ASTM G124-18

Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres

SIGNIFICANCE AND USE
5.1 This test method will allow comparisons of the burning characteristics of various metallic materials. The burning characteristics that can be evaluated include (1) burn and no-burn pressure, (2) burn and no-burn temperature, (3) regression rate of the melting interface, and (4) visual evaluation of the burning process of the test sample.
SCOPE
1.1 This test method covers test apparatus and techniques to determine the minimum test gas pressure and sample temperature that supports self-sustained burning and the regression rate of the melting surface of a standardized sample of a metallic material that has been ignited using a promoter.  
1.2 The data obtained from this test method are dependent on the precise test sample configuration and provide a basis for comparing the burning characteristics of metallic materials. No criteria are implied for relating these data for the suitability of a material's use in any actual system.  
1.3 Requirements for apparatus suitable for this test method are given, as well as an example. The example is not required to be used.  
1.4 This test method is for gaseous oxygen or any mixture of oxygen with inert diluents that will support burning, at any pressure or temperature within the capabilities of the apparatus used.  
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.6 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.  
1.7 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: 31-Oct-2018
• ICS: 77.040.30 - Chemical analysis of metals
• Technical Committee: G04 - Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres
• Drafting Committee: G04.01 - Test Methods

Relations

• Replaces: ASTM G124-10 - Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres
• Effective Date: 01-Nov-2018
• 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 G63-99(2007) - Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service
• Effective Date: 15-Mar-2007
• Refers: ASTM G94-05 - Standard Guide for Evaluating Metals for Oxygen Service
• Effective Date: 01-Sep-2005
• Refers: ASTM G88-05 - Standard Guide for Designing Systems for Oxygen Service
• Effective Date: 01-Jul-2005
• Refers: ASTM G93-03e1 - Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments
• Effective Date: 01-Nov-2003
• Refers: ASTM G63-99 - Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service
• Effective Date: 10-Mar-1999
• Refers: ASTM G94-92(1998) - Standard Guide for Evaluating Metals for Oxygen Service
• Effective Date: 10-Sep-1998
• Refers: ASTM G88-90(1997)e1 - Standard Guide for Designing Systems for Oxygen Service
• Effective Date: 01-Jan-1997
• Refers: ASTM G93-96 - Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments
• Effective Date: 10-Apr-1996
• Referred By: ASTM G128/G128M-15(2023) - Standard Guide for Control of Hazards and Risks in Oxygen Enriched Systems
• Effective Date: 01-Nov-2018
• Referred By: ASTM G94-22 - Standard Guide for Evaluating Metals for Oxygen Service
• Effective Date: 01-Nov-2018
• Referred By: ASTM G145-08(2023) - Standard Guide for Studying Fire Incidents in Oxygen Systems
• Effective Date: 01-Nov-2018
• Referred By: ASTM G126-16(2023) - Standard Terminology Relating to the Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres
• Effective Date: 01-Nov-2018
• Referred By: ASTM G125-00(2023) - Standard Test Method for Measuring Liquid and Solid Material Fire Limits in Gaseous Oxidants
• Effective Date: 01-Nov-2018

Overview

ASTM G124-18: Standard Test Method for Determining the Combustion Behavior of Metallic Materials in Oxygen-Enriched Atmospheres establishes procedures for evaluating the combustion sensitivity and burning characteristics of metallic materials when exposed to oxygen-rich environments. This standard provides a consistent approach for laboratory comparison, allowing users to determine how metals behave under elevated oxygen pressures and temperatures, which is critical in industries where oxygen service is part of the operational environment.

Key Topics

• Combustion Testing in Oxygen-Enriched Atmospheres: The standard describes methods to measure the minimum test gas pressure and sample temperature that support self-sustained burning of metallic materials. It also outlines how to gauge the regression rate of the melting interface for standardized samples ignited by a promoter.

• Test Parameters and Metrics: ASTM G124-18 test results include key data such as:

  • Burn and no-burn pressure
  • Burn and no-burn temperature
  • Regression rate of the melting interface
  • Burn length (extent of sample consumed)
  • Visual assessment of the burning process

• Apparatus and Techniques: The document specifies required equipment, such as test chambers, sample holders, pressure transducers, temperature sensors, igniters, promoters, and data acquisition systems, to ensure the integrity of results.

• Data Interpretation and Reporting: The standard details the process for interpreting test results and emphasizes the importance of documenting all conditions and variables, including sample specifications, initial/final test conditions, burning behavior, and observations.

• Safety and Environmental Considerations: ASTM G124-18 highlights the hazards of working with high-pressure oxygen systems and burning metals, recommending strict adherence to safety procedures and suitable facility and equipment design.

Applications

• Material Selection for Oxygen Service: This standard is essential for industries such as aerospace, chemical processing, medical gas systems, and energy, where metals may be exposed to high-pressure oxygen. Comparing flammability and combustion rates informs the selection of safe and reliable materials.

• Design and Safety Validation: System designers and safety engineers use ASTM G124-18 test data to make informed decisions about the appropriate metals for piping, valves, fittings, and other components used in oxygen-enriched environments.

• Quality Assurance & R&D: Manufacturers and research laboratories utilize this standardized method to qualify new alloys, verify supplier materials, and evaluate the effects of changes in composition or processing on combustion resistance.

• Regulatory and Compliance Assessment: Adhering to ASTM G124-18 can assist organizations in demonstrating compliance with safety and industry guidelines for oxygen systems, supporting regulatory documentation and certification processes.

Related Standards

For comprehensive assessment of materials in oxygen service, the following related ASTM standards and guides may also be applied:

• ASTM G63: Guide for Evaluating Nonmetallic Materials for Oxygen Service
• ASTM G88: Guide for Designing Systems for Oxygen Service
• ASTM G93: Practice for Cleaning Methods and Cleanliness Levels for Materials and Equipment Used in Oxygen-Enriched Environments
• ASTM G94: Guide for Evaluating Metals for Oxygen Service

Summary

ASTM G124-18 is a crucial reference for testing the combustion behavior of metallic materials in oxygen-enriched atmospheres, supporting safe design and operation across industries. By providing standardized metrics and methodologies for comparative analysis, this test method underpins informed material selection, risk mitigation, and compliance in oxygen system applications. For best results, users should ensure test conditions match operational realities and refer to complementary ASTM guidelines for a robust materials evaluation program.

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: G124 − 18
Standard Test Method for
Determining the Combustion Behavior of Metallic Materials
in Oxygen-Enriched Atmospheres
This standard is issued under the fixed designation G124; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 Thistestmethodcoverstestapparatusandtechniquesto 2.1 ASTM Standards:
determine the minimum test gas pressure and sample tempera-
G63Guide for Evaluating Nonmetallic Materials for Oxy-
turethatsupportsself-sustainedburningandtheregressionrate gen Service
of the melting surface of a standardized sample of a metallic G88Guide for Designing Systems for Oxygen Service
material that has been ignited using a promoter.
G93Practice for Cleaning Methods and Cleanliness Levels
for Material and Equipment Used in Oxygen-Enriched
1.2 The data obtained from this test method are dependent
Environments
ontheprecisetestsampleconfigurationandprovideabasisfor
G94Guide for Evaluating Metals for Oxygen Service
comparingtheburningcharacteristicsofmetallicmaterials.No
criteria are implied for relating these data for the suitability of
3. Terminology
a material’s use in any actual system.
3.1 Definitions:
1.3 Requirements for apparatus suitable for this test method
3.1.1 burn length, n—the burn length is the length of the
are given, as well as an example. The example is not required
sample that has been consumed by combustion.
to be used.
3.1.1.1 Discussion—The burn length is determined by sub-
1.4 This test method is for gaseous oxygen or any mixture
tracting the post-test sample length from the pretest sample
of oxygen with inert diluents that will support burning, at any
length (which does not include the promoter length or region
pressureortemperaturewithinthecapabilitiesoftheapparatus
used by the test sample support).
used.
3.1.2 flammable material, n—a material is defined in this
1.5 The values stated in SI units are to be regarded as
standard as flammable if a standard rod sample burns more
standard. The values given in parentheses after SI units are
than 3 cm (1.2 in.) above the promoter (1, 2).
providedforinformationonlyandarenotconsideredstandard.
3.1.3 highest no-burn pressure, n—the maximum gas pres-
1.6 This standard does not purport to address all of the
sure (at a specified oxygen concentration and fixed sample
safety concerns, if any, associated with its use. It is the
temperature)atwhichamaterialdoesnotburnmorethan3cm
responsibility of the user of this standard to establish appro-
(1.2 in.) above the promoter in a minimum of five tests.
priate safety, health, and environmental practices and deter-
3.1.4 highest no-burn temperature, n—the maximum
mine the applicability of regulatory limitations prior to use.
sample temperature (at a specified oxygen concentration and
1.7 This international standard was developed in accor-
pressure) at which a material does not burn more than 3 cm
dance with internationally recognized principles on standard-
(1.2 in.) above the promoter in a minimum of five tests.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3.1.5 igniter, n—a material used to ignite the promoter that
mendations issued by the World Trade Organization Technical canburnunderanelectricalinfluence,suchasasmall-diameter
Barriers to Trade (TBT) Committee. wire.
1 2
This test method is under the jurisdiction of ASTM Committee G04 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Compatibility and Sensitivity of Materials in Oxygen EnrichedAtmospheres and is contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
the direct responsibility of Subcommittee G04.01 on Test Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 1, 2018. Published December 2018. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2010 as G124–10. DOI: The boldface numbers in parentheses refer to a list of references at the end of
10.1520/G0124-18. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G124 − 18
3.1.6 lowest burn pressure, n—the minimum gas pressure 4.3 Ifthesampleisflammable,anotherstandardsamplerod
(ataspecifiedoxygenconcentrationandfixedsampletempera- istestedatareducedtestpressureortemperature.Ifthesample
ture) at which a material burns more than 3 cm (1.2 in.) above
is not flammable, testing continues until the sample is not
the promoter for one or more test specimens.
flammable in a minimum of five tests at one set of conditions.
Ithasbeenshown,foraburnprobabilityoflessthan10%,five
3.1.7 lowest burn temperature, n—the minimum sample
no burn results provide a 41% confidence level in the (no
temperature (at a specified oxygen concentration and pressure)
at which a material burns more than 3 cm (1.2 in.) above the burn) result, whereas 22 no burn results provide a 90%
confidence level (for the same burn probability of 10%). A
promoter for one or more test specimens.
thorough discussion of the burn probabilities and associated
3.1.8 promoter, n—anoptionalmaterialthatcanaddsupple-
confidence levels is given in Ref (3).
mentalheatandincreasethetemperaturetostartburningofthe
NOTE 2—Increasing the number of samples will always give a higher
metallic material being tested.
level of confidence and is recommended when possible. This method
3.1.9 regression rate of the melting interface, n—the aver-
defines the highest no-burn pressure or temperature and the lowest burn
age rate at which the solid-liquid metal (melting) interface
pressure or temperature. The maximum no-burn (and burn) temperature
advances along the test sample length during a test.
and pressure and regression rate of the melting interface can be deter-
mined from the test data.
3.1.10 sample temperature, n—theinitialtemperatureofthe
test sample being evaluated.
5. Significance and Use
3.1.10.1 Discussion—Variousmethodsofmeasuringsample
temperatures are used. The method selected must be reported
5.1 This test method will allow comparisons of the burning
with test data.
characteristics of various metallic materials. The burning
3.1.11 standard rod test sample, n—a 3.2 mm (0.125 in.) characteristics that can be evaluated include (1) burn and
diameter rod with a minimum length of 101.6 mm (4 in.). no-burn pressure, (2) burn and no-burn temperature, (3)
regression rate of the melting interface, and (4) visual evalua-
3.1.12 threshold pressure, n—this term is historically used
tion of the burning process of the test sample.
torepresentthedefinitionsofeitherthelowestburnpressureor
the highest no-burn pressure.
6. Interferences
3.1.12.1 Discussion—In this standard, it represents the low-
est burn pressure, which is used as the new term throughout.
6.1 Anymaterialsinsidethetestchamberthatmaybakeout,
3.1.13 valid test, n—a test in which the igniter and/or
ignite/burn, or vaporize during the burning process at test
promotercombinationhasmeltedthebottomsectionofthetest
temperature/pressure may interfere with the chemistry of the
sample where the igniter and/or promoter is located.
fire propagation and subsequently affect burning.
6.2 The specific atmosphere in the test chamber can have a
4. Summary of Test Method
severe chemical or thermodynamic effect, or both. Therefore,
4.1 A standard rod sample of the material to be tested is
test gas contamination or diluents (such as argon, nitrogen,
vertically suspended in a chamber filled with pressurized test
carbon dioxide, water vapor, and others) can be important
gas. The chamber contains sufficient oxygen so that not more
factors, so the oxygen gas purity and quantities and types of
than 10% of the oxygen will be consumed if the sample
diluents should be specified in the data sheet.
completely burns. A promoter (aluminum is most common,
however titanium, carbon steel, and magnesium are also used)
6.3 The standard test is conducted under non-flowing con-
may be applied to the bottom of the rod to start burning of the
ditions.Tests conducted under flowing oxygen conditions may
material in conjunction with the igniter (typically Pyrofuse or
dramatically affect the test results depending on the gas
Nichrome wire). The test chamber is pressurized to the
velocity at the burning region.Although oxygen fires typically
required test pressure and the sample is heated to the required
occurunderflowingconditionsinservice,thescopeofthistest
test temperature (if elevated temperature is one of the param-
standard is to provide a relative means for comparing burning
eters).
characteristics of metallic materials (1.2). Consequently, care
4.2 The test is initiated by ignition of the igniter wire/
should be taken when considering that a material is not
promoter(typicallythroughresistiveheating)sothattheendof
flammable in given oxygen service conditions based solely on
the test sample is melted away to produce a valid test with
Test Method G124 data performed in static oxygen conditions.
relevant data collected, as specified.
Performing this test standard under flowing conditions is not
NOTE1—In4.3assubsequentsamplesaretested,onlyoneparameterof
outside the scope of this standard, but performing this test to
temperature or pressure is varied and the other held constant within the
cover all flowing conditions would be impractical. Therefore,
tolerance allowed by this test method. It is up to the user to determine if
the non-flowing conditions outlined in this test standard were
the purpose of the test is to determine burn/no-burn pressure or burn/no-
burn temperature. Only one of these variables should be changed during selected as a basis for providing relative comparison of
a series of tests.
metallic materials.
NOTE 3—When comparing the burning characteristics of metallic
materials using Test Method G124 test data, it is important to ensure the
The trade name for aluminum-palladium wire is Pyrofuze. It is a registered
test conditions (especially the variables identified in Section 6) were
trademark of the Pyrofuze Corp., 121 S. Columbus Ave., Mt. Vernon, NY 10553,
and is available from them. comparable.
G124 − 18
7. Apparatus
7.1 System—A schematic of a typical system is shown in
Fig. 1. Other designs may also be used if they fulfill the
following requirements.
7.2 TestChamber—Across-sectionofatypicaltestchamber
is shown in Fig. 2. Appendix X1 provides criteria for estab-
lishingthelowesttestpressuresthatmeetthestatedcriterionof
using no more than 10% of the available oxidizer for various
vessel volumes. If the chamber cannot be made sufficiently
large,anaccumulatorcanbeattachedbetweenthetestchamber
and the chamber isolation valve that contains more test gas.
Thetestchamber(andaccumulatorifused)shallnotcontribute
any chemical interference to testing.
7.3 Sample Holder—capable of securing the sample at the
top and supporting it in a vertical position.
7.4 Temperature Sensor—used to measure gas or sample
temperatures in the chamber, accurate to within 61% of
reading or accuracy otherwise noted.
7.5 Pressure Transducer—used to measure gas pressure in
FIG. 2 Typical Stainless Steel Test Chamber Cross-Section
the chamber, accurate to within 61% of reading or accuracy
otherwise noted.
as an internal shield to protect the chamber and components
7.6 Liner (optional)—a burn-resistant (for example, copper
from the burning, molten slag, and other reaction products
or ceramic) liner is recommended in the test chamber to serve
produced during sample burning.
7.7 Sight Glass—(optional for tests not determining either
the regression rate of the melting interface or visual evaluation
of the burning process), capable of withstanding the maximum
test pressure anticipated (initial pressure plus pressure rise due
toheatingduringburning).Othermethodsofobservingthetest
may be possible, though direct observation is most common.
7.8 Igniter Power Supply—electrically isolated and capable
of providing adequate current to initiate the ignition within 3 s
of the application of power.
7.9 TestCell—aroomtohousethetestchamber,constructed
of non-flammable material (such as concrete or metal) with
sufficient strength to provide protection from explosion, pneu-
matic release, or fire hazards.Acontinuous ventilation system
shall circulate fresh air in the test cell. The test cell shall be
cleaned periodically to avoid contamination of the sample and
equipment and minimize fire hazards.
7.10 Piping System—which purges, pressurizes, and vents
thetestchamber.Thepipingsystemshallbedesignedtopermit
remotetestchamberpurge,pressurization,andventingwithout
unsafe exposure of personnel. It is recommended the test
chamber be purged and pressurized through one line and
vented through a separate line to minimize the chances of a
contaminant migrating into the pressurization line, which
mightinfluencesubsequenttests.Itisalsorecommendedthata
pressurereliefdevicewithanappropriatesettingbefittedtothe
pipingsystemandbeabletocommunicatetothetestchamber.
NOTE 4—Although the use of separate lines is preferred, it is not a
requirement. Periodic inspection and cleaning of lines and valves should
be done to decrease the risk of cross contamination. A typical piping
system for this test is shown in Fig. 1.
7.11 Control Area—which will isolate test personnel from
FIG. 1 Schematic of Typical System the test cell during tests. This control area shall be provided
G124 − 18
with the necessary control and instrumentation features to chromium (Nichrome) or aluminum/ palladium (Pyrofuze).
perform test chamber purge, pressurization and venting The electrical system that supplies current to the wire should
operations,andmonitoringofthetestchamberinstrumentation providesufficientcurrenttomeltandignitetheigniterin1-2s.
during the test. Aslow heat-up can increase the amount of pre-ignition energy
loss to the sample rod, which will increase the heat affected
7.12 Data Acquisition System—capable of recording,
zone of the sample and potentially produce an invalid test.
storing, and accessing the pressure, temperature, and regres-
NOTE 6—Rapid heating of the sample may result in damage to, or
sion rate data at a rate of ten samples per second (minimum).
ignition of, the igniter wire and either prevent ignition of the promoter or
It may also include a video recording device that displays the
ignite it prior to establishment of required test conditions.
“real-time” burn phenomenon. The video recording with em-
9. Hazards
bedded timer, thermocouple sensor arrays, and ultrasonic rod
length measurements are some of the methods available for
9.1 High-Pressure Oxygen System—Warning—There are
determination of the regression rate of the melting interface
hazards involving the use of a enriched-oxygen systems. The
(see Annex A1).
following guidelines will reduce the dangers:
9.1.1 Personnel should be isolated from the test system
7.13 Heating System (for elevated temperature testing
whenitispressurized.Preferably,personnelshouldbeshielded
only)—which will heat the sample to the required initial test
by both physical protection (for example, the test cell) and
sample temperature range, without interfering with the other
distance.
functions of the test system or the test chamber integrity. The
9.1.2 The test system itself should be isolated to prevent
heatingsystemisrequiredtoevaluateburningcharacteristicsat
danger to people not involved in the test.
elevated temperatures above ambient. (No heating system is
9.1.3 The test system should incorporate equipment able to
required if testing is to be done at ambient temperature only.)
handle the maximum operating pressure safely, including an
The method used can include, but is not limited to, localized
appropriate safety-factor.
heating methods including induction heating, resistive heating,
9.1.4 The test system should be kept clean to prevent
and radiant heating. Heating of the entire system has also been
unintentional ignition.
successfully used, however the vessel pressure rating must be
9.1.5 The test system should be double-isolated from the
considered due to the temperature dependency of the chamber
test gas supply system.
material strength (see 9.4), and any non-metallic materials
9.1.6 Remote readout devices should be provided so per-
exposedtoelevatedtemperaturesshouldbeusedinaccordance
sonnel do not have to approach the test system to obtain
with Guide G63.
operating data or test results, or both.
8. Reagents and Materials 9.2 Oxygen—Warning—Oxygen enrichment accelerates
combustionvigorously.Careshouldbetakenatalltimeswhen
8.1 Gaseous Oxygen—Oxygen purity equal to or greater
workingwithoxygen.CGAPamphletsG-4.0 (7)andG-4.1 (8),
than that of practical systems is preferred for the standard test,
Guide G88, Practice G93, and ASTM Manual 36 provide
and an analysis of the test oxidant is required. Other oxygen/
further details.
diluents mixtures may be used, and it is recommended that the
exact oxygen purity used be specified with the test results. (4)
ASTM Manual 36, Safe Use of Oxygen and Oxygen Systems.Available from
NOTE 5—Oxygen purity has been shown, for certain materials to
ASTM International Headquarters.
significantlyaffecttheresults.Extremelyhighpurityorlowpurityoxygen
(with diluents present) should be avoided unless conducting special
studies using gas mixtures (5), and in all cases the purity should be
specified along with any diluents present.
8.2 Promoter—Thepromotershallprovidesufficientenergy
to melt the end of the test sample to produce a valid test and,
ifflammableattestconditions,ignitethetestspecimens.Some
examples of promoter material include aluminum, Pyrofuze,
magnesium, titanium, and carbon steel (6). In some cases, a
promoter may not be necessary when the igniter itself can
provide sufficient energy to produce a valid test. Nonmetallic
promoters may be used; however, the combustion products of
suchpromotersmightcontaminatethetestmediaandcaremust
be taken to ensure that the use of nonmetallic promoters
produces a valid test result. Other ignition sources, such as
laser or electrical, may also be used. In selecting the promoter
material,thepossibilityofachemicalreactionbetweenthetest
material and the promoter should be considered.
8.3 Igniter—Theignitershallhavesufficientenergytoignite
the promoter or the sample and produce a valid test result.
Some examples of the igniter wire material are nickel/ FIG. 3 Typical Test Sample Dimensions
G124 − 18
9.3 Metal Oxides—Warning—Toxic metal and oxide dusts 10.4 Assembly—If an ignition promoter is used, it shall be
may be produced when using this test method; safety proce- coupled to the bottom-end of the sample when it is ready to be
dures appropriate to the hazard must therefore be followed. installed in the test system and coupled to the igniter wire
chosen.As shown in Fig. 4, the promoter has a groove in it to
9.4 Vessel Failures—Warning—The vessel described in
allow coupling of the igniter wire.
this standard shall contain the burning of various metallic
materials successfully. Molten metal slag produced in these
11. Preparation of Apparatus
tests can be very destructive, and as pressure or oxygen purity
11.1 General—Maintain the test chamber, its accessories,
increases, the intensity and risk of uncontrolled burning
and the test cell in a visibly clean condition in order to ensure
increases, so the possibility of a burn-
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G124 − 10 G124 − 18
Standard Test Method for
Determining the Combustion Behavior of Metallic Materials
in Oxygen-Enriched Atmospheres
This standard is issued under the fixed designation G124; 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
1.1 This test method covers test apparatus and techniques to determine the minimum test gas pressure and sample temperature
that supports self-sustained burning and the regression rate of the melting surface of a standardized sample of a metallic material
that has been ignited using a promoter.
1.2 The data obtained from this test method are dependent on the precise test sample configuration and provide a basis for
comparing the burning characteristics of metallic materials. No criteria are implied for relating these data for the suitability of a
material’s use in any actual system.
1.3 Requirements for apparatus suitable for this test method are given, as well as an example. The example is not required to
be used.
1.4 This test method is for gaseous oxygen or any mixture of oxygen with inert diluents that will support burning, at any
pressure or temperature within the capabilities of the apparatus used.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.after
SI units are provided for information only and are not considered standard.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 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.
2. Referenced Documents
2.1 ASTM Standards:
G63 Guide for Evaluating Nonmetallic Materials for Oxygen Service
G88 Guide for Designing Systems for Oxygen Service
G93 Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen-Enriched Environments
G94 Guide for Evaluating Metals for Oxygen Service
3. Terminology
3.1 Definitions:
3.1.1 burn length, n—the burn length is the length of the sample that has been consumed by combustion.
3.1.1.1 Discussion—
The burn length is determined by subtracting the post-test sample length from the pretest sample length (which does not include
the promoter length or region used by the test sample support.)support).
This test method is under the jurisdiction of ASTM Committee G04 on Compatibility and Sensitivity of Materials in Oxygen Enriched Atmospheres and is the direct
responsibility of Subcommittee G04.01 on Test Methods.
Current edition approved Nov. 1, 2010Nov. 1, 2018. Published November 2010December 2018. Originally approved in 1994. Last previous edition approved in 20032010
as G124 – 95 (2003).G124 – 10. DOI: 10.1520/G0124-10.10.1520/G0124-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G124 − 18
3.1.2 flammable material, n—a material is defined in this standard as flammable if a standard rod sample burns more than 3 cm
(1.2 in.) above the promoter (1, 2).
3.1.3 highest no-burn pressure, n—the maximum gas pressure (at a specified oxygen concentration and fixed sample
temperature) at which a material does not burn more than 3 cm (1.2 in.) above the promoter in a minimum of five tests.
3.1.4 highest no-burn temperature, n—the maximum sample temperature (at a specified oxygen concentration and pressure) at
which a material does not burn more than 3 cm (1.2 in.) above the promoter in a minimum of 5five tests.
3.1.5 igniter, n—a material used to ignite the promoter that can burn under an electrical influence, such as a small-diameter wire.
3.1.6 lowest burn pressure, n—the minimum gas pressure (at a specified oxygen concentration and fixed sample temperature)
at which a material burns more than 3 cm (1.2 in.) above the promoter for one or more teststest specimens.
3.1.7 lowest burn temperature, n—the minimum sample temperature (at a specified oxygen concentration and pressure) at which
a material burns more than 3 cm (1.2 in.) above the promoter for one or more teststest specimens.
3.1.8 promoter, n—an optional material that can add supplemental heat and increase the temperature to start burning of the
metallic material being tested.
3.1.9 regression rate of the melting interface, n—the average rate at which the solid-liquid metal (melting) interface advances
along the test sample length during a test.
3.1.10 sample temperature, n—the initial temperature of the test sample being evaluated.
3.1.10.1 Discussion—
Various methods of measuring sample temperatures are used. The method selected must be reported with test data.
3.1.11 standard rod test sample, n—a 3.2 mm (0.125 in.) diameter rod with a minimum length of 101.6 mm (4 in.).
3.1.12 threshold pressure, n—Thisthis term is historically used to represent the definitions of either the lowest burn pressure or
the highest no-burn pressure.
3.1.12.1 Discussion—
In this standard, it represents the lowest burn pressure, which is used as the new term throughout.
3.1.13 valid test, n—a test in which the igniter and/or promoter combination has melted the bottom section of the test sample
where the igniter and/or promoter is located.
4. Summary of Test Method
4.1 A standard rod sample of the material to be tested is vertically suspended in a chamber filled with pressurized test gas. The
chamber contains sufficient oxygen so that not more than 10 % of the oxygen will be consumed if the sample completely burns.
A promoter (aluminum is most common, however titanium, carbon steel, and magnesium are also used) may be applied to the
bottom of the rod to start burning of the material in conjunction with the igniter (typically Pyrofuse or Nichrome wire)wire). . The
test chamber is pressurized to the required test pressure and the sample is heated to the required test temperature (if elevated
temperature is one of the parameters).
4.2 The test is initiated by ignition of the igniter wire/promoter (typically through resistive heating) so that the end of the test
sample is melted away to produce a valid test with relevant data collected, as specified.
NOTE 1—In 4.3 as subsequent samples are tested, only one parameter of temperature or pressure is varied and the other held constant within the
tolerance allowed by this test method. It is up to the user to determine if the purpose of the test is to determine burn/no-burn pressure or burn/no-burn
temperature. Only one of these variables should be changed during a series of tests.
4.3 If the sample is flammable, another standard sample rod is tested at a reduced test pressure or temperature. If the sample
is not flammable, testing continues until the sample is not flammable in a minimum of fivetests five tests at one set of conditions.
It has been shown, for a burn probability of less than 10 %, 5five no burn results providesprovide a 41 % confidence level in the
(no burn) result, whereas twenty-two22 no burn results providesprovide a 90 % confidence level (for the same burn probability
of 10 %). A thorough discussion of the burn probabilities and associated confidence levels is given in Ref (3).
NOTE 2—Increasing the number of samples will always give a higher level of confidence and is recommended when possible. This method defines the
highest no-burn pressure or temperature and the lowest burn pressure or temperature. The maximum no-burn (and burn) temperature and pressure and
regression rate of the melting interface can be determined from the test data.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
The trade name for aluminum-palladium wire is Pyrofuze. It is a registered trademark of the Pyrofuze Corp., 121 S. Columbus Ave., Mt. Vernon, NY 10553, and is
available from them.
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5. Significance and Use
5.1 This test method will allow comparisons of the burning characteristics of various metallic materials. The burning
characteristics that can be evaluated include (1) burn and no-burn pressure, (2) burn and no-burn temperature, (3) regression rate
of the melting interface, and (4) visual evaluation of the burning process of the test sample.
6. Interferences
6.1 Any materials inside the test chamber that may bake out, ignite/burn, or vaporize during the burning process at test
temperature/pressure may interfere with the chemistry of the fire propagation and subsequently affect burning.
6.2 The specific atmosphere in the test chamber can have a severe chemical or thermodynamic effect, or both. Therefore, test
gas contamination or diluents (such as argon, nitrogen, carbon dioxide, water vapor, and others) can be important factors, so the
oxygen gas purity and quantities and types of diluents should be specified in the data sheet.
6.3 The standard test is conducted under non-flowing conditions. Depending on the final gas velocity, tests Tests conducted
under flowing oxygen conditions may dramatically affect the test results.results depending on the gas velocity at the burning
region. Although oxygen fires typically occur under flowing conditions in service, the scope of this test standard is to provide a
relative means for comparing burning characteristics of metallic materials (1.2). Consequently, care should be taken when
considering that a material is not flammable in given oxygen service conditions based solely on Test Method G124 data performed
in static oxygen conditions. Performing this test standard under flowing conditions is not outside the scope of this standard, but
performing this test to cover all flowing conditions would be impractical. Therefore, the non-flowing conditions outlined in this
test standard were selected as a basis for providing relative comparison of metallic materials.
NOTE 3—When comparing the burning characteristics of metallic materials using Test Method G124 test data, it is important to ensure the test
conditions (especially the variables identified in Section 6) were comparable.
7. Apparatus
7.1 System—A schematic of a typical system is shown in Fig. 1. Other designs may also be used if they fulfill the following
FIG. 1 Schematic of Typical System
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requirements.
7.2 Test Chamber—A cross-section of a typical test chamber is shown in Fig. 2. Appendix X1 provides criteria for establishing
the lowest test pressures that meet the stated criterion of using no more than 10 % of the available oxidizer for various vessel
volumes. If the chamber cannot be made sufficiently large, an accumulator can be attached between the test chamber and the
chamber isolation valve that contains more test gas. The test chamber (and accumulator if used) shall not contribute any chemical
interference to testing.
7.3 Sample Holder—capable of securing the sample at the top and supporting it in a vertical position.
7.4 Temperature Sensor—used to measure gas or sample temperatures in the chamber, accurate to within 61 % of reading or
accuracy otherwise noted.
7.5 Pressure Transducer—used to measure gas pressure in the chamber, accurate to within 61 % of reading or accuracy
otherwise noted.
7.6 Liner (optional)—a burn-resistant (for example, copper or ceramic) liner is recommended in the test chamber to serve as
an internal shield to protect the chamber and components from the burning, molten slag, and other reaction products produced
during sample burning.
7.7 Sight Glass—(optional for tests not determining either the regression rate of the melting interface or visual evaluation of the
burning process), capable of withstanding the maximum test pressure anticipated (initial pressure plus pressure rise due to heating
during burning). Other methods of observing the test may be possible, though direct observation is most common.
7.8 Igniter Power Supply—electrically isolated and capable of providing adequate current to initiate the ignition within 3 s of
the application of power.
7.9 Test Cell—a room to house the test chamber, constructed of non-flammable material (such as concrete or metal) with
sufficient strength to provide protection from explosion, pneumatic release, or fire hazards. A continuous ventilation system shall
circulate fresh air in the test cell. The test cell shall be cleaned periodically to avoid contamination of the sample and equipment
and minimize fire hazards.
7.10 Piping System—which purges, pressurizes, and vents the test chamber. The piping system shall be designed to permit
remote test chamber purge, pressurization, and venting without unsafe exposure of personnel. It is recommended the test chamber
be purged and pressurized through one line and vented through a separate line to minimize the chances of a contaminant migrating
into the pressurization line, which might influence subsequent tests. It is also recommended that a pressure relief device with an
appropriate setting be fitted to the piping system and be able to communicate to the test chamber.
NOTE 4—Although the use of separate lines is preferred, it is not a requirement. Periodic inspection and cleaning of lines and valves should be done
to decrease the risk of cross contamination. A typical piping system for this test is shown in Fig. 1.
7.11 Control Area—which will isolate test personnel from the test cell during tests. This control area shall be provided with the
necessary control and instrumentation features to perform test chamber purge, pressurization and venting operations, and
monitoring of the test chamber instrumentation during the test.
FIG. 2 Typical Stainless Steel Test Chamber Cross-Section
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7.12 Data Acquisition System—capable of recording, storing, and accessing the pressure, temperature, and regression rate data
at a rate of ten samples per second (minimum). It may also include a video recording device that displays the “real-time” burn
phenomenon. The video recording with embedded timer, thermocouple sensor arrays, and ultrasonic rod length measurements are
some of the methods available for determination of the regression rate of the melting interface (see Annex A1).
7.13 Heating System (for elevated temperature testing only)—which will heat the sample to the required initial test sample
temperature range, without interfering with the other functions of the test system or the test chamber integrity. The heating system
is required to evaluate burning characteristics at elevated temperatures above ambient. (No heating system is required if testing
is to be done at ambient temperature only.) The method used can include, but is not limited to, localized heating methods including
induction heating, resistive heating, and radiant heating. Heating of the entire system has also been successfully used, however the
vessel pressure rating must be considered due to the temperature dependency of the chamber material strength (see 9.4)), and any
non-metallic materials exposed to elevated temperatures should be used in accordance with Guide G63.
8. Reagents and Materials
8.1 Gaseous Oxygen—Oxygen purity equal to or greater than that of practical systems is preferred for the standard test, and an
analysis of the test oxidant is required. Other oxygen/diluents mixtures may be used, and it is recommended that the exact oxygen
purity used be specified with the test results. (4)
NOTE 5—Oxygen purity has been shown, for certain materials to significantly affect the results. Extremely high purity or low purity oxygen (with
diluents present) should be avoided unless conducting special studies using gas mixtures (5)), and in all cases the purity should be specified along with
any diluents present present.
8.2 Promoter—The promoter shall provide sufficient energy to melt the end of the test sample to produce a valid test and, if
flammable at test conditions, ignite the test specimens. Some examples of promoter material include aluminum, Pyrofuze,
magnesium, titanium, and carbon steel (6). In some cases, a promoter may not be necessary when the igniter itself can provide
sufficient energy to produce a valid test. Nonmetallic promoters may be used; however, the combustion products of such promoters
might contaminate the test media and care must be taken to ensure that the use of nonmetallic promoters produces a valid test
result. Other ignition sources, such as laser or electrical, may also be used. In selecting the promoter material, the possibility of
a chemical reaction between the test material and the promoter should be considered.
8.3 Igniter—The igniter shall have sufficient energy to ignite the promoter or the sample and produce a valid test result. Some
examples of the igniter wire material are nickel/chromium (Nichrome) or aluminum/ palladium (Pyrofuze). The electrical system
that supplies current to the wire should provide sufficient current to melt and ignite the igniter in 1-2 s. A slow heat-up can increase
the amount of pre-ignition energy loss to the sample rod, which will increase the heat affected zone of the sample and potentially
produce an invalid test.
NOTE 6—Rapid heating of the sample may result in damage to, or ignition of, the igniter wire and either prevent ignition of the promoter or ignite it
prior to establishment of required test conditions.
9. Hazards
9.1 High-Pressure Oxygen System—Warning:Warning—There are hazards involving the use of a enriched-oxygen systems.
The following guidelines will reduce the dangers:
FIG. 3 Typical Test Sample Dimensions
G124 − 18
9.1.1 Personnel should be isolated from the test system when it is pressurized. Preferably, personnel should be shielded by both
physical protection (for example, the test cell) and distance.
9.1.2 The test system itself should be isolated to prevent danger to people not involved in the test.
9.1.3 The test system should incorporate equipment able to handle the maximum operating pressure safely, including an
appropriate safety-factor.
9.1.4 The test system should be kept clean to prevent unintentional ignition.
9.1.5 The test system should be double-isolated from the test gas supply system.
9.1.6 Remote readout devices should be provided so personnel do not have to approach the test system to obtain operating data
or test results, or both.
9.2 Oxygen—Warning:Warning—Oxygen enrichment accelerates combustion vigorously. Care should be taken at all times
when working with oxygen. CGA Pamphlets G-4.0 (7) and G-4.1 (8), Guide G88, Practice G93, and ASTM Manual 36 provide
further details.
9.3 Metal Oxides—Warning:Warning—Toxic metal and oxide dusts may be produced when using this test method; safety
procedures appropriate to the hazard must therefore be followed.
9.4 Vessel Failures—Warning:Warning—The vessel described in this standard shall contain the burning of various metallic
materials successfully. Molten metal slag produced in these tests can be very destructive, and as pressure or oxygen purity
increases, the intensity and risk of uncontrolled burning increases, so the possibility of a burn-through or failure of the vessel or
associated piping cannot be ruled out. Additionally, care should be taken to consider the effects of the sample heating method
selected on the structural strength of the vessel.
10. Sampling, Test Specimens, and Test Units
10.1 Preparation of Samples—Typically, samples shall be prepared as cylindrical rods, 3.2 mm diameter and 101.6 mm long
(65 %) minimum (se
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