1、Designation: G 94 05Standard Guide forEvaluating Metals for Oxygen Service1This standard is issued under the fixed designation G 94; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber in parentheses i
2、ndicates the year of last reapproval.Asuperscriptepsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide applies to metallic materials under consider-ation for oxygen or oxygen-enriched fluid service, direct orindirect, as defined in Section 3. It is co
3、ncerned primarily withthe properties of a metallic material associated with its relativesusceptibility to ignition and propagation of combustion. Itdoes not involve mechanical properties, potential toxicity,outgassing, reactions between various materials in the system,functional reliability, or perf
4、ormance characteristics such asaging, shredding, or sloughing of particles, except when thesemight contribute to an ignition.1.2 This document applies only to metals; nonmetals arecovered in Guide G63.NOTE 1The American Society for Testing and Materials takes noposition respecting the validity of an
5、y evaluation methods asserted inconnection with any item mentioned in this guide. Users of this guide areexpressly advised that determination of the validity of any such evaluationmethods and data and the risk of use of such evaluation methods and dataare entirely their own responsibility.NOTE 2In e
6、valuating materials, any mixture with oxygen exceedingatmospheric concentration at pressures higher than atmospheric should beevaluated from the hazard point of view for possible significant increasein material combustibility.1.3 The values stated in SI units are to be regarded as thestandard.1.4 Th
7、is standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documen
8、ts2.1 ASTM Standards:2D 2512 Test Method for Compatibility of Materials withLiquid Oxygen (Impact Sensitivity Threshold and Pass-Fail Techniques)D 2863 Test Method for Measuring the Minimum OxygenConcentration to Support Candle-Like Combustion ofPlastics (Oxygen Index)D 4809 Test Method for Heat of
9、Combustion of LiquidHydrocarbon Fuels by Bomb Calorimeter (IntermediatePrecision Method)G63 Guide for Evaluating Nonmetallic Materials for Oxy-gen ServiceG72 Test Method for Autogenous Ignition Temperature ofLiquids and Solids in a High-Pressure Oxygen-EnrichedEnvironmentG86 Test Method for Determin
10、ing Ignition Sensitivity ofMaterials to Mechanical Impact in Ambient Liquid Oxy-gen and Pressurized Liquid and Gaseous Oxygen Environ-mentsG88 Guide for Designing Systems for Oxygen ServiceG93 Practice for Cleaning Methods and Cleanliness Levelsfor Material and Equipment Used in Oxygen-EnrichedEnvir
11、onmentsG 124 Test Method for Determining the Combustion Be-havior of Metallic Materials in Oxygen-Enriched Atmo-spheresG 126 Terminology Relating to the Compatibility and Sen-sitivity of Materials in Oxygen Enriched AtmospheresG 128 Guide for Control of Hazards and risks in OxygenEnriched Systems2.2
12、 ASTM Special Technical Publications (STPs) on theFlammability and Sensitivity of Materials in Oxygen-EnrichedAtmospheres:ASTM STPs in this category are listed as: 812, 910, 986,1040, 1111, 1167, 1197, 1319, 1395, and 14542.3 Compressed Gas Association Documents:Pamphlet G-4.4-2003 (EIGA Doc. 13/02)
13、, Oxygen PipelineSystems3Pamphlet G-4.8, Safe Use of Aluminum Structured Packingfor Oxygen Distillation3Pamphlet G-4.9, Safe Use of Brazed Aluminum Heat Ex-changers for Producing Pressurized Oxygen3Pamphlet P-8.4 (EIGA Doc. 65/99), Safe Operation ofReboilers Condensers in Air Separation Plants32.4 A
14、STM Adjuncts:1This guide is under the jurisdiction ofASTM Committee G04 on Compatibilityand Sensitivity of Materials in Oxygen Enriched Atmospheres and is the directresponsibility of Subcommittee G04.02 on Recommended Practices.Current edition approved Sept. 1, 2005. Published October 2005. Original
15、lyapproved in 1987. Last previous edition approved in 1998 as G 94 92 (1998).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page ont
16、he ASTM website.3Available from Compressed Gas Association, Inc., 1235 Jefferson DavisHighway, Arlington, VA.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Test Program Report on the Ignition and Combustion ofMaterials in High-Press
17、ure Oxygen43. Terminology3.1 Definitions:3.1.1 autoignition temperaturethe lowest temperature atwhich a material will spontaneously ignite in oxygen underspecific test conditions (see Guide G 126).3.1.2 direct oxygen servicein contact with oxygen duringnormal operations. Examples: oxygen compressor
18、piston rings,control valve seats (see Guide G 126).3.1.3 exemption pressurethe maximum pressure for anengineering alloy at which there are no oxygen velocityrestrictions (from CGA 4.4 and EIGA doc 13/02).3.1.4 impact-ignition resistancethe resistance of a mate-rial to ignition when struck by an obje
19、ct in an oxygenatmosphere under a specific test procedure (see Guide G 126).3.1.5 indirect oxygen servicenot normally in contact withoxygen, but which might be as a result of a reasonablyforeseeable malfunction, operator error, or process upset.Examples: liquid oxygen tank insulation, liquid oxygen
20、pumpmotor bearings (see Guide G 126).3.1.6 maximum use pressurethe maximum pressure towhich a material can be subjected due to a reasonablyforeseeable malfunction, operator error, or process upset (seeGuide G63).3.1.7 maximum use temperaturethe maximum tempera-ture to which a material can be subject
21、ed due to a reasonablyforeseeable malfunction, operator error, or process upset (seeGuide G 126).3.1.8 nonmetallicany material, other than a metal, or anycomposite in which the metal is not the most easily ignitedcomponent and for which the individual constituents cannot beevaluated independently (s
22、ee Guide G 126).3.1.9 operating pressurethe pressure expected under nor-mal operating conditions (see Guide G 126).3.1.10 operating temperaturethe temperature expectedunder normal operating conditions (see Guide G 126).3.1.11 oxygen-enrichedapplies to a fluid (gas or liquid)that contains more than 2
23、5 mol % oxygen (see Guide G 126).3.1.12 qualified technical personnelpersons such as engi-neers and chemists who, by virtue of education, training, orexperience, know how to apply physical and chemical prin-ciples involved in the reactions between oxygen and othermaterials (see Guide G 126).3.1.13 r
24、eaction effectthe personnel injury, facility dam-age, product loss, downtime, or mission loss that could occuras the result of an ignition (see Guide G 126).3.1.14 threshold pressurethere are several different defi-nitions of threshold pressure that are pertinent to the technicalliterature. It is im
25、portant that the user of the technical literaturefully understand those definitions of threshold pressure whichapply to specific investigations being reviewed. Two defini-tions for threshold pressure, based on interpretations of thebulk of the current literature, appear below.3.1.14.1 threshold pres
26、surein a promoted ignition-combustion test series conducted over a range of pressures, thisis the maximum pressure at which no burns, per the testcriteria, were observed and above which burns were experi-enced or tests were not conducted.3.1.14.2 threshold pressurethe minimum gas pressure (ata speci
27、fied oxygen concentration and ambient temperature) thatsupports self-sustained combustion of the entire standardsample (see Guide G 124).4. Significance and Use4.1 The purpose of this guide is to furnish qualified techni-cal personnel with pertinent information for use in selectingmetals for oxygen
28、service in order to minimize the probabilityof ignition and the risk of explosion or fire. It is intended foruse in selecting materials for applications in connection withthe production, storage, transportation, distribution, or use ofoxygen. It is not intended as a specification for approvingmateri
29、als for oxygen service.5. Factors Affecting Selection of Materials5.1 General:5.1.1 The selection of a material for use with oxygen oroxygen-enriched atmospheres is primarily a matter of under-standing the circumstances that cause oxygen to react with thematerial. Most materials in contact with oxyg
30、en will not ignitewithout a source of ignition energy. When an energy-inputexceeds the configuration-dependent threshold, then ignitionand combustion may occur. Thus, the materials flammabilityproperties and the ignition energy sources within a system mustbe considered. These should be viewed in the
31、 context of theentire system design so that the specific factors listed in thisguide will assume the proper relative significance. In summary,it depends on the application.5.2 Relative Amount of Data Available for Metals andNonmetals:5.2.1 Studies of the flammability of gaseous fuels werebegun more
32、than 150 years ago. A wide variety of applicationshave been studied and documented, including a wide range ofimportant subtleties such as quenching phenomena, turbulence,cool flames, influence of initial temperature, etc., all of whichhave been used effectively for safety and loss prevention. Asmall
33、er, yet still substantial, background exists for nonmetallicsolids. In contrast to this, the study of the flammability ofmetals dates only to the 1950s, and even though it hasaccelerated rapidly, the uncovering and understanding ofsubtleties have not yet matured. In addition, the heterogeneityof the
34、 metal and oxidizer systems and the heat transferproperties of metals, as well as the known, complex ignitionenergy and ignition/burning mechanisms, clearly dictate thatcaution is required when applying laboratory findings to actualapplications. In many cases, laboratory metals burning tests aredesi
35、gned on what is believed to be a worst-case basis, but couldthe particular actual application be worse? Further, because somany subtleties exist, accumulation of favorable experience(no metal fires) in some particular application may not be asfully relevant to another application as might be the cas
36、e forgaseous or nonmetallic solids where the relevance may bemore thoroughly understood.4Available from ASTM Headquarters, Order ADJG0094.G940525.2.1.1 ASTM Symposia and Special Technical Publica-tions on these symposia have contributed significantly to thestudy of the flammability and sensitivity o
37、f materials inoxygen-enriched atmospheres. See section 2.2 for listing ofSTP numbers and the References Section for key papers.5.3 Relationship of Guide G 94 with Guides G 63, G 88,and G 93:5.3.1 This guide addresses the evaluation of metals for usein oxygen systems and especially in major structura
38、l portionsof a system. Guide G63addresses the evaluation of nonmetals.Guide G88presents design and operational maxims for allsystems. In general, however, Guides G63and G88focus onphysically small portions of an oxygen system that representthe critical sites most likely to encounter ignition. Guide
39、G93covers a key issue pertinent to actual operating oxygensystems; cleaning for the service.5.3.2 The nonmetals in an oxygen system (valve seats andpacking, piston rings, gaskets, o-rings) are small; therefore, theuse of the most fire-resistant materials is usually a realistic,practical option with
40、regard to cost and availability. In com-parison, the choice of material for the major structural mem-bers of a system is much more limited, and the use of specialalloys may have to be avoided to achieve realistic costs anddelivery times. Indeed, with the exception of ceramic materi-als, which have r
41、elatively few practical uses, most nonmetalshave less fire resistance than virtually all metals. Nonmetals aretypically introduced into a system to provide a physicalproperty not achievable from metals. Nonmetals may serve as“links” in a kindling chain (see 5.6.5), and since the locationsof use are
42、typically mechanically severe, the primary thrust inachieving compatible oxygen systems rests with the minorcomponents as addressed by Guides G63 and G88 thatexplain the emphasis on using the most fire-resistant materialsand Guide G93which deals with the importance of systemcleanliness.5.3.3 Since m
43、etals are typically more fire-resistant and areused in typically less fire-prone functions, they represent asecond tier of interest. However, because metal componentsare relatively so large, a fire of a metal component is a veryimportant event, and should a nonmetal ignite, any consequen-tial reacti
44、on of the metal can aggravate the severity of anignition many times over. Hence, while the selection ofnonmetals by Guide G63and the careful design of compo-nents by Guide G88are the first line of defense, optimummetal selection is an important second-line of defense.5.3.4 Contaminants and residues
45、that are left in oxygensystems may contribute to incidents via ignition mechanismssuch as particle impact and promoted ignition-combustion(kindling chain). Therefore, oxygen system cleanliness isessential. Guide G93describes in detail the essential elementsfor cleaning oxygen systems.5.4 Differences
46、 in Oxygen Compatibility of Metals andNonmetals:5.4.1 There are several fundamental differences between theoxygen compatibility of metals and nonceramic nonmetals.These principal differences are summarized in Table 1.5.4.2 Common-use metals are harder to ignite. They havehigh autoignition temperatur
47、es in the range 900 to 2000C(1650 to 3600F). In comparison, most combustible nonmetalshave autoignition temperatures in the range 150 to 500C (300to 1000F). Metals have high thermal conductivities that helpdissipate local heat inputs that might easily ignite nonmetals.Many metals also grow protectiv
48、e oxide coatings (see 5.5) thatinterfere with ignition and propagation.5.4.3 Once ignited, however, metal combustion can behighly destructive.Adiabatic flame temperatures for metals aremuch higher than for most polymers (Table X1.7). The greaterdensity of most metals provides greater heat release po
49、tentialfrom components of comparable size. Since many metal oxidesdo not exist as oxide vapors (they largely dissociate uponvaporization), combustion of these metals inherently yieldscoalescing liquid metal oxide of high heat capacity in the flamezone at the oxide boiling point (there may be very little gaseousmetal oxide). In comparison, combustion of polymers yieldsgaseous combustion products (typically carbon dioxide andsteam) that tend to dissipate the heat release.5.4.4 Contact with a mixture of liquid metal and oxide athigh temperature results in a massive
