APPENDIX A:


40 CFR PART 68


1 TITLE 40 - PROTECTION OF ENVIRONMENT 

CHAPTER I - ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) 

PART 68 - CHEMICAL ACCIDENT PREVENTION PROVISIONS 

Subpart A - General 

Sec. 

68.1 Scope.


68.2 Stayed provisions.


68.3 Definitions.


68.10 Applicability.


68.12 General requirements.


68.15 Management.


Subpart B - Hazard Assessment 

68.20 Applicability


68.22 Offsite consequence analysis parameters.


68.25 Worst-case release scenario analysis.


68.28 Alternative release scenario analysis.


68.30 Defining offsite impacts - population.


68.33 Defining offsite impacts - environment.


68.36 Review and update.


68.39 Documentation.


68.42 Five-year accident history.


Subpart C - Program 2 Prevention Program 

68.48 Safety information.


68.50 Hazard review.


68.52 Operating procedures.


68.54 Training.


68.56 Maintenance.


68.58 Compliance audits.


68.60 Incident investigation.


Subpart D - Program 3 Prevention Program 

68.65 Process safety information.


68.67 Process hazard analysis.


68.69 Operating procedures.


68.71 Training.


68.73 Mechanical integrity.

68.75 Management of change.


68.77 Pre-startup review.


68.79 Compliance audits.


68.81 Incident investigation.


68.83 Employee participation.


68.85 Hot work permit.


68.87 Contractors.


Subpart E - Emergency Response 

68.90 Applicability.


68.95 Emergency response program.


Subpart F - Regulated Substances for Accidental Release Prevention 

68.100 Purpose.


68.115 Threshold determination.


68.120 Petition process.


68.125 Exemptions.


68.126 Exclusion.


68.130 List of substances.


Subpart G - Risk Management Plan 

68.150 Submission.


68.151 Assertion of claims of confidential business information.


68.152 Substantiating claims of confidential business information.


68.155 Executive summary.


68.160 Registration.


68.165 Offsite consequence analysis.


68.168 Five-year accident history.


68.170 Prevention program/Program 2.


68.175 Prevention program/Program 3.


68.180 Emergency response program.


68.185 Certification.


68.190 Updates.


Subpart H - Other Requirements 

68.200 Recordkeeping.


68.210 Availability of information to the public.


68.215 Permit content and air permitting authority or designated agency requirements.


68.220 Audits.


Appendix A to Part 68 - Table of Toxic Endpoints 
Authority: 42 U.S.C. 7412(r), 7601(a)(1), 7661-7661f. 

Source: 59 FR 4493, Jan. 31, 1994, unless otherwise noted.

 Subpart A - General 

§ 68.1 Scope. 

This part sets forth the list of regulated substances and thresholds, the petition process for adding 

or deleting substances to the list of regulated substances, the requirements for owners or 

operators of stationary sources concerning the prevention of accidental releases, and the State 

accidental release prevention programs approved under section 112(r). The list of substances, 

threshold quantities, and accident prevention regulations promulgated under this part do not limit 

in any way the general duty provisions under section 112(r)(1). 

§ 68.3 Definitions. 

For the purposes of this part: 

Accidental release means an unanticipated emission of a regulated substance or other 

extremely hazardous substance into the ambient air from a stationary source. 

Act means the Clean Air Act as amended (42 U.S.C. 7401 et seq.) Administrative 

controls mean written procedural mechanisms used for hazard control. 

Administrator means the administrator of the U.S. Environmental Protection Agency. 

AIChE/CCPS means the American Institute of Chemical Engineers/Center for Chemical 

Process Safety. 

API means the American Petroleum Institute. 

Article means a manufactured item, as defined under 29 CFR 1910.1200(b), that is 

formed to a specific shape or design during manufacture, that has end use functions dependent in 

whole or in part upon the shape or design during end use, and that does not release or otherwise 

result in exposure to a regulated substance under normal conditions of processing and use. 

ASME means the American Society of Mechanical Engineers. 

CAS means the Chemical Abstracts Service. 

Catastrophic release means a major uncontrolled emission, fire, or explosion, involving 

one or more regulated substances that presents imminent and substantial endangerment to public 

health and the environment. 

Classified information means ``classified information'' as defined in the Classified 

Information Procedures Act, 18 U.S.C. App. 3, section 1(a) as ``any information or material that 

has been determined by the United States Government pursuant to an executive order, statute, or 

regulation, to require protection against unauthorized disclosure for reasons of national security.'' 

Condensate means hydrocarbon liquid separated from natural gas that condenses due to 

changes in temperature, pressure, or both, and remains liquid at standard conditions. 

Covered process means a process that has a regulated substance present in more than a 

threshold quantity as determined under § 68.115. 

Crude oil means any naturally occurring, unrefined petroleum liquid. 

Designated agency means the state, local, or Federal agency designated by the state under 
the provisions of § 68.215(d). 

DOT means the United States Department of Transportation. 

Environmental receptor means natural areas such as national or state parks, forests, or 

monuments; officially designated wildlife sanctuaries, preserves, refuges, or areas; and Federal 

wilderness areas, that could be exposed at any time to toxic concentrations, radiant heat, or 

overpressure greater than or equal to the endpoints provided in § 68.22(a) , as a result of an 

accidental release and that can be identified on local U. S. Geological Survey maps. 

Field gas means gas extracted from a production well before the gas enters a natural gas 

processing plant. 

Hot work means work involving electric or gas welding, cutting, brazing, or similar flame 

or spark-producing operations. 

Implementing agency means the state or local agency that obtains delegation for an 

accidental release prevention program under subpart E, 40 CFR part 63. The implementing 

agency may, but is not required to, be the state or local air permitting agency. If no state or local 

agency is granted delegation, EPA will be the implementing agency for that state. 

Injury means any effect on a human that results either from direct exposure to toxic 

concentrations; radiant heat; or overpressures from accidental releases or from the direct 

consequences of a vapor cloud explosion (such as flying glass, debris, and other projectiles) from 

an accidental release and that requires medical treatment or hospitalization. 

Major change means introduction of a new process, process equipment, or regulated 

substance, an alteration of process chemistry that results in any change to safe operating limits, or 

other alteration that introduces a new hazard. 

Mechanical integrity means the process of ensuring that process equipment is fabricated 

from the proper materials of construction and is properly installed, maintained, and replaced to 

prevent failures and accidental releases. 

Medical treatment means treatment, other than first aid, administered by a physician or 

registered professional personnel under standing orders from a physician. 

Mitigation or mitigation system means specific activities, technologies, or equipment 

designed or deployed to capture or control substances upon loss of containment to minimize 

exposure of the public or the environment. Passive mitigation means equipment, devices, or 

technologies that function without human, mechanical, or other energy input. Active mitigation 

means equipment, devices, or technologies that need human, mechanical, or other energy input to 

function. 

NAICS means North American Industry Classification System. 

NFPA means the National Fire Protection Association. 

Natural gas processing plant (gas plant) means any processing site engaged in the 

extraction of natural gas liquids from field gas, fractionation of mixed natural gas liquids to 

natural gas products, or both, classified as North American Industrial Classification System 

(NAICS) code 211112 (previously Standard Industrial Classification (SIC) code 1321). 

Offsite means areas beyond the property boundary of the stationary source, and areas 

within the property boundary to which the public has routine and unrestricted access during or 

outside business hours. 

OSHA means the U.S. Occupational Safety and Health Administration. Owner or 

operator means any person who owns, leases, operates, controls, or supervises a stationary 

source. 
Petroleum refining process unit means a process unit used in an establishment primarily 

engaged in petroleum refining as defined in NAICS code 32411 for petroleum refining (formerly 

SIC code 2911) and used for the following: Producing transportation fuels (such as gasoline, 

diesel fuels, and jet fuels), heating fuels (such as kerosene, fuel gas distillate, and fuel oils), or 

lubricants; Separating petroleum; or Separating, cracking, reacting, or reforming intermediate 

petroleum streams. Examples of such units include, but are not limited to, petroleum based 

solvent units, alkylation units, catalytic hydrotreating, catalytic hydrorefining, catalytic 

hydrocracking, catalytic reforming, catalytic cracking, crude distillation, lube oil processing, 

hydrogen production, isomerization, polymerization, thermal processes, and blending, 

sweetening, and treating processes. Petroleum refining process units include sulfur plants. 

Population means the public. 

Process means any activity involving a regulated substance including any use, storage, 

manufacturing, handling, or on-site movement of such substances, or combination of these 

activities. For the purposes of this definition, any group of vessels that are interconnected, or 

separate vessels that are located such that a regulated substance could be involved in a potential 

release, shall be considered a single process. Produced water means water extracted from the 

earth from an oil or natural gas production well, or that is separated from oil or natural gas after 

extraction. 

Public means any person except employees or contractors at the stationary source. 

Public receptor means offsite residences, institutions (e.g., schools, hospitals), industrial, 

commercial, and office buildings, parks, or recreational areas inhabited or occupied by the public 

at any time without restriction by the stationary source where members of the public could be 

exposed to toxic concentrations, radiant heat, or overpressure, as a result of an accidental release. 

Regulated substance is any substance listed pursuant to section 112(r)(3) of the Clean Air 

Act as amended, in § 68.130. 

Replacement in kind means a replacement that satisfies the design specifications. 

Retail facility means a stationary source at which more than one-half of the income is 

obtained from direct sales to end users or at which more than one-half of the fuel sold, by 

volume, is sold through a cylinder exchange program. 

RMP means the risk management plan required under subpart G of this part. 

Stationary source means any buildings, structures, equipment, installations, or substance 

emitting stationary activities which belong to the same industrial group, which are located on one 

or more contiguous properties, which are under the control of the same person (or persons under 

common control), and from which an accidental release may occur. The term stationary source 

does not apply to transportation, including storage incident to transportation, of any regulated 

substance or any other extremely hazardous substance under the provisions of this part. A 

stationary source includes transportation containers used for storage not incident to transportation 

and transportation containers connected to equipment at a stationary source for loading or 

unloading. Transportation includes, but is not limited to, transportation subject to oversight or 

regulation under 49 CFR parts 192, 193, or 195, or a state natural gas or hazardous liquid 

program for which the state has in effect a certification to DOT under 49 U.S.C. section 60105. A 

stationary source does not include naturally occurring hydrocarbon reservoirs. Properties shall 

not be considered contiguous solely because of a railroad or pipeline right-of-way. 

Threshold quantity means the quantity specified for regulated substances pursuant to 

section 112(r)(5) of the Clean Air Act as amended, listed in § 68.130 and determined to be 
present at a stationary source as specified in § 68.115 of this part. 

Typical meteorological conditions means the temperature, wind speed, cloud cover, and 

atmospheric stability class, prevailing at the site based on data gathered at or near the site or from 

a local meteorological station. 

Vessel means any reactor, tank, drum, barrel, cylinder, vat, kettle, boiler, pipe, hose, or 

other container. 

Worst-case release means the release of the largest quantity of a regulated substance from 

a vessel or process line failure that results in the greatest distance to an endpoint defined in § 

68.22(a). 

[59 FR 4493, Jan. 31, 1994, as amended at 61 FR 31717, June 20, 1996; 63 FR 644, Jan. 6, 1998; 

64 FR 979, Jan. 6, 1999; 65 FR 13250, Mar. 13, 2000] 

§ 68.10 Applicability.

 (a) An owner or operator of a stationary source that has more than a threshold quantity of a 

regulated substance in a process, as determined under § 68.115, shall comply with the 

requirements of this part no later than the latest of the following dates:

 (1) June 21, 1999;

 (2) Three years after the date on which a regulated substance is first listed under § 68.130; or

 (3) The date on which a regulated substance is first present above a threshold quantity in a 

process.

 (b) Program 1 eligibility requirements. A covered process is eligible for Program 1 

requirements as provided in § 68.12(b) if it meets all of the following requirements:

 (1) For the five years prior to the submission of an RMP, the process has not had an accidental 

release of a regulated substance where exposure to the substance, its reaction products, 

overpressure generated by an explosion involving the substance, or radiant heat generated by a 

fire involving the substance led to any of the following offsite:

 (i) Death;

 (ii) Injury; or

 (iii) Response or restoration activities for an exposure of an environmental receptor;

 (2) The distance to a toxic or flammable endpoint for a worst-case release assessment 

conducted under Subpart B and § 68.25 is less than the distance to any public receptor, as defined 

in § 68.30; and

 (3) Emergency response procedures have been coordinated between the stationary source and 

local emergency planning and response organizations.

 (c) Program 2 eligibility requirements. A covered process is subject to Program 2 requirements 

if it does not meet the eligibility requirements of either paragraph (b) or paragraph (d) of this 

section.

 (d) Program 3 eligibility requirements. A covered process is subject to Program 3 if the 

process does not meet the requirements of paragraph (b) of this section, and if either of the 

following conditions is met:

 (1) The process is in NAICS code 32211, 32411, 32511, 325181, 325188, 325192, 325199, 

325211, 325311, or 32532; or

 (2) The process is subject to the OSHA process safety management standard, 29 CFR 
1910.119.

 (e) If at any time a covered process no longer meets the eligibility criteria of its Program level, 

the owner or operator shall comply with the requirements of the new Program level that applies 

to the process and update the RMP as provided in § 68.190.

 (f) The provisions of this part shall not apply to an Outer Continental Shelf (``OCS'') source, as 

defined in 40 CFR 55.2. 

[61 FR 31717, June 20, 1996, as amended at 63 FR 645, Jan. 6, 1998; 64 FR 979, Jan. 6, 1999] 

§ 68.12 General requirements.

 (a) General requirements. The owner or operator of a stationary source subject to this part shall 

submit a single RMP, as provided in Sec.§ 68.150 to 68.185. The RMP shall include a 

registration that reflects all covered processes.

 (b) Program 1 requirements. In addition to meeting the requirements of paragraph (a) of this 

section, the owner or operator of a stationary source with a process eligible for Program 1, as 

provided in § 68.10(b), shall:

 (1) Analyze the worst-case release scenario for the process(es), as provided in § 68.25; 

document that the nearest public receptor is beyond the distance to a toxic or flammable endpoint 

defined in § 68.22(a); and submit in the RMP the worst-case release scenario as provided in § 

68.165;

 (2) Complete the five-year accident history for the process as provided in § 68.42 of this part 

and submit it in the RMP as provided in § 68.168;

 (3) Ensure that response actions have been coordinated with local emergency planning and 

response agencies; and

 (4) Certify in the RMP the following: ``Based on the criteria in 40 CFR 68.10, the distance to 

the specified endpoint for the worst-case accidental release scenario for the following process(es) 

is less than the distance to the nearest public receptor: [list process(es)]. Within the past five 

years, the process(es) has (have) had no accidental release that caused offsite impacts provided in 

the risk management program rule (40 CFR 68.10(b)(1)). No additional measures are necessary 

to prevent offsite impacts from accidental releases. In the event of fire, explosion, or a release of 

a regulated substance from the process(es), entry within the distance to the specified endpoints 

may pose a danger to public emergency responders. Therefore, public emergency responders 

should not enter this area except as arranged with the emergency contact indicated in the RMP. 

The undersigned certifies that, to the best of my knowledge, information, and belief, formed after 

reasonable inquiry, the information submitted is true, accurate, and complete. [Signature, title, 

date signed].''

 (c) Program 2 requirements. In addition to meeting the requirements of paragraph (a) of this 

section, the owner or operator of a stationary source with a process subject to Program 2, as 

provided in § 68.10(c), shall:

 (1) Develop and implement a management system as provided in § 68.15;

 (2) Conduct a hazard assessment as provided in Sec.§ 68.20 through 68.42;

 (3) Implement the Program 2 prevention steps provided in Sec.§ 68.48 through 68.60 or 

implement the Program 3 prevention steps provided in Sec.§ 68.65 through 68.87; 
 (4) Develop and implement an emergency response program as provided in Sec.§ 68.90 to 

68.95; and

 (5) Submit as part of the RMP the data on prevention program elements for Program 2 

processes as provided in § 68.170.

 (d) Program 3 requirements. In addition to meeting the requirements of paragraph (a) of this 

section, the owner or operator of a stationary source with a process subject to Program 3, as 

provided in § 68.10(d) shall:

 (1) Develop and implement a management system as provided in § 68.15;

 (2) Conduct a hazard assessment as provided in Sec.§ 68.20 through 68.42;

 (3) Implement the prevention requirements of Sec.§ 68.65 through 68.87;

 (4) Develop and implement an emergency response program as provided in Sec.§ 68.90 to 

68.95 of this part; and

 (5) Submit as part of the RMP the data on prevention program elements for Program 3 

processes as provided in § 68.175. 

[61 FR 31718, June 20, 1996] 

§ 68.15 Management.

 (a) The owner or operator of a stationary source with processes subject to Program 2 or 

Program 3 shall develop a management system to oversee the implementation of the risk 

management program elements.

 (b) The owner or operator shall assign a qualified person or position that has the overall 

responsibility for the development, implementation, and integration of the risk management 

program elements.

 (c) When responsibility for implementing individual requirements of this part is assigned to 

persons other than the person identified under paragraph (b) of this section, the names or 

positions of these people shall be documented and the lines of authority defined through an 

organization chart or similar document. 

[61 FR 31718, June 20, 1996]

 Subpart B - Hazard Assessment

 Source: 61 FR 31718, June 20, 1996, unless otherwise noted. 

§ 68.20 Applicability.

 The owner or operator of a stationary source subject to this part shall prepare a worst-case 

release scenario analysis as provided in § 68.25 of this part and complete the five-year accident 

history as provided in § 68.42. The owner or operator of a Program 2 and 3 process must comply 

with all sections in this subpart for these processes. 

§ 68.22 Offsite consequence analysis parameters. 
 (a) Endpoints. For analyses of offsite consequences, the following endpoints shall be used:

 (1) Toxics. The toxic endpoints provided in appendix A of this part.

 (2) Flammables. The endpoints for flammables vary according to the scenarios studied:

 (i) Explosion. An overpressure of 1 psi.

 (ii) Radiant heat/exposure time. A radiant heat of 5 kw/m2 for 40 seconds.

 (iii) Lower flammability limit. A lower flammability limit as provided in NFPA documents or 

other generally recognized sources.

 (b) Wind speed/atmospheric stability class. For the worst-case release analysis, the owner or 

operator shall use a wind speed of 1.5 meters per second and F atmospheric stability class. If the 

owner or operator can demonstrate that local meteorological data applicable to the stationary 

source show a higher minimum wind speed or less stable atmosphere at all times during the 

previous three years, these minimums may be used. For analysis of alternative scenarios, the 

owner or operator may use the typical meteorological conditions for the stationary source.

 (c) Ambient temperature/humidity. For worst-case release analysis of a regulated toxic 

substance, the owner or operator shall use the highest daily maximum temperature in the 

previous three years and average humidity for the site, based on temperature/humidity data 

gathered at the stationary source or at a local meteorological station; an owner or operator using 

the RMP Offsite Consequence Analysis Guidance may use 25o C and 50 percent humidity as 

values for these variables. For analysis of alternative scenarios, the owner or operator may use 

typical temperature/humidity data gathered at the stationary source or at a local meteorological 

station.

 (d) Height of release. The worst-case release of a regulated toxic substance shall be analyzed 

assuming a ground level (0 feet) release. For an alternative scenario analysis of a regulated toxic 

substance, release height may be determined by the release scenario.

 (e) Surface roughness. The owner or operator shall use either urban or rural topography, as 

appropriate. Urban means that there are many obstacles in the immediate area; obstacles include 

buildings or trees. Rural means there are no buildings in the immediate area and the terrain is 

generally flat and unobstructed.

 (f) Dense or neutrally buoyant gases. The owner or operator shall ensure that tables or models 

used for dispersion analysis of regulated toxic substances appropriately account for gas density.

 (g) Temperature of released substance. For worst case, liquids other than gases liquified by 

refrigeration only shall be considered to be released at the highest daily maximum temperature, 

based on data for the previous three years appropriate for the stationary source, or at process 

temperature, whichever is higher. For alternative scenarios, substances may be considered to be 

released at a process or ambient temperature that is appropriate for the scenario. 

§ 68.25 Worst-case release scenario analysis.

 (a) The owner or operator shall analyze and report in the RMP:

 (1) For Program 1 processes, one worst-case release scenario for each Program 1 process;

 (2) For Program 2 and 3 processes:

 (i) One worst-case release scenario that is estimated to create the greatest distance in any 

direction to an endpoint provided in appendix A of this part resulting from an accidental release 

of regulated toxic substances from covered processes under worst-case conditions defined in § 

68.22; 
 (ii) One worst-case release scenario that is estimated to create the greatest distance in any 

direction to an endpoint defined in § 68.22(a) resulting from an accidental release of regulated 

flammable substances from covered processes under worst-case conditions defined in § 68.22; 

and

 (iii) Additional worst-case release scenarios for a hazard class if a worst-case release from 

another covered process at the stationary source potentially affects public receptors different from 

those potentially affected by the worst-case release scenario developed under paragraphs (a)(2)(i) 

or (a)(2)(ii) of this section.

 (b) Determination of worst-case release quantity. The worst-case release quantity shall be the 

greater of the following:

 (1) For substances in a vessel, the greatest amount held in a single vessel, taking into account 

administrative controls that limit the maximum quantity; or

 (2) For substances in pipes, the greatest amount in a pipe, taking into account administrative 

controls that limit the maximum quantity.

 (c) Worst-case release scenario - toxic gases. (1) For regulated toxic substances that are 

normally gases at ambient temperature and handled as a gas or as a liquid under pressure, the 

owner or operator shall assume that the quantity in the vessel or pipe, as determined under 

paragraph (b) of this section, is released as a gas over 10 minutes. The release rate shall be 

assumed to be the total quantity divided by 10 unless passive mitigation systems are in place.

 (2) For gases handled as refrigerated liquids at ambient pressure:

 (i) If the released substance is not contained by passive mitigation systems or if the contained 

pool would have a depth of 1 cm or less, the owner or operator shall assume that the substance is 

released as a gas in 10 minutes;

 (ii) If the released substance is contained by passive mitigation systems in a pool with a depth 

greater than 1 cm, the owner or operator may assume that the quantity in the vessel or pipe, as 

determined under paragraph (b) of this section, is spilled instantaneously to form a liquid pool. 

The volatilization rate (release rate) shall be calculated at the boiling point of the substance and 

at the conditions specified in paragraph (d) of this section.

 (d) Worst-case release scenario - toxic liquids. (1) For regulated toxic substances that are 

normally liquids at ambient temperature, the owner or operator shall assume that the quantity in 

the vessel or pipe, as determined under paragraph (b) of this section, is spilled instantaneously to 

form a liquid pool.

 (i) The surface area of the pool shall be determined by assuming that the liquid spreads to 1 

centimeter deep unless passive mitigation systems are in place that serve to contain the spill and 

limit the surface area. Where passive mitigation is in place, the surface area of the contained 

liquid shall be used to calculate the volatilization rate.

 (ii) If the release would occur onto a surface that is not paved or smooth, the owner or operator 

may take into account the actual surface characteristics.

 (2) The volatilization rate shall account for the highest daily maximum temperature occurring 

in the past three years, the temperature of the substance in the vessel, and the concentration of the 

substance if the liquid spilled is a mixture or solution.

 (3) The rate of release to air shall be determined from the volatilization rate of the liquid pool. 

The owner or operator may use the methodology in the RMP Offsite Consequence Analysis 

Guidance or any other publicly available techniques that account for the modeling conditions and 

are recognized by industry as applicable as part of current practices. Proprietary models that 
account for the modeling conditions may be used provided the owner or operator allows the 

implementing agency access to the model and describes model features and differences from 

publicly available models to local emergency planners upon request.

 (e) Worst-case release scenario - flammable gases. The owner or operator shall assume that the 

quantity of the substance, as determined under paragraph (b) of this section and the provisions 

below, vaporizes resulting in a vapor cloud explosion. A yield factor of 10 percent of the 

available energy released in the explosion shall be used to determine the distance to the explosion 

endpoint if the model used is based on TNT equivalent methods.

 (1) For regulated flammable substances that are normally gases at ambient temperature and 

handled as a gas or as a liquid under pressure, the owner or operator shall assume that the 

quantity in the vessel or pipe, as determined under paragraph (b) of this section, is released as a 

gas over 10 minutes. The total quantity shall be assumed to be involved in the vapor cloud 

explosion.

 (2) For flammable gases handled as refrigerated liquids at ambient pressure:

 (i) If the released substance is not contained by passive mitigation systems or if the contained 

pool would have a depth of one centimeter or less, the owner or operator shall assume that the 

total quantity of the substance is released as a gas in 10 minutes, and the total quantity will be 

involved in the vapor cloud explosion.

 (ii) If the released substance is contained by passive mitigation systems in a pool with a depth 

greater than 1 centimeter, the owner or operator may assume that the quantity in the vessel or 

pipe, as determined under paragraph (b) of this section, is spilled instantaneously to form a liquid 

pool. The volatilization rate (release rate) shall be calculated at the boiling point of the substance 

and at the conditions specified in paragraph (d) of this section. The owner or operator shall 

assume that the quantity which becomes vapor in the first 10 minutes is involved in the vapor 

cloud explosion.

 (f) Worst-case release scenario - flammable liquids. The owner or operator shall assume that 

the quantity of the substance, as determinedunder paragraph (b) of this section and the 

provisions below, vaporizesresulting in a vapor cloud explosion. A yield factor of 10 percent of 

theavailable energy released in the explosion shall be used to determine thedistance to the 

explosion endpoint if the model used is based on TNT equivalent methods.

 (1) For regulated flammable substances that are normally liquids at ambient temperature, the 

owner or operator shall assume that the entire quantity in the vessel or pipe, as determined under 

paragraph (b) of this section, is spilled instantaneously to form a liquid pool. For liquids at 

temperatures below their atmospheric boiling point, the volatilization rate shall be calculated at 

the conditions specified in paragraph (d) of this section.

 (2) The owner or operator shall assume that the quantity which becomes vapor in the first 10 

minutes is involved in the vapor cloud explosion.

 (g) Parameters to be applied. The owner or operator shall use the parameters defined in § 

68.22 to determine distance to the endpoints. The owner or operator may use the methodology 

provided in the RMP Offsite Consequence Analysis Guidance or any commercially or publicly 

available air dispersion modeling techniques, provided the techniques account for the modeling 

conditions and are recognized by industry as applicable as part of current practices. Proprietary 

models that account for the modeling conditions may be used provided the owner or operator 

allows the implementing agency access to the model and describes model features and 

differences from publicly available models to local emergency planners upon request. 
 (h) Consideration of passive mitigation. Passive mitigation systems may be considered for the 

analysis of worst case provided that the mitigation system is capable of withstanding the release 

event triggering the scenario and would still function as intended.

 (i) Factors in selecting a worst-case scenario. Notwithstanding the provisions of paragraph (b) 

of this section, the owner or operator shall select as the worst case for flammable regulated 

substances or the worst case for regulated toxic substances, a scenario based on the following 

factors if such a scenario would result in a greater distance to an endpoint defined in § 68.22(a) 

beyond the stationary source boundary than the scenario provided under paragraph (b) of this 

section:

 (1) Smaller quantities handled at higher process temperature or pressure; and

 (2) Proximity to the boundary of the stationary source. 

[61 FR 31718, June 20, 1996, as amended at 64 FR 28700, May 26, 1999] 

§ 68.28 Alternative release scenario analysis.

 (a) The number of scenarios. The owner or operator shall identify and analyze at least one 

alternative release scenario for each regulated toxic substance held in a covered process(es) and 

at least one alternative release scenario to represent all flammable substances held in covered 

processes.

 (b) Scenarios to consider. (1) For each scenario required under paragraph (a) of this section, 

the owner or operator shall select a scenario:

 (i) That is more likely to occur than the worst-case release scenario under § 68.25; and

 (ii) That will reach an endpoint offsite, unless no such scenario exists.

 (2) Release scenarios considered should include, but are not limited to, the following, where 

applicable:

 (i) Transfer hose releases due to splits or sudden hose uncoupling;

 (ii) Process piping releases from failures at flanges, joints, welds, valves and valve seals, and 

drains or bleeds;

 (iii) Process vessel or pump releases due to cracks, seal failure, or drain, bleed, or plug failure;

 (iv) Vessel overfilling and spill, or overpressurization and venting through relief valves or 

rupture disks; and

 (v) Shipping container mishandling and breakage or puncturing leading to a spill.

 (c) Parameters to be applied. The owner or operator shall use the appropriate parameters 

defined in § 68.22 to determine distance to the endpoints. The owner or operator may use either 

the methodology provided in the RMP Offsite Consequence Analysis Guidanceor any 

commercially or publicly available air dispersion modeling techniques, provided the techniques 

account for the specified modeling conditions and are recognized by industry as applicable as 

part of current practices. Proprietary models that account for the modeling conditions may be 

used provided the owner or operator allows the implementing agency access to the model and 

describes model features and differences from publicly available models to local emergency 

planners upon request.

 (d) Consideration of mitigation. Active and passive mitigation systems may be considered 

provided they are capable of withstanding the event that triggered the release and would still be 

functional. 
 (e) Factors in selecting scenarios. The owner or operator shall consider the following in 

selecting alternative release scenarios:

 (1) The five-year accident history provided in § 68.42; and

 (2) Failure scenarios identified under § 68.50 or § 68.67. 

§ 68.30 Defining offsite impacts - population.

 (a) The owner or operator shall estimate in the RMP the population within a circle with its 

center at the point of the release and a radius determined by the distance to the endpoint defined 

in § 68.22(a).

 (b) Population to be defined. Population shall include residential population. The presence of 

institutions (schools, hospitals, prisons), parks and recreational areas, and major commercial, 

office, and industrial buildings shall be noted in the RMP.

 (c) Data sources acceptable. The owner or operator may use the most recent Census data, or 

other updated information, to estimate the population potentially affected.

 (d) Level of accuracy. Population shall be estimated to two significant digits. 

§ 68.33 Defining offsite impacts - environment.

 (a) The owner or operator shall list in the RMP environmental receptors within a circle with its 

center at the point of the release and a radius determined by the distance to the endpoint defined 

in § 68.22(a) of this part.

 (b) Data sources acceptable. The owner or operator may rely on information provided on local 

U.S. Geological Survey maps or on any data source containing U.S.G.S. data to identify 

environmental receptors. 

68.36 Review and update.

 (a) The owner or operator shall review and update the offsite consequence analyses at least 

once every five years.

 (b) If changes in processes, quantities stored or handled, or any other aspect of the stationary 

source might reasonably be expected to increase or decrease the distance to the endpoint by a 

factor of two or more, the owner or operator shall complete a revised analysis within six months 

of the change and submit a revised risk management plan as provided in § 68.190. 

§ 68.39 Documentation.

 The owner or operator shall maintain the following records on the offsite consequence 

analyses:

 (a) For worst-case scenarios, a description of the vessel or pipeline and substance selected as 

worst case, assumptions and parameters used, and the rationale for selection; assumptions shall 

include use of any administrative controls and any passive mitigation that were assumed to limit 

the quantity that could be released. Documentation shall include the anticipated effect of the 

controls and mitigation on the release quantity and rate.

 (b) For alternative release scenarios, a description of the scenarios identified, assumptions and 
parameters used, and the rationale for the selection of specific scenarios; assumptions shall 

include use of any administrative controls and any mitigation that were assumed to limit the 

quantity that could be released. Documentation shall include the effect of the controls and 

mitigation on the release quantity and rate.

 (c) Documentation of estimated quantity released, release rate, and duration of release.

 (d) Methodology used to determine distance to endpoints.

 (e) Data used to estimate population and environmental receptors potentially affected. 

§ 68.42 Five-year accident history.

 (a) The owner or operator shall include in the five-year accident history all accidental releases 

from covered processes that resulted in deaths, injuries, or significant property damage on site, or 

known offsite deaths, injuries, evacuations, sheltering in place, property damage, or 

environmental damage.

 (b) Data required. For each accidental release included, the owner or operator shall report the 

following information:

 (1) Date, time, and approximate duration of the release;

 (2) Chemical(s) released;

 (3) Estimated quantity released in pounds and, for mixtures containing regulated toxic 

substances, percentage concentration by weight of the released regulated toxic substance in the 

liquid mixture;

 (4) Five- or six-digit NAICS code that most closely corresponds to the process;

 (5) The type of release event and its source;

 (6) Weather conditions, if known;

 (7) On-site impacts;

 (8) Known offsite impacts;

 (9) Initiating event and contributing factors if known;

 (10) Whether offsite responders were notified if known; and

 (11) Operational or process changes that resulted from investigation of the release and that 

have been made by the time this information is submitted in accordance with §68.168.

 (c) Level of accuracy. Numerical estimates may be provided to two significant digits. 

[61 FR 31718, June 20, 1996, as amended at 64 FR 979, Jan. 6, 1999 and 69 FR 18819, April 9, 

2004]

 Subpart C - Program 2 Prevention Program

 Source: 61 FR 31721, June 20, 1996, unless otherwise noted. 

§ 68.48 Safety information.

 (a) The owner or operator shall compile and maintain the following up-to-date safety 

information related to the regulated substances, processes, and equipment:

 (1) Material Safety Data Sheets that meet the requirements of 29 CFR 1910.1200(g);

 (2) Maximum intended inventory of equipment in which the regulated substances are stored or 
processed;

 (3) Safe upper and lower temperatures, pressures, flows, and compositions;

 (4) Equipment specifications; and

 (5) Codes and standards used to design, build, and operate the process.

 (b) The owner or operator shall ensure that the process is designed in compliance with 

recognized and generally accepted good engineering practices. Compliance with Federal or state 

regulations that address industry-specific safe design or with industry-specific design codes and 

standards may be used to demonstrate compliance with this paragraph.

 (c) The owner or operator shall update the safety information if a major change occurs that 

makes the information inaccurate. 

§ 68.50 Hazard review.

 (a) The owner or operator shall conduct a review of the hazards associated with the regulated 

substances, process, and procedures. The review shall identify the following:

 (1) The hazards associated with the process and regulated substances;

 (2) Opportunities for equipment malfunctions or human errors that could cause an accidental 

release;

 (3) The safeguards used or needed to control the hazards or prevent equipment malfunction or 

human error; and

 (4) Any steps used or needed to detect or monitor releases.

 (b) The owner or operator may use checklists developed by persons or organizations 

knowledgeable about the process and equipment as a guide to conducting the review. For 

processes designed to meet industry standards or Federal or state design rules, the hazard review 

shall, by inspecting all equipment, determine whether the process is designed, fabricated, and 

operated in accordance with the applicable standards or rules.

 (c) The owner or operator shall document the results of the review and ensure that problems 

identified are resolved in a timely manner.

 (d) The review shall be updated at least once every five years. The owner or operator shall also 

conduct reviews whenever a major change in the process occurs; all issues identified in the 

review shall be resolved before startup of the changed process. 

§ 68.52 Operating procedures.

 (a) The owner or operator shall prepare written operating procedures that provide clear 

instructions or steps for safely conducting activities associated with each covered process 

consistent with the safety information for that process. Operating procedures or instructions 

provided by equipment manufacturers or developed by persons or organizations knowledgeable 

about the process and equipment may be used as a basis for a stationary source's operating 

procedures.

 (b) The procedures shall address the following:

 (1) Initial startup;

 (2) Normal operations;

 (3) Temporary operations;

 (4) Emergency shutdown and operations; 
 (5) Normal shutdown;

 (6) Startup following a normal or emergency shutdown or a major 

change that requires a hazard review;

 (7) Consequences of deviations and steps required to correct or avoid deviations; and

 (8) Equipment inspections.

 (c) The owner or operator shall ensure that the operating procedures are updated, if necessary, 

whenever a major change occurs and prior to startup of the changed process. 

§ 68.54 Training.

 (a) The owner or operator shall ensure that each employee presently operating a process, and 

each employee newly assigned to a covered process have been trained or tested competent in the 

operating procedures provided in § 68.52 that pertain to their duties. For those employees already 

operating a process on June 21, 1999, the owner or operator may certify in writing that the 

employee has the required knowledge, skills, and abilities to safely carry out the duties and 

responsibilities as provided in the operating procedures.

 (b) Refresher training. Refresher training shall be provided at least every three years, and more 

often if necessary, to each employee operating a process to ensure that the employee understands 

and adheres to the current operating procedures of the process. The owner or operator, in 

consultation with the employees operating the process, shall determine the appropriate frequency 

of refresher training.

 (c) The owner or operator may use training conducted under Federal or state regulations or 

under industry-specific standards or codes or training conducted by covered process equipment 

vendors to demonstrate compliance with this section to the extent that the training meets the 

requirements of this section.

 (d) The owner or operator shall ensure that operators are trained in any updated or new 

procedures prior to startup of a process after a major change. 

§ 68.56 Maintenance.

 (a) The owner or operator shall prepare and implement procedures to maintain the on-going 

mechanical integrity of the process equipment. The owner or operator may use procedures or 

instructions provided by covered process equipment vendors or procedures in Federal or state 

regulations or industry codes as the basis for stationary source maintenance procedures.

 (b) The owner or operator shall train or cause to be trained each employee involved in 

maintaining the on-going mechanical integrity of the process. To ensure that the employee can 

perform the job tasks in a safe manner, each such employee shall be trained in the hazards of the 

process, in how to avoid or correct unsafe conditions, and in the procedures applicable to the 

employee's job tasks.

 (c) Any maintenance contractor shall ensure that each contract maintenance employee is 

trained to perform the maintenance procedures developed under paragraph (a) of this section.

 (d) The owner or operator shall perform or cause to be performed inspections and tests on 

process equipment. Inspection and testing procedures shall follow recognized and generally 

accepted good engineering practices. The frequency of inspections and tests of process 

equipment shall be consistent with applicable manufacturers' recommendations, industry 
standards or codes, good engineering practices, and prior operating experience. 

§ 68.58 Compliance audits.

 (a) The owner or operator shall certify that they have evaluated compliance with the provisions 

of this subpart at least every three years to verify that the procedures and practices developed 

under the rule are adequate and are being followed.

 (b) The compliance audit shall be conducted by at least one person knowledgeable in the 

process.

 (c) The owner or operator shall develop a report of the audit findings.

 (d) The owner or operator shall promptly determine and document an appropriate response to 

each of the findings of the compliance audit and document that deficiencies have been corrected.

 (e) The owner or operator shall retain the two (2) most recent compliance audit reports. This 

requirement does not apply to any compliance audit report that is more than five years old. 

§ 68.60 Incident investigation.

 (a) The owner or operator shall investigate each incident which resulted in, or could 

reasonably have resulted in a catastrophic release.

 (b) An incident investigation shall be initiated as promptly as possible, but not later than 48 

hours following the incident.

 (c) A summary shall be prepared at the conclusion of the investigation which includes at a 

minimum:

 (1) Date of incident;

 (2) Date investigation began;

 (3) A description of the incident;

 (4) The factors that contributed to the incident; and,

 (5) Any recommendations resulting from the investigation.

 (d) The owner or operator shall promptly address and resolve the investigation findings and 

recommendations. Resolutions and corrective actions shall be documented.

 (e) The findings shall be reviewed with all affected personnel whose job tasks are affected by 

the findings.

 (f) Investigation summaries shall be retained for five years.

 Subpart D - Program 3 Prevention Program

 Source: 61 FR 31722, June 20, 1996, unless otherwise noted. 

§ 68.65 Process safety information.

 (a) In accordance with the schedule set forth in § 68.67, the owner or operator shall complete a 

compilation of written process safety information before conducting any process hazard analysis 

required by the rule. The compilation of written process safety information is to enable the owner 

or operator and the employees involved in operating the process to identify and understand the 

hazards posed by those processes involving regulated substances. This process safety information 
shall include information pertaining to the hazards of the regulated substances used or produced 

by the process, information pertaining to the technology of the process, and information 

pertaining to the equipment in the process.

 (b) Information pertaining to the hazards of the regulated substances in the process. This 

information shall consist of at least the following:

 (1) Toxicity information;

 (2) Permissible exposure limits;


 (3) Physical data;


 (4) Reactivity data:


 (5) Corrosivity data;


 (6) Thermal and chemical stability data; and


 (7) Hazardous effects of inadvertent mixing of different materials that could foreseeably occur.


 Note to paragraph (b):


 Material Safety Data Sheets meeting the requirements of 29 CFR 1910.1200(g) may be used to


comply with this requirement to the extent they contain the information required by this 

subparagraph.

 (c) Information pertaining to the technology of the process.

 (1) Information concerning the technology of the process shall include at least the following:

 (i) A block flow diagram or simplified process flow diagram;

 (ii) Process chemistry;

 (iii) Maximum intended inventory;

 (iv) Safe upper and lower limits for such items as temperatures, pressures, flows or 

compositions; and,

 (v) An evaluation of the consequences of deviations.

 (2) Where the original technical information no longer exists, such information may be 

developed in conjunction with the process hazard analysis in sufficient detail to support the 

analysis.

 (d) Information pertaining to the equipment in the process.

 (1) Information pertaining to the equipment in the process shall include:

 (i) Materials of construction;

 (ii) Piping and instrument diagrams (P&ID's);

 (iii) Electrical classification;

 (iv) Relief system design and design basis;

 (v) Ventilation system design;

 (vi) Design codes and standards employed;

 (vii) Material and energy balances for processes built after June 21, 1999; and

 (viii) Safety systems (e.g. interlocks, detection or suppression systems).

 (2) The owner or operator shall document that equipment complies with recognized and 

generally accepted good engineering practices.

 (3) For existing equipment designed and constructed in accordance with codes, standards, or 

practices that are no longer in general use, the owner or operator shall determine and document 

that the equipment is designed, maintained, inspected, tested, and operating in a safe manner. 

§ 68.67 Process hazard analysis. 
 (a) The owner or operator shall perform an initial process hazard analysis (hazard evaluation) 

on processes covered by this part. The process hazard analysis shall be appropriate to the 

complexity of the process and shall identify, evaluate, and control the hazards involved in the 

process. The owner or operator shall determine and document the priority order for conducting 

process hazard analyses based on a rationale which includes such considerations as extent of the 

process hazards, number of potentially affected employees, age of the process, and operating 

history of the process. The process hazard analysis shall be conducted as soon as possible, but not 

later than June 21, 1999. Process hazards analyses completed to comply with 29 CFR 

1910.119(e) are acceptable as initial process hazards analyses. These process hazard analyses 

shall be updated and revalidated, based on their completion date.

 (b) The owner or operator shall use one or more of the following methodologies that are 

appropriate to determine and evaluate the hazards of the process being analyzed.

 (1) What-If;

 (2) Checklist;

 (3) What-If/Checklist;

 (4) Hazard and Operability Study (HAZOP);

 (5) Failure Mode and Effects Analysis (FMEA);

 (6) Fault Tree Analysis; or

 (7) An appropriate equivalent methodology.

 (c) The process hazard analysis shall address:

 (1) The hazards of the process;

 (2) The identification of any previous incident which had a likely potential for catastrophic 

consequences.

 (3) Engineering and administrative controls applicable to the hazards and their 

interrelationships such as appropriate application of detection methodologies to provide early 

warning of releases. (Acceptable detection methods might include process monitoring and 

control instrumentation with alarms, and detection hardware such as hydrocarbon sensors.);

 (4) Consequences of failure of engineering and administrative controls;

 (5) Stationary source siting;

 (6) Human factors; and

 (7) A qualitative evaluation of a range of the possible safety and health effects of failure of 

controls.

 (d) The process hazard analysis shall be performed by a team with expertise in engineering and 

process operations, and the team shall include at least one employee who has experience and 

knowledge specific to the process being evaluated. Also, one member of the team must 

beknowledgeable in the specific process hazard analysis methodology being used.

 (e) The owner or operator shall establish a system to promptly address the team's findings and 

recommendations; assure that the recommendations are resolved in a timely manner and that the 

resolution is documented; document what actions are to be taken; complete actions as soon as 

possible; develop a written schedule of when these actions are to be completed; communicate the 

actions to operating, maintenance and other employees whose work assignments are in the 

process and who may be affected by the recommendations or actions.

 (f) At least every five (5) years after the completion of the initial process hazard analysis, the 

process hazard analysis shall be updated and revalidated by a team meeting the requirements in 

paragraph (d) of this section, to assure that the process hazard analysis is consistent with the 
current process. Updated and revalidated process hazard analyses completed to comply with 29 

CFR 1910.119(e) are acceptable to meet the requirements of this paragraph.

 (g) The owner or operator shall retain process hazards analyses and updates or revalidations 

for each process covered by this section, as well as the documented resolution of 

recommendations described in paragraph (e) of this section for the life of the process. 

§ 68.69 Operating procedures.

 (a) The owner or operator shall develop and implement written operating procedures that 

provide clear instructions for safely conducting activities involved in each covered process 

consistent with the process safety information and shall address at least the following elements.

 (1) Steps for each operating phase:

 (i) Initial startup;

 (ii) Normal operations;

 (iii) Temporary operations;

 (iv) Emergency shutdown including the conditions under which emergency shutdown is 

required, and the assignment of shutdown responsibility to qualified operators to ensure that 

emergency shutdown is executed in a safe and timely manner.

 (v) Emergency operations;

 (vi) Normal shutdown; and,

 (vii) Startup following a turnaround, or after an emergency shutdown.

 (2) Operating limits:

 (i) Consequences of deviation; and

 (ii) Steps required to correct or avoid deviation.

 (3) Safety and health considerations:

 (i) Properties of, and hazards presented by, the chemicals used in the process;

 (ii) Precautions necessary to prevent exposure, including engineering controls, administrative 

controls, and personal protective equipment;

 (iii) Control measures to be taken if physical contact or airborne exposure occurs;

 (iv) Quality control for raw materials and control of hazardous chemical inventory levels; and,

 (v) Any special or unique hazards.

 (4) Safety systems and their functions.

 (b) Operating procedures shall be readily accessible to employees who work in or maintain a 

process.

 (c) The operating procedures shall be reviewed as often as necessary to assure that they reflect 

current operating practice, including changes that result from changes in process chemicals, 

technology, and equipment, and changes to stationary sources. The owner or operator shall 

certify annually that these operating procedures are current and accurate.

 (d) The owner or operator shall develop and implement safe work practices to provide for the 

control of hazards during operations such as lockout/tagout; confined space entry; opening 

process equipment or piping; and control over entrance into a stationary source by maintenance, 

contractor, laboratory, or other support personnel. These safe work practices shall apply to 

employees and contractor employees. 

§ 68.71 Training. 
 (a) Initial training. (1) Each employee presently involved in operating a process, and each 

employee before being involved in operating a newly assigned process, shall be trained in an 

overviewof the process and in the operating procedures as specified in § 68.69. The training shall 

include emphasis on the specific safety and health hazards, emergency operations including 

shutdown, and safe work practices applicable to the employee's job tasks.

 (2) In lieu of initial training for those employees already involved in operating a process on 

June 21, 1999 an owner or operator may certify in writing that the employee has the required 

knowledge, skills, and abilities to safely carry out the duties and responsibilities as specified in 

the operating procedures.

 (b) Refresher training. Refresher training shall be provided at least every three years, and more 

often if necessary, to each employee involved in operating a process to assure that the employee 

understands and adheres to the current operating procedures of the process. The owner or 

operator, in consultation with the employees involved in operating the process, shall determine 

the appropriate frequency of refresher training.

 (c) Training documentation. The owner or operator shall ascertain that each employee 

involved in operating a process has received and understood the training required by this 

paragraph. The owner or operator shall prepare a record which contains the identity of the 

employee, the date of training, and the means used to verify that the employee understood the 

training. 

§ 68.73 Mechanical integrity.

 (a) Application. Paragraphs (b) through (f) of this section apply to the following process 

equipment:

 (1) Pressure vessels and storage tanks;

 (2) Piping systems (including piping components such as valves);

 (3) Relief and vent systems and devices;

 (4) Emergency shutdown systems;

 (5) Controls (including monitoring devices and sensors, alarms, and interlocks) and,

 (6) Pumps.

 (b) Written procedures. The owner or operator shall establish and implement written 

procedures to maintain the on-going integrity of process equipment.

 (c) Training for process maintenance activities. The owner or operator shall train each 

employee involved in maintaining the on-going integrity of process equipment in an overview of 

that process and its hazards and in the procedures applicable to the employee's job tasks to assure 

that the employee can perform the job tasks in a safe manner.

 (d) Inspection and testing. (1) Inspections and tests shall be performed on process equipment.

 (2) Inspection and testing procedures shall follow recognized and generally accepted good 

engineering practices.

 (3) The frequency of inspections and tests of process equipment shall be consistent with 

applicable manufacturers' 

recommendations and good engineering practices, and more frequently if determined to be 

necessary by prior operating experience.

 (4) The owner or operator shall document each inspection and test that has been performed on 

process equipment. The documentation shall identify the date of the inspection or test, the name 
of the person who performed the inspection or test, the serial number or other identifier of the 

equipment on which the inspection or test was performed, a description of the inspection or test 

performed, and the results of the inspection or test.

 (e) Equipment deficiencies. The owner or operator shall correct deficiencies in equipment that 

are outside acceptable limits (defined by the process safety information in § 68.65) before further 

use or in a safe and timely manner when necessary means are taken to assure safe operation.

 (f) Quality assurance. (1) In the construction of new plants and equipment, the owner or 

operator shall assure that equipment as it is fabricated is suitable for the process application for 

which they will be used.

 (2) Appropriate checks and inspections shall be performed to assure that equipment is installed 

properly and consistent with design specifications and the manufacturer's instructions.

 (3) The owner or operator shall assure that maintenance materials, spare parts and equipment 

are suitable for the process application for which they will be used. 

§ 68.75 Management of change.

 (a) The owner or operator shall establish and implement written procedures to manage changes 

(except for ``replacements in kind'') to process chemicals, technology, equipment, and 

procedures; and, changes to stationary sources that affect a covered process.

 (b) The procedures shall assure that the following considerations are addressed prior to any 

change:

 (1) The technical basis for the proposed change;

 (2) Impact of change on safety and health;

 (3) Modifications to operating procedures;

 (4) Necessary time period for the change; and,

 (5) Authorization requirements for the proposed change.

 (c) Employees involved in operating a process and maintenance and contract employees whose 

job tasks will be affected by a change in the process shall be informed of, and trained in, the 

change prior to start-up of the process or affected part of the process.

 (d) If a change covered by this paragraph results in a change in the process safety information 

required by § 68.65 of this part, such information shall be updated accordingly.

 (e) If a change covered by this paragraph results in a change in the operating procedures or 

practices required by § 68.69, such procedures or practices shall be updated accordingly. 

§ 68.77 Pre-startup review.

 (a) The owner or operator shall perform a pre-startup safety review for new stationary sources 

and for modified stationary sources when the modification is significant enough to require a 

change in the process safety information.

 (b) The pre-startup safety review shall confirm that prior to the introduction of regulated 

substances to a process:

 (1) Construction and equipment is in accordance with design specifications;

 (2) Safety, operating, maintenance, and emergency procedures are in place and are adequate;

 (3) For new stationary sources, a process hazard analysis has been performed and 

recommendations have been resolved or implemented before startup; and modified stationary 
sources meet the requirements contained in management of change, § 68.75.

 (4) Training of each employee involved in operating a process has been completed. 

§ 68.79 Compliance audits.

 (a) The owner or operator shall certify that they have evaluated compliance with the provisions 

of this subpart at least every three years to verify that procedures and practices developed under 

this subpart are adequate and are being followed.

 (b) The compliance audit shall be conducted by at least one person knowledgeable in the 

process.

 (c) A report of the findings of the audit shall be developed.

 (d) The owner or operator shall promptly determine and document an appropriate response to 

each of the findings of the compliance audit, and document that deficiencies have been corrected.

 (e) The owner or operator shall retain the two (2) most recent compliance audit reports. 

[61 FR 31722, June 20, 1996, as amended at 64 FR 979, Jan. 6, 1999] 

§ 68.81 Incident investigation.

 (a) The owner or operator shall investigate each incident which resulted in, or could 

reasonably have resulted in a catastrophic release of a regulated substance.

 (b) An incident investigation shall be initiated as promptly as possible, but not later than 48 

hours following the incident.

 (c) An incident investigation team shall be established and consist of at least one person 

knowledgeable in the process involved, including a contract employee if the incident involved 

work of the contractor, and other persons with appropriate knowledge and experience to 

thoroughly investigate and analyze the incident.

 (d) A report shall be prepared at the conclusion of the investigation which includes at a 

minimum:

 (1) Date of incident;

 (2) Date investigation began;

 (3) A description of the incident;

 (4) The factors that contributed to the incident; and,

 (5) Any recommendations resulting from the investigation.

 (e) The owner or operator shall establish a system to promptly address and resolve the incident 

report findings and recommendations. Resolutions and corrective actions shall be documented.

 (f) The report shall be reviewed with all affected personnel whose job tasks are relevant to the 

incident findings including contract employees where applicable.

 (g) Incident investigation reports shall be retained for five years. 

§ 68.83 Employee participation.

 (a) The owner or operator shall develop a written plan of action regarding the implementation 

of the employee participation required by this section.

 (b) The owner or operator shall consult with employees and their representatives on the 
conduct and development of process hazards analyses and on the development of the other 

elements of process safety management in this rule.

 (c) The owner or operator shall provide to employees and their representatives access to 

process hazard analyses and to all other information required to be developed under this rule. 

§ 68.85 Hot work permit.

 (a) The owner or operator shall issue a hot work permit for hot work operations conducted on 

or near a covered process.

 (b) The permit shall document that the fire prevention and protection requirements in 29 CFR 

1910.252(a) have been implemented prior to beginning the hot work operations; it shall indicate 

the date(s) authorized for hot work; and identify the object on which hot work is to be performed. 

The permit shall be kept on file until completion of the hot work operations. 

§ 68.87 Contractors.

 (a) Application. This section applies to contractors performing maintenance or repair, 

turnaround, major renovation, or specialty work on or adjacent to a covered process. It does not 

apply to contractors providing incidental services which do not influence process safety, such as 

janitorial work, food and drink services, laundry, delivery or other supply services.

 (b) Owner or operator responsibilities. (1) The owner or operator, when selecting a contractor, 

shall obtain and evaluate information regarding the contract owner or operator's safety 

performance and programs.

 (2) The owner or operator shall inform contract owner or operator of the known potential fire, 

explosion, or toxic release hazards related to the contractor's work and the process.

 (3) The owner or operator shall explain to the contract owner or operator the applicable 

provisions of subpart E of this part.

 (4) The owner or operator shall develop and implement safe work practices consistent with § 

68.69(d), to control the entrance, presence, and exit of the contract owner or operator and 

contract employees in covered process areas.

 (5) The owner or operator shall periodically evaluate the performance of the contract owner or 

operator in fulfilling their obligations as specified in paragraph (c) of this section.

 (c) Contract owner or operator responsibilities. (1) The contract owner or operator shall assure 

that each contract employee is trained in the work practices necessary to safely perform his/her 

job.

 (2) The contract owner or operator shall assure that each contract employee is instructed in the 

known potential fire, explosion, or toxic release hazards related to his/her job and the process, 

and the applicable provisions of the emergency action plan.

 (3) The contract owner or operator shall document that each contract employee has received 

and understood the training required by this section. The contract owner or operator shall prepare 

a record which contains the identity of the contract employee, the date of training, and the means 

used to verify that the employee understood the training.

 (4) The contract owner or operator shall assure that each contract employee follows the safety 

rules of the stationary source including the safe work practices required by § 68.69(d).

 (5) The contract owner or operator shall advise the owner or operator of any unique hazards 
presented by the contract owner or operator's work, or of any hazards found by the contract 

owner or operator's work.

 Subpart E - Emergency Response

 Source: 61 FR 31725, June 20, 1996, unless otherwise noted. 

§ 68.90 Applicability.

 (a) Except as provided in paragraph (b) of this section, the owner or operator of a stationary 

source with Program 2 and Program 3 processes shall comply with the requirements of § 68.95.

 (b) The owner or operator of stationary source whose employees will not respond to accidental 

releases of regulated substances need not comply with § 68.95 of this part provided that they 

meet the following:

 (1) For stationary sources with any regulated toxic substance held in a process above the 

threshold quantity, the stationary source is included in the community emergency response plan 

developed under 42 U.S.C. 11003;

 (2) For stationary sources with only regulated flammable substances held in a process above 

the threshold quantity, the owner or operator has coordinated response actions with the local fire 

department; and

 (3) Appropriate mechanisms are in place to notify emergency responders when there is a need 

for a response. 

§ 68.95 Emergency response program.

 (a) The owner or operator shall develop and implement an emergency response program for 

the purpose of protecting public health and the environment. Such program shall include the 

following elements:

 (1) An emergency response plan, which shall be maintained at the stationary source and 

contain at least the following elements:

 (i) Procedures for informing the public and local emergency response agencies about 

accidental releases;

 (ii) Documentation of proper first-aid and emergency medical treatment necessary to treat 

accidental human exposures; and

 (iii) Procedures and measures for emergency response after an accidental release of a regulated 

substance;

 (2) Procedures for the use of emergency response equipment and for its inspection, testing, and 

maintenance;

 (3) Training for all employees in relevant procedures; and

 (4) Procedures to review and update, as appropriate, the emergency response plan to reflect 

changes at the stationary source and ensure that employees are informed of changes.

 (b) A written plan that complies with other Federal contingency plan regulations or is 

consistent with the approach in the National Response Team's Integrated Contingency Plan 

Guidance (``One Plan'') and that, among other matters, includes the elements provided in 

paragraph (a) of this section, shall satisfy the requirements of this section if the owner or operator 
also complies with paragraph (c) of this section.

 (c) The emergency response plan developed under paragraph (a)(1) of this section shall be 

coordinated with the community emergency response plan developed under 42 U.S.C. 11003. 

Upon request of the local emergency planning committee or emergency response officials, the 

owner or operator shall promptly provide to the local emergency response officials information 

necessary for developing and implementing the community emergency response plan.

 Subpart F - Regulated Substances for Accidental Release Prevention

 Source: 59 FR 4493, Jan. 31, 1994, unless otherwise noted. 

Redesignated at 61 FR 31717, June 20, 1996. 

§ 68.100 Purpose.

 This subpart designates substances to be listed under section 112(r)(3), (4), and (5) of the 

Clean Air Act, as amended, identifies their threshold quantities, and establishes the requirements 

for petitioning to add or delete substances from the list. 

§ 68.115 Threshold determination.

 (a) A threshold quantity of a regulated substance listed in § 68.130 is present at a stationary 

source if the total quantity ofthe regulated substance contained in a process exceeds the 

threshold.

 (b) For the purposes of determining whether more than a threshold quantity of a regulated 

substance is present at the stationary source, the following exemptions apply:

 (1) Concentrations of a regulated toxic substance in a mixture. If a regulated substance is 

present in a mixture and the concentration of the substance is below one percent by weight of the 

mixture, the amount of the substance in the mixture need not be considered when determining 

whether more than a threshold quantity is present at the stationary source. Except for oleum, 

toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, and toluene diisocyanate (unspecified 

isomer), if the concentration of the regulated substance in the mixture is one percent or greater by 

weight, but the owner or operator can demonstrate that the partial pressure of the regulated 

substance in the mixture (solution) under handling or storage conditions in any portion of the 

process is less than 10 millimeters of mercury (mm Hg), the amount of the substance in the 

mixture in that portion of the process need not be considered when determining whether more 

than a threshold quantity is present at the stationary source. The owner or operator shall 

document this partial pressure measurement or estimate.

 (2) Concentrations of a regulated flammable substance in a mixture. (i) General provision. If a 

regulated substance is present in a mixture and the concentration of the substance is below one 

percent by weight of the mixture, the mixture need not be considered when determining whether 

more than a threshold quantity of the regulated substance is present at the stationary source. 

Except as provided in paragraph (b)(2) (ii) and (iii) of this section, if the concentration of the 

substance is one percent or greater by weight of the mixture, then, for purposes of determining 

whether a threshold quantity is present at the stationary source, the entire weight of the mixture 

shall be treated as the regulated substance unless the owner or operator can demonstrate that the 
mixture itself does not have a National Fire Protection Association flammability hazard rating of 

4. The demonstration shall be in accordance with the definition of flammability hazard rating 4 in 

the NFPA 704, Standard System for the Identification of the Hazards of Materials for Emergency 

Response, National Fire Protection Association, Quincy, MA, 1996. Available from the National 

Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02269-9101. This incorporation 

by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 

552(a) and 1 CFR part 51. Copies may be inspected at the Environmental Protection Agency Air 

Docket (6102), Attn: Docket No. A-96-O8, Waterside Mall, 401 M. St. SW., Washington DC; or 

at the Office of Federal Register at 800 North Capitol St., NW, Suite 700, Washington, DC. 

Boiling point and flash point shall be defined and determined in accordance with NFPA 30, 

Flammable and Combustible Liquids Code, National Fire Protection Association, Quincy, MA, 

1996. Available from the National Fire Protection Association, 1 Batterymarch Park, Quincy, 

MA 02269-9101. This incorporation by reference was approved by the Director of the Federal 

Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be inspected at the 

Environmental Protection Agency Air Docket (6102), Attn: Docket No. A-96-O8, Waterside 

Mall, 401 M. St. SW., Washington DC; or at the Office of Federal Register at 800 North Capitol 

St., NW., Suite 700, Washington, DC. The owner or operator shall document the National Fire 

Protection Association flammability hazard rating.

 (ii) Gasoline. Regulated substances in gasoline, when in distribution or related storage for use 

as fuel for internal combustion engines, need not be considered when determining whether more 

than a threshold quantity is present at a stationary source.

 (iii) Naturally occurring hydrocarbon mixtures. Prior to entry into a natural gas processing 

plant or a petroleum refining process unit, regulated substances in naturally occurring 

hydrocarbon mixtures need not be considered when determining whether more than a threshold 

quantity is present at a stationary source. Naturally occurringhydrocarbon mixtures include any 

combination of the following: condensate, crude oil, field gas, and produced water, each as 

defined in § 68.3 of this part.

 (3) Articles. Regulated substances contained in articles need not be considered when 

determining whether more than a threshold quantity is present at the stationary source.

 (4) Uses. Regulated substances, when in use for the following purposes, need not be included 

in determining whether more than a threshold quantity is present at the stationary source:

 (i) Use as a structural component of the stationary source;

 (ii) Use of products for routine janitorial maintenance;

 (iii) Use by employees of foods, drugs, cosmetics, or other personal items containing the 

regulated substance; and

 (iv) Use of regulated substances present in process water or non-contact cooling water as 

drawn from the environment or municipal sources, or use of regulated substances present in air 

used either as compressed air or as part of combustion.

 (5) Activities in laboratories. If a regulated substance is manufactured, processed, or used in a 

laboratory at a stationary source under the supervision of a technically qualified individual as 

defined in § 720.3(ee) of this chapter, the quantity of the substance need not be considered in 

determining whether a threshold quantity is present. This exemption does not apply to:

 (i) Specialty chemical production;

 (ii) Manufacture, processing, or use of substances in pilot plant scale operations; and

 (iii) Activities conducted outside the laboratory. 
[59 FR 4493, Jan. 31, 1994. Redesignated at 61 FR 31717, June 20, 1996, as amended at 63 FR 

645, Jan. 6, 1998] 

§ 68.120 Petition process.

 (a) Any person may petition the Administrator to modify, by addition or deletion, the list of 

regulated substances identified in § 68.130. Based on the information presented by the petitioner, 

the Administrator may grant or deny a petition.

 (b) A substance may be added to the list if, in the case of an accidental release, it is known to 

cause or may be reasonably anticipated to cause death, injury, or serious adverse effects to human 

health or the environment.

 (c) A substance may be deleted from the list if adequate data on the health and environmental 

effects of the substance are available to determine that the substance, in the case of an accidental 

release, is not known to cause and may not be reasonably anticipated to cause death, injury, or 

serious adverse effects to human health or the environment.

 (d) No substance for which a national primary ambient air quality standard has been 

established shall be added to the list. No substance regulated under title VI of the Clean Air Act, 

as amended, shall be added to the list.

 (e) The burden of proof is on the petitioner to demonstrate that the criteria for addition and 

deletion are met. A petition will be denied if this demonstration is not made.

 (f) The Administrator will not accept additional petitions on the same substance following 

publication of a final notice of the decision to grant or deny a petition, unless new data becomes 

available that could significantly affect the basis for the decision.

 (g) Petitions to modify the list of regulated substances must contain the following:

 (1) Name and address of the petitioner and a brief description of the organization(s) that the 

petitioner represents, if applicable;

 (2) Name, address, and telephone number of a contact person for the petition;

 (3) Common chemical name(s), common synonym(s), Chemical Abstracts Service number, 

and chemical formula and structure;

 (4) Action requested (add or delete a substance);

 (5) Rationale supporting the petitioner's position; that is, how the substance meets the criteria 

for addition and deletion. A short summary of the rationale must be submitted along with a more 

detailed narrative; and

 (6) Supporting data; that is, the petition must include sufficient information to scientifically 

support the request to modify the list. Such information shall include:

 (i) A list of all support documents;

 (ii) Documentation of literature searches conducted, including, but not limited to, 

identification of the database(s) searched, the search strategy, dates covered, and printed results;

 (iii) Effects data (animal, human, and environmental test data) indicating the potential for 

death, injury, or serious adverse human and environmental impacts from acute exposure 

following an accidental release; printed copies of the data sources, in English, should be 

provided; and

 (iv) Exposure data or previous accident history data, indicating the potential for serious 

adverse human health or environmental effects from an accidental release. These data may 

include, but are not limited to, physical and chemical properties of the substance, such as vapor 
-------------------------------------------------------------------------------------------------------

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pressure; modeling results, including data and assumptions used and model documentation; and 

historical accident data, citing data sources.

 (h) Within 18 months of receipt of a petition, the Administrator shall publish in the Federal 

Register a notice either denying the petition or granting the petition and proposing a listing. 

§ 68.125 Exemptions.

 Agricultural nutrients. Ammonia used as an agricultural nutrient, when held by farmers, is 

exempt from all provisions of this part. 

§ 68.126 Exclusion.

 Flammable Substances Used as Fuel or Held for Sale as Fuel at Retail Facilities. A flammable 

substance listed in Tables 3 and 4 of § 68.130 is nevertheless excluded from all provisions of this 

part when the substance is used as a fuel or held for sale as a fuel at a retail facility. 

[65 FR 13250, Mar. 13, 2000] 

§ 68.130 List of substances.

 (a) Regulated toxic and flammable substances under section 112(r) of the Clean Air Act are 

the substances listed in Tables 1, 2, 3, and 4. Threshold quantities for listed toxic and flammable 

substances are specified in the tables.

 (b) The basis for placing toxic and flammable substances on the list of regulated substances are 

explained in the notes to the list.

 Table 1 to § 68.130 - List of Regulated Toxic Substances and Threshold Quantities for 

Accidental Release Prevention

 [Alphabetical Order - 77 Substances] 

CAS No. Threshold Basis for 

Chemical name quantity listing 

(lbs) 

Acrolein [2-Propenal] 107-02-8 5,000 b 

Acrylonitrile [2- Propenenitrile] 107-13-1 20,000 b 

Acrylyl chloride [2-Propenoyl chloride] 814-68-6 5,000 b 

Allyl alcohol [2-Propen-l-ol] 107-18-61 15,000 b 

Allylamine [2-Propen-l-amine] 107-11-9 10,000 b 

Ammonia (anhydrous) 7664-41-7 10,000 a, b 

Ammonia (conc 20% or greater) 7664-41-7 20,000 a, b 

Arsenous trichloride 7784-34-1 15,000 b 

Arsine 7784-42-1 1,000 b 

Boron trichloride [Borane, trichloro-] 10294-34-5 5,000 b 

Boron trifluoride [Borane, trifluoro-] 7637-07-2 5,000 b 
Boron trifluoride compound with methyl 353-42-4 15,000 b 

ether (1:1) [Boron, trifluoro [oxybis [metane]]-, T-4-] 

Bromine 7726-95-6 10,000 a, b 

Carbon disulfide 75-15-0 20,000 b 

Chlorine 7782-50-5 2,500 a, b 

Chlorine dioxide [Chlorine oxide (ClO2)] 10049-04-4 1,000 c 

Chloroform [Methane, trichloro-] 67-66-3 20,000 b 

Chloromethyl ether [Methane, 542-88-1 1,000 b 

oxybis[chloro-] 

Chloromethyl methyl ether [Methane, 107-30-2 5,000 b 

chloromethoxy-] 

Crotonaldehyde [2-Butenal] 4170-30-3 20,000 b 

Crotonaldehyde, (E)- [2-Butenal, (E)-] 123-73-9 20,000 b 

Cyanogen chloride 506-77-4 10,000 c 

Cyclohexylamine [Cyclohexanamine] 108-91-8 15,000 b 

Diborane 19287-45-7 2,500 b 

Dimethyldichlorosilane [Silane, 75-78-5 5,000 b 

dichlorodimethyl-] 

1,1-Dimethylhydrazine [Hydrazine, 57-14-7 15,000 b 

1,1-dimethyl-] 

Epichlorohydrin [Oxirane, (chloromethyl)-] 106-89-8 20,000 b 

Ethylenediamine [1,2- Ethanediamine] 107-15-3 20,000 b 

Ethyleneimine [Aziridine] 151-56-4 10,000 b 

Ethylene oxide [Oxirane] 75-21-8 10,000 a, b 

Fluorine 7782-41-4 1,000 b 

Formaldehyde (solution) 50-00-0 15,000 b 

Furan 110-00-9 5,000 b 

Hydrazine 302-01-2 15,000 b 

Hydrochloric acid (conc 37% or greater) 7647-01-0 15,000 d 

Hydrocyanic acid 74-90-8 2,500 a, b 

Hydrogen chloride (anhydrous) 7647-01-0 5,000 a 

[Hydrochloric acid]. 

Hydrogen fluoride/Hydrofluoric acid 7664-39-3 1,000 a, b 

(conc 50% or greater) [Hydrofluoric acid] 

Hydrogen selenide 7783-07-5 500 b 

Hydrogen sulfide 7783-06-4 10,000 a, b 

Iron, pentacarbonyl- [Iron carbonyl 13463-40-6 2,500 b 

(Fe(CO)5), (TB-5-11)-] 

Isobutyronitrile [Propanenitrile, 78-82-0 20,000 b 

2-methyl-] 

Isopropyl chloroformate [Carbonochloridic 108-23-6 15,000 b 

acid, 1- methylethyl ester] 

Methacrylonitrile [2- Propenenitrile, 126-98-7 10,000 b 

2-methyl-] 

Methyl chloride [Methane, chloro-] 74-87-3 10,000 a 
Methyl chloroformate [Carbonochloridic 79-22-1 5,000 b 

acid, methylester] 

Methyl hydrazine [Hydrazine, methyl-] 60-34-4 15,000 b 

Methyl isocyanate [Methane, isocyanato-] 624-83-9 10,000 a, b 

Methyl mercaptan [Methanethiol] 74-93-1 10,000 b 

Methyl thiocyanate [Thiocyanic acid, 556-64-9 20,000 b 

methyl ester] 

Methyltrichlorosilane [Silane, 75-79-6 5,000 b 

trichloromethyl-]. 

Nickel carbonyl 13463-39-3 1,000 b 

Nitric acid (conc 80% or greater) 7697-37-2 15,000 b 

Nitric oxide [Nitrogen oxide (NO)] 10102-43-9 10,000 b 

Oleum (Fuming Sulfuric acid) 8014-95-7 10,000 e 

[Sulfuric acid, mixture with sulfur trioxide] \1\. 

Peracetic acid [Ethaneperoxoic acid] 79-21-0 10,000 b 

Perchloromethylmercaptan 594-42-3 10,000 b 

[Methanesulfenyl chloride, trichloro-] 

Phosgene [Carbonic dichloride] 75-44-5 500 a, b 

Phosphine 7803-51-2 5,000 b 

Phosphorus oxychloride [Phosphoryl 10025-87-3 5,000 b 

chloride] 

Phosphorus trichloride [Phosphorous 7719-12-2 15,000 b 

trichloride]. 

Piperidine 110-89-4 15,000 b 

Propionitrile [Propanenitrile] 107-12-0 10,000 b 

Propyl chloroformate [Carbonochloridic 109-61-5 15,000 b 

acid, propylester] 

Propyleneimine [Aziridine, 2-methyl-] 75-55-8 10,000 b 

Propylene oxide [Oxirane, methyl-] 75-56-9 10,000 b 

Sulfur dioxide (anhydrous) 7446-09-5 5,000 a, b 

Sulfur tetrafluoride [Sulfur fluoride 7783-60-0 2,500 b 

(SF4), (T-4)-] 

Sulfur trioxide 7446-11-9 10,000 a, b 

Tetramethyllead [Plumbane, tetramethyl-] 75-74-1 10,000 b 

Tetranitromethane [Methane, tetranitro-] 509-14-8 10,000 b 

Titanium tetrachloride [Titanium chloride 7550-45-0 2,500 b 

(TiCl4) (T- 4)-] 

Toluene 2,4-diisocyanate [Benzene, 584-84-9 10,000 a 

2,4-diisocyanato-1-methyl-] \1\. 

Toluene 2,6-diisocyanate [Benzene, 91-08-7 10,000 a 

1,3-diisocyanato-2-methyl-] \1\. 

Toluene diisocyanate (unspecified 26471-62-5 10,000 a 

isomer) [Benzene, 1,3-diisocyanatomethyl-] \1\. 

Trimethylchlorosilane [Silane, 75-77-4 10,000 b 

chlorotrimethyl-] 
----------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------

Vinyl acetate monomer [Acetic 108-05-4 15,000 b 

acid ethenyl ester]. 

\1\ The mixture exemption in § 68.115(b)(1) does not apply


 to the substance.


Note: Basis for Listing:


a Mandated for listing by Congress.


b On EHS list, vapor pressure 10 mmHg or greater.


c Toxic gas.


d Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.


e Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of


accidents.


 Table 2 to § 68.130 - List of Regulated Toxic Substances and Threshold Quantities for 

Accidental Release Prevention

 [CAS Number Order - 77 Substances] 

Chemical name Threshold Basis for 

CAS No. quantity listing 

(lbs) 

50-00-0 Formaldehyde (solution) 15,000 b 

57-14-7 1,1-Dimethylhydrazine 15,000 b 

[Hydrazine, 1,1-dimethyl-] 

60-34-4 Methyl hydrazine 

[Hydrazine, methyl-]. 

15,000 b 

67-66-3 Chloroform 20,000 b 

[Methane, trichloro-] 

74-87-3 Methyl chloride 10,000 a 

74-90-8 

[Methane, chloro-]. 

Hydrocyanic acid 2,500 a, b 

74-93-1 Methyl mercaptan 10,000 b 

75-15-0 

[Methanethiol] 

Carbon disulfide 20,000 b 

75-21-8 Ethylene oxide 10,000 a, b 

[Oxirane]. 

75-44-5 Phosgene 500 a, b 

75-55-8 

[Carbonic dichloride] 

Propyleneimine 10,000 b 

[Aziridine, 2-methyl-] 

75-56-9 Propylene oxide 10,000 b 

[Oxirane, methyl-] 

75-74-1 Tetramethyllead 10,000 b 
[Plumbane, tetramethyl-] 

75-77-4 Trimethylchlorosilane 10,000 b 

[Silane, chlorotrimethyl-] 

75-78-5 Dimethyldichlorosilane 5,000 b 

[Silane, dichlorodimethyl-] 

75-79-6 Methyltrichlorosilane 5,000 b 

[Silane, trichloromethyl-] 

78-82-0 Isobutyronitrile 20,000 b 

[Propanenitrile, 2- methyl-] 

79-21-0 Peracetic acid 10,000 b 

[Ethaneperoxoic acid]. 

79-22-1 Methyl chloroformate 5,000 b 

[Carbonochloridic acid, methylester]. 

91-08-7 Toluene 2,6-diisocyanate 10,000 a 

[Benzene, 1,3-diisocyanato-2-methyl-]\1\. 

106-89-8 Epichlorohydrin 20,000 b 

[Oxirane, (chloromethyl)-] 

107-02-8 Acrolein [2-Propenal] 5,000 b 

107-11-9 Allylamine 10,000 b 

[ 2-Propen-1- amine] 

107-12-0 Propionitrile 

[Propanenitrile] 

10,000 b 

107-13-1 Acrylonitrile 20,000 b 

[2- Propenenitrile] 

107-15-3 Ethylenediamine 20,000 b 

[1,2- Ethanediamine] 

107-18-6 Allyl alcohol 

[2- Propen-1-ol] 

15,000 b 

107-30-2 Chloromethyl methyl ether 5,000 b 

[Methane, chloromethoxy-] 

108-05-4 Vinyl acetate monomer 15,000 b 

[Acetic acid ethenyl ester] 

108-23-6 Isopropyl chloroformate 15,000 b 

[Carbonochloridic acid, 1-methylethyl ester] 

108-91-8 Cyclohexylamine 15,000 b 

[Cyclohexanamine] 

109-61-5 Propyl chloroformate 15,000 b 

[Carbonochloridic acid, propylester] 

110-00-9 Furan 5,000 b 

110-89-4 Piperidine 15,000 b 

123-73-9 Crotonaldehyde, (E)- 20,000 b 

[2-Butenal, (E)-]


126-98-7 Methacrylonitrile 10,000 b


 [2-Propenenitrile, 2- methyl-].


151-56-4 Ethyleneimine 10,000 b

[Aziridine] 

302-01-2 Hydrazine 15,000 b 

353-42-4 Boron trifluoride compound 15,000 b 

with methyl ether (1:1) [Boron, trifluoro[oxybis[methane]]-, T-4-] 

506-77-4 Cyanogen chloride 10,000 c 

509-14-8 Tetranitromethane 10,000 b 

[Methane, tetranitro-] 

542-88-1 Chloromethyl ether 1,000 b 

[Methane, oxybis[chloro-] 

556-64-9 Methyl thiocyanate 20,000 b 

[Thiocyanic acid, methyl ester] 

584-84-9 Toluene 2,4- diisocyanate 10,000 a 

[Benzene, 2,4-diisocyanato-1-methyl-]\1\ 

594-42-3 Perchloromethylmercaptan 10,000 b 

[Methanesulfenyl chloride, trichloro-] 

624-83-9 Methyl isocyanate 10,000 a, b 

[Methane, isocyanato-] 

814-68-6 Acrylyl chloride 5,000 b 

[2- Propenoyl chloride] 

4170-30-3 Crotonaldehyde 20,000 b 

[2-Butenal] 

7446-09-5 Sulfur dioxide (anhydrous) 5,000 a, b 

7446-11-9 Sulfur trioxide 10,000 a, b 

7550-45-0 Titanium tetrachloride 2,500 b 

[Titanium chloride (TiCl4) (T-4)-] 

7637-07-2 Boron trifluoride 5,000 b 

[Borane, trifluoro-] 

7647-01-0 Hydrochloric acid 15,000 d 

(conc 37% or greater). 

7647-01-0 Hydrogen chloride 5,000 a 

(anhydrous) [Hydrochloric acid] 

7664-39-3 Hydrogen fluoride/ 1,000 a, b 

Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid] 

7664-41-7 Ammonia (anhydrous) 10,000 a, b 

7664-41-7 Ammonia (conc 20% or 20,000 a, b 

greater) 

7697-37-2 Nitric acid (conc 80% 15,000 b 

or greater) 

7719-12-2 Phosphorus trichloride 15,000 b 

[Phosphorous trichloride] 

7726-95-6 Bromine 10,000 a, b 

7782-41-4 Fluorine 1,000 b 

7782-50-5 Chlorine 2,500 a, b 

7783-06-4 Hydrogen sulfide 10,000 a, b 

7783-07-5 Hydrogen selenide 500 b 
--------------------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------

-----------------------------------------------------------------------------------------------

7783-60-0 Sulfur tetrafluoride 2,500 b 

[Sulfur fluoride (SF4), (T-4)-] 

7784-34-1 Arsenous trichloride 15,000 b 

7784-42-1 Arsine 1,000 b 

7803-51-2 Phosphine 5,000 b 

8014-95-7 Oleum 10,000 e 

(Fuming Sulfuric acid) [Sulfuric acid, mixture with sulfur trioxide]\1\ 

10025-87-3 Phosphorus oxychloride 5,000 b 

[Phosphoryl chloride] 

10049-04-4 Chlorine dioxide 1,000 c 

[Chlorine oxide (ClO2)] 

10102-43-9 Nitric oxide 10,000 b 

[Nitrogen oxide (NO)] 

10294-34-5 Boron trichloride 5,000 b 

[Borane, trichloro-] 

13463-39-3 Nickel carbonyl 1,000 b 

13463-40-6 Iron, pentacarbonyl- 2,500 b

 [Iron carbonyl (Fe(CO)5), (TB-5-11)-] 

19287-45-7 Diborane 2,500 b 

26471-62-5 Toluene diisocyanate 10,000 a 

(unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-1]\1\ 

\1\ The mixture exemption in § 68.115(b)(1) does not apply to the substance.


Note: Basis for Listing:


a Mandated for listing by Congress.


b On EHS list, vapor pressure 10 mmHg or greater.


c Toxic gas.


d Toxicity of hydrogen chloride, potential to release hydrogen chloride, and history of accidents.


e Toxicity of sulfur trioxide and sulfuric acid, potential to release sulfur trioxide, and history of


accidents


Table 3 to § 68.130 - List of Regulated Flammable Substances \1\ and Threshold Quantities for 

Accidental Release Prevention

 [Alphabetical Order - 63 Substances] 

CAS No. Threshold Basis for


 Chemical name quantity listing


(lbs) 


Acetaldehyde 75-07-0 10,000 g 

Acetylene [Ethyne] 74-86-2 10,000 f 

Bromotrifluorethylene 598-73-2 10,000 f 

[Ethene, bromotrifluoro-] 

1,3-Butadiene 106-99-0 10,000 f 
Butane 106-97-8 

1-Butene 106-98-9 

2-Butene 107-01-7 

Butene 25167-67-3 

2-Butene-cis 

2-Butene-trans [2-Butene, (E)] 

Carbon oxysulfide 

[Carbon oxide sulfide (COS)] 

Chlorine monoxide 

[Chlorine oxide] 

2-Chloropropylene 

[1-Propene, 2- chloro-] 

1-Chloropropylene 

[1-Propene, 1- chloro-] 

Cyanogen [Ethanedinitrile] 

Cyclopropane 

Dichlorosilane [Silane, dichloro-] 

Difluoroethane 

[Ethane, 1,1- difluoro-] 

Dimethylamine 

[Methanamine, N- methyl-] 

2,2-Dimethylpropane 

[Propane, 2,2-dimethyl-] 

Ethane 

Ethyl acetylene [1-Butyne] 

Ethylamine [Ethanamine] 

Ethyl chloride [Ethane, chloro-] 

Ethylene [Ethene] 

Ethyl ether [Ethane, 1,1'-oxybis-] 

Ethyl mercaptan [Ethanethiol] 

Ethyl nitrite 

[Nitrous acid, ethyl ester] 

Hydrogen 

Isobutane [Propane, 2-methyl] 

Isopentane [Butane, 2-methyl-] 

Isoprene 

[1,3-Butadinene, 2-methyl-] 

Isopropylamine [2-Propanamine] 

Isopropyl chloride 

[Propane, 2- chloro-] 

Methane 

Methylamine [Methanamine] 

3-Methyl-1-butene 

2-Methyl-1-butene 

Methyl ether [Methane, oxybis-] 

590-18-1 

624-64-6 

463-58-1 

7791-21-1 

557-98-2 

590-21-6 

460-19-5 

75-19-4 

4109-96-0 

75-37-6 

124-40-3 

463-82-1 

74-84-0 

107-00-6 

75-04-7 

75-00-3 

74-85-1 

60-29-7 

75-08-1 

109-95-5 

1333-74-0 

75-28-5 

78-78-4 

78-79-5 

75-31-0 

75-29-6 

74-82-8 

74-89-5 

563-45-1 

563-46-2 

115-10-6 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 g 

10,000 g 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 g 

10,000 g 

10,000 f 

10,000 f 

10,000 f 

10,000 g 

10,000 g 

10,000 g 

10,000 g 

10,000 f 

10,000 f 

10,000 f 

10,000 g 

10,000 f 
------------------------------------------------------------------------

Methyl formate 107-31-3 10,000 g 

[Formic acid, methyl ester] 

2-Methylpropene 115-11-7 10,000 f 

[1-Propene, 2- methyl-] 

1,3-Pentadinene 504-60-9 10,000 f 

Pentane 109-66-0 10,000 g 

1-Pentene 109-67-1 10,000 g 

2-Pentene, (E)- 646-04-8 10,000 g 

2-Pentene, (Z)- 627-20-3 10,000 g 

Propadiene [1,2-Propadiene] 463-49-0 10,000 f 

Propane 74-98-6 10,000 f 

Propylene [1-Propene] 115-07-1 10,000 f 

Propyne [1-Propyne] 74-99-7 10,000 f 

Silane 7803-62-5 10,000 f 

Tetrafluoroethylene 116-14-3 10,000 f 

[Ethene, tetrafluoro-] 

Tetramethylsilane 75-76-3 10,000 g 

[Silane, tetramethyl-] 

Trichlorosilane 10025-78-2 10,000 g 

[Silane, trichloro-] 

Trifluorochloroethylene 79-38-9 10,000 f 

[Ethene, chlorotrifluoro-] 

Trimethylamine 75-50-3 10,000 f 

[Methanamine, N,N-dimethyl-] 

Vinyl acetylene [1-Buten-3-yne] 689-97-4 10,000 f 

Vinyl chloride [Ethene, chloro-] 75-01-4 10,000 a, f 

Vinyl ethyl ether [Ethene, ethoxy-] 109-92-2 10,000 g 

Vinyl fluoride [Ethene, fluoro-] 75-02-5 10,000 f 

Vinylidene chloride 75-35-4 10,000 g 

[Ethene, 1,1-dichloro-] 

Vinylidene fluoride 75-38-7 10,000 f 

[Ethene,1,1-difluoro-] 

Vinyl methyl ether 107-25-5 10,000 f 

[Ethene, methoxy-]. 

\1\ A flammable substance when used as a fuel or held for sale as a fuel at a retail facility is


excluded from all provisions of this part (see § 68.126).


Note: Basis for Listing:


a Mandated for listing by Congress.


f Flammable gas.


gVolatile flammable liquid.


Table 4 to § 68.130 - List of Regulated Flammable Substances \1\ and Threshold Quantities for


Accidental Release Prevention

----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------

 [CAS Number Order - 63 Substances] 

Threshold Basis for 

CAS No. Chemical name quantity listing 

(lbs) 

60-29-7 Ethyl ether 10,000 g 

[Ethane,1,1[prime]-oxybis-] 

74-82-8 Methane 10,000 f 

74-84-0 Ethane 10,000 f 

74-85-1 Ethylene [Ethene] 10,000 f 

74-86-2 Acetylene [Ethyne] 10,000 f 

74-89-5 Methylamine 10,000 f 

[Methanamine] 

74-98-6 Propane 10,000 f 

74-99-7 Propyne 10,000 f 

[1-Propyne] 

75-00-3 Ethyl chloride 10,000 f 

[Ethane, chloro-]


75-01-4 Vinyl chloride 10,000 a, f


[Ethene, chloro-]


75-02-5 Vinyl fluoride 10,000 f


[Ethene, fluoro-]


75-04-7 Ethylamine 10,000 f


[Ethanamine] 

75-07-0 Acetaldehyde 10,000 g 

75-08-1 Ethyl mercaptan 10,000 g 

[Ethanethiol] 

75-19-4 Cyclopropane 10,000 f 

75-28-5 Isobutane 10,000 f 

[Propane, 2-methyl] 

75-29-6 Isopropyl chloride 10,000 g 

[Propane, 2-chloro-] 

75-31-0 Isopropylamine 10,000 g


[2-Propanamine]


75-35-4 Vinylidene chloride 10,000 g


 [Ethene, 1,1-dichloro-] 

75-37-6 Difluoroethane 10,000 f 

[Ethane, 1,1-difluoro-] 

75-38-7 Vinylidene fluoride 10,000 f 

[Ethene,1,1-difluoro-] 

75-50-3 Trimethylamine 10,000 f 

[Methanamine, N, N-dimethyl-] 

75-76-3 Tetramethylsilane 10,000 g 

[Silane, tetramethyl-] 
78-78-4 Isopentane 10,000 g 

[Butane, 2-methyl-] 

78-79-5 Isoprene 10,000 g 

[1,3,-Butadiene, 2- methyl-] 

79-38-9 Trifluorochloroethylene 10,000 f 

[Ethene, chlorotrifluoro-] 

106-97-8 Butane 

106-98-9 1-Butene 

196-99-0 1,3-Butadiene 

107-00-6 Ethyl acetylene 

[1-Butyne] 

107-01-7 2-Butene 

107-25-5 Vinyl methyl ether 

[Ethene, methoxy-] 

107-31-3 Methyl formate 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 f 

10,000 g 

[Formic acid, methyl ester] 

109-66-0 Pentane 10,000 g 

109-67-1 1-Pentene 10,000 g 

109-92-2 Vinyl ethyl ether 10,000 g 

[Ethene, ethoxy-] 

109-95-5 Ethyl nitrite 10,000 f 

[Nitrous acid, ethyl ester] 

115-07-1 Propylene 

[1-Propene] 

115-10-6 Methyl ether 

[Methane, oxybis-] 

115-11-7 2-Methylpropene 

10,000 f 

10,000 f 

10,000 f 

[1-Propene, 2-methyl-] 

116-14-3 Tetrafluoroethylene 10,000 f 

[Ethene, tetrafluoro-] 

124-40-3 Dimethylamine 10,000 f 

[Methanamine, N-methyl-] 

460-19-5 Cyanogen 10,000 f 

[Ethanedinitrile] 

463-49-0 Propadiene 10,000 f 

[1,2-Propadiene] 

463-58-1 Carbon oxysulfide 10,000 f 

[Carbon oxide sulfide (COS)] 

463-82-1 2,2-Dimethylpropane 10,000 f 

[Propane, 2,2-dimethyl-] 

504-60-9 1,3-Pentadiene 10,000 f 

557-98-2 2-Chloropropylene 10,000 g 

[1-Propene, 2-chloro-] 

563-45-1 3-Methyl-1-butene 10,000 f 

563-46-2 2-Methyl-1-butene 10,000 g 
----------------------------------------------------------------------------------------------------------------

590-18-1 2-Butene-cis 10,000 f 

590-21-6 1-Chloropropylene 10,000 g 

[1-Propene, 1-chloro-] 

598-73-2 Bromotrifluorethylene 10,000 f 

[Ethene, bromotrifluoro-] 

624-64-6 2-Butene-trans 10,000 f 

[2-Butene, (E)] 


627-20-3 2-Pentene, (Z)- 10,000 g


646-04-8 2-Pentene, (E)- 10,000 g


689-97-4 Vinyl acetylene 10,000 f


[1-Buten-3-yne]


1333-74-0 Hydrogen 10,000 f


4109-96-0 Dichlorosilane 10,000 f


[Silane, dichloro-] 

7791-21-1 Chlorine monoxide 10,000 f 

[Chlorine oxide] 

7803-62-5 Silane 10,000 f 

10025-78-2 Trichlorosilane 10,000 g 

[Silane,trichloro-] 

25167-67-3 Butene 10,000 f 

\1\ A flammable substance when used as a fuel or held for sale as a fuel at a retail facility is


excluded from all provisions of this part (see § 68.126).


Note: Basis for Listing:


a Mandated for listing by Congress.


f Flammable gas.


g Volatile flammable liquid.


[59 FR 4493, Jan. 31, 1994. Redesignated at 61 FR 31717, June 20, 1996, 


as amended at 62 FR 45132, Aug. 25, 1997; 63 FR 645, Jan. 6, 1998; 65 FR 


13250, Mar. 13, 2000]


 Subpart G - Risk Management Plan

 Source: 61 FR 31726, June 20, 1996, unless otherwise noted. 

§ 68.150 Submission.

 (a) The owner or operator shall submit a single RMP that includes the information required by 

§§68.155 through 68.185 for all covered processes. The RMP shall be submitted in the method 

and format to the central point specified by EPA as of the date of submission.

 (b) The owner or operator shall submit the first RMP no later than the latest of the following 

dates:

 (1) June 21, 1999; 
 (2) Three years after the date on which a regulated substance is first listed under § 68.130; or

 (3) The date on which a regulated substance is first present above a threshold quantity in a 

process.

 (c) The owner or operator of any stationary source for which an RMP was submitted before 

June 21, 2004, shall revise the RMP to include the information required by §68.160(b)(6) and 

(14) by June 21, 2004 in the manner specified by EPA prior to that date. Any such submission 

shall also include the information required by §68.160(b)(20) (indicating that the submission is a 

correction to include the information required by §68.160(b)(6) and (14) or an update under 

§68.190).

 (d) RMPs submitted under this section shall be updated and corrected in accordance with 

§§68.190 and 68.195.

 (e) Notwithstanding the provisions of Sec.§ 68.155 to 68.190, the RMP shall exclude 

classified information. Subject to appropriate procedures to protect such information from public 

disclosure, classified data or information excluded from the RMP may be made available in a 

classified annex to the RMP for review by Federal and state representatives who have received 

the appropriate security clearances.

 (f) Procedures for asserting that information submitted in the RMP is entitled to protection as 

confidential business information are set forth in Sec.§ 68.151 and 68.152. 

[61 FR 31726, June 20, 1996, as amended at 64 FR 979, Jan. 6, 1999 and 69 FR 18819, April 9, 

2004] 

§ 68.151 Assertion of claims of confidential business information.

 (a) Except as provided in paragraph (b) of this section, an owner or operator of a stationary 

source required to report or otherwise provide information under this part may make a claim of 

confidential business information for any such information that meets the criteria set forth 

in 40 CFR 2.301.

 (b) Notwithstanding the provisions of 40 CFR part 2, an owner or operator of a stationary 

source subject to this part may not claim as confidential business information the following 

information:

 (1) Registration data required by § 68.160(b)(1) 

through (b)(6) and (b)(8), (b)(10) through (b)(13) and NAICS code and Program level of the 

process set forth in § 68.160(b)(7);

 (2) Offsite consequence analysis data required by § 68.165(b)(4), (b)(9), (b)(10), (b)(11), and 

(b)(12).

 (3) Accident history data required by § 68.168;

 (4) Prevention program data required by § 68.170(b), (d), (e)(1), (f) through (k);

 (5) Prevention program data required by § 68.175(b), (d), (e)(1), (f) through (p); and

 (6) Emergency response program data required by § 68.180.

 (c) Notwithstanding the procedures specified in 40 CFR part 2, an owner or operator asserting 

a claim of CBI with respect to information contained in its RMP, shall submit to EPA at the time 

it submits the RMP the following:

 (1) The information claimed confidential, provided in a format to be specified by EPA;

 (2) A sanitized (redacted) copy of the RMP, with the notation ``CBI'' substituted for the 
information claimed confidential, except that a generic category or class name shall be 

substituted for any chemical name or identity claimed confidential; and

 (3) The document or documents substantiating each claim of confidential business 

information, as described in § 68.152. 

[64 FR 979, Jan. 6, 1999] 

§ 68.152 Substantiating claims of confidential business information.

 (a) An owner or operator claiming that information is confidential business information must 

substantiate that claim by providing documentation that demonstrates that the claim meets the 

substantivecriteria set forth in 40 CFR 2.301.

 (b) Information that is submitted as part of the substantiation may be claimed confidential by 

marking it as confidential business information. Information not so marked will be treated as 

public and may be disclosed without notice to the submitter. If information that is submitted as 

part of the substantiation is claimed confidential, the owner or operator must provide a sanitized 

and unsanitized version of the substantiation.

 (c) The owner, operator, or senior official with management responsibility of the stationary 

source shall sign a certification that the signer has personally examined the information 

submitted and that based on inquiry of the persons who compiled the information, the 

information is true, accurate, and complete, and that those portions of the substantiation claimed 

as confidential business information would, if disclosed, reveal trade secrets or other confidential 

business information. 

[64 FR 980, Jan. 6, 1999] 

§ 68.155 Executive summary.

 The owner or operator shall provide in the RMP an executive summary that includes a brief 

description of the following elements:

 (a) The accidental release prevention and emergency response policies at the stationary source;

 (b) The stationary source and regulated substances handled;

 (c) The general accidental release prevention program and chemical-specific prevention steps;

 (d) The five-year accident history;

 (e) The emergency response program; and

 (f) Planned changes to improve safety. 

[61 FR 31726, June 20, 1996, as amended at 69 FR 18819, April 9, 2004] 

§ 68.160 Registration.

 (a) The owner or operator shall complete a single registration form and include it in the RMP. 

The form shall cover all regulated substances handled in covered processes.

 (b) The registration shall include the following data:

 (1) Stationary source name, street, city, county, state, zip code, latitude and longitude, method 
for obtaining latitude and longitude, and description of location that latitude and longitude 

represent;

 (2) The stationary source Dun and Bradstreet number;

 (3) Name and Dun and Bradstreet number of the corporate parent company;

 (4) The name, telephone number, and mailing address of the owner or operator;

 (5) The name and title of the person or position with overall responsibility for RMP elements 

and implementation, and (optional) the e-mail address for that person or position; 

(6) The name, title, telephone number, 24-hour telephone number, and, as of June 21, 2004, 

the e-mail address (if an e-mail address exists) of the emergency contact;

 (7) For each covered process, the name and CAS number of each regulated substance held 

above the threshold quantity in the process, the maximum quantity of each regulated substance or 

mixture in the process (in pounds) to two significant digits, the five- or six-digit NAICS code 

that most closely corresponds to the process, and the Program level of the process;

 (8) The stationary source EPA identifier;

 (9) The number of full-time employees at the stationary source;

 (10) Whether the stationary source is subject to 29 CFR 1910.119;

 (11) Whether the stationary source is subject to 40 CFR part 355;

 (12) If the stationary source has a CAA Title V operating permit, the permit number; and

 (13) The date of the last safety inspection of the stationary source by a Federal, state, or local 

government agency and the identity of the inspecting entity.

 (14) As of June 21, 2004, the name, the mailing address, and the telephone number of the 

contractor who prepared the RMP (if any);

 (15) Source or Parent Company E-Mail Address (Optional);

 (16) Source Homepage address (Optional)

 (17) Phone number at the source for public inquiries (Optional);

 (18) Local Emergency Planning Committee (Optional);

 (19) OSHA Voluntary Protection Program status (Optional);

 (20) As of June 21, 2004, the type of and reason for any changes being made to a previously 

submitted RMP; the types of changes to RMP are categorized as follows: 

(i) Updates and re-submissions required under §68.190(b); 

(ii) Corrections under §68.195 or for purposes of correcting minor clerical errors, 

updating administrative information, providing missing data elements or reflecting facility 

ownership changes, and which do not require an update and re-submission as specified in 

§68.190(b); 

(iii) De-registrations required under §68.190(c); and 

(iv) Withdrawals of an RMP for any facility that was erroneously considered subject to 

this part 68. 

[61 FR 31726, June 20, 1996, as amended at 64 FR 980, Jan. 6, 1999 and 69 FR 18819, April 9, 

2004] 

§ 68.165 Offsite consequence analysis.

 (a) The owner or operator shall submit in the RMP information:

 (1) One worst-case release scenario for each Program 1 process; and 
 (2) For Program 2 and 3 processes, one worst-case release scenario to represent all regulated 

toxic substances held above the threshold quantity and one worst-case release scenario to 

represent all regulated flammable substances held above the threshold quantity. If additional 

worst-case scenarios for toxics or flammables are required by 

§ 68.25(a)(2)(iii), the owner or operator shall submit the same information on the additional 

scenario(s). The owner or operator of Program 2 and 3 processes shall also submit information 

on one alternative release scenario for each regulated toxic substance held above the threshold 

quantity and one alternative release scenario to represent all regulated flammable substances held 

above the threshold quantity.

 (b) The owner or operator shall submit the following data:

 (1) Chemical name;

 (2) Percentage weight of the chemical in a liquid mixture (toxics only);

 (3) Physical state (toxics only);

 (4) Basis of results (give model name if used);

 (5) Scenario (explosion, fire, toxic gas release, or liquid spill and evaporation);

 (6) Quantity released in pounds;

 (7) Release rate;

 (8) Release duration;

 (9) Wind speed and atmospheric stability class (toxics only);

 (10) Topography (toxics only);

 (11) Distance to endpoint;

 (12) Public and environmental receptors within the distance;

 (13) Passive mitigation considered; and

 (14) Active mitigation considered (alternative releases only); 

[61 FR 31726, June 20, 1996, as amended at 64 FR 980, Jan. 6, 1999] 

§ 68.168 Five-year accident history.

 The owner or operator shall submit in the RMP the information provided in § 68.42(b) on each 

accident covered by § 68.42(a). 

§ 68.170 Prevention program/Program 2.

 (a) For each Program 2 process, the owner or operator shall provide in the RMP the 

information indicated in paragraphs (b) through (k) of this section. If the same information 

applies to more than one covered process, the owner or operator may provide the information 

only once, but shall indicate to which processes the information applies.

 (b) The five- or six-digit NAICS code that most closely corresponds to the process.

 (c) The name(s) of the chemical(s) covered.

 (d) The date of the most recent review or revision of the safety information and a list of 

Federal or state regulations or industry-specific design codes and standards used to demonstrate 

compliance with the safety information requirement.

 (e) The date of completion of the most recent hazard review or update.

 (1) The expected date of completion of any changes resulting from the hazard review; 
 (2) Major hazards identified;

 (3) Process controls in use;

 (4) Mitigation systems in use;

 (5) Monitoring and detection systems in use; and

 (6) Changes since the last hazard review.

 (f) The date of the most recent review or revision of operating procedures.

 (g) The date of the most recent review or revision of training programs;

 (1) The type of training provided - classroom, classroom plus on the job, on the job; and

 (2) The type of competency testing used.

 (h) The date of the most recent review or revision of maintenance procedures and the date of 

the most recent equipment inspection or test and the equipment inspected or tested.

 (i) The date of the most recent compliance audit and the expected date of completion of any 

changes resulting from the compliance audit.

 (j) The date of the most recent incident investigation and the expected date of completion of 

any changes resulting from the investigation.

 (k) The date of the most recent change that triggered a review or revision of safety 

information, the hazard review, operating or maintenance procedures, or training. 

[61 FR 31726, June 20, 1996, as amended at 64 FR 980, Jan. 6, 1999] 

§ 68.175 Prevention program/Program 3.

 (a) For each Program 3 process, the owner or operator shall provide the information indicated 

in paragraphs (b) through (p) of this section. If the same information applies to more than one 

covered process, the owner or operator may provide the information only once, but shall indicate 

to which processes the information applies.

 (b) The five- or six-digit NAICS code that most closely corresponds to the process.

 (c) The name(s) of the substance(s) covered.

 (d) The date on which the safety information was last reviewed or revised.

 (e) The date of completion of the most recent PHA or update and the technique used.

 (1) The expected date of completion of any changes resulting from the PHA;

 (2) Major hazards identified;

 (3) Process controls in use;

 (4) Mitigation systems in use;

 (5) Monitoring and detection systems in use; and

 (6) Changes since the last PHA.

 (f) The date of the most recent review or revision of operating procedures.

 (g) The date of the most recent review or revision of training programs;

 (1) The type of training provided - classroom, classroom plus on the job, on the job; and

 (2) The type of competency testing used.

 (h) The date of the most recent review or revision of maintenance procedures and the date of 

the most recent equipment inspection or test and the equipment inspected or tested.

 (i) The date of the most recent change that triggered management of change procedures and the 

date of the most recent review or revision of management of change procedures.

 (j) The date of the most recent pre-startup review. 
 (k) The date of the most recent compliance audit and the expected date of completion of any 

changes resulting from the compliance audit;

 (l) The date of the most recent incident investigation and the expected date of completion of 

any changes resulting from the 

investigation;

 (m) The date of the most recent review or revision of employee participation plans;

 (n) The date of the most recent review or revision of hot work permit procedures;

 (o) The date of the most recent review or revision of contractor safety procedures; and

 (p) The date of the most recent evaluation of contractor safety performance. 

[61 FR 31726, June 20, 1996, as amended at 64 FR 980, Jan. 6, 1999] 

§ 68.180 Emergency response program.

 (a) The owner or operator shall provide in the RMP the following information:

 (1) Do you have a written emergency response plan?

 (2) Does the plan include specific actions to be taken in response to an accidental releases of a 

regulated substance?

 (3) Does the plan include procedures for informing the public and local agencies responsible 

for responding to accidental releases?

 (4) Does the plan include information on emergency health care?

 (5) The date of the most recent review or update of the emergency response plan;

 (6) The date of the most recent emergency response training for employees.

 (b) The owner or operator shall provide the name and telephone number of the local agency 

with which emergency response activities and the emergency response plan is coordinated.

 (c) The owner or operator shall list other Federal or state emergency plan requirements to 

which the stationary source is subject. 

[61 FR 31726, June 20, 1996, as amended at 64 FR 980, Jan. 6, 1999] 

§ 68.185 Certification.

 (a) For Program 1 processes, the owner or operator shall submit in the RMP the certification 

statement provided in § 68.12(b)(4).

 (b) For all other covered processes, the owner or operator shall submit in the RMP a single 

certification that, to the best of the signer's knowledge, information, and belief formed after 

reasonable inquiry, the information submitted is true, accurate, and complete. 

§ 68.190 Updates.

 (a) The owner or operator shall review and update the RMP as specified in paragraph (b) of this 

section and submit it in the method and format to the central point specified by EPA as of the 

date of submission.

 (b) The owner or operator of a stationary source shall revise and update the RMP submitted 

under § 68.150 as follows: 
 (1) At least once every five years from the date of its initial submission or most recent update 

required by paragraphs (b)(2) through (b)(7) of this section, whichever is later. For purposes of 

determining the date of initial submissions, RMPs submitted before June 21, 1999 are considered 

to have been submitted on that date.

 (2) No later than three years after a newly regulated substance is first listed by EPA;

 (3) No later than the date on which a new regulated substance is first present in an already 

covered process above a threshold quantity;

 (4) No later than the date on which a regulated substance is first present above a threshold 

quantity in a new process;

 (5) Within six months of a change that requires a revised PHA or hazard review;

 (6) Within six months of a change that requires a revised offsite consequence analysis as 

provided in § 68.36; and

 (7) Within six months of a change that alters the Program level that applied to any covered 

process.

 (c) If a stationary source is no longer subject to this part, the owner or operator shall submit a 

de-registration to EPA within six months indicating that the stationary source is no longer 

covered. 

[61 FR 31727, June 20, 1996, as amended at 69 FR 18819, April 9, 2004] 

§68.195 Required corrections.

 The owner or operator of a stationary source for which a RMP was submitted shall correct the 

RMP as follows:

 (a) New accident history information – For any accidental release meeting the five-year 

accident history reporting criteria of §68.42 and occurring after [insert date of publication of this 

final rule], the owner or operator shall submit the data required under §§68.168, 68.170(j), and 

68.175(l) with respect to that accident within six months of the release or by the time the RMP is 

updated under §68.190, whichever is earlier.

 (b) Emergency contact information – Beginning June 21, 2004, within one month of any 

change in the emergency contact information required under §68.160 (b)(6), the owner or 

operator shall submit a correction of that information. 

[69 FR 18819, April 9, 2004]

 Subpart H - Other Requirements

 Source: 61 FR 31728, June 20, 1996, unless otherwise noted. 

§ 68.200 Recordkeeping.

 The owner or operator shall maintain records supporting the implementation of this part for 

five years unless otherwise provided in subpart D of this part. 

§ 68.210 Availability of information to the public. 
 (a) The RMP required under subpart G of this part shall be available to the public under 42 

U.S.C. 7414(c).

 (b) The disclosure of classified information by the Department of Defense or other Federal 

agencies or contractors of such agencies shall be controlled by applicable laws, regulations, or 

executive orders concerning the release of classified information. 

§ 68.215 Permit content and air permitting authority or designated agency requirements.

 (a) These requirements apply to any stationary source subject to this part 68 and parts 70 or 71 

of this chapter. The 40 CFR part 70 or part 71 permit for the stationary source shall contain:

 (1) A statement listing this part as an applicable requirement;

 (2) Conditions that require the source owner or operator to submit:

 (i) A compliance schedule for meeting the requirements of this part by the date provided in § 

68.10(a) or;

 (ii) As part of the compliance certification submitted under 40 CFR 70.6(c)(5), a certification 

statement that the source is in compliance with all requirements of this part, including the 

registration and submission of the RMP.

 (b) The owner or operator shall submit any additional relevant information requested by the air 

permitting authority or designated agency.

 (c) For 40 CFR part 70 or part 71 permits issued prior to the deadline for registering and 

submitting the RMP and which do not contain permit conditions described in paragraph (a) of 

this section, the owner or operator or air permitting authority shall initiate permit revision or 

reopening according to the procedures of 40 CFR 70.7 or 71.7 to incorporate the terms and 

conditions consistent with paragraph (a) of this section.

 (d) The state may delegate the authority to implement and enforce the requirements of 

paragraph (e) of this section to a state or local agency or agencies other than the air permitting 

authority. An up-to-date copy of any delegation instrument shall be maintained by the air 

permitting authority. The state may enter a written agreement with the Administrator under 

which EPA will implement and enforce the requirements of paragraph (e) of this section.

 (e) The air permitting authority or the agency designated by delegation or agreement under 

paragraph (d) of this section shall, at a minimum:

 (1) Verify that the source owner or operator has registered and submitted an RMP or a revised 

plan when required by this part;

 (2) Verify that the source owner or operator has submitted a source certification or in its 

absence has submitted a compliance schedule consistent with paragraph (a)(2) of this section;

 (3) For some or all of the sources subject to this section, use one or more mechanisms such as, 

but not limited to, a completeness check, source audits, record reviews, or facility inspections to 

ensure that permitted sources are in compliance with the requirements of this part; and

 (4) Initiate enforcement action based on paragraphs (e)(1) and (e)(2) of this section as 

appropriate. 

§ 68.220 Audits.

 (a) In addition to inspections for the purpose of regulatory development and enforcement of 

the Act, the implementing agency shall periodically audit RMPs submitted under subpart G of 

this part to review the adequacy of such RMPs and require revisions of RMPs when necessary to 
ensure compliance with subpart G of this part.

 (b) The implementing agency shall select stationary sources for audits based on any of the 

following criteria:

 (1) Accident history of the stationary source;

 (2) Accident history of other stationary sources in the same industry;

 (3) Quantity of regulated substances present at the stationary source;

 (4) Location of the stationary source and its proximity to the public and environmental 

receptors;

 (5) The presence of specific regulated substances;

 (6) The hazards identified in the RMP; and

 (7) A plan providing for neutral, random oversight.

 (c) Exemption from audits. A stationary source with a Star or Merit ranking under OSHA's 

voluntary protection program shall be exempt from audits under paragraph (b)(2) and (b)(7) of 

this section.

 (d) The implementing agency shall have access to the stationary source, supporting 

documentation, and any area where an accidental release could occur.

 (e) Based on the audit, the implementing agency may issue the owner or operator of a 

stationary source a written preliminary determination of necessary revisions to the stationary 

source's RMP to ensure that the RMP meets the criteria of subpart G of this part. The preliminary 

determination shall include an explanation for the basis for the revisions, reflecting industry 

standards and guidelines (such as AIChE/CCPS guidelines and ASME and API standards) to the 

extent that such standards and guidelines are applicable, and shall include a timetable for their 

implementation.

 (f) Written response to a preliminary determination. (1) The owner or operator shall respond in 

writing to a preliminary determination made in accordance with paragraph (e) of this section. The 

response shall state the owner or operator will implement the revisions contained in the 

preliminary determination in accordance with the timetable included in the preliminary 

determination or shall state that the owner or operator rejects the revisions in whole or in part. 

For each rejected revision, the owner or operator shall explain the basis for rejecting such 

revision. Such explanation may include substitute revisions.

 (2) The written response under paragraph (f)(1) of this section shall be received by the 

implementing agency within 90 days of the issue of the preliminary determination or a shorter 

period of time as the implementing agency specifies in the preliminary determination as 

necessary to protect public health and the environment. Prior to the written response being due 

and upon written request from the owner or operator, the implementing agency may provide in 

writing additional time for the response to be received.

 (g) After providing the owner or operator an opportunity to respond under paragraph (f) of this 

section, the implementing agency may issue the owner or operator a written final determination 

of necessary revisions to the stationary source's RMP. The final determination may adopt or 

modify the revisions contained in the preliminary determination under paragraph (e) of this 

section or may adopt or modify the substitute revisions provided in the response under paragraph 

(f) of this section. A final determination that adopts a revision rejected by the owner or operator 

shall include an explanation of the basis for the revision. A final determination that fails to adopt 

a substitute revision provided under paragraph (f) of this section shall include an explanation of 

the basis for finding such substitute revision unreasonable. 
------------------------------------------------------------------------------------

------------------------------------------------------------------------------------

 (h) Thirty days after completion of the actions detailed in the implementation schedule set in 

the final determination under paragraph 

(g) of this section, the owner or operator shall be in violation of subpart G of this part and this 

section unless the owner or operator revises the RMP prepared under subpart G of this part as 

required by the final determination, and submits the revised RMP as required under § 68.150.

 (i) The public shall have access to the preliminary determinations, responses, and final 

determinations under this section in a manner 

consistent with § 68.210.

 (j) Nothing in this section shall preclude, limit, or interfere in any way with the authority of 

EPA or the state to exercise its enforcement, investigatory, and information gathering authorities 

concerning this part under the Act.

 Appendix A to Part 68 - ;Table of Toxic Endpoints

 [As defined in § 68.22 of this part] 

Toxic 

CAS No. Chemical name endpoint 

(mg/L) 

107-02-8 Acrolein [2-Propenal] 0.0011 

107-13-1 Acrylonitrile 0.076 

[2- Propenenitrile] 

814-68-6 Acrylyl chloride 0.00090 

[2-Propenoyl chloride] 

107-18-6 Allyl alcohol 0.036 

[2-Propen-1-ol] 

107-11-9 Allylamine 0.0032 

[2-Propen-1-amine] 

7664-41-7 Ammonia (anhydrous) 0.14 

7664-41-7 Ammonia (conc 20% or greater) 0.14 

7784-34-1 Arsenous trichloride 0.010 

7784-42-1 Arsine 0.0019 

10294-34-5 Boron trichloride 0.010 

[Borane, trichloro-] 

7637-07-2 Boron trifluoride 0.028 

[Borane, trifluoro-] 

353-42-4 Boron trifluoride compound 0.023 

with methyl ether (1:1) Boron, trifluoro[oxybis[methane]]-, T-4 

7726-95-6 Bromine 0.0065 

75-15-0 Carbon disulfide 0.16 

7782-50-5 Chlorine 0.0087 

10049-04-4 Chlorine dioxide 0.0028 

[Chlorine oxide (ClO2)] 

67-66-3 Chloroform 0.49 
[Methane, trichloro-] 

542-88-1 Chloromethyl ether 0.00025 

[Methane, oxybis[chloro-] 

107-30-2 Chloromethyl methyl ether 0.0018 

[Methane, chloromethoxy-] 

4170-30-3 Crotonaldehyde [2-Butenal] 0.029 

123-73-9 Crotonaldehyde, (E)-, 0.029 

[2- Butenal, (E)-] 

506-77-4 Cyanogen chloride 0.030 

108-91-8 Cyclohexylamine 0.16 

[Cyclohexanamine] 

19287-45-7 Diborane 0.0011 

75-78-5 Dimethyldichlorosilane 0.026 

[Silane, dichlorodimethyl-] 

57-14-7 1,1-Dimethylhydrazine 0.012 

[Hydrazine, 1,1-dimethyl-] 

106-89-8 Epichlorohydrin 0.076 

[Oxirane, (chloromethyl)-] 

107-15-3 Ethylenediamine 0.49 

[1,2-Ethanediamine] 

151-56-4 Ethyleneimine [Aziridine] 0.018 

75-21-8 Ethylene oxide [Oxirane] 0.090 

7782-41-4 Fluorine 0.0039 

50-00-0 Formaldehyde (solution) 0.012 

110-00-9 Furan 0.0012 

302-01-2 Hydrazine 0.011 

7647-01-0 Hydrochloric acid 0.030 

(conc 37% or greater) 

74-90-8 Hydrocyanic acid 0.011 

7647-01-0 Hydrogen chloride (anhydrous) 0.030 

[Hydrochloric acid] 

7664-39-3 Hydrogen fluoride/ 0.016 

Hydrofluoric acid (conc 50% or greater) [Hydrofluoric acid] 

7783-07-5 Hydrogen selenide 0.00066 

7783-06-4 Hydrogen sulfide 0.042 

13463-40-6 Iron, pentacarbonyl- 0.00044 

[Iron carbonyl (Fe(CO)5), (TB-5-11)-] 

78-82-0 Isobutyronitrile 0.14 

[Propanenitrile, 2-methyl-] 

108-23-6 Isopropyl chloroformate 0.10 

[Carbonochloride acid, 1-methylethyl ester] 

126-98-7 Methacrylonitrile 0.0027 

[2-Propenenitrile, 2-methyl-] 

74-87-3 Methyl chloride 0.82 

[Methane, chloro-] 
79-22-1 Methyl chloroformate 0.0019 

[Carbonochloridic acid, methylester] 

60-34-4 Methyl hydrazine 0.0094 

[Hydrazine, methyl-] 

624-83-9 Methyl isocyanate 0.0012 

[Methane, isocyanato-] 

74-93-1 Methyl mercaptan 0.049 

[Methanethiol] 

556-64-9 Methyl thiocyanate 0.085 

[Thiocyanic acid, methyl ester] 

75-79-6 Methyltrichlorosilane 0.018 

[Silane, trichloromethyl-] 

13463-39-3 Nickel carbonyl 0.00067 

7697-37-2 Nitric acid (conc 80% or greater) 0.026 

10102-43-9 Nitric oxide 0.031 

[Nitrogen oxide (NO)]. 

8014-95-7 Oleum (Fuming Sulfuric acid) 0.010 

[Sulfuric acid, mixture with sulfur trioxide] 

79-21-0 Peracetic acid 0.0045 

[Ethaneperoxoic acid] 

594-42-3 Perchloromethylmercaptan 0.0076 

[Methanesulfenyl chloride, trichloro-] 

75-44-5 Phosgene [Carbonic dichloride] 0.00081 

7803-51-2 Phosphine 0.0035 

10025-87-3 Phosphorus oxychloride 0.0030 

[Phosphoryl chloride] 

7719-12-2 Phosphorus trichloride 0.028 

[Phosphorous trichloride] 

110-89-4 Piperidine 0.022 

107-12-0 Propionitrile [Propanenitrile] 0.0037 

109-61-5 Propyl chloroformate 0.010 

[Carbonochloridic acid, propylester]. 

75-55-8 Propyleneimine 0.12 

[Aziridine, 2- methyl-] 

75-56-9 Propylene oxide 0.59 

[Oxirane, methyl-] 

7446-09-5 Sulfur dioxide (anhydrous) 0.0078 

7783-60-0 Sulfur tetrafluoride 0.0092 

[Sulfur fluoride (SF4), (T-4)-] 

7446-11-9 Sulfur trioxide 0.010 

75-74-1 Tetramethyllead 0.0040 

[Plumbane, tetramethyl-] 

509-14-8 Tetranitromethane 0.0040 

[Methane, tetranitro-] 

7750-45-0 Titanium tetrachloride 0.020 
------------------------------------------------------------------------

[Titanium chloride (TiCl4) (T- 4)-] 

584-84-9 Toluene 2,4-diisocyanate 0.0070 

[Benzene, 2,4-diisocyanato-1-methyl-] 

91-08-7 Toluene 2,6-diisocyanate 0.0070 

[Benzene, 1,3-diisocyanato-2-methyl-] 

26471-62-5 Toluene diisocyanate 0.0070 

(unspecified isomer) [Benzene, 1,3-diisocyanatomethyl-] 

75-77-4 Trimethylchlorosilane 0.050 

[Silane, chlorotrimethyl-] 

108-05-4 Vinyl acetate monomer 0.26 

[Acetic acid ethenyl ester] 

[61 FR 31729, June 20, 1996, as amended at 62 FR 45132, Aug. 25, 1997] 
APPENDIX B:


SELECTED 2002 NAICS CODES


Selected 2002 NAICS Codes 

Visit http://www.census.gov/epcd/www/naics.html for a complete listing of 2002 NAICS Codes 

11 Agriculture, Forestry, Fishing and Hunting	 11194 Hay Farming 

111940 Hay Farming 

111 Crop Production	 11199 All Other Crop Farming 

1111 Oilseed and Grain Farming	 111991 Sugar Beet Farming 

11111 Soybean Farming	 111992 Peanut Farming 

111110 Soybean Farming	 111998 All Other Miscellaneous Crop Farming 

11112 Oilseed (except Soybean) Farming	 112 Animal Production 

111120 Oilseed (except Soybean) Farming	 1121 Cattle Ranching and Farming 

11113 Dry Pea and Bean Farming	 11211 Beef Cattle Ranching and Farming, including 

111130 Dry Pea and Bean Farming	 Feedlots 

11114 Wheat Farming	 112111 Beef Cattle Ranching and Farming 

111140 Wheat Farming	 112112 Cattle Feedlots 

11115 Corn Farming	 11212 Dairy Cattle and Milk Production 

111150 Corn Farming	 112120 Dairy Cattle and Milk Production 

11116 Rice Farming	 11213 Dual-Purpose Cattle Ranching and Farming 

111160 Rice Farming	 112130 Dual-Purpose Cattle Ranching and Farming 

11119 Other Grain Farming	 1122 Hog and Pig Farming 

111191 Oilseed and Grain Combination Farming	 11221 Hog and Pig Farming 

111199 All Other Grain Farming	 112210 Hog and Pig Farming 

1112 Vegetable and Melon Farming	 1123 Poultry and Egg Production 

11121 Vegetable and Melon Farming	 11231 Chicken Egg Production 

111211 Potato Farming	 112310 Chicken Egg Production 

111219 Other Vegetable (except Potato) and Melon	 11232 Broilers and Other Meat Type Chicken 

Farming	 Production 

1113 Fruit and Tree Nut Farming	 112320 Broilers and Other Meat Type Chicken 

11131 Orange Groves	 Production 

111310 Orange Groves	 11233 Turkey Production 

11132 Citrus (except Orange) Groves	 112330 Turkey Production 

111320 Citrus (except Orange) Groves	 11234 Poultry Hatcheries 

11133 Noncitrus Fruit and Tree Nut Farming	 112340 Poultry Hatcheries 

111331 Apple Orchards	 11239 Other Poultry Production 

111332 Grape Vineyards	 112390 Other Poultry Production 

111333 Strawberry Farming	 1124 Sheep and Goat Farming 

111334 Berry (except Strawberry) Farming	 11241 Sheep Farming 

111335 Tree Nut Farming	 112410 Sheep Farming 

111336 Fruit and Tree Nut Combination Farming	 11242 Goat Farming 

111339 Other Noncitrus Fruit Farming	 112420 Goat Farming 

1114 Greenhouse, Nursery, and Floriculture	 1125 Animal Aquaculture 

Production	 11251 Animal Aquaculture 

11141 Food Crops Grown Under Cover	 112511 Finfish Farming and Fish Hatcheries 

111411 Mushroom Production	 112512 Shellfish Farming 

111419 Other Food Crops Grown Under Cover	 112519 Other Animal Aquaculture 

11142 Nursery and Floriculture Production	 1129 Other Animal Production 

111421 Nursery and Tree Production	 11291 Apiculture 

111422 Floriculture Production	 112910 Apiculture 

1119 Other Crop Farming 11292 Horses and Other Equine Production 

11191 Tobacco Farming 112920 Horses and Other Equine Production 

111910 Tobacco Farming 11293 Fur-Bearing Animal and Rabbit Production 

11192 Cotton Farming 112930 Fur-Bearing Animal and Rabbit Production 

111920 Cotton Farming 11299 All Other Animal Production 

11193 Sugarcane Farming 112990 All Other Animal Production 

111930 Sugarcane Farming	 113 Forestry and Logging 
Appendix B 

Selected 2002 NAICS Codes B-2 

1131 Timber Tract Operations 

11311 Timber Tract Operations 

113110 Timber Tract Operations 

1132 Forest Nurseries and Gathering of Forest 

Products 

11321 Forest Nurseries and Gathering of Forest 

Products 

113210 Forest Nurseries and Gathering of Forest 

Products 

1133 Logging 

11331 Logging 

113310 Logging 

114 Fishing, Hunting and Trapping 

1141 Fishing 

11411 Fishing 

114111 Finfish Fishing 

114112 Shellfish Fishing 

114119 Other Marine Fishing 

1142 Hunting and Trapping 

11421 Hunting and Trapping 

114210 Hunting and Trapping 

115 Support Activities for Agriculture and Forestry 

1151 Support Activities for Crop Production 

11511 Support Activities for Crop Production 

115111 Cotton Ginning 

115112 Soil Preparation, Planting, and Cultivating 

115113 Crop Harvesting, Primarily by Machine 

115114 Postharvest Crop Activities (except Cotton 

Ginning) 

115115 Farm Labor Contractors and Crew Leaders 

115116 Farm Management Services 

1152 Support Activities for Animal Production 

11521 Support Activities for Animal Production 

115210 Support Activities for Animal Production 

1153 Support Activities for Forestry 

11531 Support Activities for Forestry 

115310 Support Activities for Forestry 

21 Mining 

211 Oil and Gas Extraction 

2111 Oil and Gas Extraction 

21111 Oil and Gas Extraction 

211111 Crude Petroleum and Natural Gas Extraction 

211112 Natural Gas Liquid Extraction 

212 Mining (except Oil and Gas) 

2121 Coal Mining 

21211 Coal Mining 

212111 Bituminous Coal and Lignite Surface Mining 

212112 Bituminous Coal Underground Mining 

212113 Anthracite Mining 

2122 Metal Ore Mining 

21221 Iron Ore Mining 

212210 Iron Ore Mining 

21222 Gold Ore and Silver Ore Mining 

212221 Gold Ore Mining 

212222 Silver Ore Mining 

21223 

212231 

212234 

21229 

212291 

212299 

2123 

21231 

212311 

212312 

Copper, Nickel, Lead, and Zinc Mining 

Lead Ore and Zinc Ore Mining 

Copper Ore and Nickel Ore Mining 

Other Metal Ore Mining 

Uranium-Radium-Vanadium Ore Mining 

All Other Metal Ore Mining 

Nonmetallic Mineral Mining and Quarrying 

Stone Mining and Quarrying 

Dimension Stone Mining and Quarrying 

Crushed and Broken Limestone Mining and 

Quarrying 

212313 Crushed and Broken Granite Mining and 

Quarrying 

212319 Other Crushed and Broken Stone Mining and 

Quarrying 

21232 Sand, Gravel, Clay, and Ceramic and Refractory 

Minerals Mining and Quarrying 

212321 Construction Sand and Gravel Mining 

212322 Industrial Sand Mining 

212324 Kaolin and Ball Clay Mining 

212325 Clay and Ceramic and Refractory Minerals 

Mining 

21239 Other Nonmetallic Mineral Mining and 

Quarrying 

212391 

212392 

212393 

212399 

213 

2131 

21311 

213111 

213112 

213113 

213114 

213115 

Potash, Soda, and Borate Mineral Mining 

Phosphate Rock Mining 

Other Chemical and Fertilizer Mineral Mining 

All Other Nonmetallic Mineral Mining 

Support Activities for Mining 

Support Activities for Mining 

Support Activities for Mining 

Drilling Oil and Gas Wells 

Support Activities for Oil and Gas Operations 

Support Activities for Coal Mining 

Support Activities for Metal Mining 

Support Activities for Nonmetallic Minerals 

(except Fuels) 

22 Utilities 

221 Utilities 

2211 Electric Power Generation, Transmission and 

Distribution 

22111 

221111 

221112 

221113 

221119 

22112 

Electric Power Generation 

Hydroelectric Power Generation 

Fossil Fuel Electric Power Generation 

Nuclear Electric Power Generation 

Other Electric Power Generation 

Electric Power Transmission, Control, and 

Distribution 

221121 

221122 

2212 

22121 

221210 

2213 

22131 

Electric Bulk Power Transmission and Control 

Electric Power Distribution 

Natural Gas Distribution 

Natural Gas Distribution 

Natural Gas Distribution 

Water, Sewage and Other Systems 

Water Supply and Irrigation Systems 
Appendix B 

B-3 Selected 2002 NAICS Codes 

221310 Water Supply and Irrigation Systems 

22132 Sewage Treatment Facilities 

221320 Sewage Treatment Facilities 

22133 Steam and Air-Conditioning Supply 

221330 Steam and Air-Conditioning Supply 

23 Construction 

236 Construction of Buildings 

2361 Residential Building Construction 

23611 Residential Building Construction 

236115 New Single-Family Housing Construction 

(except Operative Builders) 

236116 New Multifamily Housing Construction (except 

Operative Builders) 

236117 New Housing Operative Builders 

236118 Residential Remodelers 

2362 Nonresidential Building Construction 

23621 Industrial Building Construction 

236210 Industrial Building Construction 

23622 Commercial and Institutional Building 

Construction 

236220 Commercial and Institutional Building 

Construction 

237 Heavy and Civil Engineering Construction 

2371 Utility System Construction 

23711 Water and Sewer Line and Related Structures 

Construction 

237110 Water and Sewer Line and Related Structures 

Construction 

23712 Oil and Gas Pipeline and Related Structures 

Construction 

237120 Oil and Gas Pipeline and Related Structures 

Construction 

23713 Power and Communication Line and Related 

Structures Construction 

237130 Power and Communication Line and Related 

Structures Construction 

2372 Land Subdivision 

23721 Land Subdivision 

237210 Land Subdivision 

2373 Highway, Street, and Bridge Construction 

23731 Highway, Street, and Bridge Construction 

237310 Highway, Street, and Bridge Construction 

2379 Other Heavy and Civil Engineering Construction 

23799 Other Heavy and Civil Engineering Construction 

237990 Other Heavy and Civil Engineering Construction 

238 Specialty Trade Contractors 

2381 Foundation, Structure, and Building Exterior 

Contractors 

23811 Poured Concrete Foundation and Structure 

Contractors 

238110 Poured Concrete Foundation and Structure 

Contractors 

23812 Structural Steel and Precast Concrete Contractors 

238120 Structural Steel and Precast Concrete Contractors 

23813 Framing Contractors 

238130 Framing Contractors 

23814 Masonry Contractors 

238140 Masonry Contractors 

23815 Glass and Glazing Contractors 

238150 Glass and Glazing Contractors 

23816 Roofing Contractors 

238160 Roofing Contractors 

23817 Siding Contractors 

238170 Siding Contractors 

23819 Other Foundation, Structure, and Building 

Exterior Contractors 

238190 Other Foundation, Structure, and Building 

Exterior Contractors 

2382 Building Equipment Contractors 

23821 Electrical Contractors 

238210 Electrical Contractors 

23822 Plumbing, Heating, and Air-Conditioning 

Contractors 

238220 Plumbing, Heating, and Air-Conditioning 

Contractors 

23829 Other Building Equipment Contractors 

238290 Other Building Equipment Contractors 

2383 Building Finishing Contractors 

23831 Drywall and Insulation Contractors 

238310 Drywall and Insulation Contractors 

23832 Painting and Wall Covering Contractors 

238320 Painting and Wall Covering Contractors 

23833 Flooring Contractors 

238330 Flooring Contractors 

23834 Tile and Terrazzo Contractors 

238340 Tile and Terrazzo Contractors 

23835 Finish Carpentry Contractors 

238350 Finish Carpentry Contractors 

23839 Other Building Finishing Contractors 

238390 Other Building Finishing Contractors 

2389 Other Specialty Trade Contractors 

23891 Site Preparation Contractors 

238910 Site Preparation Contractors 

23899 All Other Specialty Trade Contractors 

238990 All Other Specialty Trade Contractors 

31-33 Manufacturing 

311 Food Manufacturing 

3111 Animal Food Manufacturing 

31111 Animal Food Manufacturing 

311111 Dog and Cat Food Manufacturing 

311119 Other Animal Food Manufacturing 

3112 Grain and Oilseed Milling 

31121 Flour Milling and Malt Manufacturing 

311211 Flour Milling 

311212 Rice Milling 

311213 Malt Manufacturing 

31122 Starch and Vegetable Fats and Oils 

Manufacturing 

311221 Wet Corn Milling 

311222 Soybean Processing 
Appendix B 

Selected 2002 NAICS Codes B-4 

311223 Other Oilseed Processing 

311225 Fats and Oils Refining and Blending 

31123 Breakfast Cereal Manufacturing 

311230 Breakfast Cereal Manufacturing 

3113 Sugar and Confectionery Product Manufacturing 

31131 Sugar Manufacturing 

311311 Sugarcane Mills 

311312 Cane Sugar Refining 

311313 Beet Sugar Manufacturing 

31132 Chocolate and Confectionery Manufacturing 

from Cacao Beans 

311320 Chocolate and Confectionery Manufacturing 

from Cacao Beans 

31133 Confectionery Manufacturing from Purchased 

Chocolate 

311330 Confectionery Manufacturing from Purchased 

Chocolate 

31134 Nonchocolate Confectionery Manufacturing 

311340 Nonchocolate Confectionery Manufacturing 

3114 Fruit and Vegetable Preserving and Specialty 

Food Manufacturing 

31141 Frozen Food Manufacturing 

311411 Frozen Fruit, Juice, and Vegetable 

Manufacturing 

311412 Frozen Specialty Food Manufacturing 

31142 Fruit and Vegetable Canning, Pickling, and 

Drying 

311421 Fruit and Vegetable Canning 

311422 Specialty Canning 

311423 Dried and Dehydrated Food Manufacturing 

3115 Dairy Product Manufacturing 

31151 Dairy Product (except Frozen) Manufacturing 

311511 Fluid Milk Manufacturing 

311512 Creamery Butter Manufacturing 

311513 Cheese Manufacturing 

311514 Dry, Condensed, and Evaporated Dairy Product 

Manufacturing 

31152 Ice Cream and Frozen Dessert Manufacturing 

311520 Ice Cream and Frozen Dessert Manufacturing 

3116 Animal Slaughtering and Processing 

31161 Animal Slaughtering and Processing 

311611 Animal (except Poultry) Slaughtering 

311612 Meat Processed from Carcasses 

311613 Rendering and Meat Byproduct Processing 

311615 Poultry Processing 

3117 Seafood Product Preparation and Packaging 

31171 Seafood Product Preparation and Packaging 

311711 Seafood Canning 

311712 Fresh and Frozen Seafood Processing 

3118 Bakeries and Tortilla Manufacturing 

31181 Bread and Bakery Product Manufacturing 

311811 Retail Bakeries 

311812 Commercial Bakeries 

311813 Frozen Cakes, Pies, and Other Pastries 

311822 Flour Mixes and Dough Manufacturing from 

Purchased Flour 

311823 Dry Pasta Manufacturing 

31183 Tortilla Manufacturing 

311830 Tortilla Manufacturing 

3119 Other Food Manufacturing 

31191 Snack Food Manufacturing 

311911 Roasted Nuts and Peanut Butter Manufacturing 

311919 Other Snack Food Manufacturing 

31192 Coffee and Tea Manufacturing 

311920 Coffee and Tea Manufacturing 

31193 Flavoring Syrup and Concentrate Manufacturing 

311930 Flavoring Syrup and Concentrate Manufacturing 

31194 Seasoning and Dressing Manufacturing 

311941 Mayonnaise, Dressing, and Other Prepared Sauce 

Manufacturing 

311942 

31199 

311991 

311999 

312 

3121 

31211 

312111 

312112 

312113 

31212 

312120 

31213 

312130 

31214 

312140 

3122 

31221 

312210 

31222 

312221 

312229 

313 

3131 

31311 

313111 

313112 

313113 

3132 

31321 

313210 

31322 

Spice and Extract Manufacturing 

All Other Food Manufacturing 

Perishable Prepared Food Manufacturing 

All Other Miscellaneous Food Manufacturing 

Beverage and Tobacco Product Manufacturing 

Beverage Manufacturing 

Soft Drink and Ice Manufacturing 

Soft Drink Manufacturing 

Bottled Water Manufacturing 

Ice Manufacturing 

Breweries 

Breweries 

Wineries 

Wineries 

Distilleries 

Distilleries 

Tobacco Manufacturing 

Tobacco Stemming and Redrying 

Tobacco Stemming and Redrying 

Tobacco Product Manufacturing 

Cigarette Manufacturing 

Other Tobacco Product Manufacturing 

Textile Mills 

Fiber, Yarn, and Thread Mills 

Fiber, Yarn, and Thread Mills 

Yarn Spinning Mills 

Yarn Texturizing, Throwing, and Twisting Mills 

Thread Mills 

Fabric Mills 

Broadwoven Fabric Mills 

Broadwoven Fabric Mills 

Narrow Fabric Mills and Schiffli Machine 

Embroidery 

313221 Narrow Fabric Mills 

313222 Schiffli Machine Embroidery 

31323 Nonwoven Fabric Mills 

313230 Nonwoven Fabric Mills 

31324 Knit Fabric Mills 

Manufacturing 313241 Weft Knit Fabric Mills 

31182 Cookie, Cracker, and Pasta Manufacturing 313249 Other Knit Fabric and Lace Mills 

311821 Cookie and Cracker Manufacturing 3133 Textile and Fabric Finishing and Fabric Coating 
Appendix B 

B-5 Selected 2002 NAICS Codes 

Mills 

31331 Textile and Fabric Finishing Mills 

313311 Broadwoven Fabric Finishing Mills 

313312 Textile and Fabric Finishing (except Broadwoven 

Fabric) Mills 

31332 Fabric Coating Mills 

313320 Fabric Coating Mills 

314 Textile Product Mills 

3141 Textile Furnishings Mills 

31411 Carpet and Rug Mills 

314110 Carpet and Rug Mills 

31412 Curtain and Linen Mills 

314121 Curtain and Drapery Mills 

314129 Other Household Textile Product Mills 

3149 Other Textile Product Mills 

31491 Textile Bag and Canvas Mills 

314911 Textile Bag Mills 

314912 Canvas and Related Product Mills 

31499 All Other Textile Product Mills 

314991 Rope, Cordage, and Twine Mills 

314992 Tire Cord and Tire Fabric Mills 

314999 All Other Miscellaneous Textile Product Mills 

Manufacturing 

322 Paper Manufacturing 

3221 Pulp, Paper, and Paperboard Mills 

32211 Pulp Mills 

322110 Pulp Mills 

32212 Paper Mills 

322121 Paper (except Newsprint) Mills 

322122 Newsprint Mills 

32213 Paperboard Mills 

322130 Paperboard Mills 

3222 Converted Paper Product Manufacturing 

32221 Paperboard Container Manufacturing 

322211 Corrugated and Solid Fiber Box Manufacturing 

322212 Folding Paperboard Box Manufacturing 

322213 Setup Paperboard Box Manufacturing 

322214 Fiber Can, Tube, Drum, and Similar Products 

Manufacturing 

322215 Nonfolding Sanitary Food Container 

Manufacturing 

32222 Paper Bag and Coated and Treated Paper 

Manufacturing 

322221 Coated and Laminated Packaging Paper and 

Plastics Film Manufacturing 

322222 Coated and Laminated Paper Manufacturing 

322223 Plastics, Foil, and Coated Paper Bag 

Manufacturing 

322224 Uncoated Paper and Multiwall Bag 

Manufacturing 

322225 Laminated Aluminum Foil Manufacturing for 

Flexible Packaging Uses 

322226 Surface-Coated Paperboard Manufacturing 

32223 Stationery Product Manufacturing 

322231 Die-Cut Paper and Paperboard Office Supplies 

Manufacturing 

322232 Envelope Manufacturing 

322233 Stationery, Tablet, and Related Product 

Manufacturing 

32229 Other Converted Paper Product Manufacturing 

322291 Sanitary Paper Product Manufacturing 

322299 All Other Converted Paper Product 

Manufacturing 

323 Printing and Related Support Activities 

3231 Printing and Related Support Activities 

32311 Printing 

323110 Commercial Lithographic Printing 

323111 Commercial Gravure Printing 

323112 Commercial Flexographic Printing 

323113 Commercial Screen Printing 

323114 Quick Printing 

323115 Digital Printing 

323116 Manifold Business Forms Printing 

323117 Books Printing 

323118 Blankbook, Looseleaf Binders, and Devices 

Manufacturing 

323119 Other Commercial Printing 

32312 Support Activities for Printing 

323121 Tradebinding and Related Work 

323122 Prepress Services 

324 Petroleum and Coal Products Manufacturing 

3241 Petroleum and Coal Products Manufacturing 

32411 Petroleum Refineries 

324110 Petroleum Refineries 

32412 Asphalt Paving, Roofing, and Saturated Materials 

Manufacturing 

324121 Asphalt Paving Mixture and Block 

Manufacturing 

324122 Asphalt Shingle and Coating Materials 

Manufacturing 

32419 Other Petroleum and Coal Products 

Manufacturing 

324191 Petroleum Lubricating Oil and Grease 

Manufacturing 

324199 All Other Petroleum and Coal Products 

Manufacturing 

325 Chemical Manufacturing 

3251 Basic Chemical Manufacturing 

32511 Petrochemical Manufacturing 

325110 Petrochemical Manufacturing 

32512 Industrial Gas Manufacturing 

325120 Industrial Gas Manufacturing 

32513 Synthetic Dye and Pigment Manufacturing 

325131 Inorganic Dye and Pigment Manufacturing 

325132 Synthetic Organic Dye and Pigment 

Manufacturing 

32518 Other Basic Inorganic Chemical Manufacturing 

325181 Alkalies and Chlorine Manufacturing 

325182 Carbon Black Manufacturing 

325188 All Other Basic Inorganic Chemical 

Manufacturing 

32519 Other Basic Organic Chemical Manufacturing 

325191 Gum and Wood Chemical Manufacturing 
Appendix B 

Selected 2002 NAICS Codes B-6 

325192 Cyclic Crude and Intermediate Manufacturing 

325193 Ethyl Alcohol Manufacturing 

325199 All Other Basic Organic Chemical Manufacturing 

3252 Resin, Synthetic Rubber, and Artificial Synthetic 

Fibers and Filaments Manufacturing 

32521 Resin and Synthetic Rubber Manufacturing 

325211 Plastics Material and Resin Manufacturing 

325212 Synthetic Rubber Manufacturing 

32522 Artificial and Synthetic Fibers and Filaments 

Manufacturing 

325221 Cellulosic Organic Fiber Manufacturing 

325222 Noncellulosic Organic Fiber Manufacturing 

3253 Pesticide, Fertilizer, and Other Agricultural 

Chemical Manufacturing 

32531 Fertilizer Manufacturing 

325311 Nitrogenous Fertilizer Manufacturing 

325312 Phosphatic Fertilizer Manufacturing 

325314 Fertilizer (Mixing Only) Manufacturing 

32532 Pesticide and Other Agricultural Chemical 

Manufacturing 

325320 Pesticide and Other Agricultural Chemical 

Manufacturing 

3254 Pharmaceutical and Medicine Manufacturing 

32541 Pharmaceutical and Medicine Manufacturing 

325411 Medicinal and Botanical Manufacturing 

325412 Pharmaceutical Preparation Manufacturing 

325413 In-Vitro Diagnostic Substance Manufacturing 

325414 Biological Product (except Diagnostic) 

Manufacturing 

3255 Paint, Coating, and Adhesive Manufacturing 

32551 Paint and Coating Manufacturing 

325510 Paint and Coating Manufacturing 

32552 Adhesive Manufacturing 

325520 Adhesive Manufacturing 

3256 Soap, Cleaning Compound, and Toilet 

Preparation Manufacturing 

32561 Soap and Cleaning Compound Manufacturing 

325611 Soap and Other Detergent Manufacturing 

325612 Polish and Other Sanitation Good Manufacturing 

325613 Surface Active Agent Manufacturing 

32562 Toilet Preparation Manufacturing 

325620 Toilet Preparation Manufacturing 

3259 Other Chemical Product and Preparation 

Manufacturing 

32591 Printing Ink Manufacturing 

325910 Printing Ink Manufacturing 

32592 Explosives Manufacturing 

325920 Explosives Manufacturing 

32599 All Other Chemical Product and Preparation 

Manufacturing 

325991 Custom Compounding of Purchased Resins 

325992 Photographic Film, Paper, Plate, and Chemical 

Manufacturing 

325998 All Other Miscellaneous Chemical Product and 

Preparation Manufacturing 

326 Plastics and Rubber Products Manufacturing 

3261 Plastics Product Manufacturing 

32611 Plastics Packaging Materials and Unlaminated 

Film and Sheet Manufacturing 

326111 Plastics Bag Manufacturing 

326112 Plastics Packaging Film and Sheet (including 

Laminated) Manufacturing 

326113 Unlaminated Plastics Film and Sheet (except 

Packaging) Manufacturing 

32612 Plastics Pipe, Pipe Fitting, and Unlaminated 

Profile Shape Manufacturing 

326121 Unlaminated Plastics Profile Shape 

Manufacturing 

326122 Plastics Pipe and Pipe Fitting Manufacturing 

32613 Laminated Plastics Plate, Sheet (except 

Packaging), and Shape Manufacturing 

326130 Laminated Plastics Plate, Sheet (except 

Packaging), and Shape Manufacturing 

32614 Polystyrene Foam Product Manufacturing 

326140 Polystyrene Foam Product Manufacturing 

32615 Urethane and Other Foam Product (except 

Polystyrene) Manufacturing 

326150 Urethane and Other Foam Product (except 

Polystyrene) Manufacturing 

32616 Plastics Bottle Manufacturing 

326160 Plastics Bottle Manufacturing 

32619 Other Plastics Product Manufacturing 

326191 Plastics Plumbing Fixture Manufacturing 

326192 Resilient Floor Covering Manufacturing 

326199 All Other Plastics Product Manufacturing 

3262 Rubber Product Manufacturing 

32621 Tire Manufacturing 

326211 Tire Manufacturing (except Retreading) 

326212 Tire Retreading 

32622 Rubber and Plastics Hoses and Belting 

Manufacturing 

326220 Rubber and Plastics Hoses and Belting 

Manufacturing 

32629 Other Rubber Product Manufacturing 

326291 Rubber Product Manufacturing for Mechanical 

Use 

326299 All Other Rubber Product Manufacturing 

327 Nonmetallic Mineral Product Manufacturing 

3271 Clay Product and Refractory Manufacturing 

32711 Pottery, Ceramics, and Plumbing Fixture 

Manufacturing 

327111 Vitreous China Plumbing Fixture and China and 

Earthenware Bathroom Accessories Manufacturing 

327112 Vitreous China, Fine Earthenware, and Other 

Pottery Product Manufacturing 

327113 Porcelain Electrical Supply Manufacturing 

32712 Clay Building Material and Refractories 

Manufacturing 

327121 Brick and Structural Clay Tile Manufacturing 

327122 Ceramic Wall and Floor Tile Manufacturing 

327123 Other Structural Clay Product Manufacturing 

327124 Clay Refractory Manufacturing 

327125 Nonclay Refractory Manufacturing 

3272 Glass and Glass Product Manufacturing 
Appendix B 

B-7 Selected 2002 NAICS Codes 

32721 Glass and Glass Product Manufacturing 

327211 Flat Glass Manufacturing 

327212 Other Pressed and Blown Glass and Glassware 

Manufacturing 

327213 Glass Container Manufacturing 

327215 Glass Product Manufacturing Made of Purchased 

Glass 

3273 Cement and Concrete Product Manufacturing 

32731 Cement Manufacturing 

327310 Cement Manufacturing 

32732 Ready-Mix Concrete Manufacturing 

327320 Ready-Mix Concrete Manufacturing 

32733 Concrete Pipe, Brick, and Block Manufacturing 

327331 Concrete Block and Brick Manufacturing 

327332 Concrete Pipe Manufacturing 

32739 Other Concrete Product Manufacturing 

327390 Other Concrete Product Manufacturing 

3274 Lime and Gypsum Product Manufacturing 

32741 Lime Manufacturing 

327410 Lime Manufacturing 

32742 Gypsum Product Manufacturing 

327420 Gypsum Product Manufacturing 

3279 Other Nonmetallic Mineral Product 

Manufacturing 

32791 Abrasive Product Manufacturing 

327910 Abrasive Product Manufacturing 

32799 All Other Nonmetallic Mineral Product 

Manufacturing 

327991 Cut Stone and Stone Product Manufacturing 

327992 Ground or Treated Mineral and Earth 

Manufacturing 

327993 Mineral Wool Manufacturing 

327999 All Other Miscellaneous Nonmetallic Mineral 

Product Manufacturing 

331 Primary Metal Manufacturing 

3311 Iron and Steel Mills and Ferroalloy 

Manufacturing 

33111 Iron and Steel Mills and Ferroalloy 

Manufacturing 

331111 Iron and Steel Mills 

331112 Electrometallurgical Ferroalloy Product 

Manufacturing 

3312 Steel Product Manufacturing from Purchased 

Steel 

33121 Iron and Steel Pipe and Tube Manufacturing 

from Purchased Steel 

331210 Iron and Steel Pipe and Tube Manufacturing 

from Purchased Steel 

33122 Rolling and Drawing of Purchased Steel 

331221 Rolled Steel Shape Manufacturing 

331222 Steel Wire Drawing 

3313 Alumina and Aluminum Production and 

Processing 

33131 Alumina and Aluminum Production and 

Processing 

331311 Alumina Refining 

331312 Primary Aluminum Production 

331314 Secondary Smelting and Alloying of Aluminum 

331315 Aluminum Sheet, Plate, and Foil Manufacturing 

331316 Aluminum Extruded Product Manufacturing 

331319 Other Aluminum Rolling and Drawing 

3314 Nonferrous Metal (except Aluminum) Production 

and Processing 

33141 Nonferrous Metal (except Aluminum) Smelting 

and Refining 

331411 Primary Smelting and Refining of Copper 

331419 Primary Smelting and Refining of Nonferrous 

Metal (except Copper and Aluminum) 

33142 Copper Rolling, Drawing, Extruding, and 

Alloying 

331421 Copper Rolling, Drawing, and Extruding 

331422 Copper Wire (except Mechanical) Drawing 

331423 Secondary Smelting, Refining, and Alloying of 

Copper 

33149 Nonferrous Metal (except Copper and 

Aluminum) Rolling, Drawing, Extruding, and Alloying 

331491 Nonferrous Metal (except Copper and 

Aluminum) Rolling, Drawing, and Extruding 

331492 Secondary Smelting, Refining, and Alloying of 

Nonferrous Metal (except Copper and Aluminum) 

3315 Foundries 

33151 Ferrous Metal Foundries 

331511 Iron Foundries 

331512 Steel Investment Foundries 

331513 Steel Foundries (except Investment) 

33152 Nonferrous Metal Foundries 

331521 Aluminum Die-Casting Foundries 

331522 Nonferrous (except Aluminum) Die-Casting 

Foundries 

331524 Aluminum Foundries (except Die-Casting) 

331525 Copper Foundries (except Die-Casting) 

331528 Other Nonferrous Foundries (except Die-Casting) 

332 Fabricated Metal Product Manufacturing 

3321 Forging and Stamping 

33211 Forging and Stamping 

332111 Iron and Steel Forging 

332112 Nonferrous Forging 

332114 Custom Roll Forming 

332115 Crown and Closure Manufacturing 

332116 Metal Stamping 

332117 Powder Metallurgy Part Manufacturing 

3322 Cutlery and Handtool Manufacturing 

33221 Cutlery and Handtool Manufacturing 

332211 Cutlery and Flatware (except Precious) 

Manufacturing 

332212 Hand and Edge Tool Manufacturing 

332213 Saw Blade and Handsaw Manufacturing 

332214 Kitchen Utensil, Pot, and Pan Manufacturing 

3323 Architectural and Structural Metals 

Manufacturing 

33231 Plate Work and Fabricated Structural Product 

Manufacturing 

332311 Prefabricated Metal Building and Component 

Manufacturing 
Appendix B 

Selected 2002 NAICS Codes B-8 

332312 Fabricated Structural Metal Manufacturing 

332313 Plate Work Manufacturing 

33232 Ornamental and Architectural Metal Products 

Manufacturing 

332321 Metal Window and Door Manufacturing 

332322 Sheet Metal Work Manufacturing 

332323 Ornamental and Architectural Metal Work 

Manufacturing 

3324 Boiler, Tank, and Shipping Container 

Manufacturing 

33241 Power Boiler and Heat Exchanger Manufacturing 

332410 Power Boiler and Heat Exchanger Manufacturing 

33242 Metal Tank (Heavy Gauge) Manufacturing 

332420 Metal Tank (Heavy Gauge) Manufacturing 

33243 Metal Can, Box, and Other Metal Container 

(Light Gauge) Manufacturing 

332431 Metal Can Manufacturing 

332439 Other Metal Container Manufacturing 

3325 Hardware Manufacturing 

33251 Hardware Manufacturing 

332510 Hardware Manufacturing 

3326 Spring and Wire Product Manufacturing 

33261 Spring and Wire Product Manufacturing 

332611 Spring (Heavy Gauge) Manufacturing 

332612 Spring (Light Gauge) Manufacturing 

332618 Other Fabricated Wire Product Manufacturing 

3327 Machine Shops; Turned Product; and Screw, 

Nut, and Bolt Manufacturing 

33271 Machine Shops 

332710 Machine Shops 

33272 Turned Product and Screw, Nut, and Bolt 

Manufacturing 

332721 Precision Turned Product Manufacturing 

332722 Bolt, Nut, Screw, Rivet, and Washer 

Manufacturing 

3328 Coating, Engraving, Heat Treating, and Allied 

Activities 

33281 Coating, Engraving, Heat Treating, and Allied 

Activities 

332811 Metal Heat Treating 

332812 Metal Coating, Engraving (except Jewelry and 

Silverware), and Allied Services to Manufacturers 

332813 Electroplating, Plating, Polishing, Anodizing, 

and Coloring 

3329 Other Fabricated Metal Product Manufacturing 

33291 Metal Valve Manufacturing 

332911 Industrial Valve Manufacturing 

332912 Fluid Power Valve and Hose Fitting 

Manufacturing 

332913 Plumbing Fixture Fitting and Trim 

Manufacturing 

332919 Other Metal Valve and Pipe Fitting 

Manufacturing 

33299 All Other Fabricated Metal Product 

Manufacturing 

332991 Ball and Roller Bearing Manufacturing 

332992 Small Arms Ammunition Manufacturing 

332993 Ammunition (except Small Arms) Manufacturing 

332994 Small Arms Manufacturing 

332995 Other Ordnance and Accessories Manufacturing 

332996 Fabricated Pipe and Pipe Fitting Manufacturing 

332997 Industrial Pattern Manufacturing 

332998 Enameled Iron and Metal Sanitary Ware 

Manufacturing 

332999 All Other Miscellaneous Fabricated Metal 

Product Manufacturing 

333 Machinery Manufacturing 

3331 Agriculture, Construction, and Mining 

Machinery Manufacturing 

33311 Agricultural Implement Manufacturing 

333111 Farm Machinery and Equipment Manufacturing 

333112 Lawn and Garden Tractor and Home Lawn and 

Garden Equipment Manufacturing 

33312 Construction Machinery Manufacturing 

333120 Construction Machinery Manufacturing 

33313 Mining and Oil and Gas Field Machinery 

Manufacturing 

333131 Mining Machinery and Equipment 

Manufacturing 

333132 Oil and Gas Field Machinery and Equipment 

Manufacturing 

3332 Industrial Machinery Manufacturing 

33321 Sawmill and Woodworking Machinery 

Manufacturing 

333210 Sawmill and Woodworking Machinery 

Manufacturing 

33322 Plastics and Rubber Industry Machinery 

Manufacturing 

333220 Plastics and Rubber Industry Machinery 

Manufacturing 

33329 Other Industrial Machinery Manufacturing 

333291 Paper Industry Machinery Manufacturing 

333292 Textile Machinery Manufacturing 

333293 Printing Machinery and Equipment 

Manufacturing 

333294 Food Product Machinery Manufacturing 

333295 Semiconductor Machinery Manufacturing 

333298 All Other Industrial Machinery Manufacturing 

3333 Commercial and Service Industry Machinery 

Manufacturing 

33331 Commercial and Service Industry Machinery 

Manufacturing 

333311 Automatic Vending Machine Manufacturing 

333312 Commercial Laundry, Drycleaning, and Pressing 

Machine Manufacturing 

333313 Office Machinery Manufacturing 

333314 Optical Instrument and Lens Manufacturing 

333315 Photographic and Photocopying Equipment 

Manufacturing 

333319 Other Commercial and Service Industry 

Machinery Manufacturing 

3334 Ventilation, Heating, Air-Conditioning, and 

Commercial Refrigeration Equipment Manufacturing 

33341 Ventilation, Heating, Air-Conditioning, and 
Appendix B 

B-9 Selected 2002 NAICS Codes 

Commercial Refrigeration Equipment Manufacturing 

333411 Air Purification Equipment Manufacturing 

333412 Industrial and Commercial Fan and Blower 

Manufacturing 

333414 Heating Equipment (except Warm Air Furnaces) 

Manufacturing 

333415 Air-Conditioning and Warm Air Heating 

Equipment and Commercial and Industrial Refrigeration 

Equipment Manufacturing 

3335 Metalworking Machinery Manufacturing 

33351 Metalworking Machinery Manufacturing 

333511 Industrial Mold Manufacturing 

333512 Machine Tool (Metal Cutting Types) 

Manufacturing 

333513 Machine Tool (Metal Forming Types) 

Manufacturing 

333514 Special Die and Tool, Die Set, Jig, and Fixture 

Manufacturing 

333515 Cutting Tool and Machine Tool Accessory 

Manufacturing 

333516 Rolling Mill Machinery and Equipment 

Manufacturing 

333518 Other Metalworking Machinery Manufacturing 

3336 Engine, Turbine, and Power Transmission 

Equipment Manufacturing 

33361 Engine, Turbine, and Power Transmission 

Equipment Manufacturing 

333611 Turbine and Turbine Generator Set Units 

Manufacturing 

333612 Speed Changer, Industrial High-Speed Drive, and 

Gear Manufacturing 

333613 Mechanical Power Transmission Equipment 

Manufacturing 

333618 Other Engine Equipment Manufacturing 

3339 Other General Purpose Machinery Manufacturing 

33391 Pump and Compressor Manufacturing 

333911 Pump and Pumping Equipment Manufacturing 

333912 Air and Gas Compressor Manufacturing 

333913 Measuring and Dispensing Pump Manufacturing 

33392 Material Handling Equipment Manufacturing 

333921 Elevator and Moving Stairway Manufacturing 

333922 Conveyor and Conveying Equipment 

Manufacturing 

333923 Overhead Traveling Crane, Hoist, and Monorail 

System Manufacturing 

333924 Industrial Truck, Tractor, Trailer, and Stacker 

Machinery Manufacturing 

33399 All Other General Purpose Machinery 

Manufacturing 

333991 Power-Driven Handtool Manufacturing 

333992 Welding and Soldering Equipment 

Manufacturing 

333993 Packaging Machinery Manufacturing 

333994 Industrial Process Furnace and Oven 

Manufacturing 

333995 Fluid Power Cylinder and Actuator 

Manufacturing 

333996 Fluid Power Pump and Motor Manufacturing 

333997 Scale and Balance (except Laboratory) 

Manufacturing 

333999 All Other Miscellaneous General Purpose 

Machinery Manufacturing 

334 Computer and Electronic Product Manufacturing 

3341 Computer and Peripheral Equipment 

Manufacturing 

33411 Computer and Peripheral Equipment 

Manufacturing 

334111 Electronic Computer Manufacturing 

334112 Computer Storage Device Manufacturing 

334113 Computer Terminal Manufacturing 

334119 Other Computer Peripheral Equipment 

Manufacturing 

3342 Communications Equipment Manufacturing 

33421 Telephone Apparatus Manufacturing 

334210 Telephone Apparatus Manufacturing 

33422 Radio and Television Broadcasting and Wireless 

Communications Equipment Manufacturing 

334220 Radio and Television Broadcasting and Wireless 

Communications Equipment Manufacturing 

33429 Other Communications Equipment 

Manufacturing 

334290 Other Communications Equipment 

Manufacturing 

3343 Audio and Video Equipment Manufacturing 

33431 Audio and Video Equipment Manufacturing 

334310 Audio and Video Equipment Manufacturing 

3344 Semiconductor and Other Electronic Component 

Manufacturing 

33441 Semiconductor and Other Electronic Component 

Manufacturing 

334411 Electron Tube Manufacturing 

334412 Bare Printed Circuit Board Manufacturing 

334413 Semiconductor and Related Device 

Manufacturing 

334414 Electronic Capacitor Manufacturing 

334415 Electronic Resistor Manufacturing 

334416 Electronic Coil, Transformer, and Other Inductor 

Manufacturing 

334417 Electronic Connector Manufacturing 

334418 Printed Circuit Assembly (Electronic Assembly) 

Manufacturing 

334419 Other Electronic Component Manufacturing 

3345 Navigational, Measuring, Electromedical, and 

Control Instruments Manufacturing 

33451 Navigational, Measuring, Electromedical, and 

Control Instruments Manufacturing 

334510 Electromedical and Electrotherapeutic Apparatus 

Manufacturing 

334511 Search, Detection, Navigation, Guidance, 

Aeronautical, and Nautical System and Instrument 

Manufacturing 

334512 Automatic Environmental Control Manufacturing 

for Residential, Commercial, and Appliance Use 

334513 Instruments and Related Products Manufacturing 
Appendix B 

Selected 2002 NAICS Codes B-10 

for Measuring, Displaying, and Controlling Industrial 

Process Variables 

334514 Totalizing Fluid Meter and Counting Device 

Manufacturing 

334515 Instrument Manufacturing for Measuring and 

Testing Electricity and Electrical Signals 

334516 Analytical Laboratory Instrument Manufacturing 

334517 Irradiation Apparatus Manufacturing 

334518 Watch, Clock, and Part Manufacturing 

334519 Other Measuring and Controlling Device 

Manufacturing 

3346 Manufacturing and Reproducing Magnetic and 

Optical Media 

33461 Manufacturing and Reproducing Magnetic and 

Optical Media 

334611 Software Reproducing 

334612 Prerecorded Compact Disc (except Software), 

Tape, and Record Reproducing 

334613 Magnetic and Optical Recording Media 

Manufacturing 

335 Electrical Equipment, Appliance, and Component 

Manufacturing 

3351 Electric Lighting Equipment Manufacturing 

33511 Electric Lamp Bulb and Part Manufacturing 

335110 Electric Lamp Bulb and Part Manufacturing 

33512 Lighting Fixture Manufacturing 

335121 Residential Electric Lighting Fixture 

Manufacturing 

335122 Commercial, Industrial, and Institutional Electric 

Lighting Fixture Manufacturing 

335129 Other Lighting Equipment Manufacturing 

3352 Household Appliance Manufacturing 

33521 Small Electrical Appliance Manufacturing 

335211 Electric Housewares and Household Fan 

Manufacturing 

335212 Household Vacuum Cleaner Manufacturing 

33522 Major Appliance Manufacturing 

335221 Household Cooking Appliance Manufacturing 

335222 Household Refrigerator and Home Freezer 

Manufacturing 

335224 Household Laundry Equipment Manufacturing 

335228 Other Major Household Appliance 

Manufacturing 

3353 Electrical Equipment Manufacturing 

33531 Electrical Equipment Manufacturing 

335311 Power, Distribution, and Specialty Transformer 

Manufacturing 

335312 Motor and Generator Manufacturing 

335313 Switchgear and Switchboard Apparatus 

Manufacturing 

335314 Relay and Industrial Control Manufacturing 

3359 Other Electrical Equipment and Component 

Manufacturing 

33591 Battery Manufacturing 

335911 Storage Battery Manufacturing 

335912 Primary Battery Manufacturing 

33592 Communication and Energy Wire and Cable 

Manufacturing 

335921 Fiber Optic Cable Manufacturing 

335929 Other Communication and Energy Wire 

Manufacturing 

33593 Wiring Device Manufacturing 

335931 Current-Carrying Wiring Device Manufacturing 

335932 Noncurrent-Carrying Wiring Device 

Manufacturing 

33599 All Other Electrical Equipment and Component 

Manufacturing 

335991 Carbon and Graphite Product Manufacturing 

335999 All Other Miscellaneous Electrical Equipment 

and Component Manufacturing 

336 Transportation Equipment Manufacturing 

3361 Motor Vehicle Manufacturing 

33611 Automobile and Light Duty Motor Vehicle 

Manufacturing 

336111 Automobile Manufacturing 

336112 Light Truck and Utility Vehicle Manufacturing 

33612 Heavy Duty Truck Manufacturing 

336120 Heavy Duty Truck Manufacturing 

3362 Motor Vehicle Body and Trailer Manufacturing 

33621 Motor Vehicle Body and Trailer Manufacturing 

336211 Motor Vehicle Body Manufacturing 

336212 Truck Trailer Manufacturing 

336213 Motor Home Manufacturing 

336214 Travel Trailer and Camper Manufacturing 

3363 Motor Vehicle Parts Manufacturing 

33631 Motor Vehicle Gasoline Engine and Engine Parts 

Manufacturing 

336311 Carburetor, Piston, Piston Ring, and Valve 

Manufacturing 

336312 Gasoline Engine and Engine Parts Manufacturing 

33632 Motor Vehicle Electrical and Electronic 

Equipment Manufacturing 

336321 Vehicular Lighting Equipment Manufacturing 

336322 Other Motor Vehicle Electrical and Electronic 

Equipment Manufacturing 

33633 Motor Vehicle Steering and Suspension 

Components (except Spring) Manufacturing 

336330 Motor Vehicle Steering and Suspension 

Components (except Spring) Manufacturing 

33634 Motor Vehicle Brake System Manufacturing 

336340 Motor Vehicle Brake System Manufacturing 

33635 Motor Vehicle Transmission and Power Train 

Parts Manufacturing 

336350 Motor Vehicle Transmission and Power Train 

Parts Manufacturing 

33636 Motor Vehicle Seating and Interior Trim 

Manufacturing 

336360 Motor Vehicle Seating and Interior Trim 

Manufacturing 

33637 Motor Vehicle Metal Stamping 

336370 Motor Vehicle Metal Stamping 

33639 Other Motor Vehicle Parts Manufacturing 

336391 Motor Vehicle Air-Conditioning Manufacturing 

336399 All Other Motor Vehicle Parts Manufacturing 
Appendix B 

B-11 Selected 2002 NAICS Codes 

3364 Aerospace Product and Parts Manufacturing 

33641 Aerospace Product and Parts Manufacturing 

336411 Aircraft Manufacturing 

336412 Aircraft Engine and Engine Parts Manufacturing 

336413 Other Aircraft Parts and Auxiliary Equipment 

Manufacturing 

336414 Guided Missile and Space Vehicle 

Manufacturing 

336415 Guided Missile and Space Vehicle Propulsion 

Unit and Propulsion Unit Parts Manufacturing 

336419 Other Guided Missile and Space Vehicle Parts 

and Auxiliary Equipment Manufacturing 

3365 Railroad Rolling Stock Manufacturing 

33651 Railroad Rolling Stock Manufacturing 

336510 Railroad Rolling Stock Manufacturing 

3366 Ship and Boat Building 

33661 Ship and Boat Building 

336611 Ship Building and Repairing 

336612 Boat Building 

3369 Other Transportation Equipment Manufacturing 

33699 Other Transportation Equipment Manufacturing 

336991 Motorcycle, Bicycle, and Parts Manufacturing 

336992 Military Armored Vehicle, Tank, and Tank 

Component Manufacturing 

336999 All Other Transportation Equipment 

Manufacturing 

42 Wholesale Trade 

424 Merchant Wholesalers, Nondurable Goods 

4244 Grocery and Related Product Wholesalers 

42441 General Line Grocery Merchant Wholesalers 

424410 General Line Grocery Merchant Wholesalers 

42442 Packaged Frozen Food Merchant Wholesalers 

424420 Packaged Frozen Food Merchant Wholesalers 

42443 Dairy Product (except Dried or Canned) 

Merchant Wholesalers 

424430 Dairy Product (except Dried or Canned) 

Merchant Wholesalers 

42444 Poultry and Poultry Product Merchant 

Wholesalers 

424440 Poultry and Poultry Product Merchant 

Wholesalers 

42445 Confectionery Merchant Wholesalers 

424450 Confectionery Merchant Wholesalers 

42446 Fish and Seafood Merchant Wholesalers 

424460 Fish and Seafood Merchant Wholesalers 

42447 Meat and Meat Product Merchant Wholesalers 

424470 Meat and Meat Product Merchant Wholesalers 

42448 Fresh Fruit and Vegetable Merchant Wholesalers 

424480 Fresh Fruit and Vegetable Merchant Wholesalers 

42449 Other Grocery and Related Products Merchant 

Wholesalers 

424490 Other Grocery and Related Products Merchant 

Wholesalers 

4245 Farm Product Raw Material Merchant 

Wholesalers 

42451 Grain and Field Bean Merchant Wholesalers 

424510 Grain and Field Bean Merchant Wholesalers 

42452 Livestock Merchant Wholesalers 

424520 Livestock Merchant Wholesalers 

42459 Other Farm Product Raw Material Merchant 

Wholesalers 

424590 Other Farm Product Raw Material Merchant 

Wholesalers 

4246 Chemical and Allied Products Merchant 

Wholesalers 

42461 Plastics Materials and Basic Forms and Shapes 

Merchant Wholesalers 

424610 Plastics Materials and Basic Forms and Shapes 

Merchant Wholesalers 

42469 Other Chemical and Allied Products Merchant 

Wholesalers 

424690 Other Chemical and Allied Products Merchant 

Wholesalers 

4247 Petroleum and Petroleum Products Merchant 

Wholesalers 

42471 Petroleum Bulk Stations and Terminals 

424710 Petroleum Bulk Stations and Terminals 

42472 Petroleum and Petroleum Products Merchant 

Wholesalers (except Bulk Stations and Terminals) 

424720 Petroleum and Petroleum Products Merchant 

Wholesalers (except Bulk Stations and Terminals) 

4248 Beer, Wine, and Distilled Alcoholic Beverage 

Merchant Wholesalers 

42481 Beer and Ale Merchant Wholesalers 

424810 Beer and Ale Merchant Wholesalers 

42482 Wine and Distilled Alcoholic Beverage Merchant 

Wholesalers 

424820 Wine and Distilled Alcoholic Beverage Merchant 

Wholesalers 

4249 Miscellaneous Nondurable Goods Merchant 

Wholesalers 

42491 Farm Supplies Merchant Wholesalers 

424910 Farm Supplies Merchant Wholesalers 

42492 Book, Periodical, and Newspaper Merchant 

Wholesalers 

424920 Book, Periodical, and Newspaper Merchant 

Wholesalers 

42493 Flower, Nursery Stock, and Florists' Supplies 

Merchant Wholesalers 

424930 Flower, Nursery Stock, and Florists' Supplies 

Merchant Wholesalers 

42494 Tobacco and Tobacco Product Merchant 

Wholesalers 

424940 Tobacco and Tobacco Product Merchant 

Wholesalers 

42495 Paint, Varnish, and Supplies Merchant 

Wholesalers 

424950 Paint, Varnish, and Supplies Merchant 

Wholesalers 

42499 Other Miscellaneous Nondurable Goods 

Merchant Wholesalers 

424990 Other Miscellaneous Nondurable Goods 
Appendix B 

Selected 2002 NAICS Codes B-12 

Merchant Wholesalers 484230 Specialized Freight (except Used Goods) 

Trucking, Long-Distance 

44-45 Retail Trade 

4451 Grocery Stores 

44511 Supermarkets and Other Grocery (except 

Convenience) Stores 

445110 Supermarkets and Other Grocery (except 

Convenience) Stores 

45291 Warehouse Clubs and Supercenters 

452910 Warehouse Clubs and Supercenters 

45299 All Other General Merchandise Stores 

452990 All Other General Merchandise Stores 

45431 Fuel Dealers 

454311 Heating Oil Dealers 

454312 Liquefied Petroleum Gas (Bottled Gas) Dealers 

454319 Other Fuel Dealers 

48-49 Transportation and Warehousing 

482 Rail Transportation 

4821 Rail Transportation 

48211 Rail Transportation 

482111 Line-Haul Railroads 

482112 Short Line Railroads 

483 Water Transportation 

4831 Deep Sea, Coastal, and Great Lakes Water 

Transportation 

48311 Deep Sea, Coastal, and Great Lakes Water 

Transportation 

483111 Deep Sea Freight Transportation 

483112 Deep Sea Passenger Transportation 

483113 Coastal and Great Lakes Freight Transportation 

483114 Coastal and Great Lakes Passenger 

Transportation 

4832 Inland Water Transportation 

48321 Inland Water Transportation 

483211 Inland Water Freight Transportation 

483212 Inland Water Passenger Transportation 

484 Truck Transportation 

4841 General Freight Trucking 

48411 General Freight Trucking, Local 

484110 General Freight Trucking, Local 

48412 General Freight Trucking, Long-Distance 

484121 General Freight Trucking, Long-Distance, 

Truckload 

484122 General Freight Trucking, Long-Distance, Less 

Than Truckload 

4842 Specialized Freight Trucking 

48421 Used Household and Office Goods Moving 

484210 Used Household and Office Goods Moving 

48422 Specialized Freight (except Used Goods) 

Trucking, Local 

484220 Specialized Freight (except Used Goods) 

Trucking, Local 

48423 Specialized Freight (except Used Goods) 

Trucking, Long-Distance 

486 Pipeline Transportation 

4861 Pipeline Transportation of Crude Oil 

48611 Pipeline Transportation of Crude Oil 

486110 Pipeline Transportation of Crude Oil 

4862 Pipeline Transportation of Natural Gas 

48621 Pipeline Transportation of Natural Gas 

486210 Pipeline Transportation of Natural Gas 

4869 Other Pipeline Transportation 

48691 Pipeline Transportation of Refined Petroleum 

Products 

486910 Pipeline Transportation of Refined Petroleum 

Products 

48699 All Other Pipeline Transportation 

486990 All Other Pipeline Transportation 

488 Support Activities for Transportation 

4881 Support Activities for Air Transportation 

48811 Airport Operations 

488119 Other Airport Operations 

48819 Other Support Activities for Air Transportation 

488190 Other Support Activities for Air Transportation 

4882 Support Activities for Rail Transportation 

48821 Support Activities for Rail Transportation 

488210 Support Activities for Rail Transportation 

4883 Support Activities for Water Transportation 

48831 Port and Harbor Operations 

488310 Port and Harbor Operations 

48832 Marine Cargo Handling 

488320 Marine Cargo Handling 

48833 Navigational Services to Shipping 

488330 Navigational Services to Shipping 

48839 Other Support Activities for Water 

Transportation 

488390 Other Support Activities for Water 

Transportation 

4884 Support Activities for Road Transportation 

48841 Motor Vehicle Towing 

488410 Motor Vehicle Towing 

48849 Other Support Activities for Road Transportation 

488490 Other Support Activities for Road Transportation 

4885 Freight Transportation Arrangement 

48851 Freight Transportation Arrangement 

488510 Freight Transportation Arrangement 

4889 Other Support Activities for Transportation 

48899 Other Support Activities for Transportation 

488991 Packing and Crating 

488999 All Other Support Activities for Transportation 

493 Warehousing and Storage 

4931 Warehousing and Storage 

49311 General Warehousing and Storage 

493110 General Warehousing and Storage 

49312 Refrigerated Warehousing and Storage 

493120 Refrigerated Warehousing and Storage 

49313 Farm Product Warehousing and Storage 

493130 Farm Product Warehousing and Storage 

49319 Other Warehousing and Storage 
Appendix B 

B-13 Selected 2002 NAICS Codes 

493190 Other Warehousing and Storage 561710 Exterminating and Pest Control Services 

56172 Janitorial Services 

56 Administrative and Support and Waste 561720 Janitorial Services 

Management and Remediation Services 56173 Landscaping Services 

561730 Landscaping Services 

561 Administrative and Support Services 56174 Carpet and Upholstery Cleaning Services 

5611 Office Administrative Services 561740 Carpet and Upholstery Cleaning Services 

56111 Office Administrative Services 56179 Other Services to Buildings and Dwellings 

561110 Office Administrative Services 561790 Other Services to Buildings and Dwellings 

5612 Facilities Support Services 5619 Other Support Services 

56121 Facilities Support Services 56191 Packaging and Labeling Services 

561210 Facilities Support Services 561910 Packaging and Labeling Services 

5613 Employment Services 56192 Convention and Trade Show Organizers 

56131 Employment Placement Agencies 561920 Convention and Trade Show Organizers 

561310 Employment Placement Agencies 56199 All Other Support Services 

56132 Temporary Help Services 561990 All Other Support Services 

561320 Temporary Help Services 562 Waste Management and Remediation Services 

56133 Professional Employer Organizations 5621 Waste Collection 

561330 Professional Employer Organizations 56211 Waste Collection 

5614 Business Support Services 562111 Solid Waste Collection 

56141 Document Preparation Services 562112 Hazardous Waste Collection 

561410 Document Preparation Services 562119 Other Waste Collection 

56142 Telephone Call Centers 5622 Waste Treatment and Disposal 

561421 Telephone Answering Services 56221 Waste Treatment and Disposal 

561422 Telemarketing Bureaus 562211 Hazardous Waste Treatment and Disposal 

56143 Business Service Centers 562212 Solid Waste Landfill 

561431 Private Mail Centers 562213 Solid Waste Combustors and Incinerators 

561439 Other Business Service Centers (including Copy 562219 Other Nonhazardous Waste Treatment and 

Shops) Disposal 

56144 Collection Agencies 5629 Remediation and Other Waste Management 

561440 Collection Agencies Services 

56145 Credit Bureaus 56291 Remediation Services 

561450 Credit Bureaus 562910 Remediation Services 

56149 Other Business Support Services 56292 Materials Recovery Facilities 

561491 Repossession Services 562920 Materials Recovery Facilities 

561492 Court Reporting and Stenotype Services 56299 All Other Waste Management Services 

561499 All Other Business Support Services 562991 Septic Tank and Related Services 

5615 Travel Arrangement and Reservation Services 562998 All Other Miscellaneous Waste Management 

56151 Travel Agencies Services 

561510 Travel Agencies 

56152 Tour Operators 92 Public Administration 

561520 Tour Operators 

56159 Other Travel Arrangement and Reservation 927 Space Research and Technology 

Services 9271 Space Research and Technology 

561591 Convention and Visitors Bureaus 92711 Space Research and Technology 

561599 All Other Travel Arrangement and Reservation 927110 Space Research and Technology 

Services 928 National Security and International Affairs 

5616 Investigation and Security Services 9281 National Security and International Affairs 

56161 Investigation, Guard, and Armored Car Services 92811 National Security 

561611 Investigation Services 928110 National Security 

561612 Security Guards and Patrol Services 

561613 Armored Car Services 

56162 Security Systems Services 

561621 Security Systems Services (except Locksmiths) 

561622 Locksmiths 

5617 Services to Buildings and Dwellings 

56171 Exterminating and Pest Control Services 
APPENDIX C: TECHNICAL ASSISTANCE


APPENDIX C: TECHNICAL ASSISTANCE 

WHERE CAN I GET HELP? 

This appendix provides points of contact for the resources that are available to facilities 

in complying with 40 CFR part 68 from EPA, OSHA, and several other entities involved 

in process safety and risk management issues. 

U.S. Environmental Protection Agency 

� Office of Emergency Prevention, Preparedness, and Response 

1200 Pennsylvania Ave., NW (Mailcode 5104A) 

Washington, DC 20460 

(202) 564-8600


www.epa.gov/swercepp


OEPPR (formerly CEPPO) administers the RMP program at the national level. 

The OEPPR homepage on the Internet provides access to downloadable versions 

of numerous risk management program documents, many of which are also 

available upon request from the National Service Center for Environmental 

Publications S see below. 

� EPCRA/Superfund/RCRA/CAA Call Center 

Toll-Free: (800) 424-9346 

Local: (703) 412-9810 

TDD: (800) 553-7672 

TDD Local: (703) 412-3323 

Monday - Friday, 9:00 am - 5:00 pm EST 

www.epa.gov/epaoswer/hotline/index.htm 

Questions or comments: epacallcenter@bah.com 

EPA’s RCRA, Superfund, and EPCRA Call Center is a publicly accessible 

service that provides up-to-date information on EPA programs. The Call Center 

responds to factual questions on a variety of federal EPA regulations, including 

those developed under Clean Air Act section 112(r). The Call Center also 

responds to requests for individual copies of documents. 

� National Service Center for Environmental Publications 

P.O. Box 42419


Cincinnati, OH 45242


Phone: (800) 490-9198


Fax: (513) 489-8695 


www.epa.gov/ncepihom/


Order size may be restricted due to limited supply. As supplies are depleted you 

will be referred to the National Environmental Publications Internet Site 

(NEPIS) National Technical Information Service (NTIS), the Government 
Appendix C 

Technical Assistance C-2 

Printing Office (GPO), or the Educational Resource Information Center (ERIC) 

to obtain your documents at cost. 

� National Technical Information Service 

Technology Administration 

U.S. Department of Commerce


5285 Port Royal Road


Springfield, VA 22161


Phone: (800) 553-6847 (toll-free)


Phone: (703) 605-6000 (local)


Monday - Friday, 8:00 am - 6:00 pm EST


Fax: (703) 605-6900


www.ntis.gov/


E-Mail: orders@ntis.gov


The National Technical Information Service is the official resource for 

government-sponsored U.S. and worldwide scientific, technical, engineering, 

and business-related information. Documents not available through the EPA 

Hotline are often available from NTIS. You can place your order by telephone, 

mail, fax, or e-mail. NTIS also offers online ordering using NTIS OrderNow. 

� EPA Small Business Assistance Program 

www.epa.gov/ttn/sbap/ 

The Clean Air Act Amendments of 1990 requires that all States develop a 

program to assist small businesses in meeting the requirements of the Act. EPA 

has established its own Small Business Assistance Program (SBAP) to provide 

technical assistance to these State small business programs. This site has been 

developed to allow State and EPA programs to share information about their 

small business assistance materials and activities. 

� EPA Small Business Hotline 

Small Business Ombudsman Office 

(800) 368-5888 

� Office of Air Quality Planning and Standards 

www.epa.gov/oar/oaqps/ 

The Office of Air Quality Planning and Standards administers EPA’s operating 

permit program. Permits incorporate terms and conditions to assure that the 

source complies with all applicable requirements. The RMP regulations are 

considered to be applicable requirements. 
Appendix C 

C-3 Technical Assistance 

Occupational Safety and Health Administration (OSHA) 

OSHA administers the Process Safety Management Standard (29 CFR 1910.119), which 

mandates actions similar to that of EPA’s prevention program. In about half of the states 

(see Appendix D), OSHA programs are run by state agencies. 

� Occupational Safety and Health Administration 

U.S. Department of Labor


200 Constitution Avenue, NW


Washington, DC 20210


(800) 321-OSHA


www.osha.gov


� OSHA Process Safety Management Homepage 

www.osha.gov/SLTC/processsafetymanagement/index.html 

The PSM homepage on the Internet provides access to downloadable versions of 

numerous process safety management documents. 

� OSHA Consultation Services 

http://www.osha.gov/dcsp/smallbusiness/consult.html 

Using a free consultation service largely funded by OSHA, employers can find 

out about potential hazards at their work sites, improve their occupational safety 

and health management systems, and even qualify for a one-year exemption from 

routine OSHA inspections. Primarily targeted for smaller businesses, this safety 

and health consultation program is completely separate from the OSHA 

inspection effort. 

� OSHA Office of Training & Education 

OSHA Training Institute 

2020 South Arlington Heights Road 

Arlington Heights, Illinois 60005-4102 

(847) 297-4913 

www.osha.gov/fso/ote/training/training_resources.html 

The OSHA Office of Training and Education offers short-term training through 

the OSHA Training Institute. The Office also administers the OSHA Training 

Institute Education Centers program, in which designated nonprofit 

organizations in each federal region offer the most frequently requested courses 

for the private sector and other Federal agency staff. 

� OSHA Voluntary Protection Program (VPP) 

Office of Partnerships and Recognition 

(202) 693-2213 

www.osha.gov/dcsp/vpp/index.html 
Appendix C 

Technical Assistance C-4 

OSHA Voluntary Protection Programs are designed to recognize and promote 

effective safety and health management. In the VPP, management, labor, and 

OSHA establish a cooperative relationship at a workplace that has implemented 

a strong program. 

� OSHA Publications 

U.S. Department of Labor/OSHA 

OSHA Publications 

P.O. Box 37535, Washington, D.C. 20013-7535 

Telephone: (202) 693-1888 

or by Fax: (202) 693-2498 

Or download on line at: www.osha.gov/pls/publications/pubindex.list 

The Publications Office provides copies of various OSHA documents. 

Other Organizations 

� American Institute of Chemical Engineers 

3 Park Avenue


New York, NY 10016-5991


(212) 591-7338


www.aiche.org/


AIChE provides educational and training programs and an annual Publications 

Catalog from which documents can be purchased. 

Center for Chemical Process Safety

 Park Avenue


New York, NY 10016-5991


(212) 591-7319


www.aiche.org/ccps


� Small Business Administration (SBA) 

409 Third Street, SW


Washington, DC 20416


(800) 827-5722


www.sba.gov/


SBA was created to help America's entrepreneurs form successful small 

enterprises. SBA's program offices in every state offer financing, training and 

advocacy for small firms. In addition, the SBA works with thousands of lending, 

educational, and training institutions nationwide. 
Appendix C 

C-5 Technical Assistance 

� U.S. Government Printing Office 

732 N. Capitol Street, NW 

Mail Stop: SDE 

Washington, DC 20401 

(888) 293-6498 

www.gpoaccess.gov/index.html 
APPENDIX D

OSHA GUIDANCE ON PSM

APPENDIX D

OSHA GUIDANCE ON PSM

The following text is taken directly from OSHA’s non-mandatory appendix C to the PSM 

standard (29 CFR 1910.119). The only change has been to rearrange the sections to track the order of 

part 68. 

PROCESS SAFETY INFORMATION 

Complete and accurate written information concerning process chemicals, process technology, and 

process equipment is essential to an effective process safety management program and to a process 

hazards analysis. The compiled information will be a necessary resource to a variety of users including 

the team that will perform the process hazards analysis; those developing the training programs and the 

operating procedures; contractors whose employees will be working with the process; those conducting 

the pre-startup reviews; local emergency preparedness planners; and insurance and enforcement officials. 

The information to be compiled about the chemicals, including process intermediates, needs to be 

comprehensive enough for an accurate assessment of the fire and explosion characteristics, reactivity 

hazards, the safety and health hazards to workers, and the corrosion and erosion effects on the process 

equipment and monitoring tools. Current material safety data sheet (MSDS) information can be used to 

help meet this requirement, which must be supplemented with process chemistry information including 

runaway reaction and over pressure hazards if applicable. 

Process technology information will be a part of the process safety information package and it is 

expected that it will include diagrams as well as employer established criteria for maximum inventory 

levels for process chemicals; limits beyond which would be considered upset conditions; and a 

qualitative estimate of the consequences or results of deviation that could occur if operating beyond the 

established process limits. Employers are encouraged to use diagrams which will help users understand 

the process. 

A block flow diagram is used to show the major process equipment and interconnecting process flow 

lines and show flow rates, stream composition, temperatures, and pressures when necessary for clarity. 

The block flow diagram is a simplified diagram. 

Process flow diagrams are more complex and will show all main flow streams including valves to 

enhance the understanding of the process, as well as pressures and temperatures on all feed and product 

lines within all major vessels, in and out of headers and heat exchangers, and points of pressure and 

temperature control. Also, materials of construction information, pump capacities and pressure heads, 

compressor horsepower and vessel design pressures and temperatures are shown when necessary for 

clarity. In addition, major components of control loops are usually shown along with key utilities on 

process flow diagrams. 

Piping and instrument diagrams (P&IDS) may be the more appropriate type of diagrams to show some of 

the above details and to display the information for the piping designer and engineering staff. The 

P&IDS are to be used to describe the relationships between equipment and instrumentation as well as 

other relevant information that will enhance clarity. Computer software programs which do P&IDS or 

other diagrams useful to the information package, may be used to help meet this requirement. 
Appendix D 

OSHA Guidance on PSM D-2 

The information pertaining to process equipment design must be documented. In other words, what were 

the codes and standards relied on to establish good engineering practice. These codes and standards are 

published by such organizations as the American Society of Mechanical Engineers, American Petroleum 

Institute, American National Standards Institute, National Fire Protection Association, American Society 

for Testing and Materials, National Board of Boiler and Pressure Vessel Inspectors, National Association 

of Corrosion Engineers, American Society of Exchange Manufacturers Association, and model building 

code groups. In addition, various engineering societies issue technical reports which impact process 

design. For example, the American Institute of Chemical Engineers has published technical reports on 

topics such as two phase flow for venting devices. This type of technically recognized report would 

constitute good engineering practice. 

For existing equipment designed and constructed many years ago in accordance with the codes and 

standards available at that time and no longer in general use today, the employer must document which 

codes and standards were used and that the design and construction along with the testing, inspection and 

operation are still suitable for the intended use. Where the process technology requires a design which 

departs from the applicable codes and standards, the employer must document that the design and 

construction is suitable for the intended purpose. 

PROCESS HAZARD ANALYSIS 

A process hazard analysis (PHA), sometimes called a process hazard evaluation, is one of the most 

important elements of the process safety management program. A PHA is an organized and systematic 

effort to identify and analyze the significance of potential hazards associated with the processing or 

handling of highly hazardous chemicals. A PHA provides information which will assist employers and 

employees in making decisions for improving safety and reducing the consequences of unwanted or 

unplanned releases of hazardous chemicals. 

A PHA is directed toward analyzing potential causes and consequences of fires, explosions, releases of 

toxic or flammable chemicals and major spills of hazardous chemicals. The PHA focuses on equipment, 

instrumentation, utilities, human actions (routine and non-routine), and external factors that might impact 

the process. These considerations assist in determining the hazards and potential failure points or failure 

modes in a process. 

The selection of a PHA methodology or technique will be influenced by many factors including the 

amount of existing knowledge about the process. Is it a process that has been operated for a long period 

of time with little or no innovation and extensive experience has been generated with its use? Or, is it a 

new process or one which has been changed frequently by the inclusion of innovative features? Also, the 

size and complexity of the process will influence the decision as to the appropriate PHA methodology to 

use. All PHA methodologies are subject to certain limitations. For example, the checklist methodology 

works well when the process is very stable and no changes are made, but it is not as effective when the 

process has undergone extensive change. The checklist may miss the most recent changes and 

consequently the changes would not be evaluated. Another limitation to be considered concerns the 

assumptions made by the team or analyst. The PHA is dependent on good judgment and the assumptions 

made during the study need to be documented and understood by the team and reviewer and kept for a 

future PHA. 
Appendix D 

D-3 OSHA Guidance on PSM 

The team conducting the PHA need to understand the methodology that is going to be used. A PHA team 

can vary in size from two people to a number of people with varied operational and technical 

backgrounds. Some team members may only be a part of the team for a limited time. The team leader 

needs to be fully knowledgeable in the proper implementation of the PHA methodology that is to be used 

and should be impartial in the evaluation. The other full or part time team members need to provide the 

team with expertise in areas such as process technology, process design, operating procedures and 

practices, including how the work is actually performed, alarms, emergency procedures, instrumentation, 

maintenance procedures, both routine and non-routine tasks, including how the tasks are authorized, 

procurement of parts and supplies, safety and health, and any other relevant subject as the need dictates. 

At least one team member must be familiar with the process. 

The ideal team will have an intimate knowledge of the standards, codes, specifications and regulations 

applicable to the process being studied. The selected team members need to be compatible and the team 

leader needs to be able to manage the team and the PHA study. The team needs to be able to work 

together while benefiting from the expertise of others on the team or outside the team, to resolve issues, 

and to forge a consensus on the findings of the study and the recommendations. 

The application of a PHA to a process may involve the use of different methodologies for various parts of 

the process. For example, a process involving a series of unit operations of varying sizes, complexities, 

and ages may use different methodologies and team members for each operation. Then the conclusions 

can be integrated into one final study and evaluation. 

A more specific example is the use of a checklist PHA for a standard boiler or heat exchanger and the use 

of a Hazard and Operability PHA for the overall process. Also, for batch type processes like custom 

batch operations, a generic PHA of a representative batch may be used where there are only small 

changes of monomer or other ingredient ratios and the chemistry is documented for the full range and 

ratio of batch ingredients. Another process that might consider using a generic type of PHA is a gas 

plant. Often these plants are simply moved from site to site and therefore, a generic PHA may be used 

for these movable plants. Also, when an employer has several similar size gas plants and no sour gas is 

being processed at the site, then a generic PHA is feasible as long as the variations of the individual sites 

are accounted for in the PHA. 

Finally, when an employer has a large continuous process which has several control rooms for different 

portions of the process such as for a distillation tower and a blending operation, the employer may wish 

to do each segment separately and then integrate the final results. 

Additionally, small businesses which are covered by this rule, will often have processes that have less 

storage volume, less capacity, and less complicated than processes at a large facility. Therefore, OSHA 

would anticipate that the less complex methodologies would be used to meet the process hazard analysis 

criteria in the standard. These process hazard analyses can be done in less time and with a few people 

being involved. A less complex process generally means that less data, P&IDS, and process information 

is needed to perform a process hazard analysis. 

Many small businesses have processes that are not unique, such as cold storage lockers or water 

treatment facilities. Where employer associations have a number of members with such facilities, a 

generic PHA, evolved from a checklist or what-if questions, could be developed and used by each 

employer effectively to reflect his/her particular process; this would simplify compliance for them. 
Appendix D 

OSHA Guidance on PSM D-4 

When the employer has a number of processes which require a PHA, the employer must set up a priority 

system of which PHAs to conduct first. A preliminary or gross hazard analysis may be useful in 

prioritizing the processes that the employer has determined are subject to coverage by the process safety 

management standard. Consideration should first be given to those processes with the potential of 

adversely affecting the largest number of employees. This prioritizing should consider the potential 

severity of a chemical release, the number of potentially affected employees, the operating history of the 

process such as the frequency of chemical releases, the age of the process and any other relevant factors. 

These factors would suggest a ranking order and would suggest either using a weighing factor system or 

a systematic ranking method. The use of a preliminary hazard analysis would assist an employer in 

determining which process should be of the highest priority and thereby the employer would obtain the 

greatest improvement in safety at the facility. 

OPERATING PROCEDURES 

Operating procedures describe tasks to be performed, data to be recorded, operating conditions to be 

maintained, samples to be collected, and safety and health precautions to be taken. The procedures need 

to be technically accurate, understandable to employees, and revised periodically to ensure that they 

reflect current operations. The process safety information package is to be used as a resource to better 

assure that the operating procedures and practices are consistent with the known hazards of the chemicals 

in the process and that the operating parameters are accurate. Operating procedures should be reviewed 

by engineering staff and operating personnel to ensure that they are accurate and provide practical 

instructions on how to actually carry out job duties safely. 

Operating procedures will include specific instructions or details on what steps are to be taken or 

followed in carrying out the stated procedures. These operating instructions for each procedure should 

include the applicable safety precautions and should contain appropriate information on safety 

implications. For example, the operating procedures addressing operating parameters will contain 

operating instructions about pressure limits, temperature ranges, flow rates, what to do when an upset 

condition occurs, what alarms and instruments are pertinent if an upset condition occurs, and other 

subjects. Another example of using operating instructions to properly implement operating procedures is 

in starting up or shutting down the process. In these cases, different parameters will be required from 

those of normal operation. These operating instructions need to clearly indicate the distinctions between 

startup and normal operations such as the appropriate allowances for heating up a unit to reach the 

normal operating parameters. Also the operating instructions need to describe the proper method for 

increasing the temperature of the unit until the normal operating temperature parameters are achieved. 

Computerized process control systems add complexity to operating instructions. These operating 

instructions need to describe the logic of the software as well as the relationship between the equipment 

and the control system; otherwise, it may not be apparent to the operator. 

Operating procedures and instructions are important for training operating personnel. The operating 

procedures are often viewed as the standard operating practices (SOPs) for operations. Control room 

personnel and operating staff, in general, need to have a full understanding of operating procedures. If 

workers are not fluent in English then procedures and instructions need to be prepared in a second 

language understood by the workers. In addition, operating procedures need to be changed when there is 

a change in the process as a result of the management of change procedures. The consequences of 

operating procedure changes need to be fully evaluated and the information conveyed to the personnel. 
Appendix D 

D-5 OSHA Guidance on PSM 

For example, mechanical changes to the process made by the maintenance department (like changing a 

valve from steel to brass or other subtle changes) need to be evaluated to determine if operating 

procedures and practices also need to be changed. All management of change actions must be 

coordinated and integrated with current operating procedures and operating personnel must be oriented to 

the changes in procedures before the change is made. When the process is shutdown to make a change, 

then the operating procedures must be updated before startup of the process. 

Training in how to handle upset conditions must be accomplished as well as what operating personnel are 

to do in emergencies such as when a pump seal fails or a pipeline ruptures. Communication between 

operating personnel and workers performing work within the process area, such as non-routine tasks, also 

must be maintained. The hazards of the tasks are to be conveyed to operating personnel in accordance 

with established procedures and to those performing the actual tasks. When the work is completed, 

operating personnel should be informed to provide closure on the job. 

TRAINING 

All employees, including maintenance and contractor employees, involved with highly hazardous 

chemicals need to fully understand the safety and health hazards of the chemicals and processes they 

work with for the protection of themselves, their fellow employees and the citizens of nearby 

communities. Training conducted in compliance with 1910.1200, the Hazard Communication standard, 

will help employees to be more knowledgeable about the chemicals they work with as well as familiarize 

them with reading and understanding MSDS. However, additional training in subjects such as operating 

procedures and safety work practices, emergency evacuation and response, safety procedures, routine and 

non-routine work authorization activities, and other areas pertinent to process safety and health will need 

to be covered by an employer's training program. 

In establishing their training programs, employers must clearly define the employees to be trained and 

what subjects are to be covered in their training. Employers in setting up their training program will need 

to clearly establish the goals and objectives they wish to achieve with the training that they provide to 

their employees. The learning goals or objectives should be written in clear measurable terms before the 

training begins. These goals and objectives need to be tailored to each of the specific training modules or 

segments. Employers should describe the important actions and conditions under which the employee 

will demonstrate competence or knowledge as well as what is acceptable performance. 

Hands-on-training where employees are able to use their senses beyond listening, will enhance learning. 

For example, operating personnel, who will work in a control room or at control panels, would benefit by 

being trained at a simulated control panel or panels. Upset conditions of various types could be 

displayed on the simulator, and then the employee could go through the proper operating procedures to 

bring the simulator panel back to the normal operating parameters. A training environment could be 

created to help the trainee feel the full reality of the situation but, of course, under controlled conditions. 

This realistic type of training can be very effective in teaching employees correct procedures while 

allowing them to also see the consequences of what might happens if they do not follow established 

operating procedures. Other training techniques using videos or on-the-job training can also be very 

effective for teaching other job tasks, duties, or other important information. An effective training 

program will allow the employee to fully participate in the training process and to practice their skill or 

knowledge. 
Appendix D 

OSHA Guidance on PSM D-6 

Employers need to periodically evaluate their training programs to see if the necessary skills, knowledge, 

and routines are being properly understood and implemented by their trained employees. The means or 

methods for evaluating the training should be developed along with the training program goals and 

objectives. Training program evaluation will help employers to determine the amount of training their 

employees understood, and whether the desired results were obtained. If, after the evaluation, it appears 

that the trained employees are not at the level of knowledge and skill that was expected, the employer 

will need to revise the training program, provide retraining, or provide more frequent refresher training 

sessions until the deficiency is resolved. Those who conducted the training and those who received the 

training should also be consulted as to how best to improve the training process. If there is a language 

barrier, the language known to the trainees should be used to reinforce the training messages and 

information. 

Careful consideration must be given to assure that employees including maintenance and contract 

employees receive current and updated training. For example, if changes are made to a process, impacted 

employees must be trained in the changes and understand the effects of the changes on their job tasks 

(e.g., any new operating procedures pertinent to their tasks). Additionally, as already discussed the 

evaluation of the employee's absorption of training will certainly influence the need for training. 

MECHANICAL INTEGRITY 

Employers will need to review their maintenance programs and schedules to see if there are areas where 

"breakdown" maintenance is used rather than an on-going mechanical integrity program. Equipment 

used to process, store, or handle highly hazardous chemicals needs to be designed, constructed, installed 

and maintained to minimize the risk of releases of such chemicals. This requires that a mechanical 

integrity program be in place to assure the continued integrity of process equipment. 

Elements of a mechanical integrity program include the identification and categorization of equipment 

and instrumentation, inspections and tests, testing and inspection frequencies, development of 

maintenance procedures, training of maintenance personnel, the establishment of criteria for acceptable 

test results, documentation of test and inspection results, and documentation of manufacturer 

recommendations as to meantime to failure for equipment and instrumentation. 

The first line of defense an employer has available is to operate and maintain the process as designed, 

and to keep the chemicals contained. This line of defense is backed up by the next line of defense which 

is the controlled release of chemicals through venting to scrubbers or flares, or to surge or overflow tanks 

which are designed to receive such chemicals, etc. These lines of defense are the primary lines of 

defense or means to prevent unwanted releases. The secondary lines of defense would include fixed fire 

protection systems like sprinklers, water spray, or deluge systems, monitor guns, etc., dikes, designed 

drainage systems, and other systems which would control or mitigate hazardous chemicals once an 

unwanted release occurs. These primary and secondary lines of defense are what the mechanical 

integrity program needs to protect and strengthen these primary and secondary lines of defenses where 

appropriate. 

The first step of an effective mechanical integrity program is to compile and categorize a list of process 

equipment and instrumentation for inclusion in the program. This list would include pressure vessels, 

storage tanks, process piping, relief and vent systems, fire protection system components, emergency 

shutdown systems and alarms and interlocks and pumps. For the categorization of instrumentation and 
Appendix D 

D-7 OSHA Guidance on PSM 

the listed equipment the employer would prioritize which pieces of equipment require closer scrutiny 

than others. 

Meantime to failure of various instrumentation and equipment parts would be known from the 

manufacturer’s data or the employer's experience with the parts, which would then influence the 

inspection and testing frequency and associated procedures. Also, applicable codes and standards such as 

the National Board Inspection Code, or those from the American Society for Testing and Material, 

American Petroleum Institute, National Fire Protection Association, American National Standards 

Institute, American Society of Mechanical Engineers, and other groups, provide information to help 

establish an effective testing and inspection frequency, as well as appropriate methodologies. 

The applicable codes and standards provide criteria for external inspections for such items as foundation 

and supports, anchor bolts, concrete or steel supports, guy wires, nozzles and sprinklers, pipe hangers, 

grounding connections, protective coatings and insulation, and external metal surfaces of piping and 

vessels, etc. These codes and standards also provide information on methodologies for internal 

inspection, and a frequency formula based on the corrosion rate of the materials of construction. Also, 

erosion both internal and external needs to be considered along with corrosion effects for piping and 

valves. Where the corrosion rate is not known, a maximum inspection frequency is recommended, and 

methods of developing the corrosion rate are available in the codes. Internal inspections need to cover 

items such as vessel shell, bottom and head; metallic linings; nonmetallic linings; thickness 

measurements for vessels and piping; inspection for erosion, corrosion, cracking and bulges; internal 

equipment like trays, baffles, sensors and screens for erosion, corrosion or cracking and other 

deficiencies. Some of these inspections may be performed by state or local government inspectors under 

state and local statutes. However, each employer needs to develop procedures to ensure that tests and 

inspections are conducted properly and that consistency is maintained even where different employees 

may be involved. Appropriate training is to be provided to maintenance personnel to ensure that they 

understand the preventive maintenance program procedures, safe practices, and the proper use and 

application of special equipment or unique tools that may be required. This training is part of the overall 

training program called for in the standard. 

A quality assurance system is needed to help ensure that the proper materials of construction are used, 

that fabrication and inspection procedures are proper, and that installation procedures recognize field 

installation concerns. The quality assurance program is an essential part of the mechanical integrity 

program and will help to maintain the primary and secondary lines of defense that have been designed 

into the process to prevent unwanted chemical releases or those which control or mitigate a release. "As 

built" drawings, together with certifications of coded vessels and other equipment, and materials of 

construction need to be verified and retained in the quality assurance documentation. 

Equipment installation jobs need to be properly inspected in the field for use of proper materials and 

procedures and to assure that qualified craftsmen are used to do the job. The use of appropriate gaskets, 

packing, bolts, valves, lubricants and welding rods need to be verified in the field. Also, procedures for 

installation of safety devices need to be verified, such as the torque on the bolts on ruptured disc 

installations, uniform torque on flange bolts, proper installation of pump seals, etc. If the quality of parts 

is a problem, it may be appropriate to conduct audits of the equipment supplier's facilities to better assure 

proper purchases of required equipment which is suitable for its intended service. Any changes in 

equipment that may become necessary will need to go through the management of change procedures. 
Appendix D 

OSHA Guidance on PSM D-8 

MANAGEMENT OF CHANGE 

To properly manage changes to process chemicals, technology, equipment and facilities, one must define 

what is meant by change. In this process safety management standard, change includes all modifications 

to equipment, procedures, raw materials and processing conditions other than "replacement in kind." 

These changes need to be properly managed by identifying and reviewing them prior to implementation 

of the change. For example, the operating procedures contain the operating parameters (pressure limits, 

temperature ranges, flow rates, etc.) and the importance of operating within these limits. While the 

operator must have the flexibility to maintain safe operation within the established parameters, any 

operation outside of these parameters requires review and approval by a written management of change 

procedure. Management of change covers changes in process technology and changes to equipment and 

instrumentation. Changes in process technology can result from changes in production rates, raw 

materials, experimentation, equipment unavailability, new equipment, new product development, change 

in catalyst and changes in operating conditions to improve yield or quality. Equipment changes include 

among others change in materials of construction, equipment specifications, piping pre-arrangements, 

experimental equipment, computer program revisions and changes in alarms and interlocks. Employers 

need to establish means and methods to detect both technical changes and mechanical changes. 

Temporary changes have caused a number of catastrophes over the years, and employers need to 

establish ways to detect temporary changes as well as those that are permanent. It is important that a 

time limit for temporary changes be established and monitored since, without control, these changes may 

tend to become permanent. Temporary changes are subject to the management of change provisions. In 

addition, the management of change procedures are used to insure that the equipment and procedures are 

returned to their original or designed conditions at the end of the temporary change. Proper 

documentation and review of these changes is invaluable in assuring that the safety and health 

considerations are being incorporated into the operating procedures and the process. Employers may 

wish to develop a form or clearance sheet to facilitate the processing of changes through the management 

of change procedures. A typical change form may include a description and the purpose of the change, 

the technical basis for the change, safety and health considerations, documentation of changes for the 

operating procedures, maintenance procedures, inspection and testing, P&IDS, electrical classification, 

training and communications, pre-startup inspection, duration if a temporary change, approvals and 

authorization. Where the impact of the change is minor and well understood, a check list reviewed by an 

authorized person with proper communication to others who are affected may be sufficient. 

However, for a more complex or significant design change, a hazard evaluation procedure with approvals 

by operations, maintenance, and safety departments may be appropriate. Changes in documents such as 

P&IDS, raw materials, operating procedures, mechanical integrity programs, electrical classifications, 

etc., need to be noted so that these revisions can be made permanent when the drawings and procedure 

manuals are updated. Copies of process changes need to be kept in an accessible location to ensure that 

design changes are available to operating personnel as well as to PHA team members when a PHA is 

being done or one is being updated. 

PRE-STARTUP REVIEW 

For new processes, the employer will find a PHA helpful in improving the design and construction of the 

process from a reliability and quality point of view. The safe operation of the new process will be 

enhanced by making use of the PHA recommendations before final installations are completed. P&IDs 
Appendix D 

D-9 OSHA Guidance on PSM 

are to be completed along with having the operating procedures in place and the operating staff trained to 

run the process before startup. The initial startup procedures and normal operating procedures need to be 

fully evaluated as part of the pre-startup review to assure a safe transfer into the normal operating mode 

for meeting the process parameters. 

For existing processes that have been shutdown for turnaround, or modification, etc., the employer must 

assure that any changes other than "replacement in kind" made to the process during shutdown go 

through the management of change procedures. P&IDS will need to be updated as necessary, as well as 

operating procedures and instructions. If the changes made to the process during shutdown are significant 

and impact the training program, then operating personnel as well as employees engaged in routine and 

non-routine work in the process area may need some refresher or additional training in light of the 

changes. Any incident investigation recommendations, compliance audits or PHA recommendations need 

to be reviewed as well to see what impacts they may have on the process before beginning the startup. 

COMPLIANCE AUDITS 

Employers need to select a trained individual or assemble a trained team of people to audit the process 

safety management system and program. A small process or plant may need only one knowledgeable 

person to conduct an audit. The audit is to include an evaluation of the design and effectiveness of the 

process safety management system and a field inspection of the safety and health conditions and 

practices to verify that the employer's systems are effectively implemented. The audit should be 

conducted or led by a person knowledgeable in audit techniques and who is impartial towards the facility 

or area being audited. The essential elements of an audit program include planning, staffing, conducting 

the audit, evaluation and corrective action, follow-up and documentation. 

Planning in advance is essential to the success of the auditing process. Each employer needs to establish 

the format, staffing, scheduling and verification methods prior to conducting the audit. The format should 

be designed to provide the lead auditor with a procedure or checklist which details the requirements of 

each section of the standard. The names of the audit team members should be listed as part of the format 

as well. The checklist, if properly designed, could serve as the verification sheet which provides the 

auditor with the necessary information to expedite the review and assure that no requirements of the 

standard are omitted. This verification sheet format could also identify those elements that will require 

evaluation or a response to correct deficiencies. This sheet could also be used for developing the 

follow-up and documentation requirements. 

The selection of effective audit team members is critical to the success of the program. Team members 

should be chosen for their experience, knowledge, and training and should be familiar with the processes 

and with auditing techniques, practices and procedures. The size of the team will vary depending on the 

size and complexity of the process under consideration. For a large, complex, highly instrumented plant, 

it may be desirable to have team members with expertise in process engineering and design, process 

chemistry, instrumentation and computer controls, electrical hazards and classifications, safety and health 

disciplines, maintenance, emergency preparedness, warehousing or shipping, and process safety auditing. 

The team may use part-time members to provide for the depth of expertise required as well as for what is 

actually done or followed, compared to what is written. 

An effective audit includes a review of the relevant documentation and process safety information, 

inspection of the physical facilities, and interviews with all levels of plant personnel. Using the audit 
Appendix D 

OSHA Guidance on PSM D-10 

procedure and checklist developed in the preplanning stage, the audit team can systematically analyze 

compliance with the provisions of the standard and any other corporate policies that are relevant. For 

example, the audit team will review all aspects of the training program as part of the overall audit. The 

team will review the written training program for adequacy of content, frequency of training, 

effectiveness of training in terms of its goals and objectives as well as to how it fits into meeting the 

standard's requirements, documentation, etc. Through interviews, the team can determine the employee's 

knowledge and awareness of the safety procedures, duties, rules, emergency response assignments, etc. 

During the inspection, the team can observe actual practices such as safety and health policies, 

procedures, and work authorization practices. This approach enables the team to identify deficiencies 

and determine where corrective actions or improvements are necessary. 

An audit is a technique used to gather sufficient facts and information, including statistical information, 

to verify compliance with standards. Auditors should select as part of their preplanning a sample size 

sufficient to give a degree of confidence that the audit reflects the level of compliance with the standard. 

The audit team, through this systematic analysis, should document areas which require corrective action 

as well as those areas where the process safety management system is effective and working in an 

effective manner. This provides a record of the audit procedures and findings, and serves as a baseline of 

operation data for future audits. It will assist future auditors in determining changes or trends from 

previous audits. 

Corrective action is one of the most important parts of the audit. It includes not only addressing the 

identified deficiencies, but also planning, follow up, and documentation. The corrective action process 

normally begins with a management review of the audit findings. The purpose of this review is to 

determine what actions are appropriate, and to establish priorities, timetables, resource allocations and 

requirements and responsibilities. In some cases, corrective action may involve a simple change in 

procedure or minor maintenance effort to remedy the concern. Management of change procedures need 

to be used, as appropriate, even for what may seem to be a minor change. Many of the deficiencies can be 

acted on promptly, while some may require engineering studies or in-depth review of actual procedures 

and practices. There may be instances where no action is necessary and this is a valid response to an 

audit finding. All actions taken, including an explanation where no action is taken on a finding, needs to 

be documented as to what was done and why. 

It is important to assure that each deficiency identified is addressed, the corrective action to be taken 

noted, and the audit person or team responsible be properly documented by the employer. 

To control the corrective action process, the employer should consider the use of a tracking system. This 

tracking system might include periodic status reports shared with affected levels of management, specific 

reports such as completion of an engineering study, and a final implementation report to provide closure 

for audit findings that have been through management of change, if appropriate, and then shared with 

affected employees and management. This type of tracking system provides the employer with the status 

of the corrective action. It also provides the documentation required to verify that appropriate corrective 

actions were taken on deficiencies identified in the audit. 

INCIDENT INVESTIGATION 

Incident investigation is the process of identifying the underlying causes of incidents and implementing 

steps to prevent similar events from occurring. The intent of an incident investigation is for employers to 
Appendix D 

D-11 OSHA Guidance on PSM 

learn from past experiences and thus avoid repeating past mistakes. Some of the events are sometimes 

referred to as "near misses," meaning that a serious consequence did not occur, but could have. 

Employers need to develop in-house capability to investigate incidents that occur in their facilities. A 

team needs to be assembled by the employer and trained in the techniques of investigation including how 

to conduct interviews of witnesses, needed documentation and report writing. A multi-disciplinary team 

is better able to gather the facts of the event and to analyze them and develop plausible scenarios as to 

what happened, and why. Team members should be selected on the basis of their training, knowledge 

and ability to contribute to a team effort to fully investigate the incident. 

Employees in the process area where the incident occurred should be consulted, interviewed or made a 

member of the team. Their knowledge of the events form a significant set of facts about the incident 

which occurred. The report, its findings and recommendations are to be shared with those who can 

benefit from the information. The cooperation of employees is essential to an effective incident 

investigation. The focus of the investigation should be to obtain facts, and not to place blame. The team 

and the investigation process should clearly deal with all involved individuals in a fair, open and 

consistent manner. 

EMPLOYEE PARTICIPATION 

Section 304 of the Clean Air Act Amendments states that employers are to consult with their employees 

and their representatives regarding the employers efforts in the development and implementation of the 

process safety management program elements and hazard assessments. Section 304 also requires 

employers to train and educate their employees and to inform affected employees of the findings from 

incident investigations required by the process safety management program. Many employers, under their 

safety and health programs, have already established means and methods to keep employees and their 

representatives informed about relevant safety and health issues and employers may be able to adapt 

these practices and procedures to meet their obligations under this standard. Employers who have not 

implemented an occupational safety and health program may wish to form a safety and health committee 

of employees and management representatives to help the employer meet the obligations specified by this 

standard. These committees can become a significant ally in helping the employer to implement and 

maintain an effective process safety management program for all employees. 

HOT WORK PERMIT 

Non-routine work which is conducted in process areas needs to be controlled by the employer in a 

consistent manner. The hazards identified involving the work that is to be accomplished must be 

communicated to those doing the work, but also to those operating personnel whose work could affect 

the safety of the process. A work authorization notice or permit must have a procedure that describes the 

steps the maintenance supervisor, contractor representative or other person needs to follow to obtain the 

necessary clearance to get the job started. The work authorization procedures need to reference and 

coordinate, as applicable, lockout/tagout procedures, line breaking procedures, confined space entry 

procedures and hot work authorizations. This procedure also needs to provide clear steps to follow once 

the job is completed to provide closure for those that need to know the job is now completed and 

equipment can be returned to normal. 
Appendix D 

OSHA Guidance on PSM D-12 

CONTRACTORS 

Employers who use contractors to perform work in and around processes that involve highly hazardous 

chemicals, will need to establish a screening process so that they hire and use contractors who 

accomplish the desired job tasks without compromising the safety and health of employees at a facility. 

For contractors, whose safety performance on the job is not known to the hiring employer, the employer 

will need to obtain information on injury and illness rates and experience and should obtain contractor 

references. Additionally, the employer must assure that the contractor has the appropriate job skills, 

knowledge and certifications (such as for pressure vessel welders). Contractor work methods and 

experiences should be evaluated. For example, does the contractor conducting demolition work swing 

loads over operating processes or does the contractor avoid such hazards? 

Contract employees must perform their work safely. Considering that contractors often perform very 

specialized and potentially hazardous tasks such as confined space entry activities and non-routine repair 

activities it is quite important that their activities be controlled while they are working on or near a 

covered process. A permit system or work authorization system for these activities would also be helpful 

to all affected employers. The use of a work authorization system keeps an employer informed of 

contract employee activities, and as a benefit the employer will have better coordination and more 

management control over the work being performed in the process area. A well run and well maintained 

process where employee safety is fully recognized will benefit all of those who work in the facility 

whether they be contract employees or employees of the owner. 
APPENDIX E:

Supplemental Risk Management Program Guidance for

Ammonia Refrigeration Facilities
Appendix E -2- NH3 

Appendix E: Supplemental Risk Management Program Guidance for 

Ammonia Refrigeration Facilities 

This appendix supplements the main body of the General Guidance to provide 

additional information for food processors, food distributors, and refrigerated 

warehouses who use ammonia as a refrigerant, as well as any other facility that has 

an ammonia refrigeration system. If you have other processes that use regulated 

substances other than ammonia, refer to the main body of the General Guidance (and 

any other applicable industry-specific appendix) for information on compliance with 

the rule for those processes. The appendix covers Risk Management Program 

elements in the same general order as those elements are addressed in the main 

document. However, note that the appendix does not address some generic RMP 

elements (e.g., Management System). For elements not addressed in this appendix, 

simply refer to the applicable guidance in the main document. 

E.1 General Applicability 

EXEMPTION FOR FARMS 

The rule exempts ammonia when held by a farmer for use as an agricultural nutrient 

on a farm. This exemption does not apply to agricultural suppliers, fertilizer 

manufacturers, or the use of ammonia as a refrigerant. It does not apply to farm 

cooperatives or to groups of farmers who buy, use, and sell ammonia. 

THRESHOLD QUANTITY 

The threshold quantity for anhydrous ammonia is 10,000 pounds. 

CO-LOCATION OF PROCESS VESSELS 

For ammonia, a release from a single vessel will not normally lead to a release from 

others unless the vessel fails catastrophically and explodes, sending metal fragments 

into other vessels. Co-located vessels containing ammonia, however, may well be 

involved in a release caused by a fire or explosion that occurs from another source. 

E.2 Applicability of Program Levels 

QUICK RULES FOR DETERMINING PROGRAM 1 ELIGIBILITY 

If you have a process containing more than a threshold quantity of ammonia that is 

not liquefied by refrigeration alone (i.e., you hold it as a gas or liquefied under 

pressure), the distance to the endpoint estimated for a worst-case release may be 

several miles. As a result, the distance to endpoint is unlikely to be less than the 

distance to public receptors, unless the process is very remote. In some cases, 
NH3 -3- Appendix E 

however, ammonia in processes contained in enclosed areas may be eligible for 

Program 1. 

If you have a process containing anhydrous ammonia liquefied by refrigeration alone, 

and your worst-case release would take place into a diked area, the chances are good 

that the process may be eligible for Program 1, unless there are public receptors very 

close to the process. Even if you have many times the threshold quantity of 

ammonia, the process may still be eligible for Program 1. 

PROGRAM 3 

Most ammonia refrigeration processes that are not eligible for Program 1 will be 

subject to Program 3 requirements because they are subject to the OSHA PSM 

Standard. 

PROGRAM 2 

Ammonia refrigeration processes will usually not be eligible for this program level 

because they are covered by OSHA PSM. If your ammonia process is not eligible for 

Program 1, it will generally be subject to Program 3. If your ammonia refrigeration 

process is subject to Program 2 requirements, this appendix does not contain 

additional information on prevention program elements; consult chapter 6 in the main 

document. 

E.3 Offsite Consequence Analysis 

This section gives simple guidance on how to perform the hazard assessment for 

anhydrous ammonia in ammonia refrigeration facilities. Additional technical 

information is provided in a separate document entitled “Technical Background 

Document for Offsite Consequence Analysis for Anhydrous Ammonia, Aqueous 

Ammonia, Chlorine and Sulfur Dioxide,” henceforth known as the “Technical 

Background Document”. This document is available from EPA’s website at 

www.epa.gov/emergencies. 

E.3.1 Worst-Case Release Scenario Analysis 

MANDATORY INPUTS 

The following inputs are required by the Risk Management Program rule: 

Release Quantity: The worst-case release quantity (lb) shall be the greater of the 

following: 

— For substances in a vessel, the greatest amount held in a vessel, taking into 

account administrative controls that limit the maximum quantity; or 
Appendix E -4- NH3 

— For substances in pipes, the greatest amount in a pipe, taking into account 

administrative controls that limit the maximum quantity. 

Section E.3.3 shows that, for ammonia refrigeration systems, a storage vessel or 

receiver is the place where the worst-case release quantity is expected to reside. 

Per §68.25(c)(1), because ammonia is a vapor at ambient temperature and is handled 

as a liquid under pressure in most parts of a refrigeration system, the release quantity 

is assumed to be completely released from the vessel over a period of 10 minutes. 

This applies whether the release takes place outside or in a building. 

Wind speed/atmospheric stability class: The owner or operator shall use a wind 

speed of 1.5 meters per second and F stability class. If the owner or operator can 

demonstrate that local meteorological data show a higher minimum wind speed or a 

less stable atmosphere at all times during the previous three years, these site-specific 

conditions may be used. For simplicity’s sake, the guidance presented below is 

restricted to a wind speed of 1.5 meters per second and F stability class. 

Toxic Endpoint: The toxic endpoint for ammonia is 200 ppm (0.14 mg/L). This 

airborne concentration has been published by the American Industrial Hygiene 

Association (AIHA) and is the maximum airborne concentration below which it is 

believed that nearly all individuals can be exposed for up to one hour without 

experiencing or developing irreversible or other serious health effects or symptoms 

which could impair an individual's ability to take protective action. The rule requires 

you to assume that the toxic endpoint is constant, even though the duration of release 

is only 10 minutes. 

QUANTITY RELEASED AND RELEASE RATE IN THE WORST-CASE RELEASE SCENARIO 

Quantity Released: Take the largest quantity (lb) of ammonia that is liquefied under 

pressure in any vessel in the ammonia refrigeration system. For many systems, this 

vessel will be the high pressure receiver with typical pressures in the range 100 to 

200 psig. Other candidate vessels include: a) an outside vessel in which ammonia is 

stored as a liquid at ambient temperature (some, but not all, facilities have such a 

vessel); b) an intermediate receiver with typical pressures in the range 20 to 60 psig 

(typical of two-stage ammonia refrigeration systems); or c) a low-pressure receiver 

with pressures in the range 10-60 psig (typical of single-stage refrigeration systems). 

In the case of a vessel, the quantity does not include any liquid ammonia in pipework 

connected to the vessel and in any other vessel that can discharge directly into 

pipework connected to the vessel. In addition, the maximum amount of ammonia 

that could be in the vessel at any one time, not just during normal operation, should 

be considered. For example, if the vessel is used to store some or all of the ammonia 

while the rest of the system is being serviced, then the quantity released should 

include the additional quantity of ammonia that is in the vessel at such a time. 

However, if there are administrative controls that limit the amount of ammonia that is 

allowed in the vessel at any one time, this limit can also be taken into account when 
NH3 -5- Appendix E 

estimating the quantity released. Similarly, if the largest quantity resides in a 

pipeline, you do not need to consider the quantity of ammonia in connected vessels. 

Release Rate - Unmitigated Releases: For the worst-case scenario for a substance 

that is a gas under ambient conditions, the largest vessel is assumed to fail in a 

catastrophic manner, and the release occurs over a period of 10 minutes. The worstcase release rate is: 

QR = Q/10 (1) 

where: QR = Release rate (lbs/min) 

Q = Quantity released (lbs) 

The rapid release of ammonia initially liquefied under pressure leads to an airborne 

mixture of vapor and droplets. If the vessel is outdoors, all of the vapor and droplets 

remain airborne, and the release rate (QR) is the total inventory uniformly distributed 

over 10 minutes, as required by the rule. 

Release Rate - Mitigated Releases: The rule allows you to consider passive 

mitigation in estimating the worst-case release rate. Figure E-1 displays the procedure 

to be followed to determine the release rate for the worst-case scenario. If the release 

takes place in a building, the building can be considered to provide passive 

mitigation, unless: 

— The building may fail as a result of the release. This is unlikely except in the 

case of a large vessel in a very small room. As a rough rule of thumb, if the 

room volume (V) divided by the quantity of ammonia (Q) in the vessel is less 

than 0.1 ft3

/lb, you should look at the possibility that the release of ammonia 

will cause failures such as windows blowing out or doors blowing open. 

— The release takes place facing an opening in the building (door or window). 

In this case, you should assume that the door or window will be open, and 

the ammonia will be released through these openings. 

If the building may fail as a result of the release, estimate the release rate as for an 

unmitigated release (Equation 1, QR = Q/10 lb/min). Similarly, if the release would 

take place facing doors or windows, the release rate is again the entire inventory 

uniformly distributed over 10 minutes (Equation 1). 

If the above conditions do not apply, you can assume that rain-out of liquid droplets 

is facilitated by impingement on surfaces (in a compressor room, for example), and 

only a portion of the released material will become airborne. The remainder collects 

in relatively slowly evaporating pools and makes only a small contribution to the rate 

of release from the building. To estimate the mitigated release rate, assume the 

following: 
Appendix E -6- NH3 

— The amount of material airborne in the building is four-tenths of the total 

inventory, or 0.4 Q. 

— The airborne material includes 0.2 Q vapor and 0.2 Q liquid droplets. 

— Exhibit E-1 provides factors for estimating the mitigated release rate from a 

building. 

To estimate the release rate using these factors, do the following: 

— Estimate 1 as follows: 

- Determine room volume, V, in ft3 

- Calculate 1 from room volume divided by the quantity of ammonia initially 

released as vapor, or 1(ft3

/lb) = V/(0.2 Q) 

— Determine the active ventilation rate, Nv, in room volumes exchanged per 

hour (hr-1), for the building. 

— From Exhibit E-1, find the 10-minute building attenuation factor, FR10, 

corresponding to your estimated 1 and the ventilation rate, Nv. 

— Estimate the release rate in lbs/min from the building attenuation factor and 

the airborne quantity (0.4 Q) as follows, assuming the release takes place 

over 10 minutes: 

QRB = (FR10 × 0.4Q)/10 (2) 

Example 1 

A high-pressure receiver containing 5,000 lb of ammonia is in a room of dimensions 

20 feet x 50 feet x 30 feet = 30,000 ft3

. Hence, 1 = 30,000/(5,000 x 0.2) = 30 ft3/lb. 

The nearest value of 1 on Exhibit E-1 is 1 = 25. The ventilation rate for the building 

is 5 hr-1. For 1 = 25 and Nv = 5, FR10 = 0.35, and the release rate to the atmosphere is 

QRB = (0.35)(0.4)(5,000)/10 = 70 lb/min, using Equation 2 above. 
Figure E-1 

Guidance on Effectiveness of Building Mitigation for Worst-Case Scenarios 

Identify Quantity (Q) in Largest Vessel 

Indoors 

or 

Outside? 

Indoors 

Outside Release Rate = 

0.1Q lb/min 

Release Rate = 0.1Q lb/min 

Adjacent 

to Door or

 Window? 

Yes 

Airborne Mass 0.4Q 

Calculate θ = V/(0.2Q) 

Choose NV (hr-1) 

Identify FR10 (Exhibit E-1) 

No 
Appendix E -8- NH3 

Exhibit E-1

Ten-Minute Building Release Attenuation Factors for Prolonged Releases

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

150.0 0 0.07 10.0 0 0.61 

1 0.08 1 0.61 

5 0.32 5 0.61 

10 0.51 10 0.61 

20 0.71 20 0.71 

30 0.80 30 0.80 

40 0.85 40 0.85 

100.0 0 0.11 5.0 0 0.79 

1 0.11 1 0.79 

5 0.32 5 0.79 

10 0.51 10 0.79 

20 0.71 20 0.79 

30 0.80 30 0.80 

40 0.85 40 0.85 

50.0 0 0.20 1.0 0 0.96 

1 0.20 1 0.96 

5 0.32 5 0.96 

10 0.51 10 0.96 

20 0.71 20 0.96 

30 0.80 30 0.96 

40 0.85 40 0.96 

25.0 0 0.35 0.5 0 0.98 

1 0.35 1 0.98 

5 0.35 5 0.98 

10 0.51 10 0.98 

20 0.71 20 0.98 

30 0.80 30 0.98 

40 0.85 40 0.98 
NH3 -9- Appendix E 

Example 2 

The 5,000 lb vessel in Example 1 is outside. The release rate is, therefore, 5,000/10 

= 500 lb/min. It can be seen that the building provides extensive attenuation. 

However, to take advantage of this potential attenuation, you must be certain that the 

worst-case scenario cannot occur outside or adjacent to a door or window that may be 

open. 

OTHER POTENTIAL WORST-CASE SCENARIOS 

The rule requires that you look for other potential scenarios that could affect offsite 

populations further away from the site or in different areas than does the release from 

the largest vessel. Thus, even if an outside storage vessel is smaller than your highpressure receiver, you should consider the release of its contents over a 10-minute 

period as a possible worst-case scenario. Similarly, if a pipe containing ammonia 

liquefied under pressure is outside for part of its length, you should consider the 

release of the contents of that pipe as a possible worst-case scenario. 

DISTANCE TO THE TOXIC ENDPOINT 

Take the estimated worst-case rate of release QR (unmitigated) or QRB (in a building) 

and go to Exhibit E-2. Find the entry in the “Rate of Release” column that is closest 

to your estimated release rate. Read off the corresponding distance from the urban or 

the rural column. This is the “distance to the endpoint” that must be submitted (in 

miles) in the RMP information. 

To decide whether the site is rural or urban, the rule gives the following guidance in 

§ 68.22(e): “Urban means that there are many obstacles in the immediate area; 

obstacles include buildings or trees. Rural means that there are no buildings in the 

immediate area and the terrain is generally flat and unobstructed.” 

Figure E-2 represents Exhibit E-2 in graphical form. Both apply to releases of 10 

minutes duration. 

Example 3 

Take the 500 lb/min release rate from Example 2. From Exhibit E-2, the predicted 

distance to the toxic endpoint is ~ 1.3 miles at a rural site and ~ 0.9 miles at an urban 

site. For the 70 lb/min release of Example 1, these distances become 0.5 miles and 

0.3 miles, respectively. 
Appendix E -10- NH3 

Exhibit E-2

Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure

F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 0.1 <0.1* 

2 0.1 0.1 

5 0.1 0.1 

10 0.2 0.1 

15 0.2 0.2 

20 0.3 0.2 

30 0.3 0.2 

40 0.4 0.3 

50 0.4 0.3 

60 0.5 0.3 

70 0.5 0.3 

80 0.5 0.4 

90 0.6 0.4 

100 0.6 0.4 

150 0.7 0.5 

200 0.8 0.6 

250 0.9 0.6 

300 1.0 0.7 

400 1.2 0.8 

500 1.3 0.9 

600 1.4 0.9 

700 1.5 1.0 

750 1.6 1.0 

800 1.6 1.1 

900 1.7 1.2 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1,000 1.8 1.2 

1,500 2.2 1.5 

2,000 2.6 1.7 

2,500 2.9 1.9 

3,000 3.1 2.0 

4,000 3.6 2.3 

5,000 4.0 2.6 

6,000 4.4 2.8 

7,000 4.7 3.1 

7,500 4.9 3.2 

8,000 5.1 3.3 

9,000 5.4 3.4 

10,000 5.6 3.6 

15,000 6.9 4.4 

20,000 8.0 5.0 

25,000 8.9 5.6 

30,000 9.7 6.1 

40,000 11 7.0 

50,000 12 7.8 

75,000 15 9.5 

100,000 18 10 

150,000 22 13 

200,000 ** 15 

250,000 ** 17 

750,000 ** ** 

*Report distance as 0.1 mile ** More than 25 miles (report distance as 25 miles) 
Figure E-2

Worst-Case Scenario - Predicted Distances to Toxic Endpoint

Anhydrous Ammonia @ Atmospheric Stability Class F with Wind speed 1.5 m/s
Appendix E -12- NH3 

E.3.2 Alternative Release Scenario Analysis 

The owner or operator must identify and analyze at least one “alternative” release 

scenario. 

CHOICE OF THE ALTERNATIVE SCENARIO 

Your alternative scenario for a covered process must be one that is more likely to 

occur than the worst-case scenario and that reaches an endpoint offsite, unless no 

such scenario exists. Note that this requirement means that the release rate for the 

alternative scenario for ammonia must be fairly large, or it generally will not reach 

the ammonia endpoint offsite. 

ALTERNATIVE SCENARIOS FOR AMMONIA AT REFRIGERATION FACILITIES 

For the alternative scenario analysis, you need to estimate the release rate of 

ammonia and the distance to the toxic endpoint. Exhibit E-3 and Figure E-3 provide 

distances to the endpoint for a range of release rates under the weather conditions 

discussed above. Note that Exhibit E-3 and Figure E-3 (and Equations 6 and 7 in 

Section E.3.4) are intended to apply to releases of any duration. 

For the purposes of this guidance, a simple alternative scenario has been chosen: an 

outdoor release through a hole in a tank or pipe containing ammonia liquefied under 

pressure, leading to an airborne release. For the release of liquid, you can estimate the 

release rate from the Bernoulli Equation; for ammonia liquefied under pressure, you 

can assume the liquid vaporizes immediately, and the release rate of the liquid is the 

same as the release rate to air. The following is a simplified version of the Bernoulli 

Equation, incorporating chemical-specific factors for ammonia: 

QR = HA × (203)(Pg)

1⁄2 (3) 

where: QR = Release rate (pounds per minute) 

HA = Hole area (square inches) 

Pg = Gauge pressure (psig) 

See Section E.3.4 for a discussion of the Bernoulli Equation and the derivation of the 

simplified equation above. 
NH3 -13- Appendix E 

Exhibit E-3

Distances to Toxic Endpoint for Anhydrous Ammonia Liquefied Under Pressure

D Stability, Wind Speed 3 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

<10 <0.1* 

<0.1* 

10 0.1 

15 0.1 

20 0.1 

30 0.1 

40 0.1 

50 0.1 

60 0.2 0.1 

70 0.2 0.1 

80 0.2 0.1 

90 0.2 0.1 

100 0.2 0.1 

150 0.2 0.1 

200 0.3 0.1 

250 0.3 0.1 

300 0.3 0.1 

400 0.4 0.2 

500 0.4 0.2 

600 0.5 0.2 

700 0.5 0.2 

750 0.5 0.2 

800 0.5 0.2 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

900 0.6 0.2 

1,000 0.6 0.2 

1,500 0.7 0.3 

2,000 0.8 0.3 

2,500 0.9 0.3 

3,000 1.0 0.4 

4,000 1.2 0.4 

5,000 1.3 0.5 

7,500 1.6 0.5 

10,000 1.8 0.6 

15,000 2.2 0.7 

20,000 2.5 0.8 

25,000 2.8 0.9 

30,000 3.1 1.0 

40,000 3.5 1.1 

50,000 3.9 1.2 

75,000 4.8 1.4 

100,000 5.4 1.6 

150,000 6.6 1.9 

200,000 7.6 2.1 

250,000 8.4 2.3 

300,000 9.2 2.5 

* Report distance as 0.1 mile 
Figure E-3

Alternative Release Scenario - Estimated Distances to Toxic Endpoint for Anhydrous Amm

Stability Class D, Wind Speed 3 Meters per Second
NH3 -15- Appendix E 

Exhibit E-4 provides release rates and distances for pressures of 100 to 180 psig and 

hole diameters of 1/4 inch to 12 inches. (The distances are based on Exhibit E-3). 

You may use this exhibit to estimate the distance to the endpoint if this type of 

scenario is reasonable for your site. 

Exhibit E-4

Release Rates and Distances to Toxic Endpoint for Leaks of Anhydrous Ammonia 

(Alternative Release Scenario)

ALTERNATIVE RELEASE SCENARIOS INSIDE A BUILDING 

The alternative release scenario inside a building is handled in much the same way as 

is the worst-case scenario. See Figure E-4 for a flow chart describing the procedure. 

To use the factors provided in Exhibit E-1 for estimating the release rate in a 

building, you must assume the release takes place over a ten-minute period. The total 

quantity released will be your estimated release rate multiplied by 10. If a ten minute 

release is not a reasonable alternative scenario for your site, you will need to do 

additional calculations or use a different method for releases in buildings. 
Figure E-4 

Guidance on Effectiveness of Building Mitigation for Alternative Release Scenarios 

Calculate Release Rate QR (lb/min) 

Indoors 

or 

Outside? 

Indoors 

Outside Release Rate = 

QR lb/min 

Release Rate = QR lb/min 

Adjacent 

to Door or 

Window? 

Yes 

Airborne Mass M = 0.4Q 

Calculate θ = V/(0.2Q) 

Choose NV (hr-1) 

Identify FR10 

(Exhibit E-1) 

Rele0.1F

lb/m

No 

Release 

Entirely 

Vapor? 

Yes 

No 

Calculate θ = V/Q 

Airborne Mass M = Q 
NH3 -17- Appendix E 

Example 4 

Suppose the release from a 1⁄2-inch hole in a tank with pressure 180 psig, cited in 

Exhibit E-4, resulting in a release rate of 550 lb/min of flashing liquid ammonia, 

takes place inside a building with a ventilation rate Nv = 5 hr-1. The release is 

assumed to take place over ten minutes, and the total quantity released is 550 × 10 = 

5,500 lb, of which 0.4 × 5,500 = 2,200 lb becomes airborne. Of the airborne quantity, 

1,100 lb is vapor and 1,100 lb is liquid that remains entrained in the vapor. The 

remaining 3,300 lb of liquid forms an evaporating pool on the floor. The building 

volume is 50 feet x 20 feet x 20 feet = 20,000 ft3

, so that 1 = 20,000/1,100 = 18 

ft3

/lb. 

From Exhibit E-1, FR10 = 0.35 for 1 = 25 ft3/lb (the number closest to 18) and Nv = 

5. Assuming a ten-minute release, the rate of release from the building is 77 lb/min 

[QRB = (0.35)(0.4)(5,500)/10 from Equation 2 in section E.3.1]. Using Exhibit E-3, 

the predicted distance to the toxic endpoint is 0.2 mile for a rural site and 0.1 mile for 

an urban site, compared to 0.4 mile (rural) and 0.2 mile (urban) for the same release 

outdoors. 

As noted above, the attenuation factors in Exhibit E-1 apply to ten-minute releases. If 

you want to use the same method to perform a calculation for a different duration of 

release in a building, consult the Technical Background Document cited at the 

beginning of this appendix for additional information on how to carry out such 

calculations. 
Appendix E -18- NH3 

E.3.3 Brief Summary of the Various States in Which Ammonia Exists in a Typical 

Refrigeration Facility 

A typical block diagram of a two-stage ammonia refrigeration facility is shown on 

the next page; a similar diagram of a single-stage facility is shown on the following 

page. 

AMMONIA LIQUEFIED UNDER PRESSURE 

In many parts of a typical refrigeration system, there is ammonia liquefied under 

pressure. If the pressure and temperature are sufficiently high, and if there is a sudden 

release of liquid ammonia, it will all become and remain airborne as a mixture of 

ammonia vapor and very fine liquid droplets that do not fall to the ground, provided 

that no obstacles are encountered in the immediate vicinity of the release. 

Experimental results clearly show that this is a real physical phenomenon (Goldwire 

et al., 1985; Kaiser, 1989). The droplets evaporate quickly as air is entrained. The 

evaporation process cools the air so that a cold mixture of air and ammonia vapor is 

formed. The mixture is denser than air, and a heavy vapor dispersion model is 

required to adequately predict airborne concentrations downwind of the point of 

release. 

In many refrigeration facilities, the ammonia travels from the discharge of the 

compressors through the evaporative condensers to the high-pressure receiver. The 

next page shows a range of typical pressures in the high-pressure receiver from 100­

200 psig (approximately 8-15 atmospheres). The figure shows ammonia vapor 

pressure as a function of temperature. Pressures of 8-15 atmospheres correspond to 

ammonia temperatures of approximately 10-40 degrees C, or superheats (number of 

degrees above the atmospheric boiling point) of about 40-70 degrees C. These 

conditions are definitely such as to ensure that all of any liquid ammonia release will 

become and remain airborne. 

Some (but by no means all) refrigeration facilities have an ammonia storage vessel in 

addition to the high-pressure receiver. This vessel will, in all likelihood, be outside, 

and its pressure will fluctuate with the external temperature. However, at an ambient 

temperature of 25 degrees C, the superheat would be about 60 degrees C so that the 

characteristics of any release from such a vessel are expected to be similar to those of 

a release from the high-pressure receiver. A release from such a vessel should be 

considered as a candidate for the worst case. 

Some refrigeration facilities may not have a high-pressure receiver. In such facilities, 

ammonia at pressures as high as 180 psig is confined to pipework, and there may be a 

low-pressure receiver with a typical pressure in the range 10-60 psig (~ 2-5 

atmospheres), also containing ammonia liquefied under pressure. From Figure E-5, 

the corresponding temperatures are -20-0 degrees C, or superheats of 10-30 degrees 

C. It is only slightly conservative to assume that all of the ammonia released from 

such a vessel becomes airborne. Two-stage systems have an intermediate receiver, 
NH3 -19- Appendix E 

which has a range of operating pressures similar to those for low-pressure receivers 

in a single-stage system. 

Exhibit E-5 Two-Stage Ammonia Refrigeration System 
Appendix E -20- NH3 

Exhibit E-6

Single-Stage Ammonia Refrigeration System with

High-Side Float Regulator and Pump Circulation
NH3 -21- Appendix E 

Figure E-5. Vapor Pressure of Ammonia as a Function of Temperature 
Appendix E -22- NH3 

AMMONIA AT SUBATMOSPHERIC PRESSURES 

In some facilities (e.g., food processing plants), even colder ammonia may be needed 

(when, for example, very rapid freezing of food is necessary). The first figure shows 

a low-pressure receiver with subatmospheric pressures as low as 15 inches of water, 

which corresponds to a temperature well below the atmospheric boiling point. If 

released, the ammonia will spill onto the ground and, over an average period of 10 

minutes or more, will evaporate at a much lower rate than a release from a worst-case 

rupture in such a vessel as the high-pressure receiver. In addition, these low 

temperature vessels are generally inside buildings, and it is likely that this would 

further reduce the effective rate of release to the atmosphere external to the 

refrigeration plant. 

AMMONIA GAS 

Finally, in ammonia refrigeration systems there is ammonia gas (vapor) in the system 

under a range of temperatures and pressures. If there is a rupture in the vapor space of 

the high-pressure receiver, there will be a buoyant ammonia jet (i.e., the ammonia 

vapor is less dense than air). However, for a given hole size and a given pressure, the 

rate of release of ammonia gas is very much less than that of liquid ammonia, so that 

it is unlikely that a vapor release would be the worst-case. 
NH3 -23- Appendix E 

E.3.4 Equations for Log-log Graphs and Calculations 

LOG-LOG EQUATIONS 

The guidance on Figure E-2 is essentially in the form of a straight line on a log-log

plot:

D = 0.0607(QR)0.4923 (4)

for a rural site and

D = 0.0443(QR)0.4782 (5)

for an urban site, where:

D = Distance to the endpoint (miles) and,

QR = Release rate (lb/min)

If you wish, you can use Equation 4 or 5 instead of Exhibit E-2 or Figure E-2. 

The curves on Figure E-3 are approximately straight lines on a log-log plot:

D = 0.0222(QR)0.4780 (6)

at a rural site, and

D = 0.0130(QR)0.4164 (7)

at an urban site.

If you wish, you can use Equation 6 or 7 instead of Exhibit E-3 or Figure E-3.

ALTERNATIVE RELEASE SCENARIOS 

There are many possible alternative scenarios. Some of those identified from a 

review of past incidents in refrigeration facilities include: 

— Plant upsets leading to the lifting of relief valves 

— Pipeline failures 

— A blocked-in, liquid-full pipeline rupturing as it heats up 

— Failures during ammonia delivery, such as a hose leak 
Appendix E -24- NH3 

The rule states that other scenarios, (discussed in Section 4.3 of the main document), 

should be considered In addition, active and passive mitigation systems may be 

considered, provided that they can be shown to withstand the cause of the release. It 

is apparent that there is a great variety of alternative scenarios. However, EPA 

requires that only one such scenario be identified and modeled. Many scenarios are 

effectively equivalent to a small hole of diameter 1⁄4 inch to 1⁄2 inch (e.g., a gasket 

rupture or a pump seal leak). Remember, however, that the alternative scenario must 

result in offsite consequences, unless you can show that no such scenario exists. 

The rate of release QR for a liquid release through a hole may be calculated using 

Bernoulli's formula:

QR = cDLA(2Pg/DL+2gh)0.5

where:

c = a constant (typical value 0.8)

DL = the density of the liquid in the vessel (639 kg/m3

 for ammonia)

A = the area of the hole (m2

)

Pg = the gauge pressure in the vessel (Pa)

g = the acceleration due to gravity (9.82 m/s

2

)

h = the static head (m)

The static head is likely to be negligible when the tank pressure is high, as is likely

for liquefied ammonia; therefore, the 2gh term in the equation can be ignored. The

following equation drops the 2gh term and includes conversion factors:

QR = 132.2×6.4516 x 10-4×0.8×639×HA×(2×(Pg/639)×6895)1⁄2

where: QR = Release rate (pounds per minute)

HA = Hole area (square inches)

132.2 = Conversion factor for kilograms per second to pounds per minute 

6.4516 x 10-4= Conversion factor for square inches to square meters (HA) 

0.8 = Discharge coefficient (0.8)

639 = Liquid density of ammonia (kg/m3

)

Pg = Gauge pressure in tank (psi)
NH3 -25- Appendix E 

6,895 = Conversion factor for psi to Pascals (Pg) 

Combining the conversion factors and incorporating the density of ammonia, leads to 

the equation presented in the text as Equation 3 for the release rate through a hole of 

ammonia liquefied under pressure: 

QR = 203×HA×(Pg)

1⁄2 

Note that this is the formula for the release of a pure liquid and would apply to a 

breach in the wall of a vessel or to the rupture of a very short pipe. For long pipes, 

there is a pressure drop between the vessel and the hole that leads to flashing in the 

pipe and a reduced rate of release. 

The scenario needs to be modeled in typical weather conditions. For many sites, 

Atmospheric Stability Category D with a moderate wind speed (e.g., 3 m/s) is close 

to average. The distance to the toxic endpoint can then be estimated from Figure E-3 

or from Exhibit E-3, which is a tabulation of Figure E-3. These results could simply 

be quoted in the Risk Management Plan. 

You also may identify your own alternative scenario(s). Consult your trade 

association (e.g., the International Institute of Ammonia Refrigeration) for guidance 

on other scenarios. Your Process Hazards Analysis is another potential source of 

pertinent information. However, remember that the regulation requires that releases 

large enough to have the potential to exceed the toxic endpoint offsite be considered. 

E.3.5 Additional Guidance on Modeling 

If the owner or operator decides to perform his/her own modeling, there are two 

major items that are not trivial. These are: 

a) Correct characterization of the source term (e.g., rate of release, 

temperature, density, momentum, aerosol content, etc.) 

b) Choice of a suitable dispersion model 

It is not possible to cover in detail all of the issues that need to be addressed, although 

there are sources of useful advice. The quadrennial conferences on vapor cloud 

dispersion modeling that are organized by the Center for Chemical Process Safety 

(CCPS) are a good source of information on the latest developments in source term 

and dispersion modeling (CCPS, 1987, 1991, 1995). There are also CCPS 

Guidebooks, such as "Guidelines for Use of Vapor Cloud Dispersion Models ­

Second Edition". 

EPA has also published additional guidance. There is one document that looks 

carefully at the definition of source terms (USEPA, 1993). There is another that 

describes EPA's own screening model for accidental releases of accidental chemicals 

TSCREEN (USEPA, 1992). EPA has also performed an evaluation of dense gas 
Appendix E -26- NH3 

dispersion models (USEPA, 1991). Another review of available models has been 

given by Hanna, et. al. (1991). 

E.4 References and Additional Sources of Information 

American National Standards Institute (1999), American National Standard for 

Equipment, Design, and Installation of Ammonia Mechanical Refrigeration Systems, 

ANSI/IIAR Standard 2. 

American National Standards Institute (2001), American National Standard: Safety 

Code for Mechanical Refrigeration, ANSI/ASHRAE Standard 15. 

Brighton, P.W.M. (1989). "Pressures Produced by Instantaneous Releases of 

Chlorine Inside Buildings," United Kingdom Health and Safety Executive Report 

SRD/HSE/R467, Her Majesty's Stationery Office, London. 

Center for Chemical Process Safety (CCPS, 1987). "Proceedings of the International 

Symposium on Vapor Cloud Modeling," Boston, MA; American Institute of Chemical 

Engineers, New York, NY. 

Center for Chemical Process Safety (CCPS, 1991). "International Conference and 

Workshop on Modeling and Mitigating the Consequences of Accidental Releases of 

Hazardous Materials," New Orleans, LA; American Institute of Chemical Engineers, 

New York, NY. 

Center for Chemical Process Safety (CCPS, 1995). "International Conference and 

Workshop on Modeling and Mitigating the Consequences of Accidental releases of 

Hazardous Materials," New Orleans, LA; American Institute of Chemical Engineers, 

New York, NY. 

Goldwire, Jr., H.C., T.G. McRae, G.W. Johnson, D.L. Hipple, R.P. Koopman, J.W. 

McLure, L.K. Morris and R.T. Cederwall (1985). "Desert Tortoise Series Data 

Report - 1983 Pressurized Ammonia Spills," Lawrence Livermore National 

Laboratories Report UCID-20562, Livermore, CA. 

Hanna, S.R., D.G. Strimatis and Joseph C. Chang (1991). "Uncertainties in 

Hazardous Model Gas Predictions," in CCPS (1991), pp. 345-368. 

International Institute of Ammonia Refrigeration (IIAR), Ammonia Data Book. 

International Institute of Ammonia Refrigeration (1997). Guidelines for Suggested 

Safety and Operating Procedures When Making Refrigeration Plant Tie-ins, IIAR B107. 

International Institute of Ammonia Refrigeration (1986). Guidelines for Water 

Contamination in Ammonia Refrigeration Systems, IIAR B-108 
NH3 -27- Appendix E 

International Institute of Ammonia Refrigeration (1998). Guidelines for: IIAR 

Minimum Safety Criteria for a Safe Ammonia Refrigeration System, IIAR B-109. 

International Institute of Ammonia Refrigeration (1993). Guidelines for Start-Up, 

Inspection, and Maintenance of Ammonia Refrigeration Systems, IIAR B-110. 

International Institute of Ammonia Refrigeration (1991). Guidelines for Ammonia 

Machinery Room Ventilation, IIAR Bulletin 111. 

International Institute of Ammonia Refrigeration (1991). Guidelines for 

Identification of Ammonia Refrigeration Piping and System Components, IIAR B114. 

International Institute of Ammonia Refrigeration (1992). Guidelines for Avoiding 

Component Failure in Industrial Refrigeration Systems Caused by Abnormal 

Pressure or Shock, IIAR B-116. 

United States Environmental Protection Agency (USEPA, 1991). "Evaluation of 

Dense Gas Simulation Models," EPA-450/R-89-018, Research Triangle Park, NC. 

United States Environmental Protection Agency (USEPA, 1993). "Contingency 

Analysis for Superfund Sites and Other Industrial Sources," EPA-454/R-93-001, 

Research Triangle Park, NC. 

United States Environmental Protection Agency (USEPA, 1999). “Technical 

Background Document for Offsite Consequence Analysis for Anhydrous Ammonia, 

Aqueous Ammonia, Chlorine, and Sulfur Dioxide,” EPA-550-B99-017, Washington, 

DC. 

United States Environmental Protection Agency (USEPA, 2001). Chemical Safety 

Alert: “Hazards of Ammonia Releases at Ammonia Refrigeration Facilities 

(Update),” EPA 550-F-01-009. Available through EPA website at: 

www.epa.gov/emergencies. 
APPENDIX F:

Supplemental Risk Management Program Guidance for

Wastewater Treatment Plants
Appendix F -2- WWTP 

Appendix F: Supplemental Risk Management Program Guidance for 

Wastewater Treatment Plants 

This appendix supplements the main body of the General Guidance to provide 

additional information for wastewater treatment plants (WWTPs), including publicly 

owned treatment works (POTWs) and other industrial treatment systems. It provides 

guidance on how to comply with part 68 with respect to chlorine, ammonia 

(anhydrous and aqueous), sulfur dioxide, and digester gas, the substances WWTPs 

usually use for treatment or produce as a result of treatment. We expect that any 

regulated substances present in your waste streams will be in concentrations too low 

to require compliance. If you have other processes that use regulated substances 

other than these, refer to the main body of the General Guidance (and any other 

applicable industry-specific appendix) for information on compliance with the rule 

for those processes. The appendix covers Risk Management Program elements in the 

same general order as those elements are addressed in the main document. However, 

note that the appendix does not address some generic RMP elements (e.g., 

Management System). For elements not addressed in this appendix, simply refer to 

the applicable guidance in the main document. 

F.1 General Applicability 

The following list includes the chemicals regulated under part 68 and OSHA PSM 

that are commonly used at WWTPs, along with their associated threshold quantity: 

Chemical EPA Threshold Quantity OSHA Threshold Quantity 

Chlorine 

Anhydrous Ammonia 

Aqueous Ammonia 

(concentration 20% or greater) 

Anhydrous Sulfur Dioxide 

Methane 

2,500 pounds 

10,000 pounds 

20,000 pounds 

5,000 pounds 

10,000 pounds 

1,500 pounds 

10,000 pounds 

15,000 pounds 

(>44%) 

1,000 pounds 

(Liquid) 

10,000 pounds 

For methane, the 10,000-pound threshold applies to the total weight of the flammable 

mixture of digester gases, not just the weight of methane or flammables in the 

mixture. However, if your WWTP uses methane (or a methane mixture) as fuel or 

sells it as fuel (as a retail facility), the amount of methane that you use or sell as fuel 

is not covered under part 68. For aqueous ammonia, the threshold applies only to the 

weight of ammonia in the mixture. 

In general, regulated chemicals in a waste stream at a POTW will not exceed one 

percent of a mixture and thus will not be covered by part 68. If an industrial WWTP 

has more than 1 percent of a regulated substance in the waste stream, the quantity of 
WWTP -3- Appendix F 

the substance in the waste stream will have to be determined and compared to the 

threshold quantity. Oxygen is not subject to either part 68 or OSHA PSM. Ozone is 

also not subject to part 68, although it is covered by OSHA PSM. 

F.2 Program Levels 

Program levels for private WWTPs and industrial wastewater treatment processes are 

determined in the same manner as other covered processes (See Chapter 2 of the 

main document for more information). However, a POTW will determine its 

Program levels based, in part, on the state or territory in which it is located. If OSHA 

has delegated its programs to the state or territory in which your POTW is located, 

you are covered by OSHA standards under state law (it is a condition of gaining 

delegation that the state apply OSHA rules to state and local governments). If you are 

in one of the states or territories with a delegated OSHA program (listed in Exhibit F2), your processes will be in Program 1, if eligible; otherwise, processes involving 

regulated toxics substances or digester gas production not used for fuel will be in 

Program 3 because they are subject to OSHA PSM. 

Several states have not been granted delegation by federal OSHA (listed in Exhibit F1). However, some of these states have enacted legislation or promulgated 

regulations that adopt the federal OSHA PSM standard and applied them to state and 

local governments. If you are in one of these states, your POTW process will be in 

either Program 1 or Program 3. 

If you are in one of the states without a delegated OSHA program and the state has 

not incorporated the federal OSHA PSM standard by reference into state law or code, 

your processes will generally be in either Program 1 or Program 2. An exception to 

this would be in cases where a POTW in a Federal OSHA state is operated by 

contractor employees. Since the private contractors employees are subject to Federal 

OSHA regulations, these POTW processes will be subject to Program 1 or Program 

3. 
Appendix F -4- WWTP 

Exhibit F-1: Federal OSHA States 

Alabama Kansas North Dakota 

Arkansas Louisiana Ohio 

Colorado Maine Oklahoma 

Delaware Massachusetts Pennsylvania 

DC Missouri Rhode Island 

Florida Mississippi South Dakota 

Georgia Montana Texas 

Idaho Nebraska West Virginia 

Illinois New Hampshire Wisconsin 

New Jersey 

Exhibit F-2: States with Delegated OSHA Programs 

Alaska Maryland South Carolina 

Arizona Michigan Tennessee 

California Minnesota Utah 

Connecticut Nevada Vermont 

Hawaii New Mexico Virginia 

Indiana New York Virgin Islands 

Iowa North Carolina Washington 

Kentucky Oregon Wyoming 

Puerto Rico 
WWTP -5- Appendix F 

F.2.1 QUICK RULES FOR DETERMINING PROGRAM 1 ELIGIBILITY 

TOXIC GASES 

If you have a process containing more than a threshold quantity of chlorine, 

ammonia, or sulfur dioxide or any other regulated toxic gas that is not liquefied by 

refrigeration alone (i.e., you hold it as a gas or liquefied under pressure), the distance 

to the endpoint estimated for a worst-case release of the toxic gas will generally be 

several miles. As a result, the distance to endpoint is unlikely to be less than the 

distance to public receptors, unless the process is very remote. In some cases, 

however, toxic gases in processes in enclosed areas may be eligible for Program 1. 

REFRIGERATED TOXIC GASES 

If you have a process containing anhydrous ammonia liquefied by refrigeration alone, 

and your worst-case release would take place into a diked area, the chances are good 

that the process may be eligible for Program 1, unless there are public receptors very 

close to the process. Even if you have many times the threshold quantity of ammonia, 

the process may still be eligible for Program 1. The worst-case analysis for a process 

containing chlorine liquefied by refrigeration is unlikely to show eligibility for 

Program 1, unless your site is extremely remote from the public or the release would 

occur within an enclosure. 

TOXIC LIQUIDS 

The distance to an endpoint for a worst-case release involving toxic liquids kept 

under ambient conditions may be smaller than the distance to public receptors in a 

number of cases. If public receptors are not found very close to the process (within 1⁄2 

mile), the process may be eligible for Program 1. However, facilities on small 

acreage sites are highly unlikely to meet to be eligible for Program 1 if they are in a 

developed area. Remotely located facilities or processes found near the center of 

large (acreage) sites are more likely to be eligible. 

WATER SOLUTIONS OF TOXIC SUBSTANCES 

Processes containing water solutions of toxic substances (e.g., aqueous ammonia) at 

ambient temperatures may be eligible for Program 1 (depending in some cases on the 

concentration of the solution), if spills would be contained in diked areas and public 

receptors are not located close to the process (within 1⁄2 mile). As noted above, 

facilities on small acreage sites in developed areas are highly unlikely to be eligible 

for Program 1; remotely located facilities or processes found near the center of large 

acreage sites are more likely to be eligible. 
Appendix F -6- WWTP 

FLAMMABLE SUBSTANCES 

Many processes containing regulated flammable substances are likely to be eligible 

for Program 1, unless there are public receptors within a very short distance. If you 

have a process containing up to about 20,000 pounds (twice the threshold quantity) 

of methane, your process is likely to be eligible for Program 1 if you have no public 

receptors within about 400 yards (1,200 feet) of the process. If you have up to 

100,000 pounds in a process (ten times the threshold quantity), the process may be 

eligible for Program 1 if there are no public receptors within about 700 yards (2,000 

feet). In general, it would be worthwhile to conduct a worst-case analysis for any 

processes containing only flammables to determine Program 1 eligibility, unless you 

have public receptors very close to the process. Consequently, you may have to 

conduct more worst-case analyses if you want to qualify processes for Program 1; for 

Program 2 and 3 processes, you need analyze only one worst-case release scenario to 

cover all flammables. For Program 1, you must be able to demonstrate, through your 

worst-case analysis, that every process you claim is Program 1 meets the criteria. 

Remember that the Program level designation for a process is based on the regulated 

substance that has the greatest distance to an endpoint. If your digesters are 

considered part of a process that includes chlorine, ammonia, or sulfur dioxide, the 

toxics will determine whether the process is eligible for Program 1 because the 

distances to an endpoint will be greater for the toxics. 

F.2.2 PROGRAM 3 

Any covered process that is not eligible for Program 1 and is subject to OSHA PSM 

under federal or state law is subject to Program 3 requirements, which include risk 

management measures and requirements virtually identical to the OSHA PSM 

Standard. (The other criterion for Program 3 applicability (§ 68.10(d)(1)) does not 

apply to WWTPs.) 

Private WWTPs are likely to be subject to OSHA PSM for processes containing more 

than a threshold quantity of chlorine, anhydrous ammonia, or sulfur dioxide. POTWs 

in states with delegated OSHA programs or in non-state-plan states that have adopted 

the PSM standard to cover state and local governments are subject to the PSM 

standard if they have more than a threshold quantity of these substances. OSHA’s 

thresholds are generally lower than EPA’s so it is possible that you may have a 

process that is subject to OSHA PSM and is not covered by part 68. For example, if 

you store a single, one-ton cylinder of chlorine, OSHA PSM will cover it because it 

has a 1,500 pound threshold for chlorine, but EPA’s part 68 will not because its 

threshold quantity for chlorine is 2,500 pounds. 

OSHA PSM covers aqueous ammonia at a concentration of greater than 44 percent 

(as opposed to EPA’s 20 percent or greater); therefore, your aqueous ammonia 

process may not be subject to OSHA PSM. 
WWTP -7- Appendix F 

F.2.3 PROGRAM 2 

Program 2 is considered a default program level because any covered process that is 

not eligible for Program 1 or assigned to Program 3 is, by default, subject to Program 

2 requirements, including a streamlined accident prevention program. One or more 

processes at your facility are likely to be in Program 2 if: 

— You are a publicly owned and operated facility in a state that does not have a 

delegated OSHA program, and the state has not incorporated the OSHA PSM 

standard by reference into state law or code. 

— You use aqueous ammonia in solutions with greater than 20 percent 

concentration but less than 44 percent concentration. 

— You use regulated acids in solution in activities. 

— You store regulated liquid flammable substances in atmospheric storage 

tanks. 

The last two of these conditions are unlikely to apply to WWTPs. 

F.3 Offsite Consequence Analysis 

This section gives guidance on how to perform the OCA for the five regulated 

substances that are typically used or produced at WWTPs: 

— Chlorine (toxic) 

— Sulfur dioxide (toxic) 

— Anhydrous ammonia (toxic) 

— Aqueous ammonia (20 percent or greater, toxic) 

— Methane (digester gas, flammable) 

This chapter presents discussions and tables for the worst-case scenario for all five 

substances listed above, followed by discussions and tables for alternative scenarios 

for the six substances. Because many WWTPs store chlorine and sulfur dioxide in 

buildings, we have included methods for estimating the mitigating effects of 

buildings. The remaining sections provide guidance on defining offsite impacts, 

documentation, and the symbols used in the chapter. The guidance presented in this 

chapter is intended for users - that is, it does not contain any explanations of how the 

guidance was derived. Those readers who are interested in obtaining an explanation 

can obtain from EPA a document entitled Technical Background Document for 

Offsite Consequence Analysis for Anhydrous Ammonia, Aqueous Ammonia, Chlorine 

and Sulfur Dioxide. 
Appendix F -8- WWTP 

F.3.1 Worst-Case Release Scenarios 

This subsection provides guidance on how to analyze worst-case scenarios for 

chlorine, sulfur dioxide, anhydrous ammonia, aqueous ammonia, and methane. For 

information on the general requirements of the regulations pertaining to worst-case 

scenarios, refer to chapter 4 of the main document. 

The toxic endpoints are: 

Ammonia: 0.14 mg/L (200 ppm)

Chlorine: 0.0087 mg/L (3 ppm)

Sulfur Dioxide: 0.0078 mg/L (3 ppm)

The regulations require you to use tables or models for atmospheric dispersion 

analysis that appropriately account for gas density. For the specific case of WWTPs, 

chlorine and sulfur dioxide are always dense gases (that is, denser than air). 

Anhydrous ammonia, if released from the liquid space of a container in which it is 

liquefied under pressure, forms a denser-than-air vapor cloud. Ammonia evaporating 

from a pool of aqueous ammonia is treated as neutrally buoyant (that is, it has about 

the same density as air). 

CHLORINE 

At WWTPs, chlorine is most likely to be present in 150-lb cylinders, in one-ton 

(2,000-lb) cylinders, in 17-ton tank trucks, or in 90-ton railcars. The worst-case 

scenario assumes that these quantities are completely released over a period of 10 

minutes (e.g., a 150-lb worst case corresponds to a 15-lb/min rate of release). The 

predicted distances to the toxic endpoint for each of these scenarios is given in 

Exhibit F-3. These distances are for releases that are assumed to take place outdoors. 

See Section F.3.3 for a discussion on buildings. 
WWTP -9- Appendix F 

Exhibit F-3

Distances to Toxic Endpoints - Chlorine

F Stability, Wind Speed 1.5 Meters per Second

Scenario Release Rate (lbs/min) Distance to Toxic Endpoint (miles) 

Rural Urban 

150-lb cylinder 15 0.8 0.4 

1-ton cylinder 200 3.0 1.3 

17-ton tank trucks 3,400 12 5.8 

90-ton rail car 18,000 >25 14 

If your facility does not fit into the standard pattern of 150-lb cylinders, one-ton 

cylinders, 17-ton tank trucks, or 90-ton railcars, you should use Figure F-1 or Exhibit 

F-4. Identify the chlorine vessel that contains the largest quantity of any in your 

facility and divide that mass by 10 to obtain the release rate in lb/min. Look for that 

release rate, or the rate nearest to it, in Exhibit F-4. Then read across to the rural or 

urban distances. 

Alternatively, look along the bottom axis of Figure F-1, read up to the curve(s) and 

then across to the corresponding distances on the vertical axis. As noted above, the 

results presented in Exhibits F-3 and F-4 are for a release that is outside. Many of 

you will keep your chlorine vessels inside buildings. Some will even have specially 

designed, leak-tight buildings with chlorine or sulfur dioxide scrubbers. However, the 

intention of this section is to provide information on the worst-case scenario. There 

are times when you will be handling the cylinders outside. Nevertheless, in 

discussions with local agencies and local communities you may well want to explain 

how your facility is designed to prevent or mitigate worst-case scenarios. 
Appendix F -10- WWTP 

Exhibit F-4

Distances to Toxic Endpoint - Chlorine

F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 0.2 0.1 

2 0.3 0.1 

5 0.5 0.2 

10 0.7 0.3 

15 0.8 0.4 

20 1.0 0.4 

30 1.2 0.5 

40 1.4 0.6 

50 1.5 0.6 

60 1.7 0.7 

70 1.8 0.8 

80 1.9 0.8 

90 2.0 0.9 

100 2.2 0.9 

150 2.6 1.2 

200 3.0 1.3 

250 3.4 1.5 

300 3.7 1.6 

400 4.2 1.9 

500 4.7 2.1 

600 5.2 2.3 

700 5.6 2.5 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

750 5.8 2.6 

800 5.9 2.7 

900 6.3 2.9 

1,000 6.6 3.0 

1,500 8.1 3.8 

2,000 9.3 4.4 

2,500 10 4.9 

3,000 11 5.4 

4,000 13 6.2 

5,000 14 7.0 

6,000 16 7.6 

7,000 17 8.3 

7,500 18 8.6 

8,000 18 8.9 

9,000 19 9.4 

10,000 20 9.9 

15,000 25 12 

20,000 * 14 

25,000 * 16 

30,000 * 18 

40,000 * 20 

50,000 * 0 

* More than 25 miles (report distance as 25 miles) 

These are results that you can simply quote when you submit your RMP. 
WWTP -11- Appendix F 

SULFUR DIOXIDE 

Sulfur dioxide, if present at a WWTP, is also likely to be in 150-lb cylinders, one-ton 

cylinders, 17-ton tank cars, or 90-ton railcars. The worst-case scenario assumes that 

these quantities are completely released over a period of 10 minutes. The predicted 

distances to the toxic endpoint for each of these scenarios is given in Exhibit F-5. 

EXHIBIT F-5

Distances to Toxic Endpoint - Sulfur Dioxide

F Stability, Wind Speed 1.5 Meters per Second

Scenario Release Rate (lbs/min) Distance to Toxic Endpoint (miles) 

Rural Urban 

150-lb cylinder 15 0.7 0.3 

1-ton cylinder 200 3.1 1.3 

17-ton tank trucks 3,400 15 6.0 

90-ton rail car 18,000 >25 15 

These are results that you can simply quote when you submit your RMP. If your 

facility does not fit into the standard pattern of 150-lb cylinders, one-ton cylinders, or 

90-ton railcars, you should use Figure F-2 or Exhibit F-6. Identify the sulfur dioxide 

vessel that contains the largest quantity of any in your facility. Divide that quantity 

by 10 to obtain the release rate in lb/min and look for that rate, or the rate nearest to 

it, on Exhibit F-6. Then read across to the rural or urban distances. Alternatively, use 

Figure F-2. 
Appendix F -12- WWTP 

EXHIBIT F-6

DISTANCES TO TOXIC ENDPOINT FOR SULFUR DIOXIDE

F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 0.2 0.1 

2 0.2 0.1 

5 0.4 0.2 

10 0.6 0.2 

15 0.7 0.3 

20 0.9 0.4 

30 1.1 0.5 

40 1.3 0.5 

50 1.4 0.6 

60 1.6 0.7 

70 1.8 0.7 

80 1.9 0.8 

90 2.0 0.8 

100 2.1 0.9 

150 2.7 1.1 

200 3.1 1.3 

250 3.6 1.4 

300 3.9 1.6 

400 4.6 1.9 

500 5.2 2.1 

600 5.8 2.3 

700 6.3 2.5 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

750 6.6 2.6 

800 6.8 2.7 

900 7.2 2.9 

1,000 7.7 3.1 

1,500 9.6 3.8 

2,000 11 4.5 

2,500 13 5.0 

3,000 14 5.6 

4,000 17 6.5 

5,000 19 7.3 

6,000 21 8.1 

7,000 23 8.8 

7,500 24 9.1 

8,000 25 9.5 

9,000 * 10 

10,000 * 11 

15,000 * 13 

20,000 * 16 

25,000 * 18 

30,000 * 19 

40,000 * 23 

50,000 * * 

* More than 25 miles (report distance as 25 miles) 
WWTP -13- Appendix F 

ANHYDROUS AMMONIA 

In WWTPs, anhydrous ammonia is generally stored as a liquid under pressure in 

vessels that are kept outdoors. These vessels are relatively large (e.g., 10,000 gallons 

or ~56,000 lb). Identify the quantity of ammonia in your storage vessel and divide 

by 10 to obtain the release rate in lb/min. Look for that release rate, or the release rate 

nearest to it, on Exhibit F-7. Then read across to the rural or urban distances. 

Alternatively, use Figure F-3. 

The 10,000-gallon vessel mentioned above contains 56,000 lb when full. (You may 

take into account any administrative controls that limit the quantity of the ammonia 

in the vessel. For example, you will generally require that the vessel never be filled 

above 85 percent of its total volume to allow for the high coefficient of volumetric 

expansion of ammonia.) Assuming for the sake of the present example that 56,000 lb 

is the greatest quantity of ammonia that will ever be in the vessel, the release rate is 

5,600 lb/min. The closest release rate on Exhibit F-7 is 6,000 lb/min. The 

corresponding rural distance is approximately 4.4 miles and the corresponding urban 

distance is approximately 2.8 miles. 
Appendix F -14- WWTP 

EXHIBIT F-7

DISTANCES TO TOXIC ENDPOINT

FOR ANHYDROUS AMMONIA LIQUEFIED UNDER PRESSURE

F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 0.1 <0.1* 

2 0.1 0.1 

5 0.1 0.1 

10 0.2 0.1 

15 0.2 0.2 

20 0.3 0.2 

30 0.3 0.2 

40 0.4 0.3 

50 0.4 0.3 

60 0.5 0.3 

70 0.5 0.3 

80 0.5 0.4 

90 0.6 0.4 

100 0.6 0.4 

150 0.7 0.5 

200 0.8 0.6 

250 0.9 0.6 

300 1.0 0.7 

400 1.2 0.8 

500 1.3 0.9 

600 1.4 0.9 

700 1.5 1.0 

750 1.6 1.0 

800 1.6 1.1 

900 1.7 1.2 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1,000 1.8 1.2 

1,500 2.2 1.5 

2,000 2.6 1.7 

2,500 2.9 1.9 

3,000 3.1 2.0 

4,000 3.6 2.3 

5,000 4.0 2.6 

6,000 4.4 2.8 

7,000 4.7 3.1 

7,500 4.9 3.2 

8,000 5.1 3.3 

9,000 5.4 3.4 

10,000 5.6 3.6 

15,000 6.9 4.4 

20,000 8.0 5.0 

25,000 8.9 5.6 

30,000 9.7 6.1 

40,000 11 7.0 

50,000 12 7.8 

75,000 15 9.5 

100,000 18 10 

150,000 22 13 

200,000 ** 15 

250,000 ** 17 

750,000 ** ** 

* More than 25 miles (report distance as 25 miles) 
WWTP -15- Appendix F 

AQUEOUS AMMONIA 

Some WWTPs keep aqueous ammonia in outside storage tanks at atmospheric 

pressure. The tanks usually stand in a diked area. Commercial grades of aqueous 

ammonia vary from less than 20 weight percent to about 30 weight percent. For ease 

of presentation, the ammonia is assumed to be in a 30 weight percent solution. 

Because this has the highest vapor pressure of any of the commercial grades used in 

wastewater treatment facilities, its use is conservative if you have aqueous ammonia 

in a less than 30 weight percent solution. 

If there is a catastrophic failure, the aqueous ammonia will spill into the diked area. 

You are allowed to consider the dike, which is a passive mitigation feature. However, 

if you have any reason to believe that the dike will not withstand the event that leads 

to the spill, or if your tank does not stand in a diked area, then you should assume, as 

required by the rule, that the spill spreads out until its depth is only 1 cm (0.39 inch). 

The first step is to calculate the rate of evaporation from the pool. 

UNDIKED AREA 

For an undiked area, the rate of release of ammonia from the pool (QR) (lb/min) is 

given by: 

QR = 0.020QS (1) 

where QS is the total quantity (lb) of the spill of aqueous ammonia. For example, if 

there is a spillage of 80,000 lb, the rate of evaporation is 0.02 x 80,000 = 1,600 

lb/min. The present guidance assumes that this is the average rate of release over 10 

minutes, after which the pool will be more dilute than it was initially and will be 

evaporating much less rapidly. 

DIKED AREA 

For a diked area, the rate of evaporation is: 

QR = 0.036Ap (2) 

where Ap is the diked area in square feet. For example, if the vessel stands in a diked 

area that is 40 feet x 40 feet = 1,600 ft2

, the predicted rate of evaporation is 0.036 x 

1,600 = 58 lb/min. 

The maximum area of the pool that would be formed by the spilled liquid can be 

estimated as 0.55QS. If you have a diked area that is larger than the maximum area, 

use Equation 1 for an undiked area to estimate the release rate to air. 

RATES OF RELEASE AT TEMPERATURES OTHER THAN 25 OC 
Appendix F -16- WWTP 

The actual temperature of stored aqueous ammonia varies with the ambient 

temperature. The rule requires you to consider the release temperature to be the 

highest daily temperature observed during the last three years, or the operating 

temperature, whichever is highest. The ratio Rvp(T) represents the ratio of the partial 

pressure of ammonia at temperature T o

C to the partial pressure at 25 oC. 

Exhibit F-8 gives values of Rvp(T) for 30 percent aqueous ammonia in 1 o

C 

increments from 15 o

C to 40 oC (59 oF to 104 oF). The rates of evaporation in 

Equations 1 and 2 are proportional to the vapor pressure, so to obtain a rate of 

evaporation for a temperature T o

C other than 25 oC, simply multiply the right-hand 

side of Equation 1 or 2 by the corresponding value of Rvp(T). For example, for an 

undiked release of 80,000 lbs of ammonia at 35 o

C, the calculation is 

(0.020)(80,000)(1.45) = 2,300 lbs/min. 

The vapor pressure of ammonia at other temperatures can be obtained from the 

Handbook of Chemistry and Physics, CRC Press, 1998. 

DISTANCES TO TOXIC ENDPOINT 

Take the evaporation rate and look for that rate, or the rate nearest to it, on Exhibit F9. Then read across to the rural or urban distances. For example, for the 58 lb/min 

release rate derived above, the closest release rate on Exhibit F-9 is 60 lb/min. The 

predicted rural distance is approximately 0.4 mile and the predicted urban distance is 

approximately 0.2 mile. Alternatively, use Figure F-4. 
WWTP -17- Appendix F 

Exhibit F-8

Ratio of Vapor Pressure of Ammonia in 30% Aqueous Ammonia

(Ratio is Unity at 25 o

C)

Temperature (oC) Ratio Rvp(T) Temperature (oC) Ratio Rvp(T) 

15 0.67 28 1.12 

16 0.70 29 1.16 

17 0.73 30 1.21 

18 0.76 31 1.25 

19 0.79 32 1.30 

20 0.82 33 1.35 

21 0.86 34 1.40 

22 0.89 35 1.45 

23 0.93 36 1.50 

24 0.96 37 1.55 

25 1.00 38 1.61 

26 1.04 39 1.66 

27 1.08 40 1.72 
Appendix F -18- WWTP 

EXHIBIT F-9

Distances to Toxic Endpoint for Aqueous Ammonia

F Stability, Wind Speed 1.5 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 0.1 

<0.1* 2 0.1 

5 0.1 

10 0.2 0.1 

15 0.2 0.1 

20 0.3 0.1 

30 0.3 0.1 

40 0.4 0.1 

50 0.4 0.1 

60 0.4 0.2 

70 0.5 0.2 

80 0.5 0.2 

90 0.5 0.2 

100 0.6 0.2 

150 0.7 0.2 

200 0.8 0.3 

250 0.8 0.3 

300 0.9 0.3 

400 1.1 0.4 

500 1.2 0.4 

600 1.3 0.4 

700 1.4 0.5 

750 1.4 0.5 

800 1.5 0.5 

900 1.5 0.6 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1,000 1.6 0.6 

1,500 2.0 0.7 

2,000 2.2 0.8 

2,500 2.5 0.9 

3,000 2.7 1.0 

4,000 3.1 1.1 

5,000 3.4 1.2 

6,000 3.7 1.3 

7,000 4.0 1.4 

7,500 4.1 1.5 

8,000 4.2 1.5 

9,000 4.5 1.6 

10,000 4.7 1.7 

15,000 5.6 2.0 

20,000 6.5 2.4 

25,000 7.2 2.6 

30,000 7.8 2.8 

40,000 8.9 3.3 

50,000 9.8 3.6 

75,000 12 4.4 

100,000 14 5.0 

150,000 16 6.1 

200,000 19 7.0 

250,000 21 7.8 

750,000 ** 13 

*Report distance as 0.1 mile ** More than 25 miles (report distance as 25 miles) 
WWTP -19- Appendix F 

METHANE 

Methane is present at some wastewater treatment facilities as a component of digester 

gas. Typical constituents of digester gas are 55 to 70 percent methane by volume, 25 

to 30 percent carbon dioxide by volume, and small amounts of nitrogen and 

hydrogen. Modern facilities may well have processes containing more than 10,000 lb 

of digester gas at any one time (the entire quantity of the flammable mixture in a 

process must be compared with the threshold quantity (TQ) of 10,000 lb to determine 

whether the facility is covered; note that digester gas that is used as fuel is not 

covered). Proceed as follows: 

1. Determine the density Dm of the methane in the digester at operating temperature 

T (o

F), assuming that there is X volume percent of methane and 100 - X volume 

percent of carbon dioxide and other materials. You should determine X by analysis of 

your digester gas; if you do not know the percentage of methane, you may use 70 

percent as a conservative assumption. If X varies over time, you should use the 

largest value of X that is seen in your facility. 

Dm = 0.22 X/(460+T) (3) 

As an example, if X = 65, and the operating temperature is 95 o

F, Dm = 0.026 lb/ft3. 

2. Calculate the total volume V (ft3

) occupied by digester gas in one digester (the 

largest). Associated pipework can be neglected. 

V = Br

2

H (4) 

Here, r is the digester radius and H is the maximum digester head space. As an 

example, if H = 8 ft and r = 40 ft, then V = Br

2

H = (3.14)(40)2(8) • 40,200 ft3. 

3. Calculate the quantity Q of methane contained in V: 

Q = DmV (5) 

In the current example, Q = (0.026)(40,200) = 1,045 lb 

Note that this quantity of methane itself, as well as the total quantity of digester gas, 

is less than the 10,000-lb TQ for flammable materials. This is because the total 

amount of digester gas (i.e., not just methane) in a process is used to determine 

whether that process is covered by the regulation (assuming the digester gas is not 

being used as fuel). It may be the case that no single digester contains more than the 

TQ of digester gas, but you still will be covered if there are several digesters in your 

process and the total quantity of digester gas in all of the digesters together exceeds 

the threshold. However, you are required to consider only the quantity of methane in 

a single vessel when calculating the results of a worst-case vapor cloud explosion. 
Appendix F -20- WWTP 

4. Use the TNT-equivalency model to calculate the distance D (miles) to the 1 psi 

overpressure endpoint: 

D = 0.0082 (Q)1/3 (6) 

Equation 6 has been customized for methane. In the present example, D = 

0.0082(1,045)1/3 = 0.08 mile. Alternatively, you can use Exhibit F-10 to estimate the 

distance to the endpoint for a range of quantities of methane. 

EXHIBIT F-10

Distance to Overpressure Endpoint of 1.0 PSI

for Vapor Cloud Explosions of Methane 

Based on TNT Equivalent Method, 10 Percent Yield Factor

Quantity in Cloud 

(pounds) 

Distance to 

Endpoint 

(miles) 

500 0.07 

2,000 0.1 

5,000 0.1 

10,000 0.2 

20,000 0.2 

Quantity in Cloud 

(pounds) 

Distance to 

Endpoint 

(miles) 

50,000 0.3 

100,000 0.4 

200,000 0.5 

500,000 0.7 

1,000,000 0.8 

Some facilities have an intermediate storage vessel for digester gas, at a pressure that 

may be typically 45-50 psig. You should use the quantity of methane in such a vessel 

in Equation 6 or Exhibit F-10 if it contains the largest quantity of digester gas on site. 

F.3.2 Alternative Release Scenarios 

This subsection provides guidance on how to choose and model alternative scenarios 

for chlorine, sulfur dioxide, anhydrous ammonia, aqueous ammonia, and methane. 

For information on the general requirements of the regulations pertaining to 

alternative release scenarios, refer to chapter 4 of the main document. 

A number of scenarios other than those listed in the rule may be worth considering 

for WTTPs. Many WWTPs have single-stage, pass-through chemical scrubbers to 

neutralize compounds such as sulfur dioxide. Failure of the neutralizing solution’s 

recirculation pump and continued operation of the blower fan could not only allow a 
WWTP -21- Appendix F 

release, but also exacerbate it by mechanically evacuating the substance from the 

room. 

Accidents reported to EPA involving chlorine systems have been caused by “rust 

holes,” failure of a diaphragm, leak during hookup to a tank, a packing nut leak, 

faulty cylinders, removal of a valve in error, faulty valves, leaking gaskets, and a 

blown pressure gauge. Similar accidents involving sulfur dioxide systems have been 

reported. In addition, natural events, such as floods, tornados, earthquakes, and 

hurricanes could cause several releases to occur simultaneously. You may want to 

consider these types of scenarios when you select your alternative release scenarios. 

CHLORINE 

FLASHING LIQUID RELEASES 

Many of the potential alternative scenarios could involve the release of liquid 

chlorine from a small hole. The liquid chlorine flashes immediately to vapor and fine 

liquid droplets and is carried downwind. 

The rate of release of a liquid through an hole is given by Bernoulli’s formula for 

liquid releases (see section F.3.4). Using chemical-specific data for chlorine, the 

formula becomes: 

QR = 3,140 × Ah (8) 

where: 

Ah = the area of the hole (in2

 - for example, the area of a hole of 

diameter 1 inch is 0.785 in2

) 

3,140 = factor applicable to chlorine liquefied under a pressure of 

98.5 psig (see Section F.3.4) 

Note that this is the formula for the release of a pure liquid and would apply to a 

breach in the wall of a vessel or to the rupture of a very short pipe. For long pipes, 

there is a pressure drop between the vessel and the hole, and there will be flashing in 

the pipe and a reduced rate of release. Therefore, Equation 8 may be conservative. 

If there is a small leak from the liquid space of a large storage vessel, the reservoir 

can essentially be considered as infinite, and the chlorine will be steadily emitted at a 

constant rate for a relatively long period. Such leaks may occur because of a gasket 

failure, a pump seal leak, or a corrosion hole, for example. You can use Equation 8 

and the estimated area of the hole to calculate the release rate (QR). 

To predict the distance to the toxic endpoint, take the calculated value of QR and 

identify the closest value on Exhibit F-11 (150 lb/min). Read off the corresponding 

distance, in this case, 0.6 mile for a rural site and 0.2 mile for an urban site. 

Alternatively, use Figure F-5. 
Appendix F -22- WWTP 

Exhibit F-12 provides release rate estimates for releases of liquid chlorine through 

holes of diameter 1/16 inch to 5 inches and the distances to the endpoint 

corresponding to these release rates. You can use this table instead of Equation 8 and 

Exhibit F-11 to estimate the distance to the endpoint. 
WWTP -23- Appendix F 

EXHIBIT F-11

Distances to Toxic Endpoint for Chlorine

D Stability, Wind Speed 3 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 <0.1* 

2 0.1 <0.1*

5 0.1 

10 0.2 0.1 

15 0.2 0.1 

20 0.2 0.1 

30 0.3 0.1 

40 0.3 0.1 

50 0.3 0.1 

60 0.4 0.2 

70 0.4 0.2 

80 0.4 0.2 

90 0.4 0.2 

100 0.5 0.2 

150 0.6 0.2 

200 0.6 0.3 

250 0.7 0.3 

300 0.8 0.3 

400 0.8 0.4 

500 1.0 0.4 

600 1.0 0.4 

700 1.1 0.4 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

750 1.2 0.4 

800 1.2 0.5 

900 1.2 0.5 

1,000 1.3 0.5 

1,500 1.6 0.6 

2,000 1.8 0.6 

2,500 2.0 0.7 

3,000 2.2 0.8 

4,000 2.5 0.8 

5,000 2.8 0.9 

7,500 3.4 1.2 

10,000 3.9 1.3 

15,000 4.6 1.6 

20,000 5.3 1.8 

25,000 5.9 2.0 

30,000 6.4 2.1 

40,000 7.3 2.4 

50,000 8.1 2.7 

75,000 9.8 3.2 

100,000 11 3.6 

150,000 13 4.2 

200,000 15 4.8 

* Report distance as 0.1 mile 
Appendix F -24- WWTP 

EXHIBIT F-12

Release Rates and Distance to the Endpoint for Liquid Chlorine Releases

D Stability, Wind Speed 3 Meters per Second

Hole Diameter 

(inches) 

Release Rate 

(lb/min) 

Distance (miles) 

Rural Urban 

1/16 10 0.2 0.1 

3/16 87 0.4 0.2 

1/4 150 0.6 0.2 

5/16 240 0.7 0.3 

1/2 620 1.0 0.4 

1 2,500 2.0 0.7 

2 9,900 3.9 1.3 

3 22,200 5.3 1.8 

4 39,500 7.3 2.4 

5 61,700 8.1 2.7 

TWO-PHASE RELEASES 

In case of a release from a long pipe carrying liquid chlorine (L/dh >> 1, where L is 

the length of the pipe between the reservoir of chlorine and the atmosphere and dh is 

the diameter of the pipe), there can be flashing in the discharge pipe, resulting in a 

two-phase mixture emerging to the atmosphere. In this case, the rate of release in 

lb/min for chlorine is given by: 

QR = 1,100 × Ah × F (9) 

where: 

1,100 = chemical-specific factor applicable to chlorine at 25 o

C (see 

Ah = 

Section F.3.4) 

hole area (in2) = area of pipe opening 

F = frictional loss factor (dimensionless) with values as follows: 

F L/dh 

1 10 

0.85 50 

0.75 100 

0.65 200 

0.55 400 
WWTP -25- Appendix F 

Exhibit F-13 presents release rates for a range of pipe diameters and length-diameter 

ratios for two-phase releases of chlorine from a pipe. You can read the release rate 

from the exhibit or calculate the release rate from Equation 9, then find the distance 

to the endpoint corresponding to the release rate by referring to Exhibit F-11. 

EXHIBIT F-13

Release Rates for Two-Phase Releases from Pipes Carrying Liquid Chlorine

Pipe 

Diameter 

(inches) 

Pipe Length/Diameter (L/dh) 

10 (F=1) 50 (F=0.85) 100 (F=0.75) 200 (F=0.65) 400 (F=0.55) 

Chlorine Release Rate (lbs/min) 

1/4 54 46 40 35 30 

5/16 84 72 63 55 46 

1/2 220 180 160 140 120 

3/4 490 410 360 320 270 

1 860 730 650 560 480 

2 3,500 2,900 2,600 2,200 1,900 

3 7,800 6,600 5,800 5,100 4,300 

VAPOR RELEASES 

For a choked release of vapor (i.e., emerging at the speed of sound from the hole, 

which will invariably be the case for chlorine at atmospheric temperatures), the 

release rate for chlorine is given by: 

QR = 190 × Ah (10) 

where: 

190 = chemical-specific factor for chlorine at a tank pressure of 113 psia 

and temperature 25 o

C (see Section F.3.4) 

Ah = hole area (in2

) 

You can use Equation 10 to estimate the release rate of chlorine from a hole in the 

vapor space of a tank. For example, such a hole could result from shearing off a valve 

at the top of a tank. The distance to the endpoint can be estimated from the release 

rate, using Exhibit F-11 or Figure F-5. 
Appendix F -26- WWTP 

As an alternative to Equation 10, for releases from holes ranging from 1/16-inch to 5 

inches in diameter, you can read the release rate and the corresponding distance from 

Exhibit F-14. 

EXHIBIT F-14

Release Rates and Distance to the Endpoint for Chlorine Vapor Releases

D Stability, Wind Speed 3 Meters per Second

Hole 

Diameter 

(inches) 

Release Rate 

(lbs/min) 

Distance (miles) 

Rural Urban 

1/16 0.6 0.1 0.1 

3/16 5 0.1 0.1 

1/4 9 0.2 0.1 

5/16 15 0.2 0.1 

1/2 37 0.3 0.1 

1 150 0.6 0.2 

2 600 1.0 0.4 

3 1,300 1.6 0.6 

4 2,400 2.0 0.7 

5 3,700 2.5 0.8 

Note that the release rate estimated by the method above is conservative. As the 

release proceeds, chlorine continuously evaporates from the liquid surface in the 

cylinder. This causes the liquid to cool, the vapor pressure to decrease, and the rate of 

release to decline. However, the equations for calculating this effect are rather 

complex and not included in this guidance. 

OTHER CHLORINE SCENARIOS 

If you wish to do so, you can simply quote any of the results above, if they are 

applicable to your site, when you submit your Risk Management Plan. However, you 

may also choose to develop other scenarios, using Equations 8, 9, or 10, and Exhibit 

F-11 or Figure F-5. 
WWTP -27- Appendix F 

DURATION OF RELEASE 

You may calculate the maximum duration by dividing the quantity in the tank or the 

quantity that would be released from a pipe by the release rate. You may use 60 

minutes as a default value for maximum release duration. If you know, and can 

substantiate, how long it is likely to take to stop the release, you may use that time as 

the release duration. 

SULFUR DIOXIDE 

FLASHING LIQUID RELEASES 

Sulfur dioxide is similar to chlorine in the way that it would be released, so 

Bernoulli’s formula is applicable. Using Bernoulli’s formula, incorporating chemicalspecific data for sulfur dioxide, you can estimate the release rate from a hole in the 

liquid space of a tank from the following equation: 

QR = 2,020 × Ah (11) 

where: 

Ah = the area of the hole (in2

) 

2,020 = factor applicable to sulfur dioxide liquefied under a pressure 

of 43 psig (see Section F.3.4) 

After you have estimated the release rate, you can find the predicted distance to the 

toxic endpoint for sulfur dioxide from Exhibit F-16 or Figure F-6. Alternatively, you 

can use Exhibit F-15. This exhibit gives release rates and distances to the endpoint 

for flashing liquid releases through holes of diameter 1/16 inch to 5 inches. 
Appendix F -28- WWTP 

EXHIBIT F-15

Release Rates and Distance to the Endpoint for Liquid Sulfur Dioxide Releases

D Stability, Wind Speed 3 Meters per Second

Hole Diameter 

(inches) 

Release Rate 

(lb/min) 

Distance (miles) 

Rural Urban 

1/16 6 0.1 0.1 

3/16 56 0.4 0.2 

1/4 99 0.5 0.2 

5/16 160 0.6 0.2 

1/2 400 0.9 0.4 

1 1,600 1.9 0.6 

2 6,300 3.3 1.1 

3 14,300 5.6 1.7 

4 25,300 7.3 2.1 

5 39,600 9.2 2.6 

TWO PHASE RELEASES 

A break in a long pipe (whose length is much greater than its diameter) carrying 

liquid sulfur dioxide can result in the release of a two-phase mixture, as discussed 

above for chlorine. The release rate can be estimated from the following equation: 

QR = 252 × Ah × F (12) 

where: 

252 = chemical-specific factor applicable to sulfur dioxide at 25 oC (see 

Section F.3.4) 

Ah = hole area (in2

) = area of pipe opening 

F = frictional loss factor (dimensionless) with values as shown in the 

section on chlorine 

You can estimate the release rate from Equation 12, then find the distance to the 

endpoint corresponding to the release rate by referring to Exhibit F-11. You also can 

find the release rate for a range of pipe diameters and L/dh values in Exhibit F-17. 
WWTP -29- Appendix F 

Exhibit F-16

Distances to Toxic Endpoint for Sulfur Dioxide

D Stability, Wind Speed 3.0 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

1 <0.1* 

2 0.1 <0.1*

5 0.1 

10 0.2 0.1 

15 0.2 0.1 

20 0.2 0.1 

30 0.2 0.1 

40 0.3 0.1 

50 0.3 0.1 

60 0.4 0.2 

70 0.4 0.2 

80 0.4 0.2 

90 0.4 0.2 

100 0.5 0.2 

150 0.6 0.2 

200 0.6 0.2 

250 0.7 0.3 

300 0.8 0.3 

400 0.9 0.4 

500 1.0 0.4 

600 1.1 0.4 

700 1.2 0.4 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

750 1.3 0.5 

800 1.3 0.5 

900 1.4 0.5 

1,000 1.5 0.5 

1,500 1.9 0.6 

2,000 2.2 0.7 

2,500 2.3 0.8 

3,000 2.7 0.8 

4,000 3.1 1.0 

5,000 3.3 1.1 

7,500 4.0 1.3 

10,000 4.6 1.4 

15,000 5.6 1.7 

20,000 6.5 1.9 

25,000 7.3 2.1 

30,000 8.0 2.3 

40,000 9.2 2.6 

50,000 10 2.9 

75,000 13 3.5 

100,000 14 4.0 

150,000 18 4.7 

200,000 20 5.4 

* Report distance as 0.1 mile 
Appendix F -30- WWTP 

EXHIBIT F-17

Release Rates for Two-Phase Releases from Pipes Carrying Liquid Sulfur Dioxide

Pipe 

Diameter 

(inches) 

Pipe Length/Diameter (L/dh) 

10 (F=1) 50 (F=0.85) 100 (F=0.75) 200 (F=0.65) 400 (F=0.55) 

Sulfur Dioxide Release Rate (lb/min) 

1/4 12 11 9 8 7 

5/16 19 16 14 13 11 

1/2 49 42 37 32 27 

3/4 110 95 83 72 61 

1 200 170 150 130 110 

2 800 670 600 520 440 

3 1,800 1,500 1,300 1,200 980 

VAPOR RELEASES 

For a choked release of sulfur dioxide vapor, the release rate is given: 

QR = 91 × Ah (13) 

where: 

91 = chemical-specific factor for sulfur dioxide at a tank pressure of 58 

psia and temperature 25 o

C (see Section F.3.4) 

Ah = hole area (in2

) 

The distance to the endpoint can be estimated from the release rate, using Exhibit F16 or Figure F-6. 

As an alternative to Equation 13 and Exhibit F-16, for releases from holes ranging 

from 1/4 inch to 5 inches in diameter, you can read the release rate and the 

corresponding distance from Exhibit F-18. 
WWTP -31- Appendix F 

EXHIBIT F-18

Release Rates and Distance to Endpoint for Sulfur Dioxide Vapor Releases

D Stability, Wind Speed 3 Meters per Second

Hole Diameter 

(inches) 

Release Rate 

(lb/min) 

Distance (miles) 

Rural Urban 

1/4 4 0.1 0.1 

5/16 7 0.1 0.1 

1/2 18 0.2 0.1 

1 71 0.4 0.2 

2 280 0.8 0.3 

3 640 1.1 0.4 

4 1,100 1.5 0.5 

5 1,800 2.2 0.7 

OTHER SULFUR DIOXIDE SCENARIOS 

If you wish to do so, you can simply quote any of the results above, if they are 

applicable to your site, when you submit your Risk Management Plan. However, you 

may also choose to develop other scenarios, using Equations 11, 12, or 13, and 

Exhibit F-16 or Figure F-6. 

ANHYDROUS AMMONIA 

FLASHING LIQUID RELEASES 

Like chlorine and sulfur dioxide, ammonia will be liquefied under pressure in its own 

storage vessel. Bernoulli’s equation is applicable for flashing liquid releases (see 

Section F.3.4). The equation for ammonia liquefied under a pressure of 130 psig is: 

QR = 2,380 × Ah (14) 

where:

Ah = hole area (in2

)
Appendix F -32- WWTP 

2,380 = chemical-specific factor for ammonia liquefied under 

pressure. 

After you have estimated the release rate, you can find the predicted distance to the 

toxic endpoint for ammonia from Exhibit F-20 or Figure F-7. 

Alternatively, you can use Exhibit F-19. This exhibit gives release rates and distances 

to the endpoint for flashing liquid releases through holes of diameter 1/16 inch to 5 

inches. 

EXHIBIT F-19 

Release Rates and Distance to the Endpoint for Liquid Ammonia Releases

D Stability, Wind Speed 3 Meters per Second

Hole Diameter 

(inches) 

Release Rate 

(lb/min) 

Distance (miles) 

Rural Urban 

1/16 7 0.1 0.1 

3/16 66 0.2 0.1 

1/4 120 0.2 0.1 

5/16 180 0.4 0.2 

1/2 470 0.4 0.2 

1 1,900 0.8 0.3 

2 7,500 1.6 0.5 

3 16,800 2.2 0.7 

4 30,000 3.1 1.0 

5 46,800 3.9 1.2 
WWTP -33- Appendix F 

EXHIBIT F-20

DISTANCES TO TOXIC ENDPOINT FOR ANHYDROUS AMMONIA

D Stability, Wind Speed 3 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

<10 <0.1* 

<0.1* 

10 0.1 

15 0.1 

20 0.1 

30 0.1 

40 0.1 

50 0.1 

60 0.2 0.1 

70 0.2 0.1 

80 0.2 0.1 

90 0.2 0.1 

100 0.2 0.1 

150 0.2 0.1 

200 0.3 0.1 

250 0.3 0.1 

300 0.3 0.1 

400 0.4 0.2 

500 0.4 0.2 

600 0.5 0.2 

700 0.5 0.2 

750 0.5 0.2 

800 0.5 0.2 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

900 0.6 0.2 

1,000 0.6 0.2 

1,500 0.7 0.3 

2,000 0.8 0.3 

2,500 0.9 0.3 

3,000 1.0 0.4 

4,000 1.2 0.4 

5,000 1.3 0.5 

7,500 1.6 0.5 

10,000 1.8 0.6 

15,000 2.2 0.7 

20,000 2.5 0.8 

25,000 2.8 0.9 

30,000 3.1 1.0 

40,000 3.5 1.1 

50,000 3.9 1.2 

75,000 4.8 1.4 

100,000 5.4 1.6 

150,000 6.6 1.9 

200,000 7.6 2.1 

250,000 8.4 2.3 

* Report distance as 0.1 mile 
Appendix F -34- WWTP 

AQUEOUS AMMONIA 

Alternative scenario spills of aqueous ammonia are going to be similar to worst-case 

scenario spills in that there will be a leak of some kind and the liquid will either 

spread across a diked area or spread out until its depth is only 1 cm (0.39 inch). The 

principal difference will be in the amount spilled. 

The calculation of the rate of spillage is again performed using Bernoulli’s formula 

see Section F.3.4). The density of 30 percent aqueous ammonia is 57.33 lb/ft3, so the 

equation becomes: 

QRL = 153 × Ah × (h)0.5 (15) 

where: 

QRL = rate of spillage of ammonia solution onto the ground (lbs/min), not 

the rate of evaporation 

Ah = hole area (in2

) 

h = static head 

For example, for a 1⁄2-inch diameter opening with a static head h of 10 ft:

QRL = 153 × B × (1⁄2×1⁄2)2

 × (10)1⁄2 = 153 × 3.142 × 1/16 × 3.16 = 95 lb/min

This is the rate of spillage of the total solution of water plus ammonia as a liquid onto

the ground.

If you know, and can document, how long it will take to stop the release, you should

estimate the total quantity of solution spilled to the ground (QS) by multiplying the 

estimated rate of liquid spillage by the estimated duration of the release (in minutes). 

Then you can estimate the release rate to air (QR) as the evaporation rate of ammonia 

from the pool. For an undiked area (pool depth 1 cm): 

QR = 0.025QS (16) 

For a diked pool (pool depth greater than 1 cm) of area Ap square feet: 

QR = 0.046Ap (17) 

The maximum area of the pool that would be formed by the spilled liquid is 0.55QS. 

If you have a diked area that is larger than the maximum area, use the equation for an 

undiked area to estimate the release rate to air. 
WWTP -35- Appendix F 

It is possible that you may estimate a rate of evaporation of ammonia from the pool 

that exceeds the spill rate of the liquid solution, particularly if the liquid spill rate is 

small and the spill of the liquid may last for a fairly long time. In such a case, under 

the assumptions used in this estimation method, no pool would be formed. Instead of 

the evaporation rate, in this case, you should use the liquid spill rate (QRL) as the 

release rate to air. 

You also can determine how far the pool will spread until the rate of spillage is 

matched by the rate of evaporation of ammonia. For aqueous ammonia at 77 o

F (25 o

C), the rate of evaporation is 0.046 Ap (from Equation 17). 

The area that will cause the rate of evaporation to exactly balance the rate of spillage 

is given by: 

Ap = QR/0.046 = 22QRL (18) 

In the example given above, QRL = 95 lb/min, so Ap = 2,100 ft2

. This value should be 

compared with the available diked area and the smaller of the two values chosen. 

Thus, if the diked area happens to be 50 ft x 50 ft = 2,500 ft2

, the area chosen for 

subsequent calculation is Ap = 2,100 ft2

 and QR = 95 lb/min. (If the diked area 

happened to be smaller — say 20 ft x 20 ft = 400 ft2

 — then the spilled ammonia 

would cover the diked area, and, using Equation 17, the rate of evaporation QR 

would be (0.046)(400) = 18 lb/min.) 

To predict the distance to the toxic endpoint in typical weather conditions, take the 

value of QR calculated above and identify the closest value on Exhibit F-21. Read off 

the corresponding distance. For the 95 lb/min case, the result is 0.2 mile for a rural 

site and 0.1 mile for an urban site. Alternatively, use Figure F-8. 
Appendix F -36- WWTP 

EXHIBIT F-21

Distance to Toxic Endpoint for Aqueous Ammonia

D Stability, Wind Speed 3 Meters per Second

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

<8 <0.1* 

<0.1* 

8 0.1 

10 0.1 

15 0.1 

20 0.1 

30 0.1 

40 0.1 

50 0.2 0.1 

60 0.2 0.1 

70 0.2 0.1 

80 0.2 0.1 

90 0.2 0.1 

100 0.2 0.1 

150 0.3 0.1 

200 0.3 0.1 

250 0.4 0.2 

300 0.4 0.2 

400 0.4 0.2 

500 0.5 0.2 

600 0.6 0.2 

700 0.6 0.2 

750 0.6 0.2 

Release Rate Distance to Endpoint (miles) 

(lbs/min) Rural Urban 

800 0.7 0.2 

900 0.7 0.3 

1,000 0.8 0.3 

1,500 1.0 0.4 

2,000 1.2 0.4 

2,500 1.2 0.4 

3,000 1.5 0.5 

4,000 1.8 0.6 

5,000 2.0 0.7 

7,500 2.2 0.7 

10,000 2.5 0.8 

15,000 3.1 1.0 

20,000 3.6 1.2 

25,000 4.1 1.3 

30,000 4.4 1.4 

40,000 5.1 1.6 

50,000 5.8 1.8 

75,000 7.1 2.2 

100,000 8.2 2.5 

150,000 10 3.1 

200,000 12 3.5 

* Report distance as 0.1 mile 
WWTP -37- Appendix F 

METHANE 

Consider the case of methane released from a digester. Assuming that the full 

contents of a digester were released over a few minutes (say 10 minutes), in the 

example given in Section 4.1, the release rate would be 105 lb/min (total quantity of 

methane in the digester, 1,053 lb). The LFL for methane is 33 mg/L. Conservatively 

taking digester gas/methane as a neutrally buoyant gas (it will actually rise from the 

ground), you need to use Exhibit F-22 (for a rural site) or Exhibit F-23 (for an urban 

site) to estimate the distance to the LFL. From Exhibit F-22, the predicted distance 

for a release rate of 105 lb/min is 0.1 mile at a rural site and, from Exhibit F-23, it is 

0.1 mile at an urban site. 

It is unlikely that a BLEVE would occur. They are not known to take place in low 

pressure containment such as that of a digester. A pool fire does not need to be 

considered, because the methane is not liquefied. 

EXHIBIT F-22

Neutrally Buoyant Plume Distances to Lower Flammability Limit (LFL)

Rural Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate Distance to 

(lbs/min) Endpoint 

(miles) 

0 - 1,980 0.1 

1,980 - 7,260 0.2 

7,260 - 17,490 0.3 

17,490 - 28,380 0.4 

28,380 - 42,900 0.5 

42,900 - 56,100 0.6 

56,100 - 72,600 0.7 

72,600 - 89,100 0.8 

89,100 - 108,900 0.9 

Release Rate Distance to 

(lbs/min) Endpoint 

(miles) 

108,900 - 128,700 1.0 

128,700 - 148,500 1.1 

148,500 - 171,600 1.2 

171,600 - 191,400 1.3 

191,400 - 224,400 1.4 

224,400 - 270,600 1.6 

270,600 - 320,100 1.8 

320,100 - 363,000 2.0 

363,000 - 429,000 2.2 
Appendix F -38- WWTP 

EXHIBIT F-23

Neutrally Buoyant Plume Distances to Lower Flammability Limit (LFL)

Urban Conditions, D Stability, Wind Speed 3.0 Meters per Second

Release Rate Distance to 

(lbs/min) Endpoint 

(miles) 

0 - 4,950 0.1 

4,950 - 23,430 0.2 

23,430 - 49,500 0.3 

49,500 - 85,800 0.4 

85,800 - 132,000 0.5 

132,000 - 181,500 0.6 

181,500 - 240,900 0.7 

Release Rate 

(lbs/min) 

Distance to 

Endpoint 

(miles) 

240,900 - 303,600 0.8 

303,600 - 363,000 0.9 

363,000 - 462,000 1.0 

462,000 - 594,000 1.2 

594,000 - 858,000 1.4 

858,000 - 1,023,000 1.6 

1,023,000 - 1,254,000 1.8 

F.3.3 BUILDINGS 

In many WWTPs, chlorine and sulfur dioxide cylinders or other vessels are kept 

indoors. Unless your cylinders are delivered directly into the building (i.e., they are 

not unloaded outdoors and moved inside later), you should not consider buildings in 

your worst-case scenario, even though they are passive mitigation systems, because 

there will be some time when the vessels are outdoors. If your cylinders are delivered 

indoors or if your largest vessel is indoors, you may want to analyze the mitigating 

effects of the building when you do your worst-case analysis. You may also want to 

consider alternative scenarios that consider buildings as mitigation systems. Some 

buildings are strong, leak-tight buildings that are designed to contain the release of 

the contents of a one-ton cylinder or other vessel. Some of them contain scrubbers 

that activate upon release of chlorine or sulfur dioxide; if these scrubbers function as 

designed, they can ensure that any release to the external atmosphere would be small. 

(Scrubbers are active mitigation features that cannot be considered to work for a 

worst-case scenario.) At the other end of the spectrum, some buildings are intended 

to do no more than keep the rain off. 

MITIGATION OF RELEASES OF ANHYDROUS AMMONIA, CHLORINE, OR SULFUR DIOXIDE INTO 

BUILDINGS 

EPA’s RMP Offsite Consequence Analysis Guidance provides a simple building 

release-rate- multiplicative factor of 55 percent for toxic gases in both worst-case and 
WWTP -39- Appendix F 

alternative scenarios (i.e., the predicted rate of release is 55 percent of that for the 

same accident if it should occur outdoors). 

Example: Assume that there is a liquid chlorine release through a 5/16-inch 

opening as described in the discussion of chlorine alternative 

scenarios (see Exhibit F-12). This release takes place indoors and, 

per the discussion above, is reduced to 55 percent of the release rate 

of 240 lb/min, i.e., to 130 lb/min. From Exhibit F-11, the predicted 

distance to the toxic endpoint is 0.6 mile for a rural site and 0.2 mile 

for an urban site, compared to 0.7 mile (rural) and 0.3 mile (urban) 

for an outdoor release. 

The RMP Offsite Consequence Analysis Guidance also provides factors for toxic 

liquids of 10 percent for worst-case scenarios and 5 percent for alternative scenarios. 

These factors may be used for releases of aqueous ammonia that take place inside 

buildings. 

The following discussion provides a more sophisticated approach for considering 

effects of building mitigation for worst-case (if appropriate) and alternative scenarios 

involving release of gases and mixtures of gases and entrained liquid. Analysis of 

release scenarios inside buildings involves consideration of the structure of the 

building, liquid rain-out, and release containment issues. The procedure addressing 

these issues which is recommended for developing release rate estimates for both 

worst-case (if appropriate) and alternative scenarios is presented in Figure F-9. 

The release into the building is assumed to occur over a 10-minute period. For the 

worst-case scenario, the quantity released into the building equals the total quantity 

in the largest vessel or pipeline. For alternative scenarios, you must estimate the total 

quantity of ammonia, chlorine, or sulfur dioxide released from the equipment over a 

10-minute period. This 10-minute assumption is made to keep this guidance simple. 

Calculations of the likely rise in pressure show that, for a release distributed over 10 

minutes, building failure is unlikely to occur unless you have a very large vessel in a 

very small room. However, if the ratio of room volume to quantity in the vessel is < 

0.1 ft3

/lb for ammonia and < 0.05 ft3/lb for chlorine or sulfur dioxide, you should 

look at the possibility that the room will fail by windows blowing out or doors 

blowing open. 

If the release is indoors directed towards a door or window that is potentially open, 

the release rate to the outside is the total quantity, uniformly distributed over 10 

minutes. If the release is indoors and not directed towards a door or window, 

mitigation of the release by scrubbing, rain-out, or ventilation dilution may occur. If 

there is a scrubber, the release of material to the environment may be low. If there is 

no scrubber, the ventilation rate Nv, expressed as room volumes exchanged per hour, 

is identified, and the room volume per unit quantity of either ammonia, chlorine, or 

sulfur dioxide vapor released to the room (1) and the quantity airborne in the room 

(Qa) are calculated for either a vapor or a vapor/liquid release. 
Appendix F -40- WWTP 

For vapor releases, the amount of vapor released into the room is clearly Q, so 1 = 

V/Q. For a flashing liquid release, 20 percent of the release typically flashes to vapor, 

so 1 = V/(0.2Q). The quantity airborne in the room is the total quantity released 

from the equipment to the room in 10 minutes for vapor releases and fourteenths of 

the total quantity released from the equipment to the room in 10 minutes for 

vapor/liquid releases. The basis for this four-tenths assumption is that, in a room, a 

flashing liquid jet will encounter obstacles that will cause 60 percent of the release to 

collect as a relatively slowly evaporating pool on the ground. The release over the 

initial ten minutes leads to predictions of higher concentrations downwind than does 

the slowly evaporating pool; therefore, you can consider only the release rate of the 

airborne material (0.4Q/10) and ignore the evaporating pool in estimating the 

distance to the toxic endpoint. 

Given the values of Nv and 1, the building mitigation factor (FR10) is identified for 

10-minute releases of ammonia in Exhibit F-24, and for 10-minute releases of either 

chlorine or sulfur dioxide in Exhibit F-25, respectively. The release rate to the 

environment is the total quantity airborne in the room, reduced by the building 

mitigation factor, distributed uniformly over 10 minutes. 

Example: A 25-ton (50,000 lb) chlorine storage vessel is in a room of dimensions 40 

feet x 40 feet x 30 feet = 48,000 ft3

. There is a worst-case release, so that the 50,000 

lb is released into the building over a period of 10 minutes. The release is not 

adjacent to a potentially open door or window. Because it is a worst-case scenario, 

the scrubber (if there is one) is not operating. The ventilation rate Nv = 4. The release 

is a mixture of vapor and liquid droplets, so that 1 = V/(0.2Q) = 48,000/10,000 = 4.8 

ft3

/lb, and the airborne quantity Qa = 0.4Q = 20,000 lb. From Exhibit F-24, with Nv = 

4 and 1 = 4.8 (the closest entries on Exhibit F-25 are Nv = 5 and 1 = 4.0), FR10 = 

0.46. 

Therefore, the predicted worst-case scenario release rate from the building is:

 0.46×((0.4×50,000)/10) = 920 lb/min 

Compare this value with 5,000 lb/min from an open-air release. From Exhibit F-4, 

the predicted distance for a 920 lb/min release at a rural site is 6.3 miles and, at an 

urban site, is 2.9 miles. By comparison, the 5,000 lb/min release would lead to 

corresponding distances of 15 miles and 7 miles, respectively. 

Example: Take a chlorine alternative scenario for a flashing liquid release through a 

1/4-inch hole (see Section F.3.2). Exhibit F-13 shows a release rate of 150 lbs/min 

for this release. Assume this release takes place in a building with no scrubber for 10 

minutes at a release rate of 150 lb/min for a total release of 1,500 lb. Assume that the 

building has dimensions of 50 feet x 25 feet x 20 feet = 25,000 ft3

. The release is a 

flashing liquid and, therefore, consists of a mixture of vapor and liquid. Qa, the 

quantity that becomes airborne, is (0.4)(1,500) = 600 lb. The quantity of vapor is 

(0.2)(1,500) = 300 lb. Then 1 = 25,000/300 = 83 . 80. You will have to determine 

Nv from the characteristics of your building. For this example, assume that the 
WWTP -41- Appendix F 

building is being ventilated with Nv = 5. From Exhibit F-25, FR10 = 0.32, so that the 

rate of release to the external atmosphere is (0.1)(0.32)(600) = 19 lb/min. From 

Exhibit F-11, the predicted distance to the endpoint is 0.2 mile for a rural site and 0.1 

mile for an urban site. For the original release rate of 150 lb/min, the distances to the 

endpoint are 0.6 mile for a rural site and 0.2 mile for an urban site. 
Appendix F -42- WWTP 

EXHIBIT F-24

TEN-MINUTE BUILDING RELEASE ATTENUATION FACTORS FOR PROLONGED

RELEASES OF ANHYDROUS AMMONIA

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

150.0 0 0.07 

1 0.08 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

100.0 0 0.11 

1 0.11 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

50.0 0 0.20 

1 0.20 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

25.0 0 0.35 

1 0.35 

5 0.35 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

10.0 0 0.61 

1 0.61 

5 0.61 

10 0.61 

20 0.71 

30 0.80 

40 0.85 

5.0 0 0.79 

1 0.79 

5 0.79 

10 0.79 

20 0.79 

30 0.80 

40 0.85 

1.0 0 0.96 

1 0.96 

5 0.96 

10 0.96 

20 0.96 

30 0.96 

40 0.96 

0.5 0 0.98 

1 0.98 

5 0.98 

10 0.98 

20 0.98 

30 0.98 

40 0.98 
WWTP -43- Appendix F 

EXHIBIT F-25

TEN-MINUTE BUILDING RELEASE ATTENUATION FACTORS FOR PROLONGED

RELEASES OF CHLORINE AND SULFUR DIOXIDE

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

160.0 0 0.02 

1 0.08 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

80.0 0 0.03 

1 0.08 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

32.0 0 0.08 

1 0.08 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

16.0 0 0.15 

1 0.15 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

1 

(ft3/lb) 

Nv 

(hr-1) 

FR10 

(dim) 

8.0 0 0.28 

1 0.28 

5 0.32 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

4.0 0 0.46 

1 0.46 

5 0.46 

10 0.51 

20 0.71 

30 0.80 

40 0.85 

0.8 0 0.85 

1 0.86 

5 0.86 

10 0.86 

20 0.86 

30 0.86 

40 0.86 

0.32 0 0.94 

1 0.94 

5 0.94 

10 0.94 

20 0.94 

30 0.94 

40 0.94 
Figure F-1 

Worst-Case Scenario – Estimated Distances to Toxic Endpoint for Chlorine

Atmospheric Stability Class F with Wind Speed 1.5 m/s
Figure F-2

Worst-Case Scenario – Estimated Distances to Toxic Endpoint for Sulfur Dioxide

Atmospheric Stability Class F with Wind Speed 1.5 m/s
Figure F-3

Worst-Case Scenario – Estimated Distances to Toxic Endpoint for Anhydrous Ammonia 

Atmospheric Stability Class F with Wind Speed 1.5 m/s
Figure F-4

Worst-Case Scenario – Estimated Distances to Toxic Endpoint for Aqueous Ammonia

Atmospheric Stability Class F with Wind Speed 1.5 m/s
Figure F-5

Alternative Release Scenario – Estimated Distances to Toxic Endpoint for Chlorine

Atmospheric Stability Class D with Wind Speed 3 m/s
Figure F-6

Alternative Release Scenario – Estimated Distances to Toxic Endpoint for Sulfur Dioxide

Atmospheric Stability Class D with Wind Speed 3 m/s
Figure F-7

Alternative Release Scenario – Estimated Distances to Toxic Endpoint for Anhydrous Ammon

Atmospheric Stability Class D with Wind Speed 3 m/s
Figure F-8

Alternative Release Scenario – Estimated Distances to Toxic Endpoint for Aqueous Ammonia

Atmospheric Stability Class D with Wind Speed 3 m/s
Figure F-9 

Guidance on Effectiveness of Building Enclosures for Alternative Release Scenarios 

Indoors 

or 

Outside? 

Calculate Release Rate QR (lb/min) 

Adjacent 

to Door or 

Window? 

Indoors 

Outside 

Yes 

Airborne Mass M = 0.4Q 

Calculate θ = V/(0.2Q) 

Choose NV (hr-1) 

Identify FR10 (Exhibit 

F-24 or F-25) 

Re0.1

lb/

No 

Release 

Entirely 

Vapor? 

Yes 

No 

Calculate θ = V/Q 

Airborne Mass M = Q 

Scrubber? Yes 

No 

Release Rate = QR lb/min 

Release Rate = QR lb/min 

Minimal Release to Environment 
WWTP -53- Appendix F 

F.3.4 Equations 

AMMONIA PARTIAL PRESSURE 

The ratio Rvp(T) of the partial pressure of ammonia at temperature T oC to the partial 

pressure at 25 o

C is given by the empirical formula: 

Rvp(T) = exp[10.438 - 717.4/(T + 273.4) - 2132.5/(T + 240.25)] 

DENSITY OF METHANE IN DIGESTER 

Dm = (X/100)(0.0409)(537/(460+T)) = 0.22 X/(460+T) 

where 0.0409 lb/ft3

 is the density of pure methane at 77 oF (25 oC) and the factor 

537/(460+T) represents how the density changes with temperature, assuming that 

methane obeys the perfect gas law. The effect of the small operating pressure in 

compressing the gas has been ignored. 

ALTERNATIVE RELEASE EQUATIONS

BERNOULLI’S FORMULA

The rate of release of a liquid through an hole is given by Bernoulli’s formula for 

predicting the rate of release QR (lb/min) of liquid from a vessel: 

m = Ah Cd(DL[2g DL(HL - Hh) + 2(P0 - Pa)])

2 

where: 

m = Discharge rate (kilograms per second) 

Ah = Opening area (square meters) 

Cd = Discharge coefficient (unitless) 

g = Gravitational constant (9.8 meters per second squared) 

DL= Liquid density (kilograms per cubic meter) 

P0 = Storage pressure (Pascals) 

Pa = Ambient pressure (Pascals) 

HL = Liquid height above bottom of container (meters) 

Hh = Height of opening (meters) 
Appendix F -54- WWTP 

To create the equations in the text, this equation was converted to English units. 

GASES LIQUEFIED UNDER PRESSURE 

For gases liquefied under high pressure, the term containing the liquid height in 

Bernoulli’s formula can be neglected. The equation for the release rate for gases 

liquefied under pressure becomes: 

QR = 32.07×Ah×DL×(Pg /DL)

0.5 

To derive the chemical specific factors presented in the text for gases liquefied under 

their vapor pressure at 25 o

C, the following data were substituted into the equation: 

Liquefied Gas Liquid Density (DL), lbs/ft3 Tank Vapor Pressure (Pg), psig 

Chlorine 97.5 98.5 

Sulfur dioxide 91.3 43.3 

Ammonia 42.5 130 

LIQUID AT AMBIENT PRESSURE 

For liquids stored at ambient pressure, the difference between storage pressure and 

ambient pressure is zero, and the pressure term drops out of the equation above. The 

equation can be rewritten and converted to English units as follows: 

QR = 132.2×Ah×6.4516×10-4×(h)0.5×0.5521×0.8×(2×9.8)0.5×DL×16.018 

where: 

QR = Release rate (pounds per minute) 

132.2 = Conversion factor for kilograms per second to pounds per minute

Ah = Hole area (square inches)

6.4516 x 10-4 = Conversion factor for square inches to square meters (HA)

0.5521= Conversion factor for square root of feet to square root of meters (h)

0.8 = Discharge coefficient (0.8) 

9.8 = Gravitational constant (meters per second squared) 

DL = Liquid density (pounds per cubic foot) 
WWTP -55- Appendix F 

16.018 = Conversion factor for pounds per cubic foot to kilograms per cubic meter 

For ammonia solutions, the factor presented in the text was derived assuming a 

density of 57.33 lb/ft3

. 

TWO-PHASE RELEASE 

For long pipes (L/dh >> 1, where L is the length of the pipe between the reservoir of 

chlorine and the atmosphere and dh is the pipe diameter), there can be flashing in the 

discharge pipe, and a two-phase mixture emerges to the atmosphere. In this case, the 

rate of release in lb/min is given by: 

QR = 9,490(Ah)(F)(hL)/[vlg([T + 460]Cpl)

1⁄2] 

where those symbols not already defined are: 

F a frictional loss factor, which is dimensionless and takes on a value of 1 for 

L/dh = 10, 0.85 for L/dh = 50, 0.75 for L/dh = 100, 0.65 for L/dh = 200, and 

0.55 for L/dh = 400

hL the latent heat of vaporization (Btu/lb)

vlg the difference in specific volume between the gas and liquid (lb/ft3

)

T the reservoir temperature (o

F), and

Cpl the liquid heat capacity (Btu/lb/o

F)

For chlorine, hL is 124 Btu/lb, vlg = 0.68 lb/ft3

, T = 77 oF (25 oC), and Cpl = 0.222 

Btu/lb/o

F 

For sulfur dioxide, vlg = 1.55 ft3

/lb, hL = 80 Btu/lb, Cpl = 0.34 Btu/lb/oF 

VAPOR RELEASES 

For a gas release under choked flow conditions (i.e., emerging at the speed of sound 

from the hole, the maximum flow rate), the following equation can be used to 

estimate the release rate: 

m = Cd Ah((p0 D0[2/((+1)]((+1)/((-1))

0.5 

where: 

m = Discharge rate (kg/s)

Cd = Discharge coefficient
Appendix F -56- WWTP 

Ah = Opening area (m2) 

( = Ratio of specific heats 

p0 = Tank pressure (Pascals) 

D0 = Density (kg/m3) 

Density (D0) can be rewritten as a function of pressure and molecular weight, based 

on the ideal gas law: 

D0 = (p0×MW)/R Tt 

where: 

MW = Molecular weight (kilograms per kilomole) 

R = Gas constant (8,314 Joules per degree-kilomole) 

Tt

 = Tank temperature (K) 

The choked flow equation can be rewritten and converted to English units as follows: 

QR = 132.2×Ah×6.4516×10-4×Pa×6895 × 

0.8(([2/((+1)]((+1)/((-1))

0.5×(MW/8314×Tt

)

0.5 

where: 

0.8 = Discharge coefficient 

132.2 = Conversion factor for lbs/min to kg/s

6,895 = Conversion factor for psi to Pascals (p0)

6.4516 x 10-4 = Conversion factor for square inches to square meters (Ah)

Pa = Absolute pressure in the reservoir/tank (psia)

Ah = Hole area (inches)

To derive the chemical-specific factors for gas releases presented in the text, the 

temperature (Tt

) was assumed to be 298 K, and the following chemical-specific data 

were substituted into the choked flow equation: 
WWTP -57­ Appendix F 

Gas Molecular Wt (MW) Tank Press. (Pa) (psia) Ratio of Specific Heats (() 

Chlorine 70.91 113 1.32 

Sulfur dioxide 64.07 58 1.26 

LOG-LOG TABLE EQUATIONS 

This section presents formulas for estimating the distance to the endpoint from the 

rate of release for each of the toxic substances addressed in this appendix. The 

formulas are given in the form: 

D = a (QR)b 

where: 

D = distance to the endpoint (miles) 

a and b = chemical-specific factors 

QR = release rate (lbs/min) 

The formulas for each chemical were developed based on the best straight-line fits to 

the log-log graphs of release rate versus distance (Figures F-1 to F-8). The formulas 

are easy to use with a scientific calculator and may be used instead of the distance 

tables or figures. Since the equations are best fits to the curves on Figures F-1 to F-8, 

they may not give exactly the same predictions as appear in the corresponding 

exhibits. 

CHLORINE 

WORST CASE 

The guidance on Figure F-1 is essentially in the form of a straight line on a log-log 

plot: 

D = 0.2273(QR)0.4879 for a rural site, and 

D = 0.0878(QR)0.5134 for an urban site 

ALTERNATIVE 

Figure F-5 is roughly a straight line on a log-log plot: 

D = 0.053(QR)0.4647 for a rural site, and 

D = 0.026(QR)0.4263 for an urban site. 
Appendix F -58- WWTP 

SULFUR DIOXIDE 

WORST CASE 

The guidance on Figure F-2 is essentially in the form of a straight line on a log-log 

plot: 

D = 0.165(QR)0.5562 for a rural site, and 

D = 0.0726(QR)0.5419 for an urban site. 

ALTERNATIVE 

The curves on Figure F-6 are approximately straight lines on a log-log plot: 

D = 0.047(QR)0.4961 for a rural site, and 

D = 0.025(QR)0.4407 for an urban site. 

ANHYDROUS AMMONIA 

WORST CASE 

The guidance on Figure F-3 is essentially in the form of a straight line on a log-log 

plot: 

D = 0.0607(QR)0.4923 for a rural site, and 

D = 0.0443(QR)0.4782 for an urban site. 

ALTERNATIVE 

The curves on Figure F-7 are approximately straight lines on a log-log plot: 

D = 0.0222(QR)0.4780 at a rural site, and 

D = 0.0130(QR)0.4164 at an urban site. 

AQUEOUS AMMONIA 

WORST CASE 

The guidance on Figure F-4 is essentially in the form of a straight line on a log-log 

plot: 

D = 0.0667(QR)0.4617 for a rural site, and 

D = 0.0221(QR)0.4712 for an urban site. 
WWTP -59- Appendix F 

ALTERNATIVE 

The curves on Figure F-8 are roughly straight lines on a log-log plot: 

D = 0.02(QR)0.5174 for a rural site, and 

D = 0.0107(QR)0.4748 for an urban site. 

F.3.5 Limitations of Results 

The guidance in this appendix is summarized in the form of various tables and plots 

giving the predicted distance to the toxic endpoint as a function of the rate of release. 

There are upper and lower limits on the validity of these tables and plots—the models 

used are not valid beyond 25 miles, nor at less than 0.06 mile (100 m ~ 300 feet). It 

should be noted that the guidance presented in this chapter in the form of plots and 

tables yield estimates that are among many possible. There is, in fact, a wide range of 

uncertainty, partly due to the still incomplete theoretical understanding of the 

atmospheric dispersion of large-scale accidental releases of hazardous vapors in the 

industrial environment, partly due to the need to specify the values of a number of 

parameters, the values of which may not be well known, and partly because there are 

relatively few large-scale experimental data sets with which to “tune” the models, 

especially for the conditions applicable to the worst-case scenario. Therefore, for any 

given rate of release of a specific material, such as chlorine, there may be a wide 

variety of predictions by analysts using different models, or using the same model 

with different input parameters. The potential range of uncertainty is addressed in the 

Technical Background Document for Offsite Consequence Analysis for Anhydrous 

Ammonia, Aqueous Ammonia, Chlorine and Sulfur Dioxide. 

An attempt has been made to develop guidance in the mid-range of possibilities, with 

the hope that the most extreme conservatisms have been removed, but which is still 

modestly conservative. As a general (and much simplified) rule, you should not be 

surprised if, for worst-case scenarios, other analysts and models produce estimates 

that may be up to a factor of three higher or a factor of three lower than those 

presented here. 

The estimates in the distance tables in the exhibits and all other estimates in this 

appendix for regulated toxic chemicals are based upon the methods described in the 

Technical Background Document. That method consisted of performing a range of 

sensitivity studies and then choosing guidance that lies within that range. 

There are a number of caveats of which you should be aware. 

The results given in the exhibits and figures are not in any absolute sense the “right” 

or “correct” ones. On the contrary, the Technical Background Document contains 

estimates from many sources. The intention there is to establish a range of 

uncertainties that might be regarded as reasonable by practitioners in the field of 

atmospheric dispersion modeling, and then to locate a reasonable guidance curve 
Appendix F -60- WWTP 

(such as Figure F-1) within that range of uncertainty. In this way, it is hoped that the 

following objectives will be achieved: 

— The facts that the results are uncertain and that there is no uniquely “right” 

result are not disguised. 

— Nevertheless, there is a reasonable solution that is easy to use, and users of 

this guidance do not have to understand its derivation. 

As noted above, the further downwind, the more likely it is that you are beyond the 

range of applicability of any atmospheric dispersion model. That is why, for the 90­

ton railcar release of chlorine, the result is stated as “> 25 miles.” For such a large 

release of chlorine, few models will estimate less than this distance, and some will 

estimate considerably more. There is no way to avoid the conclusion that the distance 

to the toxic endpoint for a worst-case release from a 90-ton chlorine railcar is very 

large, even though the current state of the models does not allow us to say exactly 

how far “large” is. Note that the discussion in this paragraph applies to railcars that 

are in the open air. 

For the 150-lb and one-ton cylinder cases, the results are uncertain to within perhaps 

a factor of 5-10. The Technical Background Document shows that, under certain 

modeling assumptions, the distances could be perhaps a factor of three larger than 

those stated above or a factor of three smaller. You will also almost certainly be able 

to find a computer model that can be run to produce even smaller estimated distances. 

If you opt to do that, you will have to produce justification that the modeling is 

reasonable if you are audited by an implementing agency. [Note, however, that you 

are not obliged to use the guidance presented here; you can use whatever model you 

want provided that you have a solid scientific basis for doing so]. The fact that these 

large uncertainties exist explains why it is so difficult to develop a single guidance 

curve that everyone accepts. Many different choices for the guidance could fit 

comfortably within the range of uncertainties. 
WWTP -61- Appendix F 

F.4 Supplemental Accident Prevention Program Information 

This section provides additional information specific to WWTPs on implementation 

of selected prevention program elements, to supplement the information provided in 

the main document. 

F.4.1 Safety Information 

MAXIMUM INVENTORY 

You must document the maximum intended inventory of any vessel in which you 

store or process a regulated substance above its threshold quantity. The U1A 

certificates on all vessels constructed under the ASME Boiler and Pressure Vessel 

Code are kept on file by the National Board. The nominal nameplate capacity can 

also be found on the permanently attached nameplate for your storage tank. The 

nameplate will also have the National Board Number for your vessel, which is the 

key to retrieving your U1A form from the Board. These nameplates may be located 

on one of the hemispherical heads, the manway, or the manway cover. The nominal 

capacity will usually be the water capacity, and you may want to convert it to 

pounds. 

If you use transportation containers (railcars or tank trucks) as storage vessels, you 

can obtain the capacity from the required DOT nameplate, identification plate, or 

specification plate or from the owner of the containers. Smaller shipping containers 

are also marked. If you are not sure of the capacity of the vessel, you can obtain this 

information from the manufacturer of the vessel or tank. 

The Chlorine Institute recommends that chlorine tanks not be filled beyond 95 

percent at a maximum temperature of 122 degrees F. OSHA regulations limit liquid 

volumes of unrefrigerated anhydrous ammonia to the following: 

Type of Container Percent by Weight Percent by Volume 

Aboveground - Uninsulated 56% 82% 

Aboveground - Uninsulated* 87.5% 

Aboveground - Insulated 57% 83.5% 

Underground - Uninsulated 58% 85% 

*Aboveground uninsulated containers may be charged to 87.5 percent by volume if 

the temperature of the anhydrous ammonia being charged is determined to be not 

lower than 30 degrees F or if the charging container is stopped at the first indication 

of frost or ice formation on its outside surface and is not resumed until such frost or 

ice has disappeared. (29 CFR 1910.111(b)(11)) 
Appendix F -62- WWTP 

Aqueous ammonia may be held in various concentrations; your supplier can provide 

the density and weight. You can use this information, with your tank capacity, to 

estimate the quantity of ammonia being stored. 

The Compressed Gas Association provides the following recommendations for filling 

sulfur dioxide tanks at varying temperatures (CGA pamphlet G-3): 

Temperature of Liquid SO2 in Tank o

F Maximum Safe Volume Liquid SO2 in % of Full 

Volume at 125% Filling Density 

30 86 

40 87 

50 88 

60 89 

70 90 

80 91 

90 92 

100 93 

F.4.2 Hazard Review 

Some sample checklists for chemicals at wastewater treatment facilities are provided 

in section F.5 of this appendix, including: 

— Exhibit F-26 General Conditions, Operation and Maintenance 

— Exhibit F-27 Human Factors 

— Exhibit F-28 Checklists for Chlorine and Sulfur Dioxide 

— Exhibit F-29 Checklist for Anhydrous Ammonia Systems 

— Exhibit F-30 Checklist for Aqueous Ammonia Systems 

The examples of What-If questions in Exhibits F-31 through F-35 are derived from a 

variety of sources, including: 

— “Guidelines for Hazard Evaluation Procedures - Second Edition with Worked 

Examples,” published by the Center for Chemical Process Safety (CCPS), 

New York, 1992 
WWTP -63- Appendix F 

— Information collected from various wastewater treatment facilities during the 

development of this guidance. 

— Information from industry associations such as the Chlorine Institute, the 

International Institute of Ammonia Refrigeration (IIAR), and the American 

Water Works Association (AWWA). 

F.4.3 Additional References 

The Chlorine Institute (http://www.cl2.com) publishes information on safe use and 

handling of chlorine, including: 

— Chlorine Vaporizing Systems (Pamphlet # 9). 

— Cylinder and Ton Container Procedures for Chlorine Packaging (Pamphlet # 

17). 

— Maintenance Instructions for Chlorine Institute Standard Safety Valves, Type 

1-1/2 JQ (# 39). 

— Maintenance Instructions for Chlorine Institute Standard Angle Valve (#40). 

— Maintenance Instructions for Chlorine Institute Standard Safety Valve, Type 

4JQ (#41). 

— Maintenance Instructions for Chlorine Institute Standard Excess Flow Valves 

(#42). 

— Water and Wastewater Operators Chlorine Handbook (# 155). 

The Compressed Gas Association publishes information on safe use and handling of 

compressed gases, including: 

— Anhydrous Ammonia on properties, storage, handling, and use of anhydrous 

ammonia (Publication ID # G-2). 

— ANSI K61.1, American National Standard Safety Requirements for the 

Storage and Handling of Anhydrous Ammonia (Publication ID # G-2.1). 

— Sulfur Dioxide on properties, storage, handling, and use of sulfur dioxide 

(Publication ID # G-3). 

The Water Environment Federation provides several training programs on 

wastewater treatment operation and maintenance (the programs also include general 

procedures) including the following: 
Appendix F -64- WWTP 

— Basic Course for Wastewater Treatment Plant Operators, Instructor Set 

Order No. E0100GB, Student Workbook Order No. E0110GB. 

— Intermediate Course for Wastewater Treatment Plant Operators, Instructor 

Set Order No. E0295GB, Student Workbook Order No. E0296GB. 

— Chlorination Skill Training Course, Order No. E0312GB. Self Instruction 

Course. 

The Water Environment Federation also publishes: 

— Operation and Maintenance of Municipal Wastewater Treatment Plants 

(MOP-11). 

The Water Environment Federation is located at 601 Wythe Street, Alexandria, VA

22134, and can be contacted at (800) 666-0206 or (703) 684-2452.

In addition, the following may be useful:

— NFPA-820, Standard for Fire Protection in Wastewater Treatment and 

Collection Facilities. 
WWTP -65- Appendix F 

F.5 Hazard Review Checklists, What If Questions, and HAZOP Procedures 

Exhibit F-26

General Conditions, Operation and Maintenance

(For any WWTP)

General Conditions, Operation and Maintenance Yes/No/NA Comments 

Are work areas clean? 

Are adequate warning signs posted? 

Is ambient temperature normally comfortable 

Is lighting sufficient for all operations? 

Are the right tools provided and used? 

Is personal protective equipment (PPE) provided and adequate? 

Are containers and tanks protected from vehicular traffic? 

Are all flammable and combustible materials kept away from 

containers, tanks, and feed lines? 

Are containers, tanks, and feed line areas kept free of any objects 

that can fall on them (e.g., ladders, shelves?) 

Are leak detectors with local and remote audible and visible 

alarms present, operable, and tested? 

Are windsocks provided in a visible location? 

Are emergency repair kits available for each type of supply 

present? 

Are appropriate emergency supplies and equipment present, 

including PPE and self-contained breathing apparatus (SCBA)? 

Are emergency numbers posted in an appropriate spot? 

Are equipment, containers, and railcars inspected daily? 

Are written operating procedures available to the operators? 

Are preventative maintenance, inspections, and testing performed 

as recommended by the manufacturer and industry groups and 

documented? 
Appendix F -66- WWTP 

Exhibit F-27 

Human Factors 

(General) 

Human Factors Yes/No/NA Comments 

Have operators been trained on the written operating procedures 

and the use of PPE in normal operations (or for operators on the 

job before June 21, 1999, have you certified that they have the 

required knowledge, skills, and ability to do their duties safely)? 

Do the operators follow the written operating procedures? 

Do the operators understand the applicable operating limits on 

temperature, pressure, flow, and level? 

Do the operators understand the consequences of deviations 

above or below applicable operating limits? 

Have operators been trained on the correct response to alarms 

and conditions that exceed the operating limits of the system? 

Are operators provided with enough information to diagnose 

alarms? 

Are controls accessible and easily understood? 

Are labels adequate on instruments and controls? 

Are all major components, valves, and piping clearly and 

unambiguously labeled? 

Are all components mentioned in the procedures adequately 

labeled? 

Are safe work practices, such as lockout/tagout, hot work, and 

line opening procedures followed? 

Are personnel trained in the emergency response plan and the use 

of emergency kits, PPE, and SCBAs? 

Are contractors used at the facility? 

Are contractors trained to work as safely as your own 

employees? 

Do you have programs to monitor that contractors are working 

safely? 
WWTP -67- Appendix F 

Exhibit F-28

Checklists for Chlorine and Sulfur Dioxide

Chlorine and Sulfur Dioxide - Siting Yes/No/NA Comments 

Are storage, use, and transfer areas not located uphill from 

adjacent operations? 

Are storage, use, and transfer areas located away from sewer 

openings and other underground structures? 

Do storage, use, and transfer areas have easy access for 

emergency response? 

Are storage, use, and transfer areas free of combustible or 

incompatible materials and isolated from hydrocarbons in 

accordance with NFPA Standard No. 49, Hazardous Chemicals 

Data? 

Are storage, use and transfer areas downwind of or separated from 

most operations and support areas and ventilation intakes based on 

prevailing wind direction? 

Are storage, use, and transfer areas isolated from sources of 

corrosion, fire, and explosion and protected from vehicle impact? 

Are storage, use, and transfer areas located away from residences 

and facility boundaries? 

If cylinders are stored outside, are they protected from impact by 

vehicular traffic? 

Chlorine and Sulfur Dioxide - Hazard Recognition Yes/No/NA Comments 

Are material safety data sheets (MSDSs) readily available to those 

operating and maintaining the system? 

Do employees understand that there are certain materials with 

which Cl2 (SO2) must not be mixed? 

Do employees understand the toxicity, mobility, and ability of Cl2 

(SO2) to sustain combustion? 

Do employees understand the consequences of confining liquid 

Cl2 (SO2) without a thermal expansion device? 

Do employees understand the effect of moisture on the corrosive 

potential of Cl2 (SO2)? 
Appendix F -68- WWTP 

Do employees understand the effects of fire and elevated 

temperature on the pressure of confined chlorine (SO2) and the 

potential for release? 

Chlorine and Sulfur Dioxide - Container Shipment Unloading Yes/No/NA Comments 

Is the truck inspected for wheel chocks, proper position, and 

condition of crane? 

Are adequate warning signs posted? Are there “stops”? 

Is the shipment inspected for leakage, general condition, currency 

of hydrostatic test, and valve protective housing before accepting? 

Are containers placed in the 6 o’clock/12 o’clock position for 

storage to reduce the chance of a liquid leak through the valve? 

Chlorine and Sulfur Dioxide - Bulk Shipment Unloading Yes/No/NA Comments 

Do procedures call for hand brakes to be set and wheels chocked 

before unloading? 

Do procedures call for safety systems to be inspected prior to 

making connections for unloading or between storage tanks and 

transfer or distribution systems? 

For railcars, are derails to protect the open end located at least 50 

feet from the car being protected? 

Are railcars staged at dead-end tracks and guarded against damage 

from other railcars and motor vehicles? 

Are caution signs placed at each derail and as appropriate in the 

vicinity of Cl2 (SO2) storage, use, and transfer areas? 

Does the transfer operation incorporate an emergency shutoff 

system? 

Is a suitable operating platform provided at the transfer station for 

easy access and rapid escape? 

Is padding air for railcars from a dedicated, flow-limited, dry (to ­

40 EF or below), and oil-free source? 

Is tank car attended as long as the car is connected, in accordance 

with DOT regulations? 

Building and Housing Cl2 (SO2) Systems Yes/No/NA Comments 

Does the building conform with local building and fire codes and 

NFPA-820? 
WWTP -69- Appendix F 

Is the building constructed of non-combustible materials? 

Is continuous leak detection, using area Cl2 (SO2) monitors, 

provided in storage and process areas? 

If flammable materials are stored or used in the same building, are 

they separated from the Cl2 (SO2) areas by a fire wall? 

Are two or more exits provided from each Cl2 (SO2) storage and 

process area and building? 

Is the ventilation system appropriately designed for indoor 

operations (and scrubbing, if required) by local codes in effect at 

the time of construction or major modification? 

Are the exhaust ducts near floor level and the intake elevated? 

Can the exhaust fan be remotely started and stopped? 

If Cl2 and SO2 are stored in the same building, are storage rooms 

separated as required? 

Chlorine and Sulfur Dioxide - Piping and Appurtenances Yes/No/NA Comments 

Do piping specifications meet Cl2 (SO2) requirements for the 

service? 

Do you require suppliers to provide documentation that all piping 

and appurtenances are certified “for chlorine service” or “for 

sulfur dioxide service” by the manufacturer? 

Are piping systems properly supported, adequately sloped to 

allow drainage, and with a minimum of low spots? 

Is all piping protected from all risks of excessive fire or heat? 

Is an appropriate liquid expansion device or vapor pressure relief 

provided on every line segment or device that can be isolated? 

Chlorine and Sulfur Dioxide - Design Stage Review of 

New/Modified Process 

Yes/No/NA Comments 

Is the system designed to operate at lowest practical temperatures 

and pressures? 

If Cl2 (SO2) demand is low enough, is the system designed to feed 

gaseous chlorine (SO2) from the storage container, rather than 

liquid? 

Have the lengths of liquid Cl2 (SO2) lines been minimized (reduces 

quantity of chlorine in lines available for release)? 
Appendix F -70- WWTP 

Are low-pressure alarms and automatic shutoff valves provided on 

Cl2 (SO2) feed lines? 

Are vent-controlled spill collection sumps provided and floors 

sloped toward sumps for stationary tanks and railcars? 

Are vaporizers provided with automatic gas line shutoff valve, 

downstream pressure reducing valve, gas flow control valve, 

temperature control system and interlocks to shut down gas flow 

on low vaporizer temperature, and appropriate alarms in a 

continuously manned control room? 

Do vaporizers have a limited heat input capacity? 

Are curbs, sumps, and diking that minimize the surface of 

potential spills provided for stationary tanks and railcars? 
WWTP -71- Appendix F 

Exhibit F-29

Checklist for Anhydrous Ammonia Systems

Anhydrous Ammonia - Basic Rules Yes/No/NA Comments 

Does the storage tank have a permanently attached nameplate? 

Are container(s) at least 50 feet from wells or other sources of 

potable water supply? 

Are container(s) painted white or other light reflecting colors and 

maintained in good condition? 

Is the area free of readily ignitable materials? 

Are all main operating valves on tanks identified to show liquid or 

vapor service? 

Anhydrous Ammonia - Appurtenances Yes/No/NA Comments 

Are all appurtenances designed for maximum working pressure 

and suitable for ammonia service? 

Do all connections to containers have shut-off valves as close to 

container as practicable (except safety relief devices and gauging 

devices)? 

Are the excess flow and/or back pressure check valves located 

inside of the container or at a point outside as close as practicable 

to where line enters container? 

Are excess flow valves plainly and permanently marked with 

name of manufacturer, catalog number, and rated capacity? 

Anhydrous Ammonia - Piping Yes/No/NA Comments 

Are piping and tubing suitable for ammonia service? 

Are provisions made for expansion, contraction, jarring, vibration 

and settling? 

Is all exposed piping protected from physical damage from 

vehicles and other undue strain (2,000 lb. pull)? 

Anhydrous Ammonia - Hoses Yes/No/NA Comments 

Does the hose conform to TFI-RMA specifications for anhydrous 

ammonia? 

Is it 350 psig working, 1750 psig - burst? 
Appendix F -72- WWTP 

Is it marked every 5 feet with “Anhydrous Ammonia, xxx psig 

(maximum working pressure), manufacturer’s name or trademark, 

year of manufacture? 

Anhydrous Ammonia - Safety Relief Devices Yes/No/NA Comments 

Are safety relief valves installed? 

Are they vented upward and unobstructed to the atmosphere? 

Do they have a Rain/Dust Cap? 

Are shut-off valves not installed between safety relief valve and 

container? 

Are safety relief valves marked with “NH3" or “AA”, psig valve 

is set to start-to-discharge, CFM flow at full open, manufacturer’s 

name, and catalog number? 

Is flow capacity restricted on upstream or downstream side? 

Are hydrostatic relief valve installed between each pair of valves 

in liquid piping or hose? 

Anhydrous Ammonia - Safety Yes/No/NA Comments 

Are there two suitable full face masks with ammonia canisters as 

approved by the Bureau of Mines? Are self-contained breathing 

air apparatus required in concentrated atmospheres? 

Is an easily accessible shower or a 50 gallon drum of water 

available? 

Anhydrous Ammonia - Transfer of Liquid Yes/No/NA Comments 

Are pump(s) designed for ammonia service and at least 250 psig 

working pressure? 

Does P.D. pump have relief valve installed? 

Is a 0-400 psi pressure gauge installed on pump discharge? 

Are loading/unloading lines fitted with back flow check or excess 

flow valves? 

Are caution sign(s) posted when rail car(s) are loading/unloading? 

Are containers equipped with an approved liquid level gauging 

device (except those filed by weight)? 

Are containers fitted with a fixed tube liquid level gauge at 85% 

of water capacity? 
WWTP -73- Appendix F 

Anhydrous Ammonia - Stationary Tank Yes/No/NA Comments 

Are non-refrigerated container(s) designed for a minimum 250 

(265 in CA) psig pressure? 

Are all liquid and vapor connections to container(s) except safety 

relief valves, liquid gauging and pressure gauge connections fitted 

with orifices not larger than No. 54 drill size equipped with 

excess-flow valves? 

Are storage containers fitted with a 0-400 psi ammonia gauge? 

Are they equipped with vapor return valves(s)? 

Are containers marked on at least two sides with “Anhydrous 

Ammonia” or “Caution - Ammonia” in contrasting colors and 

minimum 4 inch high letters? 

Is a sign displayed stating name, address and phone number of 

nearest representative, agent or owner? 

Are containers installed on substantial concrete, masonry or 

structural steel supports? 

Are ammonia systems protected from possible damage by moving 

vehicles? 
Appendix F -74- WWTP 

Exhibit F-30

Checklist for Aqueous Ammonia Systems

Anhydrous Ammonia - Basic Rules Yes/No/NA Comments 

Are storage tank(s) painted white or other light reflecting colors 

and maintained in good order? 

Is storage area free of readily ignitable materials? 

Are storage tank(s) kept away from wells or other sources of 

potable water supply? 

Are storage tank(s) located with ample working space all around? 

Are storage tank(s) properly vented and away from areas where 

operators are likely to be? 

Does receiving system include a vapor return? 

Is storage capacity adequate to receive full volume of delivery 

vehicle? 

Are storage tank(s) secured against overturn by wind, earthquake 

and/or floatation? 

Are tank bottom(s) protected from external corrosion? 

Is aqua ammonia system protected from possible damage from 

moving vehicles? 

Are storage tank(s) labeled as to content? 

Are all appurtenances suitable for aqua ammonia service? 

Are all storage tank(s) fitted with liquid level gauges? 

Are liquid level gauge(s) adequately protected from physical 

damage? 

If tubing is used, is it fitted with a fail closed valve? 

Are all storage tank(s) fitted with overfill fittings or high level 

alarms? 

Are tank(s) fitted with pressure/vacuum valves? 

Is an ammonia gas scrubber system used? 

Are piping and hose materials suitable for aqua ammonia service? 
WWTP -75- Appendix F 

Is piping free of strain and provision made for expansion, 

contraction, jarring, vibration and settling? 

Is all exposed piping protected from physical damage from 

moving vehicles and other undue strain? 

Are hoses securely clamped to hose barbs? 

Are hoses inspected and renewed periodically to avoid breakage? 

Are pump(s) designed for aqua ammonia service? 

Are pump(s) fitted with splash guard around seals? 

Are pump(s) fitted with coupling guard(s)? 

Do pump(s) have local start/stop stations? 

Are two (2) suitable full face masks with ammonia canisters as 

approved by the Bureau of Mines available? Is a self-contained 

breathing air apparatus required in concentrated atmospheres? 

Is an easily accessible quick acting shower with bubble fountain 

or 250-gallon drum of clean water available? 

Is an extra pair of chemical splash proof goggles and/or full face 

shields available? 

Is an extra set of ammonia resistant gloves, boots, coat and apron 

available? 

Are fire extinguishers and a first aid kit available? 

Are handlers/operators wearing their goggles and gloves when 

working with aqua ammonia? 

Are safety and first aid information posted? 

Are emergency phone numbers and individuals to contact posted? 
Appendix F -76- WWTP 

Exhibit F-31

Sample What-If Analysis Procedure

Analysis Procedure. The steps in a What-If/Checklist analysis are as follows: 

1. Select the team (personnel experienced in the process) 

2. Assemble information (piping and instrumentation drawings (P&IDs), process flow diagrams 

(PFDs), operating procedures, equipment drawings, etc.) 

3. Develop a list of What-If questions (use the ones in Exhibits F-32 through F-35 if you want) 

4. Assemble your team in a room where each team member can view the information 

5. Ask each What-If question in turn and determine: 

g What can cause the deviation from design intent that is expressed by the 

question? 

g What adverse consequences might follow ? 

g What are the existing design and procedural safeguards? 

g Are these safeguards adequate? 

g If these safeguards are not adequate, what additional safeguards does the team 

recommend? 

6. As the discussion proceeds, record the answers to these questions in tabular format. Exhibit F-36 

provides an example. 

7. Do not restrict yourself to the list of questions that you developed before the project started. The 

team is free to ask additional questions at any time. 

8. When you have finished the What-If questions, proceed to examine the checklist. The purpose of 

this checklist is to ensure that the team has not forgotten anything. While you are reviewing the 

checklist, other What-If questions may occur to you. 

9. Make sure that you follow up all recommendations and action items that arise from the hazards 

evaluation. 
WWTP -77- Appendix F 

Exhibit F-32 

What-If Questions for Chlorine and Sulfur Dioxide Systems 

MOVEMENT OF 1-TON CL2 (SO2) CYLINDERS 

What if the cylinder is dropped from the lifting apparatus?

What if the truck rolls forward or backward?

What if a cylinder rolls and drops from the truck?

What if the cylinder swings while being lifted?

What if the Cl2 (SO2) container is not empty when removed from service?

What if the automatic container switchover system fails?

What if a Cl2 (SO2) cylinder is delivered instead of SO2 (Cl2 )

What if the cylinder is not in good condition?

TON CYLINDERS ON TRUNNION, INCL. PIGTAILS, (SUBHEADER LINES) TO MAIN HEADER LINES 

What if pigtails rupture while connected on-line?

What if pigtail connections open or leak when pressure is applied?

What if something is dropped onto cylinder or connection?

What if cracks develop in the ton cylinder flexible connection?

What if liquid Cl2 (SO2) is withdrawn through the vapor lines from the ton cylinder?

What if the cylinder valve cannot be closed during an emergency?

What if there are pinholes or small leaks at the fusible plugs?

What if ton cylinder ends change shape from concave to convex?

What if liquid is trapped between two closed valves and the temperature rises?

What if there is a fire near the cylinders?

What if the operator leaves the valve open and disconnects the pigtail?

What if water enters the system?
Appendix F -78- WWTP 

CL2 (SO2) HEADERS IN THE CHLORINATION (SULFONATION) ROOM 

What if the pressure relief valve sticks open?

What if a valve leaks?

What if there is inadequate flow in the gas line (e.g., filter clogged)?

EVAPORATORS 

What if there is overpressure in the evaporator?

What if there is high temperature in the evaporator?

What if there is low temperature in the evaporator?

What if rupture disks leak?

What if the vacuum regulator valve fails?

What if there is a gas pressure gauge leak?

What if the vacuum regulator check unit fails?

What if there is liquid Cl2 (SO2) carryover to the vacuum regulating valve

downstream of the evaporator?

CHLORINATION (SULFONATION) AND PIPES TO INJECTORS 

What if there are leaks in the chlorinator (sulfinator) unit?

What if there is rupture of the pipe from the chlorinator to the injector?

What if there is backflow of water into the Cl2 (SO2) line?

What if the water pump is not working?

GENERAL 

What if there is a power failure?

What if Cl2 (SO2) is released during maintenance?

What if a Cl2 (SO2) leak is not detected?

What if there is moisture in the Cl2 (SO2) system?
WWTP -79- Appendix F 

SCRUBBERS 

What if the system loses scrubber draft?

What if the system loses scrubber solution?

What if the manual vent to the scrubber is opened during operation?

What if the leak tightness of the building is compromised during emergency

operation of the scrubbers?

TANK TRUCKS 

What if the liquid hose leaks or ruptures?

What if the vapor return hose leaks or ruptures?

What if the truck moves?

What if the mass of Cl2 (SO2) in the truck exceeds the capacity of the tank?

What if the Cl2 tank truck is connected to an SO2 vessel (or vice versa)?

What if there is something other than Cl2 (or SO2) in the truck?

What if there is a fire under or near the truck?

What if the truck collides with pipework or a building housing Cl2 (SO2) storage

vessels?

RAILCARS 

What if the liquid hose leaks or ruptures?

What if the padding air is moist?

What if the padding air hose ruptures?

What if the railcar moves?

What if the relief valve lifts below the set pressure?

What if there is a fire under or near the truck?

What if there is a fire on or near the railcar?
Appendix F -80- WWTP 

Exhibit F-33

What-If Questions for Ammonia Systems

STORAGE VESSEL 

What if the vessel is overfilled?

What if there is fire under or near the vessel?

What if the relief valve fails to lift on demand?

What if the relief valve opens below its set pressure?

What if the deluge system fails to work on demand?

TANK TRUCK UNLOADING 

What if the liquid unloading hose partially ruptures?

What if the liquid unloading hose completely ruptures?

What if the tank truck moves?

What if the tank truck drives away before the hose is disconnected?

What if the vapor return hose partially or completely ruptures?

What if valves are not completely closed before disconnecting the hoses?

What if the tank truck contains something other than ammonia?

What if the ammonia in the tank truck contains excess oxygen?
WWTP -81- Appendix F 

Exhibit F-34

What-If Questions for Digester Systems

What if something falls onto a digester cover?

What if relief valves on a digester open?

What if an intermediate digester gas storage vessel fails?

What if air is introduced into the gas collection system?

What if the flare fails to operate?

What if the gas collection header leaks or ruptures or becomes blocked?

What if a digester gas compressor fails catastrophically?

What if there is a digester gas leak into a building (digester building, compressor

room, boiler room)?

What if the digester gas pressure exceeds the cover pressure rating?

What if the floating digester gas cover jams or tilts?
Appendix F -82- WWTP 

Exhibit F-35 

General What-If Questions 

What if the ambient temperature is abnormally high?

What if the ambient temperature is abnormally low?

What if there is a hurricane?

What if there is a tornado?

What if there is flooding?

What if there is a heavy snowfall?

What if there is an earthquake?

What if there is a tidal wave?

What if there is a failure of electric power?
Exhibit F-36 

Example What-If Checklist Log Sheet 

Company / Facility:Process Unit:

PHA Date:

Leader / Secretary:Team Members:

Description:Drawing Number:

Item Equipment/Activity Questions Causes Consequence/Hazards Safeguards Safeg

Adeq

4.1 Generic Pressure Vessel What if the set pressure of the 

equipment SRV is more than the design pressure of the equipment? 

Incorrectly set valve purchased or returned after maintenance at contractor’s shop 

Potential for rupture and release of vessel contents 

Manufacturer or repair shop’s QA 

Y 

4.2 Generic Pressure Vessel What is the SRV is incorrectly 

sized? 

Design basis for SRV incorrectly chosen or SRV sized for vapor flow when two-phase or liquid flow is possible 

SRV cannot relieve pressure, potential rupture 

Valves purchased for specific service 

Y 

4.3 Generic Pressure Vessel What if the SRV opens below Vibration, incorrect design, Release of vapor at PM program N 

its set pressure? weakened SRV spring, failure relatively low pressure 

due to inadequate PM program 

4.4 Generic Pressure Vessel What if there is a fire near or 

under the vessel? 

Spillage of flammable liquid from nearby vessel 

High pressure in vessel, potential rupture 

SRVs Deluge system 

Y 

Separation Distances Keep flammables away from vessel 
Appendix F -84- WWTP 

Exhibit F-37

HAZOP Analysis Guide Words, Meanings, and Process Parameters

In this approach, each guide word is combined with relevant process parameters and 

applied at each point (study node, process section, or operating step) in the process 

that is being examined. 

Guide Words Meaning 

No Negation of the Design Intent 

Less Quantitative Decrease 

More Quantitative Increase 

Part Of Other Material Present by Intent 

As Well As Other Materials Present Unintentionally 

Reverse Logical Opposite of the Intent 

Other Than Complete Substitution 

Common HAZOP Analysis Process Parameters 

Flow Time Frequency Mixing 

Pressure Composition Viscosity Addition 

Temperature pH Voltage Separation 

Level Speed Information Reaction 

The following is an example of creating deviations using guide words and process 

parameters: 

Guide Words Parameter Deviation

NO + FLOW = NO FLOW

MORE + PRESSURE = HIGH PRESSURE

AS WELL AS + ONE PHASE = TWO PHASE

OTHER THAN + OPERATION = MAINTENANCE

MORE + LEVEL = HIGH LEVEL
WWTP -85- Appendix F 

Guide words are applied to both the more general parameters (e.g., react, mix) and the 

more specific parameters (e.g., pressure, temperature). With the general parameters, it 

is not unusual to have more than one deviation from the application of one guide word. 

For example, “more reaction” could mean either that a reaction takes place at a faster 

rate, or that a greater quantity of product results. On the other hand, some combinations 

of guide words and parameters will yield no sensible deviation (e.g., “as well as” with 

“pressure”). 

How to Perform a Hazard and Operability (HAZOP) Review 

1. Select the team. 

2. Assemble information (P&IDs, PFDs, operating procedures, equipment drawings, 

etc.). 

3. Assemble your team in a room where each team member can view P&IDs. 

4. Divide the system you are reviewing into nodes (you can preset the nodes, or the team 

can choose them as you go along). 

5. Apply appropriate deviations to each node. For each deviation, address the following 

questions: 

— What can cause the deviation from design intent? 

— What adverse consequences might follow ? 

— What are the existing design and procedural safeguards? 

— Are these safeguards adequate? 

— If these safeguards are not adequate, what does the team recommend? 

6. As the discussion proceeds, record the answers to these questions in tabular format 

as shown below. 
Node No: 

From: To: Drawing No: Line ID: Date: Node Description: 

1 Tanker Truck Ammonia Storage Vessel Liquid loading line from tanker truck to ammonia storage vessel 

Keyword Deviation Causes Consequences Safeguards AdeqFlow High None Identified None N/A Flow Low Malfunction of truck equipment, blockage in line, 

excess pressure in tank or check valve failure 

Operational Problems N/A 

Flow No Malfunction of truck equipment, or vapor line 

excess flow valve snaps shut Hose Rupture 

Operational Problems Ammonia Leak 

N/A Emergency shutdown features 

N 

Flow Reverse Check valve and excess flow valve failure with 

hose rupture Block valves not closed when hose disconnected 

Vapor release from vessel Vapor release from vessel 

Check valve, excess flow valve, and hose inspections Operator Training 

Y Y 

Flow Wrong Type Delivery of wrong material Unknown Operational safeguards Y Flow In Addition Water, oxygen, oil Contamination, corrosion Manufacturer’s quality 

control 

Y 

Pressure High Valve closed, blockage, overfill vessel Ammonia overflow or rupture Relief valves, level 

gauges 

Y 

1Arbitrary example of recommendation: Currently, the truck must park so far away from the tank that it is necessary to connect two lengths 

ways in which truck unloading can be accomplished using only one length of hose.