under porousinsulation resulting in hot spots and internalignition have been implicated in major industrialincidents. Two such incidents are discussed insection 5.7.

As mentioned in the “Metallic Materials” sec-tion, use of appropriate coatings on carbon steelequipment that is to be insulated provides adegree of protection against corrosion under

insulation. This is of special concern when theoperating temperature of the equipment is below200°F. This temperature range is too low to evap-orate water that penetrates under the insulation.

6.4 Unloading Facilities

A number of incidents described in section 5.2resulted from contamination of EO railcars.Because of the seriousness of potential conse-quences, the user must assure that shippingcontainers are not contaminated from theprocess. A key to prevention of contamination isto provide a system totally dedicated to EO.

Facilities should not be designed for direct feedfrom an EO railcar into a chemical process.There should be intermediate storage down-stream of the offloading facility, and systems toprevent backflow from the process into EOstorage.


6-4

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LI

Ethylene OxideStorage Tank

WP FI

InternalCooler

NitrogenNitrogen

(G) (H)

RO Lock or carseal open

Figure 6.8 Representative layout of Ethylene Oxide unloading facilities - Pressurized transfer

UNLOADING WITH INERT GAS1. Open liquid valves A, G2. Open vapor valve B and apply nitrogen pressure3. Open valve H as pressure builds up

NOTE: This diagram is for illustration purposes only.Specific system design for individual applications must bedone only with consultation from professional engineer-ing services or other qualified experts.

NOMENCLATURERO – Restrictive orificeTI – Temperature indicating devicePI – Pressure indicating devicePR 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 relieveLI – Level indicating deviceWP – Wash point valveFI – Flow indicator

Acceptable means of transfer from a railcar intothe storage facility are pressurization with aninert gas and pumping. Typical layouts for a pres-sure transfer facility and a pump transfer facilityare shown in Figures 6.7, 6.8 and 6.9. If pressur-ization is used to unload railcars, a safe means ofventing off excess pressure is recommended.Shipping empty railcars at unloading pressurecan result in releases from the safety relief valvein transit. Pressurized transfer by heating is notrecommended.

Facilities for railcar loading and unloadingshould be equipped with a water deluge systemthat can be activated manually or by com-bustible gas detectors or high temperaturesensors. An elevated rack for access to the rail-car dome is preferred. Protection againstinadvertent movement of the railcar while theloading/unloading hoses are connected isrequired by DOT regulation.

6 -5

Figure 6.9 Representative layout of Ethylene Oxide unloading facilities - Pump transfer

To Process

Lock or carseal open

To Scrubber

TankCar

Process And Circulation Pump

With Low Flow, DeadheadAnd Overheating Protection

(A) (B)

ReliefValves PR 1

PIPR 2

LI

Ethylene OxideStorage Tank

WP FI

InternalCooler

Nitrogen(G) (H)

(C)

FI

(D) (E)

Transfer Pump With Low Flow, Deadhead And Overheating Protection

(F)

RO

Figure 6.7 Ethylene Oxide unloadingfacilities

UNLOADING WITH TRANSFER PUMP1. Open liquid valves A, D, E, G2. Close liquid valve C3. Open vapor valves B, F NOTE: This diagram is for illustration purposes only. Specificsystem design for individual applications must be done onlywith consultation from professional engineering services orother qualified experts.

NOMENCLATURERO – Restrictive orificeTI – Temperature indicating devicePI – Pressure indicating devicePR 1 – Pressure regulator - 35 psig setting min.PR 2 – Pressure regulator - 35 psig setting min.LI – Level indicating deviceWP – Wash point valveFI – Flow indicator

6.5 Ethylene Oxide Storage

Design Considerations

Design considerations for storage vessels in EOservice should include:

• Compliance with the current ASME Codefor Unfired Pressure Vessels for the mini-mum design working pressure consistentwith process requirements, including consid-eration of the blanket inert gas pressureneeded to maintain a non-decomposablevapor space (see next page under “Inertingof Storage”).

• Adequate capacity to accept the entire con-tents of the shipment container.

• EO storage tanks should be located within adiked area, or one otherwise designed tocontain a tank leak and to prevent otherproduct spills from entering the EO storagearea. The area should be adequately suppliedwith fire water deluges and/or fixed firewater monitors.

Because of its hazardous nature, the user of EOshould design storage facilities to minimize theworking inventory of EO.

Railcars should not be used for extended storage.They cannot be monitored for temperature orpressure increases as effectively as permanentstorage tanks. They also offer no means of heatremoval in the event of EO polymerization orreaction with a contaminant.

Instrumentation

EO storage instrumentation must provide thefollowing:

• Accurate level measurement.

• Assurance that the storage vessel is inertedat an adequate pressure to stay out of theexplosive region.

• Reliable indication of heat release from acontamination reaction.

Consider the following when designing instru-ment systems for EO storage:

• Installation of multiple, independent tem-perature measurements, and alarming onhigh temperatures.

• Installation of multiple, independent levelmeasurements, or an independent high levelalarm.

• Monitoring and alarming on rate of rise ofstorage temperature. Changes in the rateindicate intensification of a contaminationreaction and dictate when emergencyresponse plans should be activated.

• Alarming on low pressure (low pressuresindicate loss of inerting gas).

Gauge glasses have potential for fitting leaks andplugging from polymer formation. Using stain-less steel instrument lines for EO service reducesthe likelihood of polymer formation and plug-ging. The use of remote diaphragm sealeddifferential pressure transmitters, “bubbler” diptubes, ultrasonic, radar and nuclear level indica-tors can reduce the potential for erroneous levelindication caused by polymer formation. Theuser should avoid use of mercury-containinginstrument systems (e.g., manometers), as mer-cury is reactive with EO.

Inerting of Storage

Section 2.3 discusses the potential for pure EOvapor to decompose explosively in the presenceof a suitable ignition source. EO vapor spacescan be rendered non-decomposable by dilutingwith the appropriate proportion of an inert gas.In practice, vessels are inerted with nitrogen,and are maintained in the non-decomposableregion by controlling pressure.

Figure 6.10 shows minimum storage pressuresrequired to ensure that EO vapor spaces arenon-decomposable, as a function of liquid stor-age temperature. The figure assumes use ofnitrogen as the inerting gas. No margin ofsafety has been incorporated into thisgraph [6].

Inerting systems are themselves potentialsources of contamination and EO users shouldcarefully evaluate this potential. Systems inplace to prevent inert gas contaminationinclude:


6-6

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6 -7

• Dedicated sources of inert gas (e.g., directlyfrom a high pressure pipeline or from highpressure cylinders).

• Area knockout pots on nitrogen supply lineswith high liquid level alarms or interlocks.This design can prevent contamination ofEO with other chemicals or contaminationof other plant systems with EO.

• Backflow prevention systems at each user. Asingle check valve should not be relied on asthe sole means of preventing inert gas cont-amination.

• Continuous analyzers (for contaminants) oninert systems.

Refrigeration

Refrigerated storage has the following benefits:

• Lower temperatures decrease the rate of EOpolymerization, reducing potential for prod-uct specification problems, and for problemswith tank nozzle plugging, etc. However,lower temperatures reduce the solubility ofEO polymer and may cause the precipita-tion of polymer that has already formed.

• In case of contamination, refrigeration sys-tems can remove all or part of the heat ofreaction. This can allow the reaction to becontrolled. At the minimum, it will allowmore time to implement control or disposalmeasures.

• Lower EO storage temperature allows alower inert gas pressure to maintain thevapor space in the non-decomposableregion.

• Lower temperatures will result in a smallerfraction of EO being vaporized in the eventof a leak. The hazard of a pool of EO liquidmay be mitigated more successfully thanthat of a vapor cloud.

Reference [7] contains a study of the relativerisks of storing EO at moderate temperature andpressure versus low temperature and pressure.

EO storage refrigeration designs can eitherincorporate refrigerated coils within the storagetank or an external heat exchanger and circula-tion pump. Internal coils can offer better heat

removal in the event of an exothermic reactionwithin the storage tank. However, internal coilscan potentially contaminate the storage tank if aleak occurs. Heat transfer fluids such as water orglycols could react with the EO in the tank.External heat exchangers may also contaminatethe tank contents, but the leak can be morereadily isolated.

In practice, storage temperatures range from20°F to 80°F. Operating with temperatures inthe lower end of the range can result in precipi-tation of EO polymer, especially if the EO hadbeen previously stored or transported at highertemperatures.

Emergency Disposal of Tank Contents

An EO storage facility should be designed withprovisions to safely dispose of the inventory inthe event of a contamination reaction. Optionsin current practice include:

• Reacting the EO to glycols or other deriva-tives by feeding to downstream users.

• Depressuring the vessel. This can be to ascrubber, a flare system, or to an elevateddischarge point. This can be a highly effec-tive response, since evaporation of the EOduring this procedure provides an autorefrig-eration effect which cools the vesselcontents.

• Transferring to a holding system, such as a pond, and diluting with water.

EO users must carefully consider the effects ofany of these actions (e.g., venting of EO) onthe health and safety of their workers andcommunities, and on the environment. Theyshould only be taken as part of a well definedemergency response plan.

6.6 Reaction Systems

Consider the following elements in design ofreaction systems:

• Prevention of backflow from reactors intoEO storage.

• Prevention of build up of unreacted EO.

• Prevention of explosive mixtures in reactorvapor space.


6-8

Each of these elements is discussed below, as wellas reactor instrument and control designphilosophy.

Prevention of Backflow from Reactors

Catalysts in widespread use in EO reaction sys-tems, such as KOH, have the capability toinitiate EO polymerization and accelerate otherreactions if they backflow into EO storage.These reactions are exothermic, and can resultin uncontrolled heat release and vessel rupture.Positive backflow prevention must be presentbetween storage and reaction systems (see sec-tion 6.7 “Prevention of Backflow/Contamination”).

Prevention of Buildup of UnreactedEthylene Oxide

Unreacted EO in a reaction system represents aninventory of highly reactive material. The rateof reaction is generally limited by the feed rate ofEO. The presence of higher than design quanti-ties of EO can result in a reaction rate andassociated heat release that exceeds the capabili-ties of the reactor control and safety systems.

An additional hazard occurs if reactor productcontains significant quantities of unreacted EO.This can result in release of EO vapor from prod-uct storage.

To avoid these conditions, the following must becontrolled within design limits:

• EO addition rate

• Mixing of reactants and catalysts

• Concentration of catalyst

• Reaction temperature

Prevention of Flammable Mixtures inReactor Vapor Space

The amount of diluent required to provide anon-flammable mixture in the reactor vaporspace varies with temperature and unreacted EOconcentration. The reactor pressure control sys-tem should be designed to provide adequatediluent pressure to prevent flammable mixturesover the range of reactor operation.

Reactor Design

Consider designing reactor cooling systems withsufficient capacity to remove the heat generatedby an incipient runaway reaction.

Reactor vent capacity should similarly be sizedto control upset conditions.

Reactor Instrumentation & ControlDesign Philosophy

Consider designing reactor control systems tostop 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 (highOR low reactor temperature)

• Loss of utilities

Reactor instrument systems should also bedesigned to give a good temperature profile fordetection of localized reactions.

Process analyzers can be used to continuouslydetermine EO concentration in reactor vaporspace and to stop EO addition when concentra-tions approach the explosive range. Whenprocess analyzers are used as part of a safety sys-tem, adequate maintenance attention must beprovided to maintain high reliability. Analyzercycle time should be considered when relying ona non-continuous analyzer to avoid unsafe con-ditions.

6.7 Piping & Pumps

Piping

One effective element of a safe design is dedicat-ing all appropriate piping systems exclusively toEO service.

Carbon and stainless steels are suitable materials6 -9

for piping in EO service and should meet applic-able ASME and ANSI codes. Stainless steeloffers the advantage of avoiding the potential ofrust formation associated with carbon steel lines.

EO polymerization can be a significant problemin piping because of the relatively high amountof surface area. Stagnant areas in piping systemsenable polymerization to proceed over extendedperiods. Therefore, piping systems should beconstructed to avoid low points and dead spots.Lines should be designed to be as short as possi-ble with gravity drainage to points at whichcontents can be purged from the system withnitrogen. If emptying stagnant EO lines is notfeasible, for example in the case of a long EOcharging line to a batch reactor, a pipe loop thatcirculates back to the storage tank may be con-sidered. Chilled tracing of lines that may sit idlecan also reduce the polymerization potential.

All lines in EO service should beclearly labeled.

Piping in EO service should use welded andflanged construction. Screwed connectionsshould be avoided. The design process shouldminimize the number of flanges. Each flangerepresents a leak potential (including fugitiveemissions). Where flanges are necessary, theyshould be fitted with gasket materials approvedfor EO service.

Liquid EO should not be confined in linesclosed at both ends because heating(atmospheric or otherwise) can result in highliquid pressures, leading to bursting of the linesor joints. If the confining of liquids is unavoid-able, lines may be equipped with relief valveswith provision to capture vented EO and returnit to an appropriate location in the system.

Pumps

As part of the effort to reduce fugitive emissions,practices in the industry are trending away fromthe use of packed pumps and single mechanicalseals. Where packed pumps cannot be avoided,packing material should be non-reactive in con-tact with EO (e.g., flexible graphite). Pumpbodies should be of carbon steel, stainless steelor ductile iron construction. Cast iron is notacceptable.

Centrifugal pumps with double mechanical sealsare in widespread use for EO service. For doubleseal pumps, an important criterion in the selec-tion of a seal fluid should be its relativenon-reactivity in contact with EO. A 50%aqueous solution of ethylene glycol (EG) as wellas pure diethylene glycol (DEG) have been usedsuccessfully.

Magnetic drive pumps and canned motor pumpshave also been successfully used in EO service.Proper specification of magnetic drive pumps isdependent on accurate determination of NPSHrequirements, as these pumps are easily damagedby cavitation. If a sealless pump with a magneticcoupling is used, a strong magnetic filter on thesuction side of the pump is recommended to pre-vent damage from metal particles entrained inthe product stream.

Pumps represent a potential source of ignition offlammable vapors in an EO storage and process-ing area, primarily due to the potential foroverheating. The preferred location for pumps isin curbed areas separate from process or storageareas. In general, good design practice willinclude at least some of the following safeguards:

• Minimum flow shutoff.

• High (absolute) discharge temperature shut-off.

• High temperature delta (across the pump)shutoff.

• A system of detecting and alarming onpump seal leakage.

• Thrust bearing displacement shutoff (mag-netic drive pumps).

• A deluge system, activated manually, byhydrocarbon leak detectors or by high tem-perature.

• Power usage monitors to shutdown pumpson high or low power usage.

• Automatic cooled bypass to pump suctionon high discharge pressure or low flow.

Valves

Selection of valves for EO service should con-sider designs that do not trap EO in the valvecavities where it can subsequently polymerize


6-10

and render the valve inoperative. Valve selec-tion should also consider the effectiveness of thedesign in controlling fugitive emissions.Experience indicates that gate valves, globevalves and high-performance butterfly valvesperform well in EO service. By nature of theirdesign, ball valves and plug valves are subject topolymerization problems.

Prevention of Backflow &Contamination

It is essential to protect against backflow fromthe process to storage. This is typically an instru-mentation system providing tight shutoff on lowpressure differential between downstream usersand storage. Check valves should also beincluded in the system, particularly at pump dis-charges, but exclusive reliance on theirperformance is not recommended. Should acommon EO source feed multiple process units,isolation and backflow protection should be pro-vided between EO storage and each unit andbetween the separate units.

6.8 Handling of Vents & Effluent

Relief Systems

Pressure relief devices should be sized to relievepressure developed by the controlling contin-gency identified for that process. A safetyanalysis of the process must be conducted todefine the characteristics of the controlling con-tingency. However, it should be recognized thatrelief devices are unlikely to provide adequaterelief for such cases as explosive decompositionof EO. Pressure relief valves for storage tanksand for piping where liquid can be trappedshould be sized in accordance with practices rec-ommended by NFPA 58: Storage and Handlingof Liquefied Petroleum Gases.

Industry practice is mixed with regard to therouting of relief valve discharges. Some systemsare designed to vent to atmosphere; others tieinto a relief header system feeding a flare orscrubber. If vented to atmosphere, dischargesfrom pressure relief devices should be designedwith adequate height and discharge velocity toprevent contact of flammable vapor clouds withground level and potential ignition sources.

Automatic addition of steam to the relief valveoutlet piping can improve dispersion and reduceflammability of the EO plume. Relief valve dis-charge piping routed to the atmosphere shouldbe designed to minimize potential for humanexposure.

Design of relief systems in EO liquid or vapor ser-vice should consider the potential for polymerformation and plugging. EO polymer can formin the piping upstream of relief valves, reducingthe valve’s capacity. Methods to protect againstplugging include:

• Use of stainless steel piping.

• Installation of rupture disks or rupture pinsunderneath relief valves.

• Minimization of piping distance (hence thesurface area available to support polymeriza-tion) by fitting relief valves as close aspossible to the equipment they areprotecting.

• Continuous injection of small amounts of nitrogen directly under the relief valve anddirectly after the relief valve if it dischargesinto a header system.

Rupture discs or rupture pins may be useful inminimizing fugitive emissions from relief valves.However, their use as the sole means of pressurerelief is generally not recommended, as they can-not reseat when the pressure excursion hasended.

Vent Scrubbers

Aqueous systems for absorbing EO in processvents are in widespread use in industry. Thesesystems can be designed for very high efficiencyof EO removal. However, the designer of ascrubber system must take into consideration thefact that EO/water mixtures are highly non-idealand use the Raoult’s Law deviation factors givenin Appendix A.

Vent gas is typically fed to a scrubber columnfilled with random packing such as pall rings.EO is absorbed by an aqueous stream runningcountercurrent to the vent gas. Scrubbed gascan be discharged to the atmosphere, subject toenvironmental restrictions.

6 -11

Disposal of absorbed EO in scrubber effluent isthe major design problem. In general, the EO isreacted to glycol. Either strong base or acid isadded to the absorbent stream as a reaction pro-moter. However, acids are more effectivepromoters than bases. Phosphoric acid, sulfuricacid, and caustic soda are commonly used forthis purpose. Hydrochloric acid is not recom-mended due to the potential to formchlorohydrin. If this design practice is followed,extreme care must be exercised to prevent acidor alkali contamination of the process from thescrubber system. (Figure 6.11)

Flares

Several EO producers and users successfully useflares to handle EO containing vents. The mostimportant design consideration is preventingdecomposition flame propagation from the flaretip back into the relief header system. The flaredesigner must also be aware of the fact that con-ventional flame arrestors have generally notbeen tested on EO decomposition flames andshould not be assumed to be an adequate safe-guard against decomposition flame propagation.

Thermal Oxidizers

Thermal oxidizers have been used to control EOemissions from some processes. However, therehave been recent incidents in several thermaloxidizers that control EO emissions, indicatingthat some safety issues in these system designsmay not be fully understood at this time.

Sewer Systems & Waste DisposalFacilities

If EO is drained (or could inadvertently bedrained) to a sewer system, the user should beaware of the potential for EO emissions in thesewer system and treatment facility, and thepotential for accumulation of flammable vaporsin the sewers, lift stations and waste water stor-age tanks. Installation of online analyzers,nitrogen purges and emission control devicesmay warrant consideration.

It has been shown that wastewater containinglow concentrations (less than 1000 ppm) of EOcan be disposed of in biological waste treatmentfacilities after proper acclimation of the system.Section 4.2 contains a discussion of biotreat-ment of Ethylene Oxide. The waste disposalfacility must be licensed to receive EO or other-wise approved by a regulatory agency for thisservice.

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 usedwhere atmospheres contain or may contain EOunder normal or abnormal conditions. Group Cmay be used if conduit seals comply with NECparagraph 501-5(a). Chapter 5 of the NationalElectrical Code [3] deals with hazardous atmos-pheres, classifications, and equipmentrequirements. Additional references for areaclassification can be found in API RP500 [4] andNFPA 497A [2].

Other equipment, such as lighting fixtures, resis-tors, solenoid coils, etc., must have normaloperating surface temperatures that do notexceed the ignition temperature of EO. SeeSection 501 of the National Electrical Code [3]for further details.


6-12

Reactor

Cooler

Makeup

Vent fromProcess

EO VentScrubber

To Atmosphere

Purge

Heater

Figure 6.11 Ethylene Oxide Vent ScrubberSystem

6 -13

Fire Protection Systems

The user should consult NFPA 58, API 2510and 2510A in designing fire protection systemsfor EO storage and processing areas. Systems caninclude passive (insulation) and active(deluge/sprinkler) systems. Areas requiring del-uge protection can be identified using processhazards analysis methods which examine theseverity of the consequences of a fire scenario.

An ample fire water supply should be available.The fire water supply should be sufficient toensure enough water to adequately dilute a spill.Drainage should be designed with a capacity toretain emergency water whether used for cool-ing, fire fighting or dilution purposes. Storageareas should be provided with diversion walls toprevent the possibility of a pool fire underneathvessels.

Leak Detection Systems

Combustible gas detectors are often used inpetrochemical processing plants. However, thelow concentrations of allowable exposure andthe low Reportable Quantity for environmentalreleases make more sensitive leak detectionequipment desirable for EO processes. GasChromatograph-based leak detection systemssensitive to 1 ppm EO are in use both in processplants and laboratories where EO may be pre-sent. These systems generally have multiplefixed sample locations connected to a singleanalyzer.

Sampling Systems

Following are key design issues for samplingsystems:

• The system should allow a representativesample to be caught without releasing EO tothe environment or exposing the samplecollector.

• Purging the sample connection with nitro-gen and depressuring the sample system to avent collection system prior to disconnect-ing the sample cylinder is recommended.

• Dry-disconnect tubing fittings should beconsidered for the connection from the sam-ple tubing to the cylinder.

• The system should prevent overfilling of thesample cylinder with liquid. Overfillingresults in the potential for cylinder overpres-sure from liquid expansion. Typical EOsample cylinders are stainless steel, with aninternal dip tube to prevent overfilling withliquid. The cylinder must be filled whilepositioned vertically with the dip tube at thetop. The cylinders should be designed sothat only the valve with the dip tube can beconnected to the sample system.

• Sample cylinders should be stored underrefrigeration while awaiting analysis andagain after analysis until disposal of any EOremaining in the cylinder.

• Unused EO remaining in the cylindershould be returned to the process if possible,or disposed of in an environmentally soundmanner.

• Potential for personnel exposure to EO dur-ing sample preparation and analysis shouldbe minimized by use of a laboratory hood.

Figure 6.12 EO sampling system.

Personnel Exposure7.1 OSHA Ethylene OxideStandard

The EO standard was published in the FederalRegister on June 22, 1984 and amended onApril 6, 1988. The following is a summary ofits major provisions. The regulation, 29 CFR1910.1047, should be consulted for specificrequirements.

Coverage

The standard applies to all occupational expo-sures to EO. The only exception to thiscoverage is the processing, use, or handling ofproducts containing EO where objective datademonstrate that the product is not capable ofreleasing EO in air above the action level orexcursion level under expected conditions ofprocessing, use or handling. Records of theobjective data must be maintained if theexemption is used.

Exposure Limits

OSHA’s Permissible Exposure Limits or PELs,are the following:

• 1 ppm in air as an 8 hour time weightedaverage (TWA) concentration

• 5 ppm 15 minute excursion limit (EL)

There is also an action level (AL) at 0.5 ppmas an 8 hour TWA, which triggers certaincompliance activities such as exposure moni-toring, medical surveillance and training.

Exposure Monitoring

Initial monitoring is required to determine airconcentration. If concentrations are abovethe action level, periodic monitoring is alsorequired. Additional monitoring may berequired if process changes occur and employ-ees must be notified of monitoring results.

Regulated Areas

Regulated areas mustbe established wher-ever occupationalexposure may exceedthe PEL or EL. Thoseareas must be markedand access limited.Warning signs mustbe posted around reg-ulated areas stating:

Methods of Compliance

EO exposure must be limited through engi-neering and work practice controls wheneverfeasible. Where the PEL is exceeded, a writ-ten program must be established andimplemented to reduce employee exposure.

OSHA recognizes that engineering controlsare generally not feasible for certain activities,including loading and unloading of railcars,vessel cleaning, and maintenance and repairactivities. In cases where engineering controlsare not feasible to prevent exposure above thePEL, NIOSH approved respirators must beworn.

Medical Surveillance Program

The employer must institute a medical sur-veillance program for employees who arepotentially exposed to EO at or above theaction level (without regard to use of respira-tors). Specific requirements for surveillanceand medical record retention are included inthe standard.

Training

Information and training must be provided toany personnel who are potentially exposed toEO at or above the PELs. Topics for trainingare specified in the standard.

Product Exemptions

Products made from EO or containing EO areexempt from the standard if objective datashows they will not release EO at or above theaction level during normal handling or use.

DANGERETHYLENE OXIDECANCER HAZARD ANDREPRODUCTIVE HAZARD;AUTHORIZED PERSONNELONLY; RESPIRATORS ANDPROTECTIVE CLOTHINGMAY BE REQUIRED TO BEWORN IN THIS AREA.

7-1

7-2

Written Emergency Plan

An emergency plan must be developed foreach workplace where there is a possibility ofan emergency. The employer must have ameans of promptly alerting affected employeesof an emergency occurrence.

Recordkeeping

The standard contains requirements for reten-tion of medical and exposure records. Otherprovisions of the standard also contain record-keeping requirements.

7.2 Measuring Exposure

A number of methods are available for moni-toring exposure to EO. Many of these involvethe use of charcoal tubes and sampling pumps,followed by analysis of the samples by gaschromatography. Sensidyne and Draeger mar-ket hand pumps and indicator tube systems,which do not require subsequent analysis,with detection limits in the low ppm range.Portable electrochemical EO detector/alarmsare available from Interscan and Draeger.Dupont and 3M market passive badge-typemonitors for EO exposure.

OSHA has an extensive discussion of avail-able methods for monitoring exposure to EO(29 CFR 1910.1047), including an OSHA-developed method.

7.3 Personal Protective Equipment

Eye Protection

All personnel in areas where EO is handledmust carry chemical goggles. Goggles shouldbe worn at all times in those areas in whichthere is a risk of splashes from liquid EO. Faceshields (visors) provide additional protectionwhen performing any activity which has a liq-uid exposure risk. Contact lenses should notbe worn where contact with EO can occur.

In the case of visor materials, the best EOresistance is provided by fluorinated ethylene-propylene (FEP) - polycarbonate composite.FEP and PVC provide adequate resistance.

Protective Clothing

Many materials in common use are permeableto or attacked by EO. Any materials proposedfor use in protective equipment that are notknown to be EO resistant, should first betested to establish their suitability. EO perme-ation data for clothing and glove materials areprovided in Tables 7.1 and 7.2.

Permeation test data showed the followingequipment provides adequate protection inEO service:

Suit: Kappler ®1 Responder and Responder Plus, DuPont Barricade,TYCHEM 9400 and 10,000. In cases wherethere is concern of a flashfire, consider using aKappler ®1 Responder withaluminized fiberglass orPBI/Kevlar overcover.

Gloves: Safety 4-HNorth B-131Butyl RubberSilver Shield®

Pioneer A-15 nitrile rubber

Boots: Butyl RubberChlorinated Polyethylene

1. Registered U.S. Trademark of Kappler Europe Ltd.

Previously, Chemrel Max was a recommendedsuit. However, it is no longer manufactured.

Other factors to consider in the selection ofprotective clothing are durability, dexterity,heat/cold resistance and whether disposable orreusable clothing is preferred. If there ispotential for a flash fire, this factor should beconsidered in the selection process. Either aflash oversuit or an EO resistant suit incorpo-rating flash protection should be considered.

PVC, nitrile rubber, neoprene, and Viton arepermeated rapidly on contact with EO. EOand aqueous mixtures permeate leather.Clothing subjected to EO contamination

7-3

must either be discarded or decontaminatedbefore re-using. Clothing must be discarded ifit has been degraded or has absorbed EO.Leatherwear contaminated with liquid EOmust be discarded because decontamination isnot practical.

Potential for EO exposure

When there is potential for exposure to EOvapors or liquid, it is important to use theproper protective clothing. EO can betrapped against the skin and can cause severechemical blistering and burns, which take along time to heal. When released, EO liquidwill quickly change to vapor. If protectiveclothing with open sleeves and legs is worn,this vapor can readily get underneath theclothing, resulting in burns. EO can alsopenetrate protective clothing seams so it isimportant to consider suit constructionas well.

Even dilute EO solutions can result in severechemical burns if the skin remains exposed tothe solution. Figure 7.1 is a chemical burnresulting from 1.5 hours exposure to dilute EO-water mixture absorbed into leather shoes.

Respiratory Protection

If the presence of EO in excess of exposurelimits is expected or detected, respiratory pro-tection consisting of a NIOSH approvedrespirator must be used. OSHA regulation 29CFR 1910.1047 provides the following mini-mum standards for respiratory protection forairborne EO:

Airborne EO Minimum Required (PPM) Respirator Type

Less than (A) Full facepiece withor equal to EO approved canister,50 ppm front or back mounted.

Less than or (A) Positive-pressureequal to supplied air equipped2,000 ppm with full facepiece, hood

or helmet, or(B) Continuous-flow sup-plied air (positive pres-sure) equipped with hood, helmet or suit.

Above 2,000 (A) Positive-pressure selfppm or contained breathing appa-unknown (e.g., ratus (SCBA), equippedemergencies) with full facepiece,

or(B) Positive-pressure full facepiece supplied air res-pirator equipped with an auxiliary positive-pressure self-contained breathing apparatus.

Firefighting Positive-pressure self-contained breathing apparatus (SCBA), equipped with full face-piece.

Escape Any respirator described above.

Personnel Exposure

Figure 7.1 Chemical burn resulting from lowconcentration of EO in water.

* NS - Not specified in test data.

NOTE: Breakthrough times are reported from data found in vendor and other databases. Some materials havebeen tested more than once as indicated by multiple results. Formulation of clothing materials maychange, impacting break through times. Contact the supplier for specific product information or currentinformation on the testing of their products.

Table 7.1 EO Permeation Test Data for Clothing

7-4

CLOTHING MATERIALChemFab Challenger 5100ChemFab Challenger 5200DuPont BarricadeDuPont BarricadeDuPont Saranex R-23DuPont TYCHEM 10,000DuPont TYCHEM 10,000DuPont TYCHEM 7500DuPont TYCHEM 9400DuPont TYCHEM 9400DuPont TYCHEM SLDuPont TYVEK QCDuPont TYVEK-Polyethylenecoated Fairprene NeopreneILC Dover Cloropel CPEILC Dover PolyurethaneKappler CPEKappler CPF-3Kappler CPF-4Kappler Life-Guard Butyl Kappler ResponderKappler ResponderKappler Responder PlusKappler Responder PlusMar-Mac Ultra-Pro CommanderMSA BETEX Butyl/NeoprenePioneer N-44 NeopreneWheeler Acid King ButylWheeler Acid King PVCWheeler Acid King Teflon

VAPOR/LIQUIDNS*NS

LiquidVapor

NSLiquidVaporLiquidLiquidVaporVaporVapor

NS

NSNSNS

VaporVaporVapor

NSLiquidVaporLiquidVaporVapor

NSNSNSNSNS

BREAKTHROUGH TIME, minutes>950

31, 44, 64, 66>480>480

55, 6, 121, >400>480>48053

>480>480

immediateimmediate

<1

51, 158118, 37529, 65

80>480>480

44, 48, 52>180>480>180>480>18016531

55, 85, 40044, 13, 31

71

GLOVE MATERIALAnsell-Edmont 4HBest 65NFW Natural RubberBest 6780 NeopreneBest 878 ButylBest 890 VitonBest Hustler 725R PVCBest Nitri-Solve 727 NitrileBest Ultraflex 22R NitrileBest Ultraflex 32 NeopreneDayton Natural Rubber SurgicalNorth B-131 ButylNorth Silver ShieldPioneer A-14 NitrilePioneer A-15 NitrilePioneer N-44 Neoprene

VAPOR/LIQUIDVaporVaporVaporVaporVaporVaporVaporVaporVaporNS*

VaporVapor

NSNSNS

Table 7.2 EO Permeation Test Data for Gloves

* NS - Not specified in test data.

NOTE: Breakthrough times are reported from data found in vendor and other databases. Some materials havebeen 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 informationon the testing of their products.

BREAKTHROUGH TIME, minutes>240

12118948117127

3, 5>480>48032

195, >31531

Personnel Exposure

7-5

Equipment Preparationand Maintenance

8-1

8.1 Preparation for Inspection orMaintenance

General

When equipment in EO service must beopened for testing, inspection, or repairs, allprecautions applicable to equipment handlingof flammable liquids and gases must beobserved. All EO must be removed from thesystem and disposed of in accordance with fed-eral, state and local regulations.

Contaminants such as oxygen, water, andcleaning chemicals must be completely elimi-nated before equipment is placed in orreturned to EO service.

Preparations for Entry

The user should follow the requirements of theOSHA confined space standard (29 CFR1910.146). Equipment should be cleaned andpurged of EO before beginning any mainte-nance work. If it is impractical to reduceairborne concentrations in and around theequipment below 1 ppm, appropriate personalprotective equipment should be worn. Allmaintenance work on EO equipment shouldincorporate a safe work plan to ensure that allpersonnel understand the hazards involved,that proper personal protective equipment isutilized, that applicable safety precautions areobserved in each work task and that other mea-sures appropriate to working with EO areobserved.

Equipment being worked on must be thor-oughly drained and blown free of liquid EOwith nitrogen. The equipment is then washedwith cool water and drained. Care should betaken that hydrates are not formed during thisprocess, since the melting points of such mate-rials can be as high as 52°F (see Table 2.2, insection 2). Rinse water should be disposed ofin a safe and environmentally responsible man-ner. It should be noted that even dilutesolutions of EO in rinse water have causedsevere chemical burns (see section 7). Steampurging or hot water washing may be furtherrequired to remove EO polymer.

Prior to entry, the equipment must be isolated

from the process and from any potential hazardsource. Equipment atmosphere must be testedfor EO and proven safe to enter.

Persons entering equipment, vessels or anyconfined space which has been in EO servicemust be equipped with appropriate respiratoryprotection (see section 7.3), unless it is demon-strated that the atmosphere inside theequipment, vessel or confined space is withouthazard and will remain so during the time peo-ple are inside.

Special Problems with Ethylene OxidePolymer

In systems storing pure EO, it is common forpolymer to form and to accumulate gradually,especially where the EO is relatively stagnant.Polymer can retain EO after washing, which itcan gradually release even after the equipmentinitially tests free of EO. After the initial purg-ing and rinsing steps, good practice is to waitseveral hours and retest prior to opening up tothe atmosphere.

Low molecular weight polymer can generallybe removed by steaming or washing with hotwater. Because hot water and steam would bereactive with EO, the user must assure that freeEO has been removed before using hot wateror steam on equipment.

High molecular weight polymer must generallybe removed by physical means, such as highpressure water blasting.

If polymer is present and time limitations orother circumstances prevent warm watercleanup, appropriate protection must be pro-vided for personnel engaged in opening orentering the vessel.

Polymer residues are both flammable and ahealth hazard. They must be completelyremoved and the equipment certified as beingfree from all flammable residues and safe for theintended work before undertaking hot work.

Mothballing

Equipment which has been in EO service, butis being removed from service should be decon-

8-2

taminated by washing or steam cleaning to lessthan 1 ppm of EO. Such equipment should bemaintained under a nitrogen blanket and dis-connected or blinded from “live” equipment.

8.2 Preparation of InternalSurfaces

Foreign material on internal surfaces causes slowself-polymerization of EO with an attendantbuildup of the polymerized material on thosesurfaces. This self-polymerization can be mini-mized by removing foreign matter such aswelding slag, loose debris and rust on internalsurfaces prior to putting them in service.

Cleaning can be accomplished by shot or gritblasting, or by chemical methods. Shot blastingcreates dust and debris which must be removed.Where equipment surfaces, such as pipework,are inaccessible to blast cleaning, chemicalmethods may be required.

Chemical cleaning involves the use of hazardousmaterials and can cause damage to equipment ifnot properly specified and performed. The use ofa qualified contractor is advisable. A variety ofchemical cleaning processes are available forpreparing metal surfaces for EO service depend-ing on what surface contaminants are present,including:

• Alkaline or detergent degreasing, followedby thorough rinsing.

• Acid cleaning, if the metal is carbon steel. Ifboth carbon and stainless steel are present,engineering advice should be obtainedbefore acid cleaning. Rinse thoroughlyafterwards.

Common acid cleaning uses EDTA or citricacid. It may or may not be preceded by adegreasing step. If the system contains mildsteel, a neutralization and passivation should beperformed. Sodium nitrite is typically used forpassivation. The system must be flushed cleanand dried by blowing with dry, hot nitrogen.Equipment should be left under nitrogen pres-sure until ready to receive EO. Failure toadequately passivate or to keep material undernitrogen blanket will result in significant rustformation.

Caution:It is extremely important to remove allresidues of cleaning chemicals, as EO mayreact violently with them when the equip-ment is put in EO service.

The effectiveness of a given chemical cleaningprocedure or the possibility of problems shouldbe evaluated using a test sample of the samemetal as the surfaces to be cleaned.

8.3 Leak Repair Clamps

Clamp-on or bolt-on, split body style leak repairclamps have been used for temporary mitigationof small ethylene oxide leaks from piping, valvesand vessels. These leak repair clamps can beeither purchased as “off-the-shelf” clamps orengineered to fit, depending on the application.The user must evaluate the risk of using clamps.Many common sealants are not suitable for use inEO service, and all sealants should be tested formaterial compatibility and durability prior to use.

As with any moving stem valve, valves in ethyl-ene oxide service may experience fugitiveemissions leaks. Ethylene oxide valve packingglands should not be on-line repaired using thedrill-and-inject method due to the localized fric-tional heat generated during the drilling on thevalve body.

8.4 Preventive Maintenance

Equipment containing ethylene oxide should beon a routine preventive maintenance programto insure proper operability. Internal inspectionsshould focus on monitoring equipment integrityand detecting polymer formation. No flow orlow flow zones in a piping network and smallbore instrumentation tubing have the potentialfor polymer buildup and should be included inthe inspection program. Nozzles for instrumen-tation and inlets to pressure relief valves areareas that should also be inspected on a routinefrequency.

Special considerations should be made for purg-ing spare and offline piping and equipment toprevent polymer formation.

Equipment Preparationand Maintenance

9-1

9.1 Regulations

EO is classified by the United StatesDepartment of Transportation (DOT) as aprimary poison gas hazard with a subsidiaryhazard of being a flammable gas, and must beplacarded accordingly. Further, it carries thematerials poisonous by inhalation (PIH) des-ignation by the DOT.

All persons offering a loaded or empty railcarfor transportation must meet the generalawareness and familiarization as well as func-tion specific training requirements, asspecified in 49 CFR 172.704.

Special attention must be paid to the pressur-ization of empty railcars for return to theshipper. The objective is to maintain a non-flammable vapor phase, as specified by DOTRegulation CFR 49, Section 173.323(f), evenif the car heats up to 105°F. Reference shouldbe made to the special railcar pressurizationcriteria supplied by the shipper. For a givenunloading temperature, these criteria allowfor the extra nitrogen that is required forsafety over the entire range up to 105°F.

See also section 11, “Regulations Applicableto Ethylene Oxide”.

9.2 Railcars

Design

EO tank cars are designed to make thetransportation and handling of the materialsafe and easy.

The DOT requires that EO be transported inDOT class 105-J tank cars. All tank cars usedin EO service must have a tank test pressure

40' - 11" Truck Centers51' - 10" Over Strikers

54' - 5 1/2" Coupled Length

Center Lineof Angle Valve

13' - 11"

13' - 11/4"Top of Grating

2' - 101/2"

4" Glass Wool Insulation Compressed to 31/2" and0.65" (Ceramic Fiber) Thermal Protection

Gauging Device, Safety Valve, 3/4" Thermometer Well3 - 2" Angle Valves & 1/4" Sample Line Angle Value

116"Inside Dia.

1/2" Jacket Head

9/16" Tank Head

9/16" Tank

A–End B–End

Figure 9.1 DOT 105-J railcar for transporting Ethylene Oxide

Transportation & Unloading Operations

10'- 5"Over Grabs

B-End

15'- 4 15/16"

of at least 300 psi by July 1, 2006 at the latest.Most EO tank cars in service already meet thisrequirement. DOT also requires EO tank carshave a reclosing pressure relief device set tofunction at 75 psig. These requirements arespecified in 49 CFR 173.323.

DOT class 105-J tank cars meeting therequired 300 psi tank test pressure are con-structed from fusion welded carbon steel with9⁄16" minimum plate thickness, and must havean approved thermal protection system. Atypical thermal protection system consists of0.65" of ceramic fiber surrounding the tankshell, with 4" of glasswool fiberglass insulationcompressed to 31⁄2" by an outer metal jacket.The outer metal jacket is 11 gauge (about 1⁄8")

carbon steel, except at the ends of the carwhere tank puncture protection is provided by1⁄2" head shields.

An EO tank car is designed for loading andunloading from the top only with no bottomfittings. The potential for leakage from dam-aged tank fittings is greatly reduced in atransportation incident when protected topfittings and no bottom fittings are used.

EO in a tank car must always be kept under anatmosphere of an inert oxygen free gas. Drynitrogen is typically used. No air should beallowed to enter tank cars in EO service.

9-2

Figure 9.2 Dome arrangement of a class DOT 105-J railcar for Ethylene Oxide service


Liquid ValveMagnetic Gauging Device

Vapor Valve Thermowell

Safety Valve

Liquid Valve

Excess Flow Check Valves

EO tanks are equipped with float type excessflow check valves below the liquid load/unload valves and the vapor valves. This is asafety precaution as the excess flow checkvalves are designed to shut off the flow of liq-uid or vapor if these valves are sheared off in aderailment.

Caution:Carbon dioxide is more than ten times assoluble in EO as nitrogen and is not suitablefor blanketing or purging railcars or otherequipment containing EO.

An EO railcar (Type DOT 105-J) is equippedwith two eduction pipes/unloading connec-tions, one vent for loading or vapor connection,a gauging device, a reclosing pressure reliefdevice (safety valve), and a thermometer well(thermowell).

If a liquid or vapor valve is opened toorapidly, the excess flow check valve immedi-ately closes, cutting off the flow of liquid orvapor. If the liquid excess flow check valveshould happen to close while unloading atless than 120 gpm, there may be a restrictionsuch as polymer in the line creating a higherthan design pressure differential. If the excessflow check valve closes, the pressure needs tobe equalized to drop the float back down.Equalizing the pressure can be done by closingthe load/unload valve on the liquid line.

Be aware that the vapor line excess flowcheck valve can close if the car is depressuriz-ing too rapidly. If the excess flow check valvecloses, a false reading of railcar pressure canoccur, as pressure is measured in the linedownstream of the car loading/unloadingvalve.

The railcar could be mistakenly over-pres-sured and lift the pressure relief device set at75 psig. Again, by closing the load/unloadvalve the pressure can equalize on both sidesof the excess flow check valve and gravityshould drop the float back into position. Inextremely unusual circumstances, the float

can get stuck closed if there is EO polymerpresent in the vent line. Nitrogen pressuremay have to be supplied on the down streamside to force the valve back down.

In all cases, problems such as malfunctioningequipment, running gear or loading appli-ances should be reported to the EO supplier.Other than emergencies, repairs should onlybe done with supplier approval, to ensurematerial quality, equipment function anddesign requirements are maintained.Emergency repairs should be reported to thesupplier before putting the car intransportation.

9.3 Preparation for Unloading• The user should develop and provide to

unloading personnel a detailed procedureand checklist specifying each step of theunloading operation and the precautionsto be observed.

• An operator unloading log should be keptto record key information (temperature,pressure, etc.).

• The receiver of EO railcars should moni-tor temperature. The presence of higherthan normal temperature may indicatethe presence of contamination and thepotential for reaction in the railcar.Section 5.2 discusses hazards of contami-nation. Section 10 discusses emergencyresponse.

• Railcar numbers and the seal numbers onthe dome of each car should be recordedin the log.

• The DOT car specification number onthe car must be 105-J100W or 105-J300W. “Ethylene Oxide” and“Inhalation Hazard” must be stenciled onopposing sides of the railcar.

• Check the dome to assure that the seal isintact. If it is not intact, contact the rail-road and the EO supplier.

9-3

• Before breaking the dome seal or initiat-ing any testing or unloading action thefollowing precautions are suggested:

– Keep in mind that EO is highly reactive.

– The unloading area should be well-ventilated and free of sources of ignition.

– OSHA requires that exposures notexceed either 1 ppm averaged for an 8hour period or 5 ppm over a 15 minuteperiod (excursion level).

– Use appropriate respiratory protection(Section 7.3) when making/breakingconnections, and during EO productsampling.

– Know where safety showers and eyewash facilities are located in the railcarunloading area.

– Know the location, in the unloadingarea, of fire fighting equipment (extin-guishers, fire monitors, hose reels, delugesystems) 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 derail mechanism to prevent collisions with other cars.

• Set the hand brake.

• Chock the car front and back of at least one wheel.

9-5

9-6

• Ground the railcar on its bolster or on the top working area.

• Break the railcar seal.


9-7

• 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.

9-8

• Measure and record the outage level using the car’s magnetic gauge rod.

• 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 connectionson EO railcars.

Figure 9.4 Canister mask withEO specific canister

Figure 9.5 Positive pressure, “hose-line” type respirator


9-9

• Remove plugs in both vapor and liquid lines.

9.4 Unloading

Figure 9.6 Steps for unloading Ethylene Oxide

• 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.

• 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.


9-10

• Nitrogen should be attached to the vaporline to allow maintenance of the railcar nitrogen pad.

9-11

• 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 pres-sures 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.


9-12

• If sampling is part of your procedure, sample and obtain laboratory verifi-cation before unloading the railcar. The sample cylinder should begrounded to prevent static sparks.

Polymer has a tendency to build up in the railcar sampling line in carsequipped with a sampling valve. Sampling from the offloading linereduces potential for plugging.

• The excess flow check device consists of a float that becomes buoyant athigh flow. Once closed, the excess flow check valve will not reopenuntil the pressure differential on both sides of the valve is equalized.Remember that the car pressure monitor is downstream of the vaporcheck valve and therefore will not read car pressure if the check valveis closed.

It is important to note that emptying a tank or a shipping container of liq-uid EO does not remove the danger of vapor decomposition. In fact, anempty vessel can be more dangerous than one filled with liquid. As long asEO vapor remains in a vessel, full inert gas storage pressure must bemaintained.

• When all EO is unloaded, blow the lines to storage until the tank indi-cates nitrogen flow. Use nitrogen to raise the car pressure to the levelrequired for a non-combustible atmosphere as recommended by yourEO 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 environ-mentally sound manner.

• Disconnect all lines and remove valve extensions.

9-13

• Replace all plugs. Magnetic gauge andthermowell caps should be hand tight-ened. Others should be wrench-tightto prevent leaks.

• Close the dome cover and install andsecure the locking pin.

• If placards are faded or torn, replace.

• Disconnect ground wires.

• Remove chocks, derails, and signs.

9.5 Shipping Data

9.6 Transportation Emergencies

In case of an emergency involving an EOrailcar, contact the emergency assistancenumbers provided in the shipper’s MaterialSafety Data Sheet (MSDS).

Density Vapor Pressure(lb/gal) (psia)

20OF 7.59 7.1

40OF 7.47 11.6

60OF 7.34 18.0

80OF 7.21 26.9

100OF 7.08 39.1

105OF 7.05 42.7

For additional assistance orinformation call: CHEMTREC at(800)424-9300 or (202)483-7616.

10.1 Overview

Every emergency situation will be different,and it is not the intent of this publication toprovide recommendations for every situation.This section will cover the unique hazards ofEO as they apply to emergency situations andfor specific emergency situations such as fire,air release, etc. When preparing your emer-gency procedures for handling EO, the MSDSprovided by your EO supplier should bereviewed thoroughly.

Emergency responders must be properly trainedand equipped per OSHA standards on emer-gency response and emergency fire protection(29 CFR 1910.38, 1910.120 and Subpart L).The first priority in responding to an emer-gency situation is the safety of the emergencyresponders, employees, and people in the sur-rounding community. The second priority is todetermine the incident’s impact on the sur-rounding equipment, environment andproperty, and to set a strategy to stabilize thesituation and minimize the impact. The thirdpriority is the conservation or protection ofproperty and the environment.

Downwind evacuation should be considered ifEO is leaking but not on fire. For large spills,DOT recommends evacuating in all direc-tions at least 400 ft. DOT furtherrecommends evacuation of downwind areasto at least 0.2 miles (day) and 0.6 miles(night). In case of small spills, evacuation ofdownwind 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 con-sider initial evacuation for one mile in alldirections. If the fire is prolonged or uncon-trollable, or if a container is exposed to directflame, evacuation for one mile in all direc-tions for protection from flying debris if thecontainer should rupture violently. (1996North American Emergency Response Guidebook)

10.2 Potential Hazards

Health Hazards

• Liquid EO and EO/water solutions

— Are extremely irritating to skinand eyes

— Can cause blistering and severe damage

— Easily penetrate cloth, leather and sometypes of rubber. Leather cannot bedecontaminated.

• EO vapor can be absorbed by wet or sweatyskin, with potential for serious chemicalburns.

• Odor thresholds are much greater thanpermissible exposure limits; overexposureoccurs 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 sys-tem include drowsiness, nausea,convulsions and limb weakness

• IARC (International Agency for Researchon Cancer) classifies EO as class 1 – car-cinogenic to humans (IARC 1994).

• Water contaminated with EO evolves EOvapor and can be a source of exposure.

See also section 3, “Health Effects of EthyleneOxide”, and section 7, “Personnel Exposure”.

Fire Hazards

• Volatile flammable liquid with heavierthan air vapors that may travel consider-able distance to a source of ignition.

• Lower Flammable Limit: 2.6%. UpperFlammable Limit: 100%

• Fire impingement on EO-containingequipment can result in container failureand/or explosive decomposition.

• Combustion products are irritating andconsidered hazardous.

Emergency Response

10-1

• Water/EO mixtures can support combus-tion if water/EO ratio is less than 22:1(open areas).

• In closed systems such as sewers, water/ EOmixtures can potentially flash at dilutionratios up to 100:1.

See also section 2, “Properties of EO”.

Hazards of Contamination

• Reacts with water, evolving heat. Inclosed containers, reaction may be selfaccelerating, resulting in container rupture.

• Contamination with acidic or basic materi-als accelerates reactions with water.

• Contamination of pure EO with acidic, orbasic materials; metal oxides, metal chlo-rides, or active catalyst surfaces may causeexplosive polymerization.

• May polymerize violently in container ifexposed to heat.

10.3 Fire Response

Extinguishing Materials

• Carbon dioxide – small fires only

• Dry chemical – small fires only

• Alcohol foam

• Water spray

Extinguishing Techniques

• Stay upwind.

• Avoid physical contact.

• Wear self-contained breathing apparatus(SCBA) and appropriate protective cloth-ing. Wear full chemical protective suit ifcontact with material is anticipated.

• For a large fire in a storage area, useunmanned hose holders or monitor nozzles.

• Withdraw immediately in case of ventingsafety device or discoloration of tank.

• Keep fire-exposed containers and nearbyequipment cooled using water spray.Minimum 500 gpm/point of flameimpingement.

• The addition of warm (above 51°F) waterto pools of liquid ethylene oxide may tem-porarily increase vapor evolution.

If there is potential for container rupture,runaway internal reaction, or heat impinge-ment causing explosive decomposition,consider evacuation for one mile according toDOT recommendations.

Should a Fire be Extinguished?

Fire impingement on EO-containing equip-ment can result in explosive decomposition.Because of this, a responder should stronglyconsider extinguishing a fire if there is poten-tial for flame impingement on EO-containingequipment, even if the source of hydrocarbonfeeding the fire has not been stopped.

10.4 Spill Response

General Information

• Proceed with caution.

• Restrict access to spill area.

• Keep unprotected personnel upwind ofspill.

• Avoid contact with spilled product.

• Wear SCBA and a full chemical protectivesuit.

• Eliminate ignition sources.

• Prevent liquid EO and contaminatedrunoff water from entering sewers and con-fined spaces.

• Notify proper authorities as required byregulations.

10-2

• If spill has the potential of entering awaterway, notify downstream users ofpotentially contaminated water.

• Prevent intake of contaminated water intoboilers or industrial process equipment.

• Use only equipment approved for flamma-ble atmosphere in the vicinity of an EOspill.

• Be cognizant of the extremely volatile,flammable, and heavier than air nature ofEO while planning the response.

Air Release

Techniques for responding to releases to theatmosphere include:

• Evacuate local and downwind areas as con-ditions warrant to prevent exposure ofpersonnel and to allow vapor to dissipate.

• Knock down vapor with water fog or spray.Water fog or spray applied to EO vapors orfumes will absorb a substantial amount ofEO.

• Alcohol foam applied to the surface of liq-uid pools may slow the release of EOvapors into the atmosphere.

• When using water spray, small quantitiesare likely to make conditions worsebecause of acceleration of vaporization.Large quantities of water are necessary toeffectively knock down EO vapor anddilute spills.

10.5 Contamination Response

• Dispose of contaminated material asquickly as possible by feeding to down-stream users.

• Reduce reaction rate by venting to a safelocation (venting results in auto-refrigera-tion of the contained EO).

• Drain contaminated material to a holdingpond or tank and dilute with water.

• Slow temperature rise by removing heatsuch as with a sprinkler system, coolingcoils 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 emergencyresponse, the user should be aware of thefollowing:

• Water can be useful for extinguishing EOfires and cooling equipment subject to fireimpingement.

• EO and water are completely soluble ineach other, and a water spray can be usefulin knocking down EO vapors. However, awater spray directed on a pool of liquid EOwill increase evolution of EO vapors untilsignificant mixing and dilution of the liq-uid EO have occurred.

• Water/EO mixtures of less than 22:1 ratio can support combustion in open areas. Inclosed systems such as sewers, water/EOdilution ratios up to 100:1 are required toeliminate combustion potential.

From the above it can be concluded that themaximum amount of water available should beapplied to an EO release.

EO also reacts with water. At ambient condi-tions, the EO/water reaction occurs over daysand months. The responder should not hesi-tate to apply water in situations where EO hasbeen released to the environment, since thehazard of fire and personal exposure is far moresignificant than the potential for an EO/ waterreaction.

In a closed container, however, the heat releasefrom the EO/water reaction can build up thetemperature, leading to an accelerating or“runaway” reaction and loss of containment.This potential exists unless the EO in the con-tainer can be rapidly purged out or diluted to afew percent weight.

Emergency Response

10-3

11.1 Summary

The following federal regulations are directedtowards users and producers of EO and werefound by doing a scan of the Index to ChemicalRegulations. The scan was done by specificallylooking for federal regulations that mentionedor referenced ethylene oxide. This list is notrepresented as inclusive of all federal regula-tions that apply to manufacturing andhandling EO. The list specifically does notinclude:

• Federal regulations promulgated after the date of the scan.

• State and local regulations.

The reader is also advised that there arenumerous regulations that may impact EOoperations that do not specifically mentionEO and may not have been picked up bythe scan.

11.2 Regulations — Numericalwith Subject Listed

Commerce (Foreign Trade)15 CFR 799 Commodity control list for

foreign trade (polymers).

Labor – OSHA29 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 marineterminal activities and con-struction work.

.119 — Applies process safety to facilities with EO in excess of the threshold planning quantity (5,000 lbs.). Elementsof PSM program includeemployee participation; gener-ation of process safety informa-tion; process hazards analysis; generation, review and update

of operating procedures; train-ing; 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 poweredindustrial trucks in hazardous atmospheres; practically requiresa permit system covering use ofthese vehicles in an EO plant; ((c) (2) OSHA 31:6505) industrial trucks in atmospherescontaining hazardous concen-trations.

.1000 — Removes EO exposurescenarios from this general sec-tion on air contaminants and references them to 1910.1047.

.1047 — (A) Specific regulation covering

all exposure scenarios to EO except those below the action level (still requires retention of objective data for exempted operations).

(B) Establishes action level of 0.5 ppm, 8 hour time weightedaverage.

(C) Establishes permissible exposure limits of 1 ppm, 8 hourtime weighted average and 5 ppm excursion limit (15 minute average).

(D) Requirements for exposure monitoring including initial, periodic and termination sam-ples; periodic sampling requiredevery 3 or 6 months dependingon exposure levels. Also includesmonitoring accuracy and notification of employee requirements.

(E) Requires establishment of regulated areas where EO con-centrations exceed 8 hour TWAor excursion limit.

Regulations

11-1

(F) Delineates methods of compliance with exposure requirements including engi-neering controls (preferred) and personal protective equip-ment. Also requires a written compliance program, emergencyplan, leak detection surveys with annual review and updates.

(G) Outlines approved respira-tory protection, protective clothing and equipment.

(H) Requires written emergency response plan and employeealerting procedures.

(I) Outlines mandated medical surveillance plan; required forall employees exposed at or above the action level (0.5 ppm) for 30 days or more per year, without regard to respira-tory 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 overexpo-sure exist or when the employeerequests medical advice con-cerning the effects of current or past exposure on reproduc-tive capabilities.

(J) EO hazards communication program requirements includ-ing signs at demarcation zone, labels on containers, MSDS onsite and employee training programs (annual).

(K) Recordkeeping requirements including objective data to sup-port exempted operations, exposure measurements (30 year retention) and medicalsurveillance records (duration of employment plus 30 years retention).

(L) Permits employee or designatedrepresentative observation of

monitoring activities.

Appendices A, B, C and D cover non-manda-tory samples of MSDS, substance technicalguidelines, medical surveillance guidelines andsampling 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 to1910.119 but applies to theconstruction 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 explo-

sives or other dangerous car-goes 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 mini-mum requirements for guards, smoking prohibitions, hot work controls, vehicle con-trols, electrical installations, on-site emergency equipment, storage requirements and operating procedures.

33 CFR 127 USCG — Hazardous materialsTransportation Final Regulation

.1209 — Respiratory protec-tion. Each waterfront facility handling LNG must provide equipment for respiratory pro-

11-2

Regulations

11-3

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

33 CFR 154 USCG — Facilities transferringoil or hazardous materials in bulk.

.0 — Requirements for facilities including operations manual and procedures, equip-ment specifications, vapor control systems, standard spec-ifications for tank vent flame arrestors and detonation flame arrestors.

33 CFR 160 USCG — Ports and Waterways Safety

.203(E) — Requires notifi-cation of USCG for arrivals, departures, dock shifts and hazardous conditions of vessels carrying EO. May be waived by USCG.

Environmental Protection Agency42 USC 7412 Clean Air Act

Section 112 — National Emission Standards for Hazardous Air Pollutants list ofpollutants section 112b lists EO.

40 CFR 52 Illinois state implementation plan (additional requirements).

.741 App. A — Required con-trol strategies for Cook, DuPage,Kane, Lake, McHenry and Will counties. Covers EO as “miscellaneous organic chemi-cal manufacturing process”. Mandates additional control strategies, record keeping, report-

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.

40 CFR 60 Standards of performance for new stationary sources cover-ing VOC emissions from SOCMI air oxidation processes,equipment leaks, distillation operations.

.489 Subpart VV (SOCMI equipment leaks) — Requiredinspection program, correc-tive 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, mon-itoring, reporting and record keeping.

.667 Subpart NNN (SOCMI Distillation Operations) — required control strategies, emissions limitations, moni-toring, reporting and record-keeping.

40 CFR 61 National emissions standards for hazardous air pollutants (NESHAP).

.340 — Producers that manu-facture EO by cracking hydro-carbons are subject to this bezene-in-wastewater NESHAP because benzene is aby-product of the process and appears in certain wastewaters.Control requirements are spec-ified for drains, conveyances, and treatment steps.

40 CFR 63 Maximum Achievable Control Technology (MACT)

for certain listed Hazardous Air Pollutants (HAP) includ-ing EO and other HAP that are present in EO manufactur-ing 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.

40 CFR 68 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.

40 CFR 180 Pesticide residue tolerances on agricultural commodities.

40 CFR 185 Pesticide residue tolerances in food products.

40 CFR 261 Identification as hazardous waste/inclusion on hazardous constituents list.

.33(F) — Classifies as a haz-ardous/toxic waste any discardedcommercial chemical product off-spec species, spill or con-tainer residues. Does not applyto process waste streams (although SOCMI HON would). EO is designated as “U115” (U list waste).

App. VIII — Hazardous con-stituents list (relates to 261.33 above).

40 CFR 266 Management of specific haz-ardous wastes including where burned for energy recovery andburned in boilers and indus-trial furnaces.

App. V — Risk specific dosages.

App. VII — Health based lim-its/residue concentration limits = 3 x 10-4 mg/kg.

40 CFR 268 Land disposal restrictions including technology based treatment standards and maxi-mum 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/elec-trolytic oxidation followed by carbon absorption or incinera-tion (2) Non-wastewaters —chemical/electrolytic oxidationor 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 haz-ardous substance underCERCLA section 102(A)with a final reportable quan-tity 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 emer-gency 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 toknow program components applicable to EO plants. Requires certain recordkeeping,reporting thresholds and schedules and notification to

11-4

Regulations

buyer of EO of product infor-mation and hazards.

.65 — Superfund, emergency planning.

40 CFR 414 Effluent guidelines and standardsfor organic chemicals, plastics and synthetic fibers.

.60(A) — Regulates effluent from EO plants under Subpart F (commodity organic chemi-cals). Requires use of BPC (best practical control tech-nology) and mandates maximumeffluent levels for BOD (bio-logical oxygen demand), TSS (total suspended solids) and pH for existing and new plants.

Transportation –U.S. Coast Guard (Shipping)46 CFR 40 USCG — Special carriage

requirements for EO transport on vessels.

.05 — EO specific requirementsfor bulk shipment.

46 CFR 150 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.

46 CFR 151 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, trans-fer operations procedures, emergency equipment, special requirements, environmental controls, electrical installation and inspection periods.

.05 — Bulk shipment minimumrequirements.

46 CFR 153 Subchapter 0 — Certain bulk dangerous cargoes — Ships carrying bulk liquid/liquefied gas or compressed gas hazardousmaterials.

.0 — Includes requirements forconstruction, ventilation, equipment, operations, cargo segregation, tank types, trans-fer operations procedures, emergency equipment, special requirements, environmental controls, electrical installation and inspection periods.

46 CFR 154 Subchapter 0 — Certain bulk dangerous cargoes safety stan-dards for self-propelled vessels carrying bulk liquefied gases.

.0 — Additional requirements covering hull structure, stability,tank arrangements, cargo con-tainment systems, tank types, cargo piping systems, hoses, pressure and temperature con-trols, electrical systems, fire-fighting systems, ventilation, instrumentation and operatingprocedures.

11-5

Transportation – Research and SpecialPrograms Administration49 CFR 172 DOT/RSPA Hazardous

materials table

.0 — Table providing chemicalspecific requirements for haz-ards class, identification num-bers, packaging groups, labeling,special requirements, quantity limitations and stowage requirements. Also covers EO/CO2 mixture and EO/ propylene oxide mixture. Subpart with HAZMAT train-ing requirements. References CERCLA RQ = 10 lb.

.101 — Subpart B Hazardous Materials Table.

This table provides informa-tion concerning the proper shipping name, hazard class or division, identification numbers,packing group, label require-ments, special provisions, packaging authorizations, quantity limitations and vessel stowage requirements for hazardous materials.

.101 (Appendix A) — List of hazardous substances reportablequantities (RQ).

This Appendix lists materials and their corresponding reportable quantities (RQs) which are listed or designated as “Hazardous Substances” under 101(14) of the compre-hensive environmental response,compensation and liability act (CERCLA).

49 CFR 173 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 RequirementsAny person who offers EO (or any hazardousmaterial) for transportation must comply withthe following subparts of:

49 CFR 172 Subpart C (Shipping Papers)Subpart D (Marking)Subpart E (Labeling)Subpart F (Placarding)

49 CFR 173 (Shippers) — General require-ments for shipments and packaging.

Subpart G (Gases, preparationand 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).

11-6

Regulations

Tables and Figures

Appendix A:

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

Lbs/Ft3

Tem

pera

ture

, F °

40

45

50

55

60

FIG

UR

E 1:

Ethy

lene

Oxi

de L

iqui

d D

ensi

ty

0120

200

240

160

40

80

Appendix A:

FIG

UR

E 1

:

A -2

°Te

mpe

ratu

re, F

Psia

FIG

UR

E 2:

1000

100 10 1

Eth

ylen

e O

xide

Vap

or P

ress

ure

01

20

20

02

40

16

04

08

0

A-3

FIG

UR

E 2

:

Appendix A:

BTU/Lb*°F

Tem

pera

ture

,

F °

0.4

0

0.4

4

0.4

8

0.5

2

0.5

6

FIG

UR

E 3

: Eth

ylene O

xid

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iquid

Heat

Capacit

y

0120

200

240

160

40

80

FIG

UR

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:

A -4

Centipoise

°Te

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0.1

0

0.1

5

0.2

0

0.2

5

0.3

0

0.3

5

0.4

0

FIG

UR

E 4:

0120

200

240

160

40

80

Ethy

lene

Oxi

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GU

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4:

A -5

A-6

Appendix A:

BTU/Ft*Hr*°F

Tem

pera

ture

,

F °

FIG

UR

E 5:

0.0

6

0.0

7

0.0

8

0.0

9

0.1

0

Ethy

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erm

al C

ondu

ctiv

ity

24

0 0

12

02

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16

04

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FIG

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:

BTU/Lb

FIG

UR

E 6:

Ethy

lene

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de H

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of V

apor

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ion

0120

200

240

160

40

80

Tem

pera

ture

,

F °

17

5

20

0

22

5

25

0

27

5

A-7

FIG

UR

E 6

:

BTU/Lb*°F

FIG

UR

E 7:

Tem

pera

ture

,

F °

0.2

0.3

0.4

Ethy

lene

Oxi

de V

apor

Hea

t C

apac

ity

0120

200

240

160

40

80

SATU

RAT

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VAP

OR

IDEA

L G

AS

Appendix A:

A-8

FIG

UR

E 7

:

Centipoise

0.0

08

0.0

09

0.0

10

0.0

11

0.0

12

0.0

13

FIG

UR

E 8:

Ethy

lene

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de V

apor

Vis

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ty

Tem

pera

ture

,

F ° 0

120

200

240

160

40

80

A-9

FIG

UR

E 8

:

BTU/Ft*Hr*°F

Tem

pera

ture

,

F °

0.0

04

0.0

05

0.0

06

0.0

07

0.0

08

0.0

09

0.0

10

0.0

11

0.0

12

0.0

13

0.0

14

FIG

UR

E 9:

Ethy

lene

Oxi

de V

apor

The

rmal

Con

duct

ivit

y

0240

120

200

160

40

80

Appendix A:

A-10

FIG

UR

E 9

:

A-11

Freezing Point, °F

FIG

UR

E 1

0:

28

24

32

36

40

44

48

52

06

08

02

04

01

00

Ethy

lene

Oxi

de in

Wat

er, w

t%

Free

zing

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nts

Ethy

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er M

ixtu

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EO

Free

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t –

170

F°

FIG

UR

E 1

0:

Cp/Cv Ratio

Tem

pera

ture

, F °

1.2

5

1.2

4

1.2

3

1.2

2

1.2

6

1.2

7

1.2

8

1.2

9

1.3

0

1.3

1

1.3

2

FIG

UR

E 11:

Cp

/C

v Fo

r S

atur

ated

Eth

ylen

e O

xide

Vap

or

01

50

25

03

00

2

00

50

10

0

Appendix A:

A-12

FIG

UR

E 1

1:

Lbs/Ft3

Tem

pera

ture

, F °

0.0

0.5

1.0

1.5

2.0

2.5

FIG

UR

E 12:

Ethy

lene

Oxi

de V

apor

Den

sity

0120

200

240

160

40

80

FIG

UR

E 1

2:

A -13

Coefficient of Cubic Expansion per °F

Tem

pera

ture

,

F °

0.0

00

7

0.0

00

9

0.0

01

1

0.0

01

3

0.0

01

5

0.0

01

7

FIG

UR

E 1

3:

Ethy

lene

Oxi

de C

oeff

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nt o

f C

ubic

Exp

ansi

on

0120

200

240

160

40

80

Appendix A:

A-14

FIG

UR

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3:

A-15

This page blank intentionally.

10

9

8

7

6

5

4

3

2

1

0 0.2 0.4 0.6 0.8 1.0Mole 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.

WaterEthylene Oxide

Terminal Regions are Expanded in the Next Figure

psia

17

35

45

55

65

psia

65

35

Di

Di =yi Pt

xi (vp)i

Where:yi = mol fraction (EO or water) in gas phasexi = mol fraction (EO or water) in liquid phaseDi = Raoult's Law Deviation Factors from Figures 14 and 15 (no units) (vp)i = pure component vapor pressure at system temperaturePt = total system pressure***

FIGURE 14: Raoult’s Law Deviation Factors for Ethylene Oxide/Water Mixtures

Appendix A:

A-16

8

7

6

5

4

0.02 0.04 0.06 0.08 0.100

psia17

Di =yi Pt

xi (vp)i

14

12

10

8

0.94 0.96 0.98 1.00

Mole Fraction Ethylene Oxide in Water

DEO

DH

2O

35455565

psia65

35

Mole Fraction Ethylene Oxide in Water

Where:yi = mol fraction (EO or water) in gas phasexi = mol fraction (EO or water) in liquid phaseDi = Raoult's Law Deviation Factors from Figures 14 and 15 (no units) (vp)i = pure component vapor pressure at system temperaturePt = total system pressure***

FIGURE 15: Raoult’s Law Deviation Factors for Ethylene Oxide/Water Mixtures

*** Any pressure units can be used, so long as the units for vapor pressure and total pressure are the same.

A-17

Table 1 Physical Property EquationsEQUATION COEFFICIENTS (ALL PROPERTIES IN SI UNITS)

PROPERTY UNITS A B C D

Solid Density KgMOL/M3 2.75E+01

Liquid Density KgMOL/M3 1.8360E+00 2.6024E-01 4.6915E+02 2.6960E-01

Coeff of Expansion per °K 2.6024E-01 4.6915E+02 2.6960E-01

Vapor Density KgMOL/M3 3.3904E+00 –5.0556E-02 2.9010E-04 -7.6743E-07

Vapor Pressure Pa 9.1944E+01 –5.2934E+03 –1.1682E+01 1.4902E-02

Heat of Vaporization J/KgMOL 3.6652E+07 3.7878E-01

Solid Heat Capacity J/KgMOL*°K –2.1143E+04 1.4903E+03 –1.1881E+01 3.8745E-02

Liquid Heat Capacity J/KgMOL*°K 1.4471E+05 –7.5887E+02 2.8261E+00 –3.0640E-03

Ideal Gas Heat Capacity J/KgMOL*°K 3.3460E+04 1.2116E+05 1.6084E+03 8.2410E+04

Second Virial Coefficient M3/KgMOL 6.0016E-02 –5.2057E+01 –1.8056E+07 6.9368E+19

Liquid Viscosity Kg/M*S –8.5210E+00 6.3420E+02 –3.3140E-01

Vapor Viscosity Kg/M*S 2.9540E-06 4.1720E-01 7.8740E+02 –2.3580E+04

Liquid Thermal Conductivity W/M*°K 2.6957E-01 –3.9840E-04

Vapor Thermal Conductivity W/M*°K –3.7880E-04 1.1150E+00 –5.6410E+03

Surface Tension N/M 7.4730E-02 1.1410E+00

Appendix A:

Table 2 Conversion FactorsTo Convert From To Multiply By Notes

KgMOL/M3 Lb/Gal 0.3676 1

Pascals Lbf/sq in 1.45E–04

J/KgMOL BTU/Lb 9.758E–06 1

J/KgMOL*°K BTU/Lb*O F 5.422E–06 1

Kg/M*S Centipoise 1E+03

W/M*OK BTU/Ft*Hr*O F 0.578

N/M Lb f/ft 6.852E–02

Notes: 1. Only valid for Ethylene Oxide.

Note: The symbol * denotes multiplication. The symbol ^ denotes exponentiation. T is temperature, deg Kelvin. Tr is reduced temperature, T/T critical.

A-18

Henry’s Law Constants can be used with the followingequation to determine solubility of these gases:

Where:Xi = mol fraction of gas (N2, Ar, Methane, or

Ethane) in liquid EOYi = mol fraction of gas in vapor space above

liquid EOPt = total pressure, AtmHi = Henry’s Law Constant for gas, Atm

USABLE RANGEMIN MAX

E °K °K EQUATIONS

161 Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4)

161 469 Y = A/(B^(1 + (1 - T/C)^D))

161 469 Y=(-D/C)*LN(B)*((1-T/C)^(D-1))

7.9840E-10 233 383 Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4)

1.0000E+00 161 469 Y = exp (A + (B/T) + (C*lnT) + (D*T^E))

161 469 Y = A*((1 - Tr)^(B + (C*Tr) + (D*Tr^2) + (E*Tr^3)))

25 161 Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4)

161 284 Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4)

7.3730E+02 50 1500 Y = A + B*((C/T)/SINH(C/T))^2 + D*((E/T)/COSH(E/T))^2

–1.7212E+22 235 1500 Y = A + (B/T) + (C/T^3) + (D/T^8) + (E/T^9)

161 284 Y = exp (A + (B/T) + (C*lnT) + (D*T^E))

161 1000 Y = (A*T^B) / (1 + (C/T) + (D/T^2))

161 284 Y = A + (B*T) + (C*T^2) + (D*T^3) + (E*T^4)

273 1000 Y = (A*T^B) / (1 + (C/T) + (D/T^2))

161 469 Y = A*((1 - Tr)^(B + (C*Tr) + (D*Tr^2) + (E*Tr^3)))

Table 3 Henry’s Law Constants (Atm/mole fraction)T(°F) Nitrogen Argon Methane Ethane

32 2800 1670 613 84.377 2180 1420 614 109122 1820 1270 595 129

A-19

Table 4 Henry’s Law Constants (MPa/mole fraction)T(°C) Nitrogen Argon Methane Ethane

0 284 169 62.1 8.525 221 144 62.2 11.050 184 129 60.3 13.1

Xi=YiPtHi

Section 2 - Physical Properties

[1] C. Hirose, Bull. Chem. Soc. Jpn, 47, No. 6 (1974), pp. 1311-1318.

[2] A. Wurtz, Justus Liebigs Ann. Chem.,110 (1859), pp. 125-128.

[3] Societe Francaise de Catalyse Generalisee. FR 729 952, 1931; 739 562, 1931 (T. E. Lefort).

[4] O. Maas and E. H. Boomer, J. Am. Chem. Soc., 44 (1922), p. 1709.

[5] D. N. Glew and N. S. Rath, J. Chem. Phys., 44 (1965), p. 1711.

[6] L. G. Hess and V. V. Tilton, Ind. Eng. Chem., 42 (1950), no. 6, pp. 1251-1258.

[7] J. D. Olson, J. Chem. Eng. Data, 22 (1977), p. 326.

[8] G. O. Curme: Gycols, (New York, Reinhold Publ. Co., 1952), pp. 74-113.

[9] J.P. Dever, K.F. George, W.C. Hoffman, H. Soo, “Ethylene Oxide,” Kirk -Othmer Encyclopedia of Chemical Technology, 4th ed., Vol. 9, pp. 915-959,Wiley, New York, 1994.

[10] Rebsdat, Siegfried, and Mayer, Dieter “Ethylene Oxide.” Ullmann’s Encyclopedia of Industrial Chemistry, NY (1987).

[11] A. Weissberger, Heterocyclic Compounds, ed. A Rosowski, vol. 19, Wiley-Interscience, New York 1964, pp. 1-523.

[12] I. Parker, Chem. Rev. 59 (1959), pp. 737-797.

[13] N. Schonfeld, Surface Active Ethylene Oxide Adducts, Pergaman, NY (1969).

[14] J. Gorzinski Smith, Synthesis, 8 (1984), pp. 629-656.

[15] B. Pesetsky, Chem. Eng. Prog. Loss. Prev., 13 (1980), pp. 132-141.

[16] R. R. Baldwin, A. Keen, R. W. Walker, J. Chem. Soc. Faraday Trans. 1,80 (1984), no. 2, pp. 435-456.

[17] Britton, Laurence G; “Thermal stabilityand deflagration of ethylene oxide” Plant/Operations Progress, vol. 9, pp. 275-86, April 1990.

[18] D. R. Stull, AICHE Monograph Series, 73 (1977), no. 10, pp. 67-68.

[19] T. H. Baize, Ind. Eng. Chem., 53(1961), p. 903.

[20] D. Conrad, Bundesgesundheitsblatt,9 (1963), pp. 139-141.

[21] W. H. Perkin, J. Chem. Soc., 63 (1893),p. 488.

[22] Y. Hashigushi, Tokyo Kogyo Shikensho Hokoku, 60 (1965), no. 3, pp. 85-91.

[23] J. Osugi, M. Okusima, and M. Hamanoue, Koatsu Gasu, 8 (1971), no. 4, pp. 201-206.

[24] S. N. Bajpai, Chem. Eng. Prog. LossPrev. Technical Manual, 13 (1980),pp. 119-122.

[25] J. H. Burgoyne and K. E. Bett, Inst. Chem. Eng. Symp. Ser., 25 (1968), pp. 1-7.

[26] J. H. Burgoyne and K. E. Bett and R. Muir, Symposium on Chem. Proc.Hazards (Inst. Chem. Eng.), ed J. M. Piric, (1960), pp. 30-36.

[27] A. Fiumara and N. Mazzei, Chim. Ind.(Milan), 65 (1983), no. 11, pp. 683-687.

[28] E. O. Haenni, N. A. Affens, H. G.Lento, A. H. Yeomans and R. A. Fulton, Ind. Eng. Chem., 51 (1959),No. 5, pp. 685-688.


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[29] L. Cider and L. Vamling, Ind. Eng. Chem. Prod. Res. Dev., 25 (1986), No. 3, pp. 424-430.

[30] D. N. Kirk, Chem. Ind., (London, 1973), No. 3, pp. 109-116.

[31] F. T. Bodurtha, Industrial Explosion Prevention and Protection, McGraw-Hill, 1980.

[32] F. G. Eichel, “Electrostatics,” Chemical Engineering, March 13, 1967.

[33] Plant Operations Progress, Vol. 7, No. 1. January 1988.

[34] D. D. Wagman, et al, The NBS Tables of Chemical Thermodynamic Properties, J. Phys. Chem Ref. Data,Vol 11, Suppl.3, 1982.

[35] CRC Handbook of Themophysical and Thermochemical Properties, CRC Press1994.

[36] W. F. Giauque and J. Gordon, J. Am. Chem. Soc., 71 (1949), pp. 2176-2181.

[37] NIST Website: http://webbook.nist.gov/cgi/cbook.exe?Name=oxirane&Units =SI&cTG=on&cTC=on&cTP =on&cTR =on#Thermo-Gas

[38] Union Carbide Industrial Gases, Bulletin L-7160, “Flammability Of Diluted Ethylene Oxide at LowPressures,”1992.

[39] V. Schroder and D Conrad, Chem. Ing. Tech., 65(1993), no3. pp. 333-335.

[40] Y. Hashiguchi, et al., Kogyo Kayaku Kyokaishi, 28(1967), No 2, pp. 128-31.

[41] M. Chaigneau, Ann. Pharm. Franc., 43 (1985), pp. 193-194.

[42] G. A. Viera, L.L. Simpson, and B. C. Ream, “Lessons Learned from the Ethylene Oxide Explosion at Seadrift Texas,” Chemical Engineering Progress,August 1993.

[43] Shell Chemical Company Internal Communication.

[44] Product Catalog from Polysciences, Inc., Polymer/Monomer Catalog 1996-1997.

[45] Nye Clinton, Paul Matlock, “1,2-Epoxide Polymers,” Encyclopedia of Polymer Science and Engineering, v. 6, p. 234, John Wiley & Sons, New York (1985).

Section 3 – Health

[1] Occupational Safety and Health Administration, 25 CFR Ch. XVII 1910.1047.

[2] IARC, Monographs on the Evaluation of Carcinogenic Risks to Humans. Some Industrial Chemicals, Vol. 60, pp. 73-160, 1994.

[3] T.H. Gardiner, J.M. Waechter, Jr., and D.E. Stevenson, Patty’s Industrial Hygiene and Toxicology, Volume 2, Part A. eds. G.D. Clayton and F.E. Clayton. John Wiley, New York, 1993.

[4] EPA/FEMA/DOT, Technical Guidance for Hazards Analysis, December 1987, Appendix D.

[5] J.V. Setzer, W.S. Brightwell, J.M. Russo, B.L. Johnson and D.W. Lynch, “Neurophysiological and Neuropathological Primates Exposed to Ethylene Oxide and Propylene Oxide”. Toxicol. Ind. Heath, 12, 667-82, 1996.

[6] W.M. Snellings, J.P. Zelenak and C.S. Weil, “Effects on Reproduction in Fischer 344 Rats Exposed to Ethylene Oxide by Inhalation for One Generation”. Toxicology and Applied Pharmacology, 63, 382-388, 1982.

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[7] W.M. Generoso, K.T. Cain, C.V. Cornett, N.L.A. Cachiero and L.A. Hughs, “Concentration-Response Curves for Ethylene-Oxide-Induced Heritable Tranlocations and Dominant Lethal Mutations.” Environmental and Molecular Mutagenesis, 16, 126-131 1990.

[8] W.M. Generoso, C.T. Cain, L.A. Hughes, G.A. Sega, P.W. Braden, D.G. Gossless and M.D. Shelby, “Ethylene Oxide Dose and Dose-Rate Effects in the Mouse Dominant Lethal Test”. Environmental Mutagenesis, 8, 1-7, 1986.

[9] W.M. Snellings, R.R. Maranpot, J.P. Zelenak and C.P. Laffoon, “Teratology Study in Fischer 344 Rats Exposed to Ethylene Oxide by Inhalation”. Toxicology and Applied Pharmacology,64, 476-481, 1982.

[10] A.M. Saillenfait, F. Gallissott, P. Bonnet, and J.C. Protois, “Developmental Toxicity of Inhaled Ethylene Oxide in Rats Following Short-Duration Exposure”. Fundam. Appl. Toxicol. 34, 223-227, 1996.

[11] A.S. Rowland, D.D. Baird, D.L.. Shore, B. Darden and A.J. Wilcox, “Ethylene Oxide Exposure May Increase the Risk of Spontaneous Abortion, Preterm Birth, and Postterm Birth”. Epidemiology, 7, 363-368, 1996.

[12] G. Olsen, L. Lucas, and J. Teta, “Ethylene oxide exposure and risk of spontaneous abortion, preterm birth, and postterm birth (letter)”. Epidemiology, 8, 465-6, 1997.

[13] V.L. Dellarco, W.M. Generoso, G.A. Sega, J.R. Fowle, and D. Jacobson-Kram, “Review of the Mutagenicity of Ethylene Oxide”. Environ. Mol. Mutagen, 16, 85-103, 1990.Note: this is one of six papers in Volume 16 number 2by EPA on ethylene oxide mutagenicity

[14] L. Rhomberg, V.L. Dellarco, C. Siegel-Scott, K.L. Dearfield and D. Jacobson-Kram, “Quantitative Estimation of the Genetic Risk Associated with the Induction of Heritable Translocations atLow-Dose Exposure: Ethylene Oxide as an Example”. Environ. Mutagenesis, Vol. 16, No. 2, pp. 104-124, 1990.

[15] R.J. Preston, T.R. Fennel, A.P. Leber and J.A. Swenberg, “Recommendations of the Genetic Risk Assessement for Ethylene Oxide Exposures”. Environ. Mol. Mutagen, 26, 189-202, 1995.

[16] L. Golberg. Hazard Assessment of Ethylene Oxide, CRC Press, Boca Raton, FL, 1986.

[17] R.E. Shore, M.J. Gardner, and B. Pannett, “Ethylene Oxide: An Assessment of the Epidemiological Evidence on Carcinogenicity”.Brit. J. Industrial Med., 50, 971-997, 1993.

Section 4 – Environment

[1] Conway, R.A., et al., “Environmental Fate and Effects of Ethylene Oxide” Environ. Sci. Technol., Vol 17, No. 2, pp. 107-112 (1983).

[2] Verschueren, K. 1983. Handbook of Environmental Data on Organic Chemicals. Van Nostrand Reinhold, New York, NY.

[3] Hansch, C. and A.J. Leo. 1985. Medchem Project Issue No. 26. Claremont CA: Pomona College.

[4] Howard, P.H. 1983. Handbook of Environmental Fate and Exposure Data,Vol. IV. Lewis Publishers, Chelsea, MI.

[5] Lyman, W.J. et al. 1982. Chemical Property Estimation Methods.McGraw-Hill Book Co., NY.


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[6] Pitter, P. and J. Chudoba. 1990. Biodegradability of Organic Substances in the Aquatic Environment. CRC Press, Boca Raton, FL.

[7] J.P. Dever, K.F. George, W.C. Hoffman, H. Soo, “Ethylene Oxide,” Kirk– Othmer Encyclopedia of Chemical Technology, 4th ed., Vol. 9, pp 915-959, Wiley New York, 1994.

[8] Means, J.L. and S.J. Anderson. 1981. “Comparison of five different methods for measuring biodegradability in aque-ous environments.”, Water, Air, and SoilPoll. 16: 301-315.

[9] Dow Chemical Company. 1975. Unpublished report.

[10] Hazardous Substances Data Bank (HSDB), 1996.

[11] Bogyo, D. A., et. al. “Investigation ofSelected Potential EnvironmentalContaminants: Epoxides,” EPA-560/11-80-005, Office of Toxic Substances, USEnvironmental Protection Agency,Washington DC 20460, Nov. 1980.

[12] Atkinson, R., et. al., “Lifetimes andFates of Toxic Chemicals in California’sAtmosphere,” ARB-R-88/345,Statewide Air Pollution ResearchCenter, University of California,Riverside, CA, Aug. 1987.

[13] Atkinson, R., et. al., “Lifetimes andFates of Toxic Air Contaminants inCalifornia’s Atmosphere,” ARB-R-90/441, Statewide Air PollutionResearch Center, University ofCalifornia, Riverside, CA, Mar. 1990.

[14] Singh, H.B., et al., SRI International forEPA-600/3-84-082, 1984.

[15] Meylan, W.M., et al., Atmospheric Oxidation Program, pp. 26 and 35, Lewis Publishers, 1992.

[16] Howard, P.H., Handbook of Environmental Degradation Rates, pp. 144-145, Lewis Publishers, 1991.

[17] Berglund, R.L. 1988. “Fate of EO in awastewater treatment facility.” Paperpresented at the 1988 meeting of theAICHE, March 6-10, New Orleans.

[18] Rajagopalan, S., R. vanCompernolle, C.L. Meyer, M.L. Cano, and P.T. Sun. 1998. “Comparison of methods for determining biodegradation kinetics of volatile organic compounds.” Water Env. Res. 70: 291-298.

[19] Canadian Environmental ProtectionService, “Ethylene Oxide –Environmental and TechnicalInformation for Problem Spills”,May 1985.

[20] Bridie. A.L., C.J.M. Wolff, and M.Winter. 1979. “BOD and COD of somepetrochemmicals.”, Wat. Res. 13:627-630.

[21] Bridie, A.L., C.J.M. Wolff, and M. Winter. 1979. “The acute toxicity of some petrochemicals to goldfish.”, Wat.Res. 13: 623-626.

[22] Heck, W.W., and E.G. Pires. 1962.,“Growth of Plants Fumigated withSaturated and UnsaturatedHydrocarbon Gases and TheirDerivatives”, Ag. and Mech. College of Texas.

[23] McGahey, C., C. and E.J. Bouwer.1992. “Biodegradation of ethylene gly-col in simulated subsurfaceenvironments.”, Water Science and Technology, Vol. 26(1-2): pp. 41-49.

[24] “1993 Air Software Guide,”Environmental Protection. pp. 34-37,Vol 4, No. 12, December, 1993.

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[25] “Hazardous Waste Treatment, Storageand Disposal Facilities,” U.S.Environmental Protection Agency, Office of Air and Radiation,November, 1989.

[26] Wu, J.M., and Schroy, J.M., “Emissions from Spills”, Proceedings of a Specialty Conference on Control of Specific (Toxic) Pollutants, Edward R Frederick (Editor), Air Pollution Control Association, Gainesville, FL, February 13-16, 1979, pp 377-393.

[27] US EPA, Emission Standards Division,“Protocol for Equipment Leak EmissionEstimates”, EPA-453/R-93-026, June,1993.

Section 5 - Overview of Hazards

[1] Kletz, T. A., “Fires and Explosions of Hydrocarbon Oxidation Plants”, Plant/Operations Progress, Vol 89, No. 8, August 1993.

[2] Troyan, J. E. and LeVine, R. Y., “Ethylene Oxide Explosion at Doe Run”, AIChE Loss Prevention Symposium, Vol 2, pages 125-130, 1968.

[3] CEP Technical Manual on LossPrevention, Volume 2, AIChE, NewYork, pages 125-130.

[4] Vanderwater, R. G., “Ethylene OxideTank Car Explosion”, ChemicalEngineering Progress, pages 16-20,Dec. 1989.

[5] J.H. Burgoyne, ICHEME SymposiumSeries No. 25, 1969 p. 5.

[6] Viera, G. A., Simpson, L. L., and Ream,B. C., “Lessons Learned from theEthylene Oxide Explosion at Seadrift,Texas”, Chemical Engineering Progress,Vol 89, No. 8, pages 66-75, August1993.

Section 6 – Design

[1] NFPA 58, Liquefied Petroleum Gases,Storage and Handling (1986).

[2] NFPA 497A: Recommended Practices forClassification of Class I Hazardous(Classified) Locations for ElectricalInstallations in Chemical Process Areas.

[3] National Electrical Code (NFPA 70).

[4] API Recommended Practice 500A:Classification of Locations for ElectricalInstallations in Petroleum Facilities.

[5] Britton, Laurence G., “SpontaneousInsulation Fires”, AIChE LossPrevention Symposium, San Diego,CA, August 18-22, 1990.

[6] Brockwell, J. L., “Prediction ofDecomposition Limits for EthyleneOxide - Nitrogen Mixtures”,Plant/Operations Progress, Vol. 9, pages98-102, April 1990.

[7] Marshall, J., Mundt, A., Hult, M.,McKealvy, T., Meyers, P., and Sawyer,J., “The Relative Risk of Pressurized andRefrigerated Storage for SixChemicals”, Process Safety Progress,Vol. 14, No. 3, July 1995.


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