ASTM G126-16(2023)

Standard Terminology Relating to the Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres

SCOPE
1.1 This terminology defines terms related to the compatibility and sensitivity of materials in oxygen enriched atmospheres. It includes those standards under the jurisdiction of ASTM Committee G04.  
1.2 The terminology concentrates on terms commonly encountered in and specific to practices and methods used to evaluate the compatibility and sensitivity of materials in oxygen. This evaluation is usually performed in a laboratory environment, and this terminology does not attempt to include laboratory terms.  
1.3 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.

General Information

• Status: Published
• Publication Date: 30-Jun-2023
• ICS: 01.040.13 - Environment. Health protection. Safety (Vocabularies)
• ICS: 13.230 - Explosion protection
• Technical Committee: G04 - Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres
• Drafting Committee: G04.02 - Recommended Practices

Relations

• Refers: ASTM D2863-23 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Oct-2023
• Refers: ASTM D2863-95 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-like Combustion of Plastics (Oxygen Index)
• Effective Date: 29-Sep-2023
• Refers: ASTM D2863-19 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Oct-2019
• Refers: ASTM G121-18 - Standard Practice for Preparation of Contaminated Test Coupons for the Evaluation of Cleaning Agents
• Effective Date: 01-Dec-2018
• Refers: ASTM G124-18 - Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
• Effective Date: 01-Nov-2018
• Refers: ASTM D2863-17a - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Dec-2017
• Refers: ASTM D2863-17 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 15-Aug-2017
• Refers: ASTM G136-03(2016) - Standard Practice for Determination of Soluble Residual Contaminants in Materials by Ultrasonic Extraction
• Effective Date: 01-May-2016
• Refers: ASTM G131-96(2016) - Standard Practice for Cleaning of Materials and Components by Ultrasonic Techniques
• Effective Date: 01-May-2016
• Refers: ASTM D2863-13 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Sep-2013
• Refers: ASTM D2863-12e1 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Apr-2012
• Refers: ASTM D2863-12 - Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)
• Effective Date: 01-Apr-2012
• Refers: ASTM G86-98a(2011) - Standard Test Method for Determining Ignition Sensitivity of Materials to Mechanical Impact in Ambient Liquid Oxygen and Pressurized Liquid and Gaseous Oxygen Environments
• Effective Date: 01-Apr-2011
• Refers: ASTM G93-03(2011) - Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments
• Effective Date: 01-Apr-2011
• Refers: ASTM G124-10 - Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
• Effective Date: 01-Nov-2010

Overview

ASTM G126-16(2023), Standard Terminology Relating to the Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres, defines critical terms for the evaluation of materials used in oxygen-enriched environments. Developed by ASTM Committee G04, this terminology standard supports shared understanding and communication in assessing materials’ behavior and safety when exposed to high concentrations of oxygen. Such evaluations are essential for industries where oxygen’s reactivity may affect material performance, reliability, or safety.

This international standard aligns with globally recognized practices as outlined by the World Trade Organization’s Technical Barriers to Trade (TBT) Committee, ensuring broad applicability and acceptance.

Key Topics

ASTM G126-16(2023) covers a wide range of vocabulary related to oxygen compatibility and sensitivity, including:

• Material Compatibility: Terms addressing how materials react or coexist with oxygen-enriched atmospheres.
• Material Sensitivity: Definitions related to ignition, combustion, or degradation risks for both metallic and nonmetallic materials.
• Testing and Evaluation: Descriptions of common laboratory practices, testing criteria, and reference conditions used in compatibility and sensitivity assessments.
• Contamination and Cleanliness: Vocabulary on the identification, impact, and management of contaminants in oxygen systems and their effects on performance and safety.
• Aging and Degradation: Distinctions between different forms of aging (natural, artificial, accelerated) and their relevance to material sensitivity in oxygen-rich environments.
• Service Classifications: Terms defining direct and indirect oxygen service, operating conditions, and critical thresholds for safe use.
• Hazard and Risk Terms: Standardized language for discussing potential hazards, risks, and reaction effects.

Applications

This terminology standard is valuable across a multitude of industries and environments where oxygen-enriched atmospheres are present, such as:

• Aerospace and Aviation: For oxygen systems in aircraft and spacecraft, ensuring that materials meet strict safety and compatibility standards.
• Healthcare and Medical Devices: In the design and maintenance of respiratory equipment and oxygen delivery systems, where material performance directly impacts patient safety.
• Industrial Gas and Chemical Processing: Facilities dealing with compressed or liquefied oxygen for production, transportation, or storage rely on these terms for material selection and risk assessment.
• Fire Safety Engineering: Professionals assessing fire hazards in environments with elevated oxygen levels use these definitions for testing and evaluation.
• Materials Science and Research: Laboratories and test houses use standardized vocabulary for reporting on compatibility and ignition sensitivity studies.

Using a harmonized terminology set facilitates communication among engineers, scientists, manufacturers, and regulators-reducing misunderstandings and enhancing safety when working in oxygen-rich conditions.

Related Standards

ASTM G126-16(2023) references and supports understanding of several related ASTM standards that address the evaluation and handling of materials for oxygen service:

• ASTM G63: Evaluation of nonmetallic materials for oxygen service
• ASTM G72: Test method for autogenous ignition temperature in oxygen-enriched atmospheres
• ASTM G93: Cleanliness levels and cleaning methods for materials in oxygen systems
• ASTM G94: Guide for evaluating metals in oxygen applications
• ASTM G114: Practices for evaluating the age resistance of polymeric materials
• ASTM D2863: Measuring the minimum oxygen concentration to support combustion of plastics
• ASTM G124, G125, G128, G131, G136, G144, G145: Various methods relating to combustion, contamination, cleaning, and fire incident analysis

These referenced standards complement G126 by providing methods and criteria for testing, cleaning, and evaluating materials in oxygen-enriched conditions, making the terminology directly relevant to safe systems design and maintenance.

Keywords: oxygen compatibility, material sensitivity, oxygen-enriched atmosphere, ASTM G126, terminology, material safety, fire risk, contamination control, international standards.

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: G126 − 16 (Reapproved 2023)
Standard Terminology Relating to the
Compatibility and Sensitivity of Materials in Oxygen
Enriched Atmospheres
This standard is issued under the fixed designation G126; 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 gen and Pressurized Liquid and Gaseous Oxygen Envi-
ronments
1.1 This terminology defines terms related to the compat-
G88 Guide for Designing Systems for Oxygen Service
ibility and sensitivity of materials in oxygen enriched atmo-
G93 Guide for Cleanliness Levels and Cleaning Methods for
spheres. It includes those standards under the jurisdiction of
Materials and Equipment Used in Oxygen-Enriched En-
ASTM Committee G04.
vironments
1.2 The terminology concentrates on terms commonly en-
G94 Guide for Evaluating Metals for Oxygen Service
countered in and specific to practices and methods used to
G114 Practices for Evaluating the Age Resistance of Poly-
evaluate the compatibility and sensitivity of materials in
meric Materials Used in Oxygen Service
oxygen. This evaluation is usually performed in a laboratory
G120 Practice for Determination of Soluble Residual Con-
environment, and this terminology does not attempt to include
tamination by Soxhlet Extraction
laboratory terms.
G121 Practice for Preparation of Contaminated Test Cou-
1.3 This international standard was developed in accor-
pons for the Evaluation of Cleaning Agents
dance with internationally recognized principles on standard- G122 Test Method for Evaluating the Effectiveness of
ization established in the Decision on Principles for the
Cleaning Agents and Processes
Development of International Standards, Guides and Recom- G124 Test Method for Determining the Combustion Behav-
mendations issued by the World Trade Organization Technical
ior of Metallic Materials in Oxygen-Enriched Atmo-
Barriers to Trade (TBT) Committee. spheres
G125 Test Method for Measuring Liquid and Solid Material
2. Referenced Documents
Fire Limits in Gaseous Oxidants
G128 Guide for Control of Hazards and Risks in Oxygen
2.1 ASTM Standards:
Enriched Systems
D2863 Test Method for Measuring the Minimum Oxygen
G131 Practice for Cleaning of Materials and Components by
Concentration to Support Candle-Like Combustion of
Ultrasonic Techniques
Plastics (Oxygen Index)
G136 Practice for Determination of Soluble Residual Con-
G63 Guide for Evaluating Nonmetallic Materials for Oxy-
taminants in Materials by Ultrasonic Extraction
gen Service
G144 Test Method for Determination of Residual Contami-
G72 Test Method for Autogenous Ignition Temperature of
nation of Materials and Components by Total Carbon
Liquids and Solids in a High-Pressure Oxygen-Enriched
Analysis Using a High Temperature Combustion Analyzer
Environment
G145 Guide for Studying Fire Incidents in Oxygen Systems
G74 Test Method for Ignition Sensitivity of Nonmetallic
Materials and Components by Gaseous Fluid Impact
3. Terminology
G86 Test Method for Determining Ignition Sensitivity of
Materials to Mechanical Impact in Ambient Liquid Oxy-
3.1 Definitions:
aging, n—the exposure of a material to stress, such stress of
which may include time, pressure, temperature, abrasion,
This terminology is under the jurisdiction of ASTM Committee G04 on
ionizing radiation, light, impact with gas or particles, tensile
Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres and is
the direct responsibility of Subcommittee G04.02 on Recommended Practices. or compressive force (either static or cyclic), or any other
Current edition approved July 1, 2023. Published July 2023. Originally approved
feature that may be present individually or in combination.
in 1994. Last previous edition approved in 2016 as G126 – 16. DOI: 10.1520/
G114
G0126-16R23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
accelerated aging, n—a type of artificial aging whereby the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
effect of prolonged exposure during service is stimulated by
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. aging at elevated temperature. G114
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G126 − 16 (2023)
artificial aging, n—aging in which a stress variable is outside control coupon (witness coupon) , n—a coupon made from the
the domain of exposure that a material might see in a same material and prepared in exactly the same way as the
component for oxygen service or in which an alternative test coupons which is used to verify the validity of the
mechanism is used to produce an effect that simulates the method or part thereof.
results of natural aging. DISCUSSION—In practice, the control coupon is contaminated in the
same manner as the test coupons and is subjected to the identical
DISCUSSION—The degree of artificiality may vary on a large scale. An
example of mild artificiality is exposure of a material to a greater cleaning procedure. G120, G121, G131
pressure than it experiences in the use condition. An example of
degas, v—the process of removing gases from a liquid. G131,
extreme artificiality is the use of sandpaper to increase a material’s
G136
surface roughness to simulate particle-impact abrasion that occurs in
the use condition. A high degree of artificiality affects the strength of
direct incident cause, n—the mechanical or thermodynamic
conclusion that can be drawn, because it may be difficult to relate the
event (such as breakage of a component or near-adiabatic
results to the use condition. Artificial aging that accelerates natural
compression), the physicochemical property (such as heat of
aging but does not alter the resulting effect is preferred. G114
combustion), the procedure (such as a valve opening rate), or
autoignition temperature (AIT), n—the lowest temperature
any departure(s) from the intended state of any of these
at which a material will spontaneously ignite in an oxygen-
items, that leads directly to ignition, or fire, or both. G145
enriched atmosphere under specific test conditions.
direct oxygen service, n—service in contact with oxygen-
G63, G72, G94, G128
enriched atmosphere during normal operations.
average regression rate (Regression Rate of the Melting
DISCUSSION—Examples are oxygen compressor piston rings or con-
Interface [RRMI]), n—the average rate at which the melting
trol valve seats. G63, G88, G94
interface advances along the test sample length as melting of
energy threshold, n—the highest impact energy level at a
the test sample occurs. G124
given pressure for which the passing criteria have been met.
blank, n—the contamination level of a fluid when the test
G86
coupon is omitted.
DISCUSSION—Sometimes referred to as the “background level.” exemption pressure, n—the maximum pressure for an engi-
neering alloy at which there are no oxygen velocity restric-
G121
tions (from CGA 4.4 and EIGA doc IGC13). G94
burn length, n—the burn length is the length of the sample that
fibers, n—particulate matter with a length of 100 μm or greater
has been consumed by burning.
and a length-to-width ratio of 10 to 1 or greater. G93
DISCUSSION—The burn length is determined by subtracting the
post-test sample length from the pretest sample length (which does not
fire limit, n—the threshold limit conditions that will just
include the promoter length or the region used by the test sample
support self-sustained burning of a material under a combi-
support). G124
nation of specified conditions and at least one variable
characteristic elements, n—those factors that must be present
parameter. (Typically oxidant concentration, diluent nature,
for an ignition mechanism to be active in an oxygen-
pressure, temperature, geometry, flow or flame parameters
enriched atmosphere. The more characteristic elements pres-
etc.) G125
ent for a particular ignition mechanism, the more active that
flammable material, n—a material that is able to ignite and
mechanism is. G88
demonstrate self-sustained burning per specific test method
cleaning effectiveness factor (CEF), n—the fraction of con-
criteria considering configurational, environmental, and pro-
taminant removed from an initially contaminated test cou-
moter energy conditions (example: Oxidizer%, P, T, etc.).
pon as determined by gravimetric techniques. G122
DISCUSSION—It is noteworthy that a material’s flammability in
oxygen is highly-dependent on multiple factors (configuration,
cleanliness, n—the degree to which an oxygen system is free
environment, promoter energy, etc.) and caution is advised to consider
of contaminant.
these factors when evaluating a material’s flammability in a given
DISCUSSION—Cleanliness and contamination are opposing properties:
oxygen application. G124
increasing cleanliness implies decreasing contamination. G93
fractional evaporation, n—the continuous evaporation of the
contaminant (contamination), n—unwanted molecular, non-
quantity of liquid that results in a progressive concentration
volatile residue (NVR), or particulate matter, or combina-
of a less-volatile constituent(s). G145
tions thereof, that could adversely affect or degrade the
galling, n—a condition whereby excessive friction between
operation, life, or reliability of the systems or components
high spots results in localized welding with subsequent
upon which it resides.
DISCUSSION—Contamination and cleanliness are opposing properties: splitting and a further roughening of rubbing surfaces of one
increasing cleanliness implies decreasing contamination. G93, G120, or both of two mating parts. G88
G121, G131, G136, G144, G145
gaseous fluid impact-igintion resistance, n—the resistance of
contaminate, v—a process of applying contaminant. (non- a material to ignition when struck by rapidly compressed
volatile residue (NVR) and/or particulate matter). G131, high pressure gas in an oxygen enriched atmosphere under a
G136, G120, G121 specific test procedure. G63
G126 − 16 (2023)
hazard, n—source of danger; something that could harm foreseeable malfunction, operator error, or process upset.
persons or property. G63, G94
DISCUSSION—The magnitude of a hazard relates to the severity of the
mechanical impact, n—a blow delivered by a plummet that
harm it could cause. G128
has been dropped from a pre-established height onto a striker
highest no-burn pressure, n—the highest gas pressure tested
pin, in contact with a sample. G86
(at a specified oxygen concentration and fixed sample
mechanical impact-ignition resistance, n—the resistance of a
temperature) at which a material does not burn more than
material to ignition when struck by an object in an oxygen-
specific test method criteria. G124
enriched atmosphere under a specific test procedure. G63,
highest no-burn temperature, n—the maximum sample tem-
G94, G128
perature (at a specified oxygen concentration and pressure)
molecular contaminant (non-particulate contamination),
at which a material does not burn more than specific test
method criteria. G124 n—molecular contaminants that may exist in a gaseous,
liquid, or solid state and may be uniformly or nonuniformly
igniter, n—a material used to ignite the promoter that can burn
disturbed.
under an electrical influence, such as a small-diameter wire.
DISCUSSION—Molecular contaminant may be found as a solution, an
G124
emulsion, or in the form of droplets. Molecular contaminants account
for most of what constitutes Non-Volatile Residue (NVR). G120,
ignition temperature, n—the temperature at which a material
G121, G136, G144
will ignite in an oxidant under specific test or system
conditions.
natural aging, n—aging in which a material is exposed to
DISCUSSION—The ignition temperature of a material in a system is
conditions replicating those that are present in actual service
related to the temperature measured by Test Method G72 (AIT), but is
in a component for oxygen service. G114
also a function of system pressure, configuration and operation, and
thermal history of the material. G88, G128
nonmetal, n—any material other than a metal, non-polymeric
alloy, or any composite in which the metallic component is
ignition mechanisms, n—specific factors (physical attributes
such as system materials, system design, component design, not the most easily ignited component and for which the
individual constituents cannot be evaluated independently,
component performance factors, contamination, etc. as well
as system conditions such as temperature, pres
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