1. SCOPE …………………………………………………………………….2. REFERENCES 3
3. DEFINITIONS 4
4. GENERAL REQUIREMENTS ……………………………………..4.1 General 4.2 Use of Inherently Safe Design Standard (S02-E01) 4.3 Site Selection ……………………………………………………….5. DETERMINATION OF A HIGHLY TOXIC MATERIAL 5.1 Intrinsic Toxicity of Chemical 5.2 Hazard Determination Methodology …………………………6. RECOGNITION OF A TOXIC MATERIALS IN A FACILIT
6.1 Review of Process 6.2 Information Sources ………………………………………………6.3 Preliminary Survey 7. EVALUATION OF HAZARD 7.1 Evaluation Criteria …………………………………………………7.2 Process Hazard’s Analysis 7.3 Consequence Modeling 7.4 Exposure Task Evaluations …………………………………….8. CONTROL PRINCIPLES 8.1 Substitution 8.2 Isolation ……………………………………………………………….8.3 Enclosures 8.4 Ventilation 8.5 Wet Methods ………………………………………………………..8.6 Facility Siting Issues 9. ON-SITE ENGINEERING DESIGN CONSIDERATIONS 9.1 Sample Points ………………………………………………………9.2 Atmospheric Venting 9.3 Fugitive Emissions Issues 9.4 Materials of Construction ……………………………………….
9.5 Inventory and Isolation Systems 9.6 Secondary Containment 9.7 Chemical Laboratories …………………………………………..9.8 Storage Tanks 10. OFF SITE MANAGEMENT OF HTMS 10.1 Distribution of Highly Toxic Materials ……………………….10.2 Detection Systems 10.3 Community Protection 10.4 Transportation ………………………………………………………
TABLE
I Materials Defined as HTMs
APPENDIX
A Substance Hazard Index (SHI) B ERPG Values(1) (in ppm) ……………………………………………C Determination of Toxicity Guidelines
D Process Hazards Analysis
1. Scope
This standard states policies and sets forth requirements for managing highly toxic materials (HTMs).
Listed for specific coverage by this standard are substances handled, stored, or shipped in quantities that
can pose significant hazard off-site and whose substance hazard index (SHI) is greater than 4000. Also
included are substances whose SHI is less than 4000 that have been determined to pose a significant
hazard off-site. For substances with SHI above 4000 not handled in quantities that pose a significant
hazard off-site, process safety management (PSM) principles and all or a portion of this standard, as
appropriate, shall be applied based on business assessment of risk.
For substances that exhibit toxic effects of a chronic or carcinogenic nature, all or a portion of this standard
regarding control measures, as appropriate, shall be applied to ensure that the exposure levels meet the
Threshold Limit Values criteria set by the American Conference of Governmental Industrial Hygienists
(ACGIH).
2. References
American Institute of Chemical Engineers Publications:
Guidelines for the Safe Storage and Handling of Highly Toxic Hazardous
Materials-Center for Chemical Process Safety (CCPS)
Vapor Release Mitigation (CCPS)
Guidelines for Chemical Process Quantitative Risk Analysis (CCPS)
Guidelines for Engineering Design for Process Safety (CCPS)
Guidelines for Preventing Human Error in Process Safety (CCPS)
Inherently Safer Chemical Processes (CCPS)
Other Publications:
Plant Design for Safety, Trevor Kletz, Hemisphere Publishing Co. (1990)
American Industrial Hygiene Association (AIHA) Emergency Response Planning Guideline (ERPG)
ANSI (American National Standard Institute)
API (American Petroleum Institute)
ASME (American Society of Mechanical Engineers)
Dangerous Properties of Industrial Materials, van Nostrand Reinhold
Emergency Response Guidelines (American Industrial Hygienists Association)
NFPA (National Fire Protection Association)
Handbook of Chemistry & Physics, CRC Press
Hazardous Chemical Desk Reference, van Nostrand Reinhold
Merck Index, Merck Company
NIOSH/OSHA pocket Guides to Chemical Hazards
Chemical Engineers Handbook, McGraw-Hill
American Conference of Industrial Hygienists Threshold Limit Values for Chemical Substances and
Physical Agents
3. Definitions
For the purpose of understanding this standard, the following definitions apply.
Acute Toxic Effects – arise from a sudden exposure to high concentrations and may lead to immediate
acute effects such as asphyxia, unconsciousness, burning of eyes, etc.
Acute Toxic Concentration – the maximum airborne concentration below which it is believed that nearly
all individuals could be exposed for up to one hour without experiencing life threatening effects. Typically,
the acute toxic concentration represents an emergency response planning guideline level 3 (ERPG-3) or
equivalent.
Chronic Toxic Effects – arise from repeated exposure to low concentrations and may not become obvious
for months or years. May be permanent impairment, or result in death.
Emergency Response Planning Guideline, Level 3 (ERPG-3) – the maximum airborne concentration
below which it is believed that nearly all individuals could be exposed for up to one hour without
experiencing life-threatening effects. Emergency response planning guidelines (ERPGs) are established by
the American Industrial Hygiene Association (AIHA).
Hazardous Material Identification System (HMIS) – rating system that standardizes the presentation of
chemical information. This is accomplished by the use of color codes corresponding to the hazards of a
product, assigned numeric ratings indicating the degree of hazard, and alphabetical codes designating
appropriate personal protective equipment (PPE) employees should wear while handling the material.
Provides designation for chronic toxins and carcinogens.
NFPA Rating – based on NFPA 704 it provides a simple, easy to recognize and understand system of
markings that provides information regarding the hazards of a material and the severity of these hazards as
they relate to handling, fire prevention, exposure and control during a fire.
Highly Toxic Materials (HTMs) – those substances that, because of their toxic and physical properties,
pose a significant hazard to persons off-site if accidentally released. Typically, highly toxic materials have a
substance hazard index greater than 4000. Materials defined as HTMs for the purposes of this standard
are listed in the table below.
Risk Analysis – the development of an estimate of risk based on engineering evaluation and mathematical
techniques for combining estimates of incident consequences and frequencies, and can be performed
either qualitatively or quantitatively.
Risk Assessment – the process by which the results of a risk analysis (i.e., risk estimate) are used to make
decisions through relative ranking of risk reduction strategies.
Substance Hazard Index – defined as a substance’s vapor pressure (in atmospheres), multiplied by 1
million and divided by its acute toxic concentration (expressed in ppm and equivalent to life-threatening
effects from a 1-hour exposure). (See Appendix A for a more precise definition.)
4. General Requirements
4.1 General
Special attention must be paid to reactive materials that break down into HTMs. For example, titanium
tetra-chloride (SHI 1020) is included in this standard due to its extremely reactive properties with water and
the formation of hazardous materials that pose significant hazard potential off-site. When a new chemical is
being used, the same rationale must be applied and special attention must be paid to those substances
with a substance hazard index greater than 4000.
4.2 Use of : Inherently Safer Design Concepts (S02-E01)
Reliance on chemistry and physics, i.e., the quantity, properties, and conditions of use of the process
materials to prevent injuries, environmental damage, and property damage, is inherently safer than
reliance on control systems, interlocks, alarms, and procedures. Consideration should be given to the use
of inherently safer technology during the development of process technology, design scopes of work, and
during modifications. (See Inherently Safer Design Concepts S02-E01.)
4.3 Site Selection
Site selection and location of facilities on the site will consider HTMs used and proximity of neighbors and
public facilities. Consequence analysis and risk assessment as appropriate shall be used to estimate the
effect of releases on the community and the site. See Safety Considerations For Plant Layout Standard
(S01-G01) and Safety and Loss Prevention For Capital Projects Standard (S02-G01) for requirements on
site and equipment layout.
5. Determination of a Highly Toxic Material
5.1 Intrinsic Toxicity of Chemical
Toxic compounds can be used without hazard if adequate precautions are taken to limit actual contact with
them to amounts which will not cause injury. The distinction between toxicity and hazard is an important
one. The toxicity of a substance describes the nature, degree and extent of undesirable effects. It is a
biological property of a material and reflects its inherent capacity to produce injury. The effects may be
acute or chronic. Toxicity is an intrinsic property that can not be changed.
Hazard describes the likelihood of this toxicity being manifest. This hazard is the probability or likelihood of
injury resulting from actual use of the substance in the quantity and manner proposed. In evaluating the
hazard of a particular substance then, it is necessary to know not only its toxicity, but also its physical and
chemical properties and the manner and quantity in which it is to be used.
5.2 Hazard Determination Methodology
5.2.1 HTM’s
The Substance Hazard Index methodology shall be used to determine a highly toxic material for off-site
acute affects. The Substance Hazard Index (SHI) is defined as a substance’s vapor pressure (in
atmospheres), multiplied by 1 million and divided by its acute toxic concentration (expressed in ppm and
equivalent to life-threatening effects from a 1-hour exposure). Appendix A gives a more precise definition
and calculation method. Table 1 below, though not all inclusive, gives the SHI for chemicals with high SHI
values.
6.3 Preliminary Survey
A preliminary survey should be completed to document the areas that may have acute or chronic toxic
chemicals. The survey should review the following:
a. Raw materials
b. Products and by -products
c. Sources of air contaminants
d. Types of physical agents
e. Current control measures
7. Evaluation of Hazard
7.1 Evaluation Criteria
The chemicals identified that may be toxic shall be evaluated for classification as acute highly toxic
materials, or chronic (long term such as carcinogens) materials that may impact personnel on a long-term
basis. The SHI method described in section 5.1 and Appendix A can be used for classification of a HTM.
The organizations listed below publish standards, regulations, and guidelines for community exposures,
employee exposure levels, carcinogenic classification, toxic properties and health effects. The ACGIH
TLVs shall serve as design basis for engineering controls for employee exposures to both acute and
chronic toxic chemicals.
7.2 Process Hazard’s Analysis
The Process Hazard’s Analysis as required in the Standard S02-G01, Safety & Loss Prevention Philosophy
for Capital Projects, can be used to identify the risks associated with toxic materials (HTM, acute, or
chronic) associated with a process. The PHA team shall evaluate the consequences associated with the
process risk scenarios, and determine if the potential exists for personnel exposure or off-site exposure to
the community or environment. Recommendations shall be made where the team deems appropriate. The
Safety Integrity Level Analysis for Safety Instrumented Systems process determines the requirements for
systems to protect against the release of HTM’s. A simplified PHA program is included in Appendix D.
7.3 Consequence Modeling
For toxic releases, on-site or off-site, consequence modeling can be used to calculate the extent of a
possible toxic cloud dispersion. When these calculations are performed, it should be assumed that any
measures taken to reduce the consequences of accidents are effective. If the results are unacceptable,
measures to reduce the impact of the calculated effects shall be identified and the consequences
recalculated assuming the implementation of these measures. Consequence modeling is further
described in standards S01-G01 Safety Considerations for Plant Layout Levels, and S02-G01, Safety &
Loss Prevention Philosophy for Capital Projects.
7.4 Exposure Task Evaluations
For potential employee exposures, a (job/task) description, summary of responsibilities, chemicals in the
work area, physical hazard assessment and the physical requirements of the job are to be considered.
Tasks associated with equipment that may require design engineering controls are those that involve
interaction between personnel and equipment, and those that require the opening of a closed system.
Tasks that should be evaluated include but are not limited to, sampling, purging and draining of equipment,
catalyst charging and handling, chemical handling and change out. It is the responsibility of the operating
company to determine HMIS coding systems as defined in Appendix C for operating tasks.
8. Control Principles
Controls shall be used as the first line of defense to control exposures to chemicals. These topics are also
discussed in Standard S02-E01, Inherently Safer Design Concepts and Review.
8.1 Substitution
Toxic materials, equipment or processes which are capable of creating hazardous exposures can
sometimes be replaced to reduce the exposure potential. The following are illustrations of substitution
techniques; use of mechanical gauges for mercury-containing types, mechanical pump seals for gasket
pump seals, welded pipe for flanged sections, substitute a less toxic chemical for a more toxic
8.2 Isolation
A materiel, process or operation can be isolated physically to eliminate or reduce hazardous exposures.
The use of high level vents or discharge points, remote operation of wastewater treatment facilities,
consolidation of lines or equipment containing toxic materials into one area.
8.3 Enclosures
An entire process or a portion thereof can be enclosed to prevent escape of contaminants into an
environment. Plant areas which require only occasional attention can be very effectively enclosed without
interfering with operations. Effective control is accomplished if the enclosure is kept under negative
pressure.
8.4 Ventilation
Local exhaust ventilation can control toxic substances by using a good engineering design applied at a
point as close to the source of emission as possible. Dilution ventilation is applied most successfully to low
toxicity materials, particularly when there are many small sources of emission in an enclosed space.
ACGIH Industrial Ventilation Manual provides guidelines for ventilation design.
8.5 Wet Methods
This method can be used to reduce dusting when wettable material is handled and water does not
interfere with the process. By keeping the material damp or by using fogging sprays at transfer points, very
little material is disseminated into the general air.
8.6 Facility Siting Issues
The guidelines outlined in Standard S01-G01 shall be followed on facility siting and spacing of equipment.
9. On-site Engineering Design Considerations
9.1 Sample Points
Closed loop sample designs shall be used for sample points requiring routine sampling for HTMs,
carcinogens, or chemicals with health ratings of 3, or 4 as rated by the HMIS scale as provided on a
material safety data sheet. Examples are open ended valves equipped with a cup, blind flange plug or a
second valve. The second valve must always be closed.
9.2 Atmospheric Venting
Facilities will be designed, operated, and maintained so that HTMs are contained within the process or
storage facility. Pressure-relieving and disposal systems must be provided and must operate predictably,
reliably, and safely under emergency conditions. Any discharges from pressure-relieving devices must be
within acceptable concentration limits, under worst case meteorological conditions, so that people off-site
are not exposed to either life-threatening or irreversible health effects. Mitigating measures such as flaring,
scrubbing, and/or quenching may be required to achieve these limits.
9.3 Fugitive Emissions Issues
9.3.1 General
Caps and plugs shall be required for hydrocarbon emissions and leak sources. Welded joints shall be used
where feasible, pressure relief valves may be provided with rupture discs, wherever feasible to protect
against fugitive emissions. Standard S02-E01, Inherently Safer Design Concepts and Reviews, shall be
followed to keep fugitive emissions sources to a minimum. Emergency release mitigation systems (e.g.,
leak repair systems, capping kits, water sprays, water curtains, etc.) must be considered and provided
where feasible. Continuous environmental monitoring systems for vessel and stack emissions are outside
the scope of this document.
9.3.2 Continuous monitoring
Continuous monitoring systems shall be provided in process areas where there is potential for employee
exposure to a HTM, or a chemical with a health rating of 4 on an HMIS or NFPA scale, (e.g. hydrogen
sulfide, chlorine). Systems shall be designed to provide early detection and alarm of a release so that
corrective action begins as soon as possible. New and/or developing technology for detection systems for
specific HTMs or highly toxic chemicals shall be reviewed and considered.
Detection systems must be managed to the same assurance level as relief systems, safety alarms, and
interlocks.
9.4 Materials of Construction
Materials of Construction for major pieces of equipment (vessels, tanks, heat exchanger, and
pumps/compressors) and for piping, valves and fittings shall be chosen and specified for the chemicals in
service by evaluating the toxic effects, flammability, corrosivity, reactivity, and compatibility factors. A piping
specification that defines materials of construction and design ratings shall be made available to support
the facility mechanical integrity program.
9.5 Inventory and Isolation Systems
Facilities will be designed and operated in such a way as to limit the amount of highly toxic material that
could be involved in a release. During process conception, development, or improvement, overall risk of
HTMs in process and storage will be minimized consistent with sound risk management. Quantities of
HTMs in storage should be minimized consistent with sound risk management.
Where significant volumes of highly toxic material are required, including in transportation equipment,
provisions must be considered to permit deinventory of system contents.
9.6 Secondary Containment
Storage must be addressed in formal process hazard reviews and risk analysis. Secondary containment
(dikes, double-walled tanks, etc.) must be considered to limit potential release quantities from process equipment and storage. Standard S01-G01, Safety Considerations For Plant Layout Levels, provides
guidelines for drainage, sewer systems, and containment.
9.7 Chemical Laboratories
Local exhaust ventilation hoods shall be provided in laboratories working with both chronic and toxic
chemicals. The HMIS system designates “*” next to a health rating for a material that is a carcinogen or for
materials known to have an adverse effect given chronic exposure. This designation would appear next to
the numerical ranking within the blue health bar on a label, or indicated on a MSDS. Ventilation hoods
shall be provided in laboratories using chemicals designated by the HMIS system to be carcinogenic or to
have adverse effects on chronic exposure. Ventilation hoods shall be designed to ensure the chemical
exposure to the employee meets the ACGIH TLVs.
ACGIH Industrial Ventilation Manual provides estabished hood designs. The required air volume and duct
design will be dependent upon the hood design chosen. Hood openings shall be kept to a practical
minimum to keep air flow requirements as low as possible. The location of building air intakes shall comply
with Standard S01-G01, Safety Considerations For Plant Layout Levels.
Waste disposal systems shall be a collection system from other buildings to prevent the reverse flow of
toxic chemical wastes and vapors into occupied buildings.
9.8 Storage Tanks
9.8.1 Above Ground Tanks
Consideration will be given to the nature of materials being stored and additional risks such as proximity to
populated areas, design of equipment, and external hazards. The assessment of risks must include
vulnerability to vandalism, sabotage, and misoperation. NFPA 704 shall be used as guidelines for labeling
tanks.
Continuous monitoring systems shall follow the same considerations and meet the same requirements as
section 9.3.2. When evaluating systems for tanks and tank farms, consideration should be given to
manning levels and operating requirements and a cost benefit analysis methodology applied.
9.8.2 Under Ground Tanks
Underground storage tanks are limited to use at fuel dispensing facilities and addressed in Standard
S01-G01, Safety Considerations for Plant Layout Levels.
10. Off Site Management of HTMS
10.1 Distribution of Highly Toxic Materials
10.1.1 Distribution
Proper distribution, including transportation, of HTMs in all parts of the supply chain play an important role
in efforts to minimize overall risk. Distribution policies and standards will be consulted for guidance
concerning when, where, and how HTMs shall be transported or stored in connection with manufacturing
and marketing efforts. To the extent practical, manufacturing and storage processes should be de-signed
and operated in a way that minimizes the transportation and storage (on- and off-site) of HTMs and shall
include the following:
a. The minimum acceptable design and condition of owned or leased transportation equipment, if
applicable, and the maintenance requirements for such equipment.
b. The minimum acceptable design and condition of owned or leased transportation equipment if
applicable. (This may be the U.S. DOT requirement or the country specific industry standard.)
c. The design and condition of associated company owned or dedicated distribution facilities
(loading, unloading, and storage on-site as well as warehousing, transloading, and terminaling
operations).
d. Off-site storage (including warehouses, terminals, and rolling stock)
Distribution includes storage, handling, and transportation, so it is important to understand the impact on
the overall risk of an operation when considering change in a particular parameter. For example, a
proposed model change of rail to barge may require consideration of the adequacy of the dock, storage
tanks, plant piping, etc., to evaluate whether overall risk can be reduced.
10.2 Detection Systems
Sites handling chemicals as HTMs will include use of automatic or continuous specific chemical detection
systems, where technology is available and appropriate to the application, as an integral part of minimizing
the potential for harmful exposure off-site.
Systems shall be designed to provide early detection and alarm of a release so that corrective action
begins as soon as possible. New and/or developing technology for detection systems for specific HTMs
shall be reviewed and considered.
Detection systems must be managed to the same assurance level as relief systems, safety alarms, and
interlocks.
10.3 Community Protection
The risk of accidental injury or death from company operations to any off-site individual will be minimized.
Each operation and/or site will make and keep current a risk analysis for any highly toxic material process
or storage facility that could cause serious injury or illness off-site.
Where quantitative risk assessments are judged to be necessary, a qualified expert will be used.
Measures that should be considered to reduce the likelihood of community exposure include chemical
hazard elimination (quantities, substitution, etc.), process safety enhancements, deinventory systems,
neutralization, containment, mitigation, increased buffer zones, emergency response procedures,
community preparedness, and neighborhood alerting. Priority will be given to major hazard elimination.
Each site handling HTMs is required to determine the impact of a release on employees and community
neighbors and provide adequate emergency response planning for such releases.
10.4 Transportation
When transportation equipment is used as connected storage or feed tanks for HTMs, the design of the
system must meet minimum requirements for storage.
A process hazards analysis that includes the transportation equipment as a part of the holistic process
system must be completed. The system that connects to the transportation equipment must ensure no
backflow of process into the equipment. The pressure in the equipment must be controlled so that the relief
pressure is not reached. Equipment that is to be kept on sites for deinventory purposes must be maintained
to meet transportation or fixed storage standards.
HTM shipments originating at company sites and transported to other locations, including customer sites,
shall be subject to an initial review. The initial review shall precede any shipments. The review shall
include, but not be limited to, review of the destination site receiving and storage facilities, and policies and
procedures for receiving HTMs, to ensure that all such sites are physically capable of receiving, unloading,
storing, and shipping (in the case of residue containers and refused shipments) HTMs safely and in
compliance with applicable regulations. Recommendations to customers to upgrade facilities and/or
practices should be made based on HTM safety standards.
APPENDIX A
Substance Hazard Index (SHI)
A.1 Definition
Substance hazard index is defined as a substance’s vapor pressure divided by acute toxic concentration.
It is calculated as follows:
SHI = (VP/760 x 1,000,000)/ATC
Where:
VP = Vapor pressure at 20 degrees Centigrade expressed in mm Hg. ATC = Acute toxic
concentration (ppm), which is defined as the maximum airborne concentration below which it is
believed that nearly all individuals could be exposed for up to one hour without experiencing or
developing life-threatening health effects.
Where available, emergency response planning guideline level 3 (ERPG-3) data should be used. Where
ERPG-3 data is not available, the following approximations can be used for ATC.
ATC = LC 50 /30.
A.2 Using the substance hazard index to provide a relative ranking for hazard potential
Substance hazard index can be used to provide a relative ranking of hazard potential. The greater a
substance’s vapor pressure the greater the following:
a. The driving force for release
b. The rate of volatilization when released
c. The SHI
The substance hazards index has been used as a tool to provide a relative ranking of hazard potential by
the states of New Jersey and Delaware in developing their risk management rules. It has also been used
by Organization Resources Counselors, Inc. and the Chemical Manufacturers Association in developing
written comments and testimony for OSHA and EPA, respectively, during their rule-making process as
each agency carried out its Clean Air act responsibilities for developing chemical lists.
It is important to recognize that the SHI ranking substances by hazard potential is neither absolute or
precise; it is an approximation. It does not, for example, take into account a number of important hazard
potential criteria such as the following:
a. Presence or absence of an odor threshold relative to the ATC
b. Irreversibility to exposure effects at different concentrations
c. Visibility of a cloud
Recognizing its limitations, SHI can be quite useful in providing a relative ranking of hazard potential.
APPENDIX B
ERPG Values
(1) (in ppm)
(1)
ERPG values for some chemicals as of 1997. ERPG defined as below:
ERPG 1 – maximum airborne concentration below which it is believed nearly all individuals could be
exposed for up to 1 hour without experiencing other than mild transient adverse health effects or
perceiving a clearly defined objectionable odor.
ERPG 2 – maximum airborne concentration below which it is believed nearly all individuals could be
exposed for up to 1 hour without experiencing or developing irreversible or other serious health effects
or symptoms that could impair their abilities to take protective action.
ERPG 3 – maximum airborne concentration below which it is believed nearly all individuals could be
exposed for up to 1 hour without experiencing or developing life threatening health effects.
APPENDIX C
Determination of Toxicity Guidelines
NFPA 704
This widely used chemical labeling system was originally intended to provide basic information to fire
fighting, emergency, and other personnel, enabling them to more easily decide whether to evacuate the
area or to commence emergency control procedures. It was also intended to provide them with information
to assist in selecting fire fighting tactics and emergency procedures.
In addition to these original goals, this standard provides laboratory personnel with an invaluable tool to
help in establishing the appropriate level of personal protection that is required for working with a material
and the correct method of storage and use that should be employed.
NFPA 704 provides a simple, easy to recognize and understand system of markings that provides
information regarding the hazards of a material and the severity of these hazards as they relate to
handling, fire prevention, exposure and control. It should be used in conjunction with other chemical
labeling systems to maximize safe usage and storage of hazardous materials. As stated in NFPA 704,
“This standard provides a simple system of readily recognizable and easily understood markings, which
will give at a glance a general idea of the inherent hazards of any material and the order of severity of
these hazards as they relate to fire prevention, exposure, and control”.
The system is based on a diamond shaped marking that is divided into 4 regions, each assigned a color,
and a numerical rating in each region. The regions depict health hazard, fire hazard, reactivity hazard and
a region to indicate a reactivity with water, or other specific hazards if water reactivity is not an issue. An
example of the marking follows.
Toxic Materials. The health rating is intended to provide emergency response personnel with an idea of
the degree of danger posed by a specific material. It addresses only issues related to acute, or short-term,
exposures, and does not consider the danger posed from chronic or long-term exposures. The
disadvantage of this system is that it does not address exposure to carcinogenic or mutagenic materials.
The standard is concerned only with exposure as related to respiratory or contact incidents, since
ingestion is an unlikely scenario for fire fighters. A 3 or a 4 will be assigned to any material that is classified
as “Poison – Inhalation hazard” by the DOT.
Flammable Materials. The flammability rating is dependent upon the ease of ignition of a material. Many
materials will burn under one set of conditions but will not burn under any other condition. The numeric
values are assigned based on the flashpoint (the minimum temperature at which a liquid gives off vapor in
sufficient concentrations to allow the substance to ignite) of the material. The flashpoint supplies useful
information regarding the degree of hazard. First, if the material has no flashpoint, it is not a flammable
material. Second, if it has a flashpoint, it must be considered flammable or combustible. Also, the
flashpoint can be used as an indication of susceptibility of ignition – lower flashpoints indicate increased
susceptibility.
Reactive Materials. The reactivity rating measures a material’s susceptibility to violent reaction –
detonation, polymerization, explosion, etc. The violence of the reaction may be increased by addition of
heat or pressure, by mixture with other materials to form fuel-oxidizer combinations, or by contact with
incompatible substances or contaminants. Because of the complexity of these types of reactions it is not
straightforward to use a simple numeric scale to identify the degree of hazard. Rather these situations
involving reactive materials must be evaluated individually. The numeric rating will be used to rank the
ease, rate and potential quantity of energy that may be released.
Water Reactives and Oxidizers – Special Hazards. Materials which are unusually reactive with water are
denoted with a “W” with a slash through it. The number in the yellow box will then indicate the degree of
reactivity.
Materials which are capable of increasing the intensity of a fire by supplying fuel during fire situations will
be labeled with the legend “OX” in this section of the diamond.
General Rating Summary
Health (Blue)
4 Danger May be fatal on short exposure. Specialized protective equipment required
3 Warning Corrosive or toxic. Avoid skin contact or inhalation
2 Warning May be harmful if inhaled or absorbed
1 Caution May be irritating
0 No unusual hazard
Flammability (Red)
4 Danger Flammable gas or extremely flammable liquid
3 Warning Flammable liquid flash point below 100° F
2 Caution Combustible liquid flash point of 100° to 200° F
1 Combustible if heated
0 Not combustible
Reactivity (Yellow)
4 Danger Explosive material at room temperature
3 Danger May be explosive if shocked, heated under confinement or mixed with water
2 Warning Unstable or may react violently if mixed with water
1 Caution May react if heated or mixed with water but not violently
0 Stable Not reactive when mixed with water
Special Notice Key (White)
W Water Reactive
OX Oxidizing Agent
Hazardous Materials Identification System (HMIS)
The widespread use of chemicals and the need to protect employees from the hazards of those chemicals
led OSHA to issue the first hazard communication standard (HCS) in 1983. Central to the HCS is the belief
that workers who may be exposed to hazardous chemicals have a right to know about the hazards and
how to work safely with the materials. As a result, the standard requires that chemical manufacturers and
importers evaluate all chemicals for hazards, and that the information concerning those hazards be
communicated downstream from the manufacturer to the employer and then to the employee. The HCS
has three basic requirements:
Chemical manufacturers must review scientific evidence concerning the hazards of a material to determine
if they are hazardous; The manufacturer must develop material safety data sheets (MSDSs) and container
labels, which must be sent to downstream users; and Employers must develop a written hazard
communication program and provide information and training to employees about the hazards of chemicals
found in the workplace.
HMIS (Hazardous Material Identification System) helps satisfy HCS requirements by providing a format for
hazard determinations and simplifying the employee training and information process. HMIS provides
clear, recognizable information to employees by standardizing the presentation of chemical information.
This is accomplished by the use of color codes corresponding to the hazards of a product, assigned
numeric ratings indicating the degree of hazard, and alphabetical codes designating appropriate personal
protective equipment (PPE) employees should wear while handling the material.
In many respects, the HMIS is very similar to the NFPA. The color and number coding are identical. But
instead of the diamond, the HMIS uses a color bar system.
This system was developed by the paint manufacturers (National Paint and Coating Association) to
address situations more common to their environment than the situations encountered by firefighters. With
this system, the white section is used to indicate what level of protective equipment is required. Instead of
a hazard ranking, a level of protection is indicated by a letter, with each letter specifying a different level of
protection. Examples are:
This lettering system indicates the level of PPE to be worn to work safely with a material. The original
system traditionally provided letters of the alphabet corresponding to a specific grouping of PPE. However,
this did not allow employers to customize their PPE recommendations. Now employers who cannot find an
appropriate grouping of PPE will be able to design their own custom set of equipment. Each of the
individual PPE icons have been designated with a corresponding letter of the alphabet ranging from ’m’
through ’z’. An employer can list appropriate letters to customize the PPE required for handling a specific
material. To facilitate this option, container labels have been revised to allow room for the additional codes
in the PPE block of the label. Of course, employers who found the previous PPE groupings suitable for
their work places can continue to use the standard codes.
Another feature that differs from the NFPA label system is that HMIS allows an “*” to designate a material
as a carcinogen or for materials known to have an adverse effect given chronic exposure. This designation
would appear next to the numerical ranking within the blue health bar. This information is of great benefit
to laboratory workers, since this is an indication of how the material will affect them over the long-run.
Recall that, in comparison, the NFPA rating indicates only the short-term or acute affects you might
encounter in an emergency circumstance.
Comparison of NFPA and HMIS Systems
Similarities
a. Both systems have three color-coded fields to indicate the flammability (red), health (blue), and
reactivity (yellow) hazards associated with the material.
b. Both use a system of five numbers, ranging from 0 to 4, to indicate the severity of hazard, with 0
being the least and 4 being the most hazardous.
Differences
a. They differ in layout — NFPA uses four diamonds, HMIG uses vertically stacked bars.
b. The differ in interpretation of the fourth, white field (special handling in the NFPA system;
protective equipment in the HMIG system).
c. Possibly the most significant difference, however, has to do with the intended audience for each
of the systems. The HMIG (or HMIS) was devised as an HCS compliance tool, and has employees
who must handle hazardous chemicals in the workplace as the intended audience. The NFPA system
was designed to alert fire fighters arriving on the scene of a fire to the hazards associated with
materials present at that location. Therefore, the numbers assigned in the NFPA system assume that
a fire is present. No such assumption holds in the HMIG/HMIS system. For this reason, the numbers
that are assigned to the flammability, health, and reactivity hazards may differ between the NFPA and
HMIS systems, even for the exact same chemical.
Terminology
In an effort to standardize the language used on chemical labels, the following wording is based on
quantitatively measured flammability and toxicity characteristics of the material:
NFPA DIAMOND LABELING SYSTEM
APPENDIX D
Process Hazards Analysis
PROCESS HAZARDS ANALYSIS – PURPOSE
A PHA program is designed to systematically identify, evaluate, and control process hazards in processes
that could endanger personnel, the environment, contract employees, the public, and the process
equipment. The purpose of the Process Hazards Analysis (PHA) Program is to help minimize the potential
for catastrophic releases of chemicals that could affect worker safety and/or the public.
SEQUENCE OF PHA’S
Depending on the magnitude of the project more than one PHA may be required. The PHAs outlined below
vary in complexity based on different stages of the project. Major projects (unit expansion, new process)
may require a Conceptual PHA, Preliminary Design PHA, Final Design PHA, and a PSSR. Other projects
may only require a Final Design PHA.
Level I – Conceptual PHA. A conceptual PHA is used to provide a preliminary safety analysis while the
basic process or plant design is still being developed. It provides an opportunity for eliminating hazards
while fundamental changes to the process can still be made. Detailed engineering documents are not
usually available at this phase and a What-If Checklist is a good method to use. An Inherently Safer Design
checklist can be useful at this stage as well.
Level II – Preliminary Design. Once the basic design is complete, a preliminary design PHA can be done
while there are still opportunities to make major changes to the design. Documentation such as limited
block flow diagrams, preliminary process flow diagrams, and material flow diagrams should be available
and used. The What-If method, Creative What-IF, or What-If/Checklist may be chosen at this stage to verify
safety systems and issues, and document safeguards and mitigants for identified hazards, causes, and
consequences. Recommendations are made to further define requirements and to mitigate risk.
Level III – Final Design. When a complete set of P&ID’s, electrical loop drawings, MSDSs, and draft
operating manuals are available, a full line-by-line PHA/HAZOP can be done to verify and document safety
systems, design parameters, and operating procedures as safeguards and mitigants. Recommendations
from prior PHA’s are statused and documented. At this stage, major safety requirements/issues should
already have been identified and addressed in prior PHA’s. Recommendations and action items are
generated where required.
SPECIFICATIONS FOR CONDUCTING PHA’S
PHA Methods
There are a wide variety of PHA methods. Different methods are used for different applications, or a
combination may be used. The following are acceptable methods:
a. What-If
b. Checklist
c. What-If/Checklist
d. Hazard and Operability Study (HAZOP)
e. Failure Modes And Effects Analysis (FMEA)
f. Fault Tree Analysis
g. Other Appropriate Methods
PHA Content
The Process Hazard Analysis shall address:
a. The hazards of the process;
b. Any previous incident(s) which had a likely potential for catastrophic consequences in the
workplace;
c. Engineering and administrative controls applicable to the hazards and their inter-relationships
such as appropriate application of detection methods, warning devices, process monitoring and
control systems.
d Consequences of failure of engineering and administrative controls;
e. Facility siting;
f. Human factors; and
g. A qualitative evaluation of a range of possible safety and health effects of failure of controls on
employees in the workplace.
Guidelines and checklists are often used as reference to assist the facilitator in obtaining and analyzing
the required information. These guidelines and checklists can be tailored to the type of PHA methodology
being used. If a client has specific checklists that are required by their own company procedure, they
should be used. Process Safety Information is to be reviewed prior to the start of the PHA and updates
requested as necessary. The information available to the team shall be documented in the report.
The PHA Team
A team with expertise in engineering and process operations will perform the Process Hazards Analyses.
The primary responsibility of the team is to identify hazards. The team shall include at least one employee
who has experience and knowledge specific to the process being evaluated. One member of the team
must be knowledgeable in the specific process hazard analysis methodology being used. Other disciplines
with expertise in maintenance, instrument/electrical, laboratory, etc. may be used as needed. The table on
page 4 designates PHA activities and responsibilities of the team members.
DOCUMENTATION AND COMMUNICATION
PHA Report
It is the responsibility of the facilitator and the scribe to prepare a written report describing the process and
the PHA activity. PHA PRO software shall be used for documenting the PHA sessions and meeting notes.
The report documents the identified process hazards and consequences, a risk ranking, and list of action
items proposed to reduce or eliminate the probability, or mitigate the consequences of identified potential
hazardous events. The Process Safety Information that was available at the time of the PHA shall be
documented, as well as the incidents discussed during the PHA.
Tracking and Closure
Action items generated in prior PHA’s are updated for current status in sequential PHA’s. Project
management tracks the final PHA recommendations. A typical tracking sheet contains a log of what
actions are to be taken; a written schedule of when these actions are to be completed, responsible party,
specific action taken, and the closure date.
PHA Responsibilities and Requirements
