ASTM G128/G128M-15(2023)
(Guide)Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems
Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems
SIGNIFICANCE AND USE
4.1 The purpose of this guide is to introduce the hazards and risks associated with oxygen-enriched systems. This guide explains common hazards that often are overlooked. It provides an overview of the standards and documents produced by ASTM Committee G04 and other knowledgable sources as well as their uses. It does not highlight standard test methods that support the use of these practices. Table 1 provides a graphic representation of the relationship of ASTM G04 standards. Table 2 provides a list of standards published by ASTM and other organizations.
4.2 The standards discussed here focus on reducing the hazards associated with the use of oxygen. In general, they are not directly applicable to process reactors in which the deliberate reaction of materials with oxygen is sought, as in burners, bleachers, or bubblers. Other ASTM Committees and products (such as the CHETAH program5) and other outside groups are more pertinent for these.
4.3 This guide is not intended as a specification to establish practices for the safe use of oxygen. The documents discussed here do not purport to contain all the information needed to design and operate an oxygen-enriched system safely. The control of oxygen hazards has not been reduced to handbook procedures, and the tactics for using oxygen are not simple. Rather, they require the application of sound technical judgment and experience. Oxygen users should obtain assistance from qualified technical personnel to design systems and operating practices for the safe use of oxygen in their specific applications.
SCOPE
1.1 This guide covers an overview of the work of ASTM Committee G04 on Compatibility and Sensitivity of Materials in Oxygen-Enriched Atmospheres. It is a starting point for those asking the question: “What are the risks associated with my use of oxygen?” This guide is an introduction to the unique concerns that must be addressed in the handling of oxygen. The principal hazard is the prospect of ignition with resultant fire, explosion, or both. All fluid systems require design considerations, such as adequate strength, corrosion resistance, fatigue resistance, and pressure safety relief. In addition to these design considerations, one must also consider the ignition mechanisms that are specific to an oxygen-enriched system. This guide outlines these ignition mechanisms and the approach to reducing the risks.
1.2 This guide also lists several of the recognized causes of oxygen system fires and describes the methods available to prevent them. Sources of information about the oxygen hazard and its control are listed and summarized. The principal focus is on Guides G63, G88, Practice G93, and Guide G94. Useful documentation from other resources and literature is also cited.
Note 1: This guide is an outgrowth of an earlier (1988) Committee G04 videotape adjunct entitled Oxygen Safety and a related paper by Koch2 that focused on the recognized ignition source of adiabatic compression as one of the more significant but often overlooked causes of oxygen fires. This guide recapitulates and updates material in the videotape and paper.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see Sections 8 and 11.
Note 2: ASTM takes no position respecting the validity of any evaluation methods asserted in connection with any ite...
General Information
- Status
- Published
- Publication Date
- 28-Feb-2023
- Drafting Committee
- G04.02 - Recommended Practices
Relations
- Effective Date
- 01-Oct-2023
- Effective Date
- 29-Sep-2023
- Effective Date
- 01-Oct-2019
- Effective Date
- 01-Nov-2018
- Effective Date
- 01-Jul-2018
- Effective Date
- 01-Dec-2017
- Effective Date
- 15-Aug-2017
- Effective Date
- 01-Sep-2013
- Effective Date
- 01-May-2013
- Effective Date
- 01-Apr-2012
- Effective Date
- 01-Apr-2012
- Effective Date
- 01-Apr-2011
- Effective Date
- 01-Apr-2011
- Effective Date
- 01-Apr-2011
- Effective Date
- 01-Nov-2010
Overview
ASTM G128/G128M-15(2023), Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems, provides essential information for identifying, understanding, and mitigating hazards associated with oxygen-enriched environments. Developed by ASTM Committee G04, this guide focuses on unique risks present when handling and utilizing oxygen concentrations higher than those in ambient air. The document introduces users to ignition mechanisms, common fire causes, and practical strategies to control hazards in oxygen systems.
The standard is an introductory resource that summarizes relevant standards, such as ASTM Guides G63, G88, G94, and Practice G93, and points to additional information provided by other professional organizations. It is not a specification for operations or design but encourages consultation with qualified technical personnel for safe implementation.
Key Topics
Oxygen-Enriched System Hazards
The guide discusses hazards specific to systems with oxygen levels above typical atmospheric concentrations. The primary risks are increased likelihood and severity of fire or explosion, stemming from easier ignition and more intense combustion.Ignition Mechanisms
Several recognized ignition sources are addressed, including:- Particle impact
- Adiabatic compression
- Mechanical impact
- Friction (galling)
- Electric arc and static discharge
- Resonance and promoted ignition
These mechanisms highlight the importance of understanding material compatibility and system design in preventing incidents.
Risk Factors
Key system hazards are influenced by:- Oxygen concentration
- Pressure and temperature
- Phase (gas or liquid oxygen)
- Gas velocity
- Mechanical reliability and age of components
Every parameter can increase the potential for fire or explosion, requiring careful analysis and system-specific controls.
Fire Prevention Approaches
The guide emphasizes that traditional fire control-separating fuel, oxidant, and ignition-is often not possible in oxygen systems. Instead, prevention focuses on:- Selection of compatible materials, including metals and non-metals
- System cleanliness and cleaning practices
- Control of ignition sources and operating parameters
- Regular maintenance and inspection
Professional Guidance
Successful application of hazard control measures in oxygen-enriched systems requires technical expertise and sound engineering judgement. The guide urges stakeholders to consult industry standards and experienced professionals when designing or operating such systems.
Applications
The guidance in ASTM G128/G128M is broadly applicable wherever oxygen-enriched systems are found, including:
- Medical and Healthcare Facilities: Respiratory therapy, oxygen supply for critical care, and associated piping and delivery systems.
- Industrial Manufacturing: Steelmaking, chemical production, welding, and processes involving high-purity oxygen.
- Emergency Services: Firefighting and rescue equipment utilizing oxygen-enriched breathing apparatus.
- Research and Aerospace: Environments and equipment where oxygen concentrations are elevated for life-support, high-altitude, or deep-sea applications.
Adherence to the guide enhances the safety of personnel, protects property from catastrophic fire events, and assists organizations in meeting regulatory and industry best practice expectations.
Related Standards
The document references a network of relevant ASTM standards and external guides that support hazard mitigation and system design:
- ASTM G63: Evaluating Nonmetallic Materials for Oxygen Service
- ASTM G88: Designing Systems for Oxygen Service
- ASTM G93: Cleanliness Levels and Cleaning Methods for Materials and Equipment in Oxygen-Enriched Environments
- ASTM G94: Evaluating Metals for Oxygen Service
- ASTM D2863: Minimum Oxygen Concentration to Support Combustion (Oxygen Index)
- Compressed Gas Association (CGA) Standards: Cleaning and pipeline design for oxygen service
- NFPA: Standards for oxygen-fuel gas systems (NFPA 51, 53, 55, 99)
- European Industrial Gas Association (EIGA) Standards: Piping and cleaning recommendations
These documents collectively provide a comprehensive framework for addressing the compatibility and safety of materials and systems used in oxygen-enriched environments. Following ASTM G128/G128M-15(2023) and its related references fosters the responsible use and management of oxygen across industries.
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Frequently Asked Questions
ASTM G128/G128M-15(2023) is a guide published by ASTM International. Its full title is "Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems". This standard covers: SIGNIFICANCE AND USE 4.1 The purpose of this guide is to introduce the hazards and risks associated with oxygen-enriched systems. This guide explains common hazards that often are overlooked. It provides an overview of the standards and documents produced by ASTM Committee G04 and other knowledgable sources as well as their uses. It does not highlight standard test methods that support the use of these practices. Table 1 provides a graphic representation of the relationship of ASTM G04 standards. Table 2 provides a list of standards published by ASTM and other organizations. 4.2 The standards discussed here focus on reducing the hazards associated with the use of oxygen. In general, they are not directly applicable to process reactors in which the deliberate reaction of materials with oxygen is sought, as in burners, bleachers, or bubblers. Other ASTM Committees and products (such as the CHETAH program5) and other outside groups are more pertinent for these. 4.3 This guide is not intended as a specification to establish practices for the safe use of oxygen. The documents discussed here do not purport to contain all the information needed to design and operate an oxygen-enriched system safely. The control of oxygen hazards has not been reduced to handbook procedures, and the tactics for using oxygen are not simple. Rather, they require the application of sound technical judgment and experience. Oxygen users should obtain assistance from qualified technical personnel to design systems and operating practices for the safe use of oxygen in their specific applications. SCOPE 1.1 This guide covers an overview of the work of ASTM Committee G04 on Compatibility and Sensitivity of Materials in Oxygen-Enriched Atmospheres. It is a starting point for those asking the question: “What are the risks associated with my use of oxygen?” This guide is an introduction to the unique concerns that must be addressed in the handling of oxygen. The principal hazard is the prospect of ignition with resultant fire, explosion, or both. All fluid systems require design considerations, such as adequate strength, corrosion resistance, fatigue resistance, and pressure safety relief. In addition to these design considerations, one must also consider the ignition mechanisms that are specific to an oxygen-enriched system. This guide outlines these ignition mechanisms and the approach to reducing the risks. 1.2 This guide also lists several of the recognized causes of oxygen system fires and describes the methods available to prevent them. Sources of information about the oxygen hazard and its control are listed and summarized. The principal focus is on Guides G63, G88, Practice G93, and Guide G94. Useful documentation from other resources and literature is also cited. Note 1: This guide is an outgrowth of an earlier (1988) Committee G04 videotape adjunct entitled Oxygen Safety and a related paper by Koch2 that focused on the recognized ignition source of adiabatic compression as one of the more significant but often overlooked causes of oxygen fires. This guide recapitulates and updates material in the videotape and paper. 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see Sections 8 and 11. Note 2: ASTM takes no position respecting the validity of any evaluation methods asserted in connection with any ite...
SIGNIFICANCE AND USE 4.1 The purpose of this guide is to introduce the hazards and risks associated with oxygen-enriched systems. This guide explains common hazards that often are overlooked. It provides an overview of the standards and documents produced by ASTM Committee G04 and other knowledgable sources as well as their uses. It does not highlight standard test methods that support the use of these practices. Table 1 provides a graphic representation of the relationship of ASTM G04 standards. Table 2 provides a list of standards published by ASTM and other organizations. 4.2 The standards discussed here focus on reducing the hazards associated with the use of oxygen. In general, they are not directly applicable to process reactors in which the deliberate reaction of materials with oxygen is sought, as in burners, bleachers, or bubblers. Other ASTM Committees and products (such as the CHETAH program5) and other outside groups are more pertinent for these. 4.3 This guide is not intended as a specification to establish practices for the safe use of oxygen. The documents discussed here do not purport to contain all the information needed to design and operate an oxygen-enriched system safely. The control of oxygen hazards has not been reduced to handbook procedures, and the tactics for using oxygen are not simple. Rather, they require the application of sound technical judgment and experience. Oxygen users should obtain assistance from qualified technical personnel to design systems and operating practices for the safe use of oxygen in their specific applications. SCOPE 1.1 This guide covers an overview of the work of ASTM Committee G04 on Compatibility and Sensitivity of Materials in Oxygen-Enriched Atmospheres. It is a starting point for those asking the question: “What are the risks associated with my use of oxygen?” This guide is an introduction to the unique concerns that must be addressed in the handling of oxygen. The principal hazard is the prospect of ignition with resultant fire, explosion, or both. All fluid systems require design considerations, such as adequate strength, corrosion resistance, fatigue resistance, and pressure safety relief. In addition to these design considerations, one must also consider the ignition mechanisms that are specific to an oxygen-enriched system. This guide outlines these ignition mechanisms and the approach to reducing the risks. 1.2 This guide also lists several of the recognized causes of oxygen system fires and describes the methods available to prevent them. Sources of information about the oxygen hazard and its control are listed and summarized. The principal focus is on Guides G63, G88, Practice G93, and Guide G94. Useful documentation from other resources and literature is also cited. Note 1: This guide is an outgrowth of an earlier (1988) Committee G04 videotape adjunct entitled Oxygen Safety and a related paper by Koch2 that focused on the recognized ignition source of adiabatic compression as one of the more significant but often overlooked causes of oxygen fires. This guide recapitulates and updates material in the videotape and paper. 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see Sections 8 and 11. Note 2: ASTM takes no position respecting the validity of any evaluation methods asserted in connection with any ite...
ASTM G128/G128M-15(2023) is classified under the following ICS (International Classification for Standards) categories: 13.220.40 - Ignitability and burning behaviour of materials and products; 19.040 - Environmental testing. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM G128/G128M-15(2023) has the following relationships with other standards: It is inter standard links to ASTM D2863-23, ASTM D2863-95, ASTM D2863-19, ASTM G124-18, ASTM D4809-18, ASTM D2863-17a, ASTM D2863-17, ASTM D2863-13, ASTM D4809-13, ASTM D2863-12, ASTM D2863-12e1, ASTM G86-98a(2011), ASTM G175-03(2011), ASTM G93-03(2011), ASTM G124-10. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM G128/G128M-15(2023) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: G128/G128M − 15 (Reapproved 2023)
Standard Guide for
Control of Hazards and Risks in Oxygen Enriched Systems
This standard is issued under the fixed designation G128/G128M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This guide covers an overview of the work of ASTM
mine the applicability of regulatory limitations prior to use.
Committee G04 on Compatibility and Sensitivity of Materials
FOR SPECIFIC PRECAUTIONARY STATEMENTS SEE SECTIONS 8 AND 11.
in Oxygen-Enriched Atmospheres. It is a starting point for
those asking the question: “What are the risks associated with
NOTE 2—ASTM takes no position respecting the validity of any
evaluation methods asserted in connection with any item mentioned in this
my use of oxygen?” This guide is an introduction to the unique
guide. Users of this guide are expressly advised that determination of the
concerns that must be addressed in the handling of oxygen. The
validity of any such evaluation methods and data and the risk of use of
principal hazard is the prospect of ignition with resultant fire,
such evaluation methods and data are entirely their own responsibility.
explosion, or both. All fluid systems require design
1.5 This international standard was developed in accor-
considerations, such as adequate strength, corrosion resistance,
dance with internationally recognized principles on standard-
fatigue resistance, and pressure safety relief. In addition to
ization established in the Decision on Principles for the
these design considerations, one must also consider the ignition
Development of International Standards, Guides and Recom-
mechanisms that are specific to an oxygen-enriched system.
mendations issued by the World Trade Organization Technical
This guide outlines these ignition mechanisms and the ap-
Barriers to Trade (TBT) Committee.
proach to reducing the risks.
1.2 This guide also lists several of the recognized causes of
2. Referenced Documents
oxygen system fires and describes the methods available to 3
2.1 ASTM Standards:
prevent them. Sources of information about the oxygen hazard
D2512 Test Method for Compatibility of Materials with
and its control are listed and summarized. The principal focus
Liquid Oxygen (Impact Sensitivity Threshold and Pass-
is on Guides G63, G88, Practice G93, and Guide G94. Useful
Fail Techniques)
documentation from other resources and literature is also cited.
D2863 Test Method for Measuring the Minimum Oxygen
NOTE 1—This guide is an outgrowth of an earlier (1988) Committee Concentration to Support Candle-Like Combustion of
G04 videotape adjunct entitled Oxygen Safety and a related paper by
Plastics (Oxygen Index)
Koch that focused on the recognized ignition source of adiabatic
D4809 Test Method for Heat of Combustion of Liquid
compression as one of the more significant but often overlooked causes of
Hydrocarbon Fuels by Bomb Calorimeter (Precision
oxygen fires. This guide recapitulates and updates material in the
Method)
videotape and paper.
G63 Guide for Evaluating Nonmetallic Materials for Oxy-
1.3 The values stated in either SI units or inch-pound units
gen Service
are to be regarded separately as standard. The values stated in
G72 Test Method for Autogenous Ignition Temperature of
each system are not necessarily exact equivalents; therefore, to
Liquids and Solids in a High-Pressure Oxygen-Enriched
ensure conformance with the standard, each system shall be
Environment
used independently of the other, and values from the two
G74 Test Method for Ignition Sensitivity of Nonmetallic
systems shall not be combined.
Materials and Components by Gaseous Fluid Impact
1.4 This standard does not purport to address all of the
G86 Test Method for Determining Ignition Sensitivity of
safety concerns, if any, associated with its use. It is the
Materials to Mechanical Impact in Ambient Liquid Oxy-
gen and Pressurized Liquid and Gaseous Oxygen Envi-
This guide is under the jurisdiction of ASTM Committee G04 on Compatibility
ronments
and Sensitivity of Materials in Oxygen Enriched Atmospheres and is the direct
G88 Guide for Designing Systems for Oxygen Service
responsibility of Subcommittee G04.02 on Recommended Practices.
Current edition approved March 1, 2023. Published March 2023. Originally
approved in 1995. Last previous edition approved in 2015 as G128/G128M – 15.
DOI: 10.1520/G0128_G0128M-15R23. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Koch, U. H., “Oxygen System Safety,” Flammability and Sensitivity of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Materials In Oxygen-Enriched Atmospheres , Vol 6, ASTM STP 1197, ASTM, 1993, Standards volume information, refer to the standard’s Document Summary page on
pp. 349–359. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G128/G128M − 15 (2023)
G93 Guide for Cleanliness Levels and Cleaning Methods for 3.1.3 hazard, n—source of danger; something that could
Materials and Equipment Used in Oxygen-Enriched En- harm persons or property.
vironments
3.1.4 ignition mechanisms, n—these are the specific physi-
G94 Guide for Evaluating Metals for Oxygen Service
cal attributes and system conditions that cause the initial fire
G124 Test Method for Determining the Combustion Behav-
within a system. A system designer must evaluate an oxygen-
ior of Metallic Materials in Oxygen-Enriched Atmo-
enriched system for all possible ignition mechanisms. A
spheres
common ignition mechanism for metals is particle impact. A
G126 Terminology Relating to the Compatibility and Sensi-
common ignition mechanism for non-metals is adiabatic com-
tivity of Materials in Oxygen Enriched Atmospheres
pression.
G175 Test Method for Evaluating the Ignition Sensitivity
3.1.5 ignition temperature, n—the temperature at which a
and Fault Tolerance of Oxygen Pressure Regulators Used
material will ignite under specific test conditions.
for Medical and Emergency Applications
3.1.6 impact-ignition resistance, n—the resistance of a ma-
2.2 ASTM Adjuncts:
terial to ignition when struck by an object in an oxygen-
Video: Oxygen Safety
enriched atmosphere under a specific test procedure.
2.3 ASTM CHETAH Analytical Computer Software Pro-
gram:
3.1.7 nonmetal, n—a class of materials consisting of
CHETAH Chemical Thermodynamic and Energy Release polymers, certain composite materials (polymer matrix and
Evaluation
brittle matrix composites in which the most easily ignited
2.4 Compressed Gas Association (CGA) Standards: component is not a metallic constituent), ceramics, and various
G-4.1 Cleaning Equipment for Oxygen Service
organic and inorganic oils, greases, and waxes. nonmetallic,
G-4.4 Oxygen Pipeline and Piping Systems adj.
2.5 European Industrial Gas Association (EIGA) Stan-
3.1.8 oxidant compatibility, n—the ability of a substance to
dards:
coexist at an expected pressure and temperature with both an
33/XX/E Cleaning of Equipment for Oxygen Service
oxidant and a potential source(s) of ignition within a risk
13/XX/E Oxygen Pipeline and Piping Systems
parameter acceptable to the user.
2.6 National Fire Protection Association (NFPA) Stan-
3.1.9 oxygen-enriched, adj—containing more than 23.5 mol
dards:
percent oxygen.
51 Standard for the Design and Installation of Oxygen-Fuel
3.1.9.1 Discussion—Other standards such as those pub-
Gas Systems for Welding, Cutting and Allied Processes
lished by NFPA and OSHA differ from this definition in their
53 Recommended Practice on Material, Equipment, and
specification of oxygen concentration.
Systems Used in Oxygen Enriched Atmospheres
3.1.10 qualified technical personnel, n—persons such as
55 Compressed Gases and Cryogenic Fluids Code
engineers and chemists who, by virtue of education, training,
99 Health Care Facilities Code
or experience, know how to apply the physical and chemical
2.7 Military Specifications:
principles involved in the reactions between oxidants and other
MIL-PRF-27617 Performance Specification, Grease, Air-
materials.
craft and Instrument, Fuel and Oxidizer Resistant
DOD-PRF-24574 (SH) Performance Specification, Lubri- 3.1.11 risk, n—probability of loss or injury from a hazard.
cating Fluid for Low and High Pressure Oxidizing Gas
3.1.12 system conditions, n—the physical parameters of a
Mixtures
specific system. These can include local and system-wide
pressure, temperature, flow, oxygen concentration, and others.
3. Terminology
3.1.13 wetted material, n—any component of a fluid system
3.1 Definitions:
that comes into direct contact with the system fluid.
3.1.1 See Terminology G126 for the terms listed in this
section.
4. Significance and Use
3.1.2 autoignition temperature (AIT), n—the lowest tem-
4.1 The purpose of this guide is to introduce the hazards and
perature at which a material will spontaneously ignite in an
risks associated with oxygen-enriched systems. This guide
oxygen-enriched atmosphere under specific test conditions.
explains common hazards that often are overlooked. It pro-
vides an overview of the standards and documents produced by
Available from ASTM International Headquarters. Order Adjunct No.
ASTM Committee G04 and other knowledgable sources as
ADJG0088.
well as their uses. It does not highlight standard test methods
Available from ASTM International Headquarters, 100 Barr Harbor Drive,
that support the use of these practices. Table 1 provides a
West Conshohocken, PA 19428, Order # DSC 51C, Version 7.2.
graphic representation of the relationship of ASTM G04
Available from Compressed Gas Association (CGA), 4221 Walney Rd., 5th
Floor, Chantilly, VA 20151-2923, http://www.cganet.com.
standards. Table 2 provides a list of standards published by
Available from European Industrial Gas Association, Publication de la Soudure
ASTM and other organizations.
Autogene, 32 Boulevard de la Chapelle, 75880 Paris Cedex 18, France.
Available from National Fire Protection Association (NFPA), 1 Batterymarch
4.2 The standards discussed here focus on reducing the
Park, Quincy, MA 02169-7471, http://www.nfpa.org.
hazards associated with the use of oxygen. In general, they are
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
not directly applicable to process reactors in which the delib-
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
dodssp.daps.dla.mil. erate reaction of materials with oxygen is sought, as in burners,
G128/G128M − 15 (2023)
TABLE 1 Relationship of ASTM Standards for Oxygen-Enriched Systems
bleachers, or bubblers. Other ASTM Committees and products 6.2 Oxygen has many commercial uses. For example, it is
(such as the CHETAH program ) and other outside groups are used in the metals industry for steel making, flame cutting, and
more pertinent for these. welding. In the chemical industry it is used for production of
synthetic gas, gasoline, methanol, ammonia, aldehydes, alco-
4.3 This guide is not intended as a specification to establish
hol production, nitric acid, ethylene oxide, propylene oxide,
practices for the safe use of oxygen. The documents discussed
and many others. It is also used for oxygen-enriched fuel
here do not purport to contain all the information needed to
combustion and wastewater treatment. For life support systems
design and operate an oxygen-enriched system safely. The
it is used in high-altitude flight, deep-sea diving, clinical
control of oxygen hazards has not been reduced to handbook
respiratory therapy or anesthesiology, and emergency medical
procedures, and the tactics for using oxygen are not simple.
and fire service rescues.
Rather, they require the application of sound technical judg-
ment and experience. Oxygen users should obtain assistance
7. Production and Distribution
from qualified technical personnel to design systems and
operating practices for the safe use of oxygen in their specific
7.1 Most oxygen is produced cryogenically by distilling
applications.
liquid air. The demand for ultrahigh purity within the semicon-
ductor industry has led to a more thorough distillation of
5. Summary
cryogenic oxygen. Further, noncryogenic production has be-
come significant in recent years. The principal difference
5.1 Oxygen and its practical production and use are re-
among these sources of oxygen is the resulting oxygen purity
viewed. The recognized hazards of oxygen are described.
detailed below. The hazards of oxygen are affected greatly by
Accepted and demonstrated methods to reduce those hazards
purity and, in general, higher purity is more hazardous
are reviewed. Applicable ASTM standards from Committee
However, fire events can and do occur in any oxygen–enriched
G04 and how these standards are used to help mitigate
atmosphere.
oxygen-enriched system hazards are discussed. Similar useful
documents from the National Fire Protection Association, the
7.2 Cryogenic Production—Cryogenically produced oxy-
Compressed Gas Association, and the European Industrial Gas
gen is distilled in a five-step process in which air is: (1) filtered
Association also are cited.
to remove particles; (2) compressed to approximately 700 kPa
[100 psig] pressure; (3) dried to remove water vapor and
6. Oxygen
carbon dioxide; (4) cooled to −160 °C [−256 °F] to liquefy it
6.1 Oxygen is the most abundant element, making up 21 % partially; and (5) distilled to separate each component gas. The
of the air we breathe and 55 % of the earth’s crust. It supports end products are oxygen, nitrogen, and inert gases such as
plant and animal life. Oxygen also supports combustion, causes argon and neon; the principal secondary products are nitrogen
iron to rust, and reacts with most metals. Pure oxygen gas is and argon. Commercial oxygen is produced to a minimum
colorless, odorless, and tasteless. Liquid oxygen is light blue 99.5 % purity, but typical oxygen marketed today is more
and boils at −183 °C [−297 °F] under ambient pressure. likely to be near 99.9 % purity.
G128/G128M − 15 (2023)
7.2.1 For high-volume bulk users, such as steel or chemical
plants, the oxygen plant is often adjacent to the user’s facility,
and gaseous oxygen is delivered by pipeline at low to medium
pressures, usually 700 kPa to 5500 kPa [100 psig to 800 psig].
7.2.2 Cryogenic liquid oxygen is delivered by trailer to
other large-volume users, who utilize liquid storage tanks, then
vaporize the liquid, and distribute the gas (Fig. 1 and Fig. 2).
7.2.3 Most users buy oxygen in small amounts, usually in
20 MPa or 2500 psig cylinders, and use it directly from the
cylinders or through manifolds and a piping distribution
system. Usually, the pressure is reduced with a regulator at the
cylinder or manifold.
7.3 Ultrahigh-Purity Oxygen—There are a few markets that
require high- and ultrahigh-purity oxygen. High-purity oxygen
typically delivers >99.99 % purity, whereas the demands of the
semiconductor industry have resulted in the marketing of
>99.999 % purity oxygen.
7.4 Noncryogenic Production—Noncryogenic oxygen pro-
duction processes include pressure swing adsorption (PSA),
vacuum swing adsorption (VSA), and membrane separation. In
general, these methods produce oxygen less pure than cryo-
genically produced oxygen—typically <97 %, with the balance
being nitrogen, argon, and carbon dioxide. However, these
processes use less power and offer a cost advantage for
high-volume users who do not need higher purity.
FIG. 2 Cryogenic Oxygen Storage
The equipment for these systems is typically large and is
Image courtesy of Air Liquide America
located on site. However, small medical-oxygen generators
used in the home also are included in this category.
21 % oxygen, are common. The injuries, loss of life, and
8. Hazards and Risks
property damage these fires cause can be devastating. Fires and
8.1 How can oxygen be hazardous? It is all around us. It explosions that occur in oxygen-enriched atmospheres can be
supports life and is used to support or resuscitate a person with even more devastating due to the intensity of the combustion.
oxygen deficiency (hypoxemia). It may have been used in a
8.3 Oxygen is not flammable by itself, but it supports
common familiar system for years without a problem. Could it
combustion. Fire typically occurs when an oxidant such as
be that oxygen is not hazardous? No, oxygen-enriched systems
oxygen is combined chemically with a fuel in the presence of
present definite hazards.
an ignition source or sufficient heat (Fig. 3). Hence, although
8.2 Oxygen makes materials easier to ignite and their oxygen is not flammable, its contribution to the production of
fire is otherwise comparable to that of the fuel. If there is no
subsequent combustion more intense, more complete, and
more explosive than in air alone. Fires in air, which contain just fuel, there is no fire. If there is no oxygen, there is no fire.
8.4 The ability to support and enhance combustion after
ignition is the hazard associated with an oxygen-enriched
atmosphere. The risk to people and property that accompanies
this hazard is variable. Sometimes the human risk is grave;
sometimes the economic risk is severe. In these instances, the
need to prevent combustion is imperative. Occasionally the
FIG. 1 Skid-Mounted Cryogenic Oxygen Storage FIG. 3 The Fire Triangle
Image courtesy of Essex Industries ©NFPA, reproduced with permission. Text ©ASTM International 2014.
G128/G128M − 15 (2023)
risk is small enough that it can be accepted and other tactics oxygen, at various concentrations and pressures, by tests that
may be developed to minimize the risk. The overall concepts of relate to the common ignition mechanisms.
hazard and risk have been lumped into the term “oxygen
9.1.2 Guides G63 and G94 provide the designer with
compatibility.” compilations of data obtained by the above ASTM test methods
8.4.1 ASTM Committee G04 first codified its interpretation
and present a structured approach to using that data in practical
of the concept of “oxygen compatibility” in its Technical and applications. Guide G88 presents a systematic approach to
Professional Training course textbook Manual 36, Safe Use of
system design with emphasis on the special factors that should
Oxygen and Oxygen Systems: Guidelines for Oxygen System be considered to minimize the risk of ignition and fire.
Design, Materials Selection, Operations, Storage, and Trans-
9.1.3 Practice G93 covers the selection of methods and
portation:
materials to clean equipment for oxygen service. Examples are
Oxygen compatibility is the ability of a substance to coexist
provided for specific materials and applications.
with both oxygen and a potential source(s) of ignition within
9.1.4 ASTM Committee G04 sponsors an international
the acceptable risk parameter of the user [at an expected
Symposium on the Flammability and Sensitivity of Materials
pressure and temperature].
in Oxygen-Enriched Atmospheres every two to three years.
8.4.1.1 In this definition, a system is oxygen compatible if it
The papers presented at these symposia cover topics from
cannot burn or is unlikely to burn, if the occurrence of fires is
combustion theory to practical applications and fire experi-
adequately infrequent, or even if potential fires can be isolated
ences. They are published in Special Technical Publications,
and their effects can be tolerated.
which, along with their extensive list of references, represent
the largest existing collection of published work on this
8.5 Other organizations have a similar respect for the
subject.
hazards of oxygen. NFPA 53 is a concise, readable booklet that
9.1.5 A two-day Technical and Professional Training
describes oxygen, its uses and hazards, design guidelines, aids
Course, “Fire Hazards in Oxygen Handling Systems,” is
to material selection, and references. Significantly, NFPA 53
presented by ASTM G04 members at least twice a year at a
presents more than 40 case studies of accidents with oxygen
variety of locations. This course introduces participants to the
that shows just how serious, yet subtle, the hazard can be.
fire risk in oxygen-enriched systems and presents a systematic
Further, in most of its publications (NFPA 51, NFPA 55, NFPA
approach to reducing the fire risk through the application of
99), the NFPA view of oxygen compatibility is given as:
relevant ASTM and other industry standard publications. The
“Compatibility involves both combustibility and ease of igni-
textbook, Fire Hazards in Oxygen Systems, teaches how to
tion. Materials that burn in air will burn violently in pure
apply the many resources available to reduce the risk of oxygen
oxygen at normal pressure and explosively in pressurized
fires. The video used in the course, Oxygen Safety, is a brief
oxygen. Also many materials that do not burn in air will do so
introduction to some of the hazards present in oxygen-enriched
in pure oxygen, particularly under pressure. Metals for con-
systems, particularly those often overlooked.
tainers and piping must be carefully selected, depending on
service conditions. The various steels are acceptable for many
9.2 Industry associations such as the Compressed Gas
applications, but some service conditions may call for other
Association, National Fire Protection Association, and Euro-
materials (usually copper or its alloys) because of their greater
pean Industrial Gas Association have developed product
resistance to ignition and lower rates of combustion.
standards, design guides, codes, and training aides to assist in
“Similarly, materials that can be ignited in air have lower
reducing the risk of oxygen-enriched system fires.
ignition energies in oxygen. Many such materials may be
9.3 Government agencies serving aerospace programs, the
ignited by friction at a valve seat or stem packing or by
military, and national research laboratories, offer oxygen sys-
adiabatic compression produced when oxygen at high pressure
tem safety information. In some countries, product testing and
is rapidly introduced in a system initially at low pressure.”
approval services are available through national laboratories.
9. Sources of Information
9.4 Most oxygen producers provide their users with safety
publications and offer resources to assist in design, operation,
9.1 Despite the hazards inherent with pure oxygen and its
and training for personnel. A few examples of such publica-
mixtures, the risk of injury and economic loss can largely be
tions are listed in Appendix X1. That list is neither complete
controlled using methods documented in ASTM publications
nor is it an endorsement of those publications.
and many other sources. This guide is an overview of such
sources, intended only to assist the reader in finding additional
10. Causes of Fires in Oxygen
information.
9.1.1 Designing equipment and systems to function safely
10.1 Particle Impact—This ignition mechanism is typically
in oxygen-enriched environments requires information about
found to ignite metals. Particle impact ignition occurs when a
the behavior of materials in such environments. ASTM stan-
particle at high linear velocity strikes a flammable target. The
dard test methods have been developed to measure the ignition
high linear velocity can occur within several components in the
and combustion properties of materials in gaseous and liquid
system. Flow control valves, orifices, regulators, check valves
and other fluid components can all provide flow restrictions
that result in high linear velocity. The kinetic energy of the
For more information regarding Standards Technology Training Courses and
particle creates heat at the point of impact, which can ignite the
corresponding text material, contact ASTM International Headquarters, Standards
Technology Training, 100 Barr Harbor Drive, West Conshohocken, PA 19428. particle, the target, or both.
G128/G128M − 15 (2023)
10.2 Adiabatic Compression—This ignition mechanism is nents due to either the components’ inability to transmit the
typically found to ignite non-metals. Adiabatic compression heat or the components’ low heat of combustion.
ignition occurs when there is rapid pressurization of a system
10.9 Thermal Ignition—This ignition mechanism is typi-
volume with an exposed non-metal. The rapid pressurization
cally found to ignite non-metals. Thermal ignition occurs when
results in heating that causes the temperature to rise above the
an outside heat source raises the temperature of a material
auto-ignition temperature of the non-metal material and the
above its auto-ignition temperature and ignites the material.
material starts to burn.
10.10 There is a considerable body of useful information
10.3 Mechanical Impact—This ignition mechanism is typi-
that can aid in understanding the principles of ignition and
cally found to ignite non-metals. Mechanical impact ignition
flammability in oxygen-enriched environments. New theories
occurs when a material experiences impacts that generate heat
are under development, as frequently reported at Committee
in excess of the auto-ignition temperature and the material
G04 symposia. These developments are expanding our knowl-
starts to burn.
edge of oxygen safety. Indeed, some oxygen fires have not
10.4 Galling and Friction (Frictional Heating)—This igni- been explained fully and their causes are not known. However,
tion mechanism can be found to ignite both metals and many common ignition mechanisms and causes of oxygen-
non-metals. Frictional heating ignition in non-metals occurs enriched system fires are recognized and well understood. For
when two surfaces are rubbing in a way that the non-metal a more detailed explanation of these ignition mechanisms
material heats above the auto-ignition temperature. Frictional please refer to the other standards published through the ASTM
heating ignition in metals occurs when the two surfaces are G04 committee.
rubbing and the metal oxide layer is removed, which exposes
11. Hazards
the active, bare metal to the enriched oxygen.
11.1 Recognized Hazards—Within any system, a number of
10.5 Electric Arc—This ignition mechanism can be found to
conditions are recognized that can increase the hazard and
ignite both metals and non-metals. Electric arc ignition occurs
make ignition more likely: (1) oxygen concentration and
when powered components are ungrounded or otherwise build
associated diluents; (2) pressure; (3) temperature; (4) phase; (5)
an electrical charge that once released provides sufficient heat
velocity; (6) time and age; and (7) mechanical failure.
to ignite the material.
11.1.1 Oxygen Concentration and Associated Diluents—
10.6 Static Discharge—This ignition mechanism can be
Higher oxygen concentrations increase the hazards of ignition
found to ignite both metals and non-metals. Static discharge
and fire intensity because more oxygen is available to mix with
ignition is similar to electric arc ignition. It occurs when
the fuel. The nature of the diluent gases can have a significant
electrical charge builds and is released providing sufficient heat
effect on the overall hazard. Inert diluents of large molecular
to ignite the material.
weight are most effective at reducing the hazard. In a few
10.7 Resonance—This ignition mechanism can be found to
extreme cases, even small amounts of diluents (tenths of a
ignite both metals and non-metals. Resonance ignition occurs
percent) can reduce the flammability of some materials.
when particles or the gas molecules vibrate with increasing
11.1.2 Pressure—Higher pressures increase the hazards of
amplitude inside a cavity. The resonance generates sufficient
ignition and fire intensity. Pressure increases the density of the
heat to ignite the particles or nearby material.
gas, with the same effect as increasing the concentration: more
oxygen is available to the fuel, so materials ignite easier and
10.8 Promoted Ignition/Kindling Chain—This ignition
burn faster. Pressure also increases the linear gas velocity at
mechanism can be found to ignite both metals and non-metals.
restrictions such as valves, regulators, and intersections which
Promoted ignition/kindling chain ignition occurs when a burn-
increases particle impact and compression heating effects.
ing material has a heat of combustion sufficient to ignite a
11.1.3 Temperature—Temperatures most often encountered
nearby material. The fire continues to ignite nearby compo-
in oxygen-enriched systems have relatively little effect on the
intensity of combustion and resulting damage. However,
higher temperatures tend to increase the likelihood of ignition.
They may enable combustion to occur in a system that is not
otherwise flammable because less energy must be added to
reach the ignition temperature of a material. In addition, high
temperatures can accelerate the aging of polymers and thereby
reduce their compatibility with oxygen.
11.1.4 Phase—Liquid oxygen exists at cryogenic
temperatures, and low temperatures generally result in a
decreased likelihood of ignition, fire intensity, and resulting
damage. However, the density of liquid oxygen is hundreds of
times greater than that of gas and it is 100 % pure, making far
FIG. 4 Adiabatic Compression Can Occur When Oxygen Under
more oxygen available to the fuel than does high pressure
High Pressure is Released Quickly into a Low-pressure System.
gaseous oxygen. Further, combustion generates enormous
The Gas Flow Can Reach the Speed of Sound, and if it Encoun-
pressures as the liquid changes to a gas. If liquid oxygen is
ters an Obstruction, the Temperature Can Rise High Enough to
Initiate Ignition and Cause a Fire mixed with high-surface-area flammable materials the resulting
G128/G128M − 15 (2023)
fire can be explosive. Indeed, liquid oxygen in combination In each instance, the preceding levels are not omitted, rather,
with carbon particles has been used as a high explosive. For they become even more strict to form the foundation on which
this reason, liquid oxygen containing fine particles represents the following levels are built.
an exceptionally severe hazard.
12.2 Ordinary methods of preventing fires in air, separating
11.1.5 Velocity—Increased oxygen velocities in flowing sys-
the oxidant, fuel, and ignition sources, do not apply in
tems lead to higher particle velocities, which increase the
oxygen-enriched systems because: (1) the process fluid is the
likelihood of ignition by particle impact.
oxidant and cannot be removed; (2) the materials used to build
11.1.6 Time and Age—Time and age are important hazards.
the system are flammable in oxygen under at least some
Many fires in oxygen-enriched atmospheres occur the first time
conditions, hence the system is the fuel and cannot be
the system is used or the first time it is operated after a
eliminated; and (3) ignition sources exist within the system
shutdown. Contributing factors include poor design, incorrect
itself. Therefore, fire prevention in oxygen-enriched systems
operation, inadequate cleaning, and foreign objects left in the
requires a new focus to control these inseparable elements.
system. Systems fabricated with materials not considered
Combustible materials cannot be eliminated, but their selection
compatible, based on the guidance of ASTM standards, may
can be controlled. Similarly, ignition sources in the system
operate successfully for extended periods. However, with time,
must be identified and controlled.
polymers in the system may age and become brittle or porous,
12.2.1 Like in air systems, there is a series of control
contamination may increase, and mechanical failures may
measures that must be taken to prevent fires in oxygen services,
become more likely. Thus, it becomes easier to initiate the
depending on the severity of the fire hazard. Progressively
kindling chain that results in a system fire.
more stringent practices are applied in this order: cleaning,
11.1.7 Mechanical Failure—Mechanical failures in oxygen-
compatible lubricants, compatible polymers and other
enriched systems frequently lead to ignition and become more
nonmetals, and compatible metals. When oxygen concentration
likely as the system becomes older. The mechanical impact of
and pressures are low, the hazard is lowest and cleaning may be
broken parts can ignite components. Rubbing, in a compressor,
the only control necessary. As oxygen enrichment and pressure
for example, can generate heat to ignite parts and can shed
increase, all wetted material including lubricants, metals, and
particles that could be ignited as they are generated or from
non-metals must be selected more carefully.
impact as they are carried elsewhere in the system. Particles
12.3 Recognizing, identifying, and controlling potential
also can be generated as polymers wear and age and lead to a
sources of ignition and possible causes of fire is not simple.
mechanical failure. Failed seals can lead to rapid pressuriza-
Present knowledge does not enable us to identify all potential
tion. Hence, every oxygen-enriched system component should
ignition sources. Hence, few oxygen-enriched systems can
be designed for high mechanical reliability and special atten-
enjoy a certainty that fires are not possible. There is a strong
tion should be given to the potential effect of mechanical
empirical influence in the approach to oxygen-enriched system
failures.
safety practices. To a large extent, one does what has been
successful in the past, provided it has been successful often, for
12. Fire Prevention
long periods of time, and is based on sound principles. For this
12.1 Combustion in open air, which contains about 21 % reason, ASTM Committee G04 standards take a multi-pronged
oxygen, is a familiar hazard. Well-known fire prevention approach that attempts to align as many factors as possible
methods focus on separating the three elements essential to toward reducing the likelihood of ignition and fire.
creating a fire: (1) the oxidant; (2) the fuel; and (3) the ignition 12.3.1 This approach is based on using the extensive body
sources. Preventive measures are applied progressively, de- of information available on the ignition and flammability of
pending on the severity of the fire hazard. materials and on methods with demonstrated ability to reduce
the number and severity of fires in oxygen. Guides G63, G88,
12.1.1 For example, in an area where combustible materials
and G94, and Practice G93 describe many factors affecting
of minimal hazard are stored, it may be sufficient simply to
oxygen-enriched systems and describe how to reduce the
maintain good housekeeping practices, preventing accumula-
hazards associated with these systems.
tions of combustible trash and to prohibit open fires. In a
12.3.2 Those discussions correlate control of oxygen-
flammable solvent storage area, the fire hazard is greater;
enriched system hazards with special attention to: (1) system
consequently, prevention includes more strict housekeeping,
design; (2) component selection; (3) system operation; (4)
elimination of all other combustible storage, and prohibition of
all open flames and sparks. If flammable liquids are used in cleaning; (5) lubricants; (6) polymers and other nonmetals; (7)
metals; or (8) isolation and shielding. Each of these elements is
open containers, allowing the vapors to mix with air, one
would do all of the above and add such measures as explosion- discussed in detail below.
proof electrical systems to control ignition sources. Finally, if
13. System Design
highly flammable materials are used in large quantities or in
processes, it may become necessary to displace the air with an
13.1 Oxygen-enriched system design should not be under-
inert gas to eliminate the oxidant, in addition to taking all the
taken casually. These systems require careful and specialized
preceding measures.
design considerations. The first and most important rule is:
12.1.2 This example shows that as the severity of the fire Consult an expert! Guides G63, G88, G94, and G128/G128M,
hazard in air increases, progressively more stringent precau- and Practice G93 define “qualified technical personnel” and
tions are taken and prevention moves to the next higher level. provide vital information for use by these experts. Indeed in
G128/G128M − 15 (2023)
many companies, specific individuals are designated as spe- products can be marketed under a blanket claim of meeting any
cialists to acquire the expertise and assist others in oxygen- of the four applicable standards (G63, G88, G93, or G94).
enriched system design. Clearly, the thrust of these standards is to provide guidelines to
qualified technical personnel who can evaluate system needs in
13.2 Oxygen-enriched system design should begin with the
the context of a particular application. As the application
same principles as conventional air or gas system design and
changes, such as exposure to higher pressure, a host of
follow the same nationally recognized codes and standards.
conditions change, or hazard thresholds are crossed, and that
There are no special codes that mandate how to design
may render previously acceptable products unacceptable for
oxygen-enriched systems. The added hazards inherent in the
further use. Therefore, although there may be a few products
use of oxygen should then be evaluated to modify conventional
that are acceptable in any and all oxygen applications, one
practices. In general, that leads to a more, not less, conservative
cannot consider products to be “approved for oxygen service”
design.
under the procedures of these standards without also specifying
13.3 The severity of system operating conditions is defined
the conditions for which the approvals are intended.
by five of the seven hazards discussed in Section 11:
14.2 Some products are marketed for oxygen service, but
concentration, pressure, temperature, phase, and time. As these
not every experienced designer will agree that every one of
factors increase the hazards, the system design must be
these products has adequate oxygen compatibility or even that
modified to a greater extent. Oxygen concentration and phase
a blanket approval is reasonable. Some companies do list
are established by the system function, but the others can be
materials approved across the board, but many others tie
influenced by design. For example, the hazard of high pressure
approval to specific applications and level of application
can be minimized by placing a regulator as close as possible to
hazard. The user must determine whether the properties of the
the gas source. Temperatures can be limited, for example, by
particular products (whether or not they are marketed for
including protection from runaway heaters. The effects of time
oxygen service) actually meet the needs of the user’s specific
and age can be mitigated by designing for effective preventive
application.
maintenance.
14.2.1 Performance tests conducted by hardware manufac-
13.3.1 Linear velocity is a hazard that is controlled primar-
turers generally do not simulate any specific application.
ily by overall system design. Line sizes should be selected to
follow guides for oxygen-enriched system velocity. System Laboratory tests cannot duplicate the endless variety of actual
operating conditions; such tests only indicate a predicted result
velocity is generally lower than the limits used in conventional
systems. Abrupt size changes and the location of intersections in a controlled laboratory setting and cannot ensure the same
result in a particular application or service.
and components can be controlled by system design to mini-
mize particle impact and compression heating ignition
14.2.2 Material qualification tests also are method specific
mechanisms, especially near polymers. CGA G-4.4 recom-
and rarely afford blanket approval. The user should evaluate
mends that linear velocities should be limited wherever pos-
the material test results along with the test method to determine
sible and means should be provided to increase the resistance
if they correspond to the way the material will be used in a
to ignition at locations where high linear velocities may occur.
specific design.
13.4 The considerations discussed below must be evaluated
14.3 It is also important to note that most common industrial
individually and also integrated into the overall design. For
components, such as valves, fittings, filters, regulators, gages,
example, initial cleanliness is established as components are
and other instruments, are not designed for specific applica-
built and the system is fabricated. The system design must
tions. Rather, they are versatile, general-purpose products that
consider maintaining the required level of cleanliness
can be used properly in many types of applications and
thereafter, such as by preventing contamination during opera-
systems. Hardware manufacturers in general have neither the
tion and maintenance and by providing for inspection and
experience nor expertise to select the most appropriate com-
cleaning throughout the life of the system.
ponents for a specific use, such as an oxygen-enriched system.
Only the oxygen-enriched system designer or user can have
13.5 Guide G88, CGA G-4.4, NFPA 51 and 55, and many
full knowledge of the entire system and each component’s
others provide excellent guidelines for system design, although
function, which must be considered when selecting the system
these references are not handbooks. The ASTM G04 Commit-
components. Oxygen-enriched system designers and users both
tee Technical and Professional Training course Fire Hazards in
must be sensitive to product function, material compatibility,
Oxygen Handling System teaches the fundamentals of oxygen
adequate ratings, and proper installation, operation, and main-
safety for oxygen process designers and equipment specifiers
tenance.
and includes a textbook. This course introduces participants
to the fire risk in oxygen-enriched systems and presents a
14.4 Valve selection requires special attention by the system
systematic approach to reducing the fire risk through the
designer, because valves are one of the few mechanical items
application of relevant ASTM and other industry standard
that are actuated routinely while the system is in use. The
publication.
designer must determine the type of valve, its location, how it
will be operated, and, often neglected, how it might be
14. Component Selection
operated incorrectly. For example, a ball valve sometimes is
14.1 ASTM Committee G04 standards do not recommend included in a system as a quick-closing valve for emergency
specific products for oxygen service and do not imply that shut off in case of a system fire. However, such emergency shut
G128/G128M − 15 (2023)
off valves have been used improperly to pressurize or vent the designer may require the manufacturer to provide a quality
system and thereby caused ignition by adiabatic compression. plan with hold points for customer inspection. These hold
14.4.1 Particular attention should be directed to valve pres- points may include:
sure and temperature ratings, internal materials of construction, 14.5.4.1 Confirming Bill of Materials,
and how readily the valve can be cleaned and kept clean.
14.5.4.2 Confirming components are free of burrs, sharp
Valves often are selected with higher ratings, greater wall
edges and mechanical damage,
thicknesses, and more fire-resistant materials than the rest of
14.5.4.3 Confirming application of the proper amount and
the system because they are exposed to more severe service
type of lubricant, and
conditions.
14.5.4.4 Inspecting for oxygen cleanliness (e.g. free of oil,
grease, lubricants, sealant anti-seizing paste or preservatives).
14.5 As valves are opened and closed, they almost always
This inspection may be done by visual inspection under
generate localized high linear velocities near the valve seat or
UV-light or white light.
immediately downstream. This creates a local increase in the
hazard level at the valve loc
...
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