ASTM G114-98

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Designation:G 114–98
Standard Practice for
Aging Oxygen-Service Materials Prior to Ignitibility or
Flammability Testing
This standard is issued under the fixed designation G 114; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope Federal Specification BB-0-925 Oxygen, Technical, Gas
and Liquid
1.1 This practice covers methods to determine the influence
of time and stress on a material’s oxygen compatibility.
3. Terminology
1.2 This practice addresses both methods that have a foun-
3.1 Definitions of Terms Specific to This Standard:
dation of experience and potential methods that have yet to be
3.1.1 aging—theexposureofamaterialtostress,suchstress
verifiedforvalidity.Thelatterareincludedtopromoteresearch
of which may include time, pressure, contact with materials or
and later elaboration in this practice as methods of the former
chemicals, temperature, abrasion, ionizing radiation, light,
type.
impact with gas or particles, tensile, or compressive force
1.3 The values stated in SI units are to be regarded as the
(eitherstaticorcyclic),oranyotherfeaturethatmaybepresent
standard, however, all numerical values must also be cited in
during a material’s service life. These stressors may be present
the systems in which they were actually measured.
individually or in combination.
1.4 This standard does not purport to address all of the
3.1.2 artificial aging—aging in which a stress variable is
safety concerns, if any, associated with its use. It is the
outside the domain of exposure that the material might see in
responsibility of the user of this standard to establish appro-
a component for oxygen service or in which an alternative
priate safety and health practices and determine the applica-
mechanism is used to produce an effect that simulates the
bility of regulatory limitations prior to use. Specific precau-
results of natural aging. The degree of artificiality may vary on
tionary statements are given in Section 9.
a large scale. An example of mild artificiality might be
2. Referenced Documents exposure of a material to a greater pressure than it experiences
in the use conditions. An example of extreme artificiality
2.1 ASTM Standards:
would be the use of sand paper to increase a material’s surface
D 4809 Test Method for Heat of Combustion of Liquid
roughness to simulate particle-impact abrasion that occurs in
Hydrocarbon Fuels by Bomb Calorimeter (Intermediate
the use condition. A high degree of artificiality affects the
Precision Method)
strength of conclusion that can be drawn, because it may be
G 72 Test Method for Autogenous Ignition Temperature of
difficult to relate the results to the use condition. Artificial
Liquids and Solids in a High-Pressure Oxygen-Enriched
3 aging is preferred that accelerates natural aging but does not
Environment
alter it.
G 74 Test Method for Ignition Sensitivity of Materials to
3 3.1.3 natural aging—aginginwhichthematerialisexposed
Gaseous Fluid Impact
to conditions replicating those that are present in actual service
G 86 Test Method for Determining Ignition Sensitivity of
in a component for oxygen service.
Materials to Mechanical Impact in Pressurized Oxygen
Environments
4. Summary of Practice
G 125 Test Method for Measuring Liquid and Solid Mate-
3 4.1 This practice allows a systematic evaluation of the
rial Fire Limits in Gaseous Oxidants
influence of age and use on a material’s oxygen compatibility.
2.2 Federal Standard:
To apply its principle, the user first characterizes the material
of interest, then subjects the material to an aging stressor, and
recharacterizes the material. The effect of the aging is then
This guide is under the jurisdiction ofASTM Committee G-4 on Compatibility
reported as positive or negative depending upon whether the
and Sensitivity of Materials in Oxygen Enriched Atmospheres and is the direct
material’s compatibility is improved or degraded, and the
responsibility of Subcommittee G04.02 on Recommended Practices.
Current edition approved Sept. 10, 1998. Published February 1999. Originally
published as G 114 – 93. Last previous edition G 114 – 93.
2 4
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G114
measure of the influence is reported as the degree to which the useful, it must demonstrate an ability to discern at least some
measured properties changed. In incident studies, in which significant changes in at least some materials as a result of
initial characterization data are not available, then historical or aging.
average-property data may be used to draw somewhat coarser 7.3 Aging of specimens can potentially result in numerous
conclusions. changes to the material. Aging may modify the surface of a
specimen; exposure to ozone, light, or mechanical wear can
4.2 This practice describes a rationale for selecting aging
increase the surface area through the development of cracks
procedures and relating them to key fire properties. Most of the
(crazing) or erosion. Chemical exposure may result in etching
possible studies have not been verified for significance. How-
of a surface. Aging may alter the chemistry of a material;
ever, one general procedure that involves aging at pressure and
oxides may form or molecular chains may be broken. Aging
temperature has been used and found to yield meaningful
may introduce free oxygen into the structure of a material;
results, and it is described in specific detail as an example. As
diffusion may lead to oxygen molecules permeating the mate-
data become available to validate other specific meaningful
rial structure and entering pores that may be present in the
aging procedures, they too will be included as examples.
material.
7.4 Some changes resulting from aging may alter a materi-
5. Significance and Use
al’s fire properties, including its ignition and propagation
5.1 Amaterial’s fire resistance is a crucial material selection
tendencies. In some cases, aging may render a material less
property. However, after a period of service, the material may
susceptible to fire, while others may make it more susceptible
metamorphosize into something quite different than that which
to fire. Hence, aging tests may be used to evaluate whether a
it was when new. For example, all materials for oxygen service
material may become unacceptable in time or whether it can be
should have good mechanical properties, because mechanical
conditioned (artificially aged) as a means to improve its
failure often leads to ignition and fire damage. Therefore, any
long-term properties. For example, temperature aging may
mechanism that may compromise a material’s mechanical
drive off volatile materials that can compromise ignition
properties can invalidate it for use.
temperature, without necessarily destroying mechanical prop-
5.2 This practice allows the user to gain insight into the
erties and render batch testing less necessary.
effects of aging on the materials in a system.
7.5 In general, aging is expected to have a greater influence
on a material’s ignition properties than its propagation prop-
6. Apparatus
erties. To date, the only background on aging influences is that
6.1 The apparatus used to age materials can vary greatly. of the Bundesanstalt Für Materialforschung und -Prüfung
This practice will focus on small-scale aging methods involv- (BAM) which has for years assessed the effect on a material’s
ing only a few specimens at most. The scale of the aging autogenousignitiontemperatureofagingitatelevatedpressure
procedure can be increased in numerous ways, provided care is and temperature. BAM has used the results of the testing to
taken to ensure safety. When possible, the apparatus used to establish maximum constraints on the use of materials at
perform the fire test may also serve as a vehicle for the aging elevated pressure and temperature.
step, and that is the premise that will be discussed here.
8. Reagents and Materials
6.2 An example of an aging procedure might be to insert a
8.1 Oxygen—Typically oxygen conforming to Federal
specimen into the autogenous ignition test vessel of Test
Method G 72 and to both pressurize it and warm it to Specification BB-0-925, Type I or oxygen of 99.5 % minimum
purityisused.Oxygenofotherpuritiesorinmixturewithother
preselected soak levels for an aging cycle. In this case, the
apparatus is the same as in Test Method G 72. materials may be necessary depending upon the intent of the
study.
6.3 Aging related to gaseous impact might involve placing
8.2 A wide range of reagents and materials may find
the specimen in the Test Method G 74 apparatus and soaking it
application in the use of this practice. For example, solvent
at pressure (or elevated temperatures the apparatus, or both, is
exposure of an elastomer may represent a stressor that requires
able to safely contain). In this case, the apparatus is that ofTest
study. It is not practical to itemize such materials in this
Method G 74.
practice, as they are associated with normal or upset use
6.4 Specimen preparation for larger scale experiments or
conditions. Therefore, the identification of such solvents must
unique combinations of stressors that qualify as research may
rest with the user of this practice.
utilize other hardware that allows safe aging. Safety must be
carefully evaluated for any aging arrangement.
9. Safety Precautions
9.1 Oxygen
7. Rationale for Aging Tests
NOTE 1—Warning: Oxygen vigorously accelerates combustion.
7.1 This practice addresses methods to age materials so that
Keep oil and grease away. Do not use oil or grease on regulators, gages
aging effects on fire properties may be assessed using standard
fire-test methods.
7.2 The body of information for aging influences is small,
Wegener, W., Binder, C., Hengstenberg, P., Herrmann, K. P., and Weinert, P.,
and so, this practice is intended to encourage such testing as a
“Tests to Evaluate the Suitability of Materials for Oxygen Service,” Flammability
part of its goal of proposing methods to age and analyze the
and Sensitivity of Materials in Oxygen-Enriched Atmospheres: Third Volume, ASTM
materials. In principle, for an aging test to be meaningful and STP 986, D. W. Schroll, Ed. ASTM, 1988, pp. 268–278.
G114
or control equipment.
explore absorbed oxygen that may be mixed with volatile
Use only with equipment conditioned for oxygen service by carefully
material or particulates in the pores, the gaseous impact test,
cleaning to remove oil, grease and other combustibles.
Test Method G 74 may be most desirable. However, Test
Keep combustibles away from oxygen and eliminate ignition sources.
Methods G 86 and G 72 may also yield insight. However, the
Keepsurfacescleantopreventignitionorexplosion,orboth,oncontact
user might be surprised to see a change in the heat of
with oxygen.
combustion, Test Method D 4809, or oxygen index, Test
Always use a pressure regulator. Release regulator tension before
opening cylinder valve.
Method G 125.
All equipment and containers used must be suitable and recommended
10.1.1.4 Friction/Erosion—Friction erosion are mecha-
for oxygen service.
nisms that tend to increase the specific surface area of smooth
Never attempt to transfer oxygen from cylinder in which it is received
surfaces and to decrease the specific surface area of rough
to any other cylinder.
surfaces. Increased surface area suggests autoignition tests, see
Do not drop cylinder. Make sure cylinder is secured at all times.
Keep cylinder valve closed when not in use.
Test Method G 72, gaseous impact tests, see Test Method G 74
Stand away from outlet when opening cylinder valve.
and perhaps mechanical impact tests, see Test Method G 86,
For technical use only. Do not use for inhalation purposes.
might all detect changes. Unless the surface was of different
Keep cylinder out of the sun and away from heat.
composition than the interior of the specimens, the user would
Keep cylinder away from corrosive environment.
not expect to see great changes in the heat of combustion, see
Do not use cylinder without label.
Test Method D 4809, or oxygen index, seeTest Method G 125.
Do not use dented or damaged cylinders.
10.1.1.5 Chemical Exposure—Chemical exposure can pro-
9.1.1 See Compressed Gas Association Pamphlets G-4 and
duce several changes in a material. Solvents can extract
G-4.1 for details on the safe use of oxygen.
materialsorbecomedissolvedinthematerialthemselves.They
9.2 Refer to the safety precautions sections of referenced
can attack the material surface and alter its specific surface
standards for further safety information applicable to the use of
area. And they can change a material’s mechanical properties,
each standard and therefore applicable to this practice when
turning it hard, gummy or otherwise. This wide assortment of
used in conjunction with it.
prospects suggests any of the test methods may reveal aging
changes.
10. Procedure
10.2 Characterizing the Original Material:
10.1 Choosing Aging Criteria and Test Methods:
10.1.1 The user must first identify the factors most likely to 10.2.1 The material should be in the exact condition for use
contribute to aging of the material, as well as the test method
prior to aging.Any cleaning should be consistent with cleaning
that is most likely to measure the change.
required for the application of interest.
10.1.1.1 Time—Time may be the most elemental aging
10.2.2 Test the material as specified in the test method(s)
factor. Time alone may alter a material. Aging through time
chosen: Test Methods G 72, G 74, G 86, G 125, D 4809, or
alone cannot be accelerated.As a result, it may be desirable in
other. If time is suspected to be a key aging parameter, retain
some instances to test materials that have been in service or in
some of the material in its original condition for later testing in
storage and to compare the results with historical data or
concert with the aged material.
generic averages for the particular material. Time may affect
10.2.3 If desired to increase the data base obtained, the
any of the properties, and hence characterization with any of
material may be further characterized prior to aging by
the test procedures may be worthwhile.
weighing it, checking its physical properties, (hardness, flex-
10.1.1.2 Elevated Temperature—Elevated temperature may
ibility, tensi
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