1、Designation: G94 05 (Reapproved 2014)Standard Guide forEvaluating Metals for Oxygen Service1This standard is issued under the fixed designation G94; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.Anumber
2、in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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 Sect
3、ion 3. It is concerned 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 relia
4、bility, or performance 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
5、 validity of any 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 responsibi
6、lity.NOTE 2In evaluating 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 the
7、standard.1.4 This 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. Ref
8、erenced Documents2.1 ASTM Standards:2D2512 Test Method for Compatibility of Materials withLiquid Oxygen (Impact Sensitivity Threshold and Pass-Fail Techniques)D2863 Test Method for Measuring the Minimum OxygenConcentration to Support Candle-Like Combustion ofPlastics (Oxygen Index)D4809 Test Method
9、for Heat of Combustion of LiquidHydrocarbon Fuels by Bomb Calorimeter (PrecisionMethod)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 Determini
10、ng Ignition Sensitivity ofMaterials to Mechanical Impact in Ambient Liquid Oxy-gen and Pressurized Liquid and Gaseous Oxygen Envi-ronmentsG88 Guide for Designing Systems for Oxygen ServiceG93 Practice for Cleaning Methods and Cleanliness Levelsfor Material and Equipment Used in Oxygen-EnrichedEnviro
11、nmentsG124 Test Method for Determining the Combustion Behav-ior of Metallic Materials in Oxygen-Enriched Atmo-spheresG126 Terminology Relating to the Compatibility and Sensi-tivity of Materials in Oxygen Enriched AtmospheresG128 Guide for Control of Hazards and Risks in OxygenEnriched Systems2.2 AST
12、M 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) Oxy
13、gen 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 Oxygen31This guide is under the jurisdiction ofASTM Committee G04 on Compatibilityand Sensitivity of Materials in Ox
14、ygen Enriched Atmospheres and is the directresponsibility of Subcommittee G04.02 on Recommended Practices.Current edition approved Jan. 1, 2014. Published January 2014. Originallyapproved in 1987. Last previous edition approved in 2005 as G94 05. DOI:10.1520/G0094-05R14.2For referenced ASTM standard
15、s, 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 onthe ASTM website.3Available from Compressed Gas Association (CGA), 4221 Walney Rd., 5thFloor, Chantilly, VA
16、 20151-2923, http:/.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Pamphlet P-8.4 (EIGA Doc. 65/99) Safe Operation of Re-boilers Condensers in Air Separation Plants32.4 ASTM Adjuncts:Test Program Report on the Ignition and Combustion
17、 ofMaterials in High-Pressure Oxygen43. Terminology3.1 Definitions:3.1.1 autoignition temperaturethe lowest temperature atwhich a material will spontaneously ignite in oxygen underspecific test conditions (see Guide G126).3.1.2 direct oxygen servicein contact with oxygen duringnormal operations. Exa
18、mples: oxygen compressor piston rings,control valve seats (see Guide G126).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 ignitio
19、n when struck by an object in an oxygenatmosphere under a specific test procedure (see Guide G126).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 ins
20、ulation, liquid oxygen pumpmotor bearings (see Guide G126).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 m
21、aterial can be subjected due to a reasonablyforeseeable malfunction, operator error, or process upset (seeGuide G126).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 beevalu
22、ated independently (see Guide G126).3.1.9 operating pressurethe pressure expected under nor-mal operating conditions (see Guide G126).3.1.10 operating temperaturethe temperature expectedunder normal operating conditions (see Guide G126).3.1.11 oxygen-enrichedapplies to a fluid (gas or liquid)that co
23、ntains more than 25 mol % oxygen (see Guide G126).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 Guid
24、e G126).3.1.13 reaction effectthe personnel injury, facilitydamage, product loss, downtime, or mission loss that couldoccur as the result of an ignition (see Guide G126).3.1.14 threshold pressurethere are several different defi-nitions of threshold pressure that are pertinent to the technicalliterat
25、ure. It is important 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 t
26、hreshold pressurein 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 pressu
27、re (ata specified oxygen concentration and ambient temperature) thatsupports self-sustained combustion of the entire standardsample (see Guide G124).4. Significance and Use4.1 The purpose of this guide is to furnish qualified techni-cal personnel with pertinent information for use in selectingmetals
28、 for oxygen 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 app
29、rovingmaterials 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 conta
30、ct with oxygen 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 v
31、iewed in the 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 wer
32、ebegun more 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 preven
33、tion. Asmaller, 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 heterog
34、eneityof the 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 actual4Available from ASTM International Headquarters. Order A
35、djunct No.ADJG0094. Original adjunct produced in 1986.G94 05 (2014)2applications. In many cases, laboratory metals burning tests aredesigned on what is believed to be a worst-case basis, but couldthe particular actual application be worse? Further, because somany subtleties exist, accumulation of fa
36、vorable experience(no metal fires) in some particular application may not be asfully relevant to another application as might be the case forgaseous or nonmetallic solids where the relevance may bemore thoroughly understood.5.2.1.1 ASTM Symposia and Special Technical Publica-tions on these symposia
37、have contributed significantly to thestudy of the flammability and sensitivity of materials inoxygen-enriched atmospheres. See section 2.2 for listing ofSTP numbers and the References Section for key papers.5.3 Relationship of Guide G94 with Guides G63, G88, andG93:5.3.1 This guide addresses the eva
38、luation of metals for usein oxygen systems and especially in major structural portionsof a system. Guide G63 addresses the evaluation of nonmetals.Guide G88 presents design and operational maxims for allsystems. In general, however, Guides G63 and G88 focus onphysically small portions of an oxygen s
39、ystem that representthe critical sites most likely to encounter ignition. Guide 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
40、 the most fire-resistant materials is usually a realistic,practical option with regard to cost and availability. Incomparison, the choice of material for the major structuralmembers of a system is much more limited, and the use ofspecial alloys may have to be avoided to achieve realistic costsand de
41、livery times. Indeed, with the exception of ceramicmaterials, which have relatively few practical uses, mostnonmetals have less fire resistance than virtually all metals.Nonmetals are typically introduced into a system to provide aphysical property not achievable from metals. Nonmetals mayserve as “
42、links” in a kindling chain (see 5.6.5), and since thelocations of use are typically mechanically severe, the primarythrust in achieving compatible oxygen systems rests with theminor components as addressed by Guides G63 and G88 thatexplain the emphasis on using the most fire-resistant materialsand G
43、uide G93 which deals with the importance of systemcleanliness.5.3.3 Since metals 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 v
44、eryimportant event, and should a nonmetal ignite, any consequen-tial reaction of the metal can aggravate the severity of anignition many times over. Hence, while the selection ofnonmetals by Guide G63 and the careful design of componentsby Guide G88 are the first line of defense, optimum metalselect
45、ion is an important second-line of defense.5.3.4 Contaminants and residues 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 G93 describes
46、 in detail the essential elementsfor cleaning oxygen systems.5.4 Differences 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 C
47、ommon-use metals are harder to ignite. They havehigh autoignition temperatures 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 he
48、at inputs that might easily ignite nonmetals.Many metals also grow protective 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 (Tab
49、le X1.7). The greaterdensity of most metals provides greater heat release potentialfrom 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
