1、Designation: G 145 96 (Reapproved 2001)Standard Guide forStudying Fire Incidents in Oxygen Systems1This standard is issued under the fixed designation G 145; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers procedures and material for examin-ing fires in oxygen systems for the purposes of identifyingpotential causes a
3、nd preventing recurrence.1.2 This guide is not comprehensive and is not intended forforensic use. The analysis of oxygen fire incidents is not ascience, and definitive causes have not been established forsome events.1.3 The procedures and analyses in this guide have beenfound useful for interpreting
4、 fire events, for helping identifypotential causes, and for excluding other potential causes. Theinclusion or omission of any analytical strategy is not intendedto suggest either applicability or inapplicability of that methodin any actual incident study. Indeed, some material in this guideis consid
5、ered useful, and therefore worthy of inclusion andconsideration in a study, but not necessarily of demonstratedvalidity.NOTE 1Although this guide has been found applicable for assistingqualified technical personnel to analyze incidents, each incident is uniqueand must be approached as a unique event
6、. Therefore, the selection ofspecific tactics and the sequence of application of those tactics must beconscious decisions of those studying the event.NOTE 2The incident may require the formation of a team to providethe necessary expertise and experience to conduct the study. The personnelanalyzing a
7、n incident, or at least one member of the team, should know theprocess under study and the equipment installation.1.4 WarningDuring combustion, gases, vapors, aerosols,fumes, or combination thereof, are evolved, which may bepresent and may be hazardous to people. CautionAdequateprecautions should be
8、 taken to protect those conducting astudy.1.5 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 regulator
9、y limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E 620 Practice for Reporting Opinions of Technical Ex-perts2E 678 Practice for Evaluation of Technical Data2E 860 Practice for Examining and Testing Items That Are orMay Become Involved in Products Liability Litigation2E 1020 Pract
10、ice for Reporting Incidents2E 1138 Terminology of Technical Aspects of Products Li-ability Litigation2E 1188 Practice for Collection and Preservation of Informa-tion and Physical Items by a Technical Investigator2E 1459 Guide for Physical Evidence Labeling and RelatedDocumentation2E 1492 Practice fo
11、r Receiving, Documenting, Storing, andRetrieving Evidence in a Forensic Science Laboratory2G 63 Guide for Evaluating Nonmetallic Materials for Oxy-gen Service3G 88 Guide for Designing Systems for Oxygen Service3G 93 Practice for Cleaning Methods for Material andEquipment Used in Oxygen-Enriched Envi
12、ronments3G 94 Guide for Evaluating Metals for Oxygen Service3G 114 Practice for Aging Oxygen-Service Materials Prior toFlammability Testing3G 124 Test Method for Determining the Combustion Be-havior of Metallic Materials in Oxygen-Enriched Atmo-spheres3G 128 Guide for Control of Hazards and Risks in
13、 Oxygen-Enriched Systems32.2 ASTM Adjunct:Video: Oxygen Safety42.3 Compressed Gas Association (CGA) Standards:5G-4.4 Industrial Practices for Gaseous Oxygen Transmis-sion and Distribution Piping SystemsG-4.8 Safe Use of Aluminum Structured Packing for Oxy-gen Distillation2.4 National Fire Protection
14、 Association (NFPA) Stan-dard:6NFPA 53 Fire Hazards in Oxygen Enriched Atmospheres1This guide is under the jurisdiction of ASTM Committee G4 on Compatibilityand Sensitivity of Materials in Oxygen-Enriched Atmospheres and is the directresponsibility of Subcommittee G04.02 on Practices.Current edition
15、 approved Oct. 10, 1996. Published January 1997.2Annual Book of ASTM Standards, Vol 14.02.3Annual Book of ASTM Standards, Vol 14.04.4Available from ASTM Customer Service, 100 Barr Harbor Drive, WestConshohocken, PA 19428-2959. Request PCN 12-700880-31.5Available from Compressed Gas Association, 1725
16、 Jefferson Davis Highway,Suite 1004, Arlington, VA 22202.6Available from National Fire Protection Association, 1 Batterymarch Park, Box9101, Quincy, MA 02269-9101.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.5 Occupational Safet
17、y and Health Act:7OSHA Process Safety Management Compliance Manual3. Terminology3.1 DefinitionsSee Guides G 63, G 94, and G 128 for theterms listed in this section.3.1.1 oxygen compatibility, nthe ability of a substance tocoexist both with oxygen and with a potential source(s) ofignition at an expec
18、ted pressure and temperature with amagnitude of risk acceptable to the user.3.1.2 qualified technical personnel, npersons such asengineers and chemists who, by virtue of education, training,or experience, know how to apply the physical and chemicalprinciples involved in the reactions between oxygen
19、and othermaterials.3.1.3 oxygen-enriched, adjapplies to a fluid (gas or liq-uid) that contains more than 25 mol % oxygen.3.2 Definitions of Terms Specific to This Standard:3.2.1 incident, nan ignition or fire, or both, that is bothundesired and unanticipated or an undesired and unanticipatedconseque
20、nce of an ignition or fire that was anticipated.3.2.2 direct incident cause, nthe mechanical or thermo-dynamic event (such as breakage of a component or near-adiabatic compression), the physicochemical property (such asheat of combustion), the procedure (such as a valve openingrate), or any departur
21、e(s) from the intended state of any ofthese items, that leads directly to ignition or fire, or both.3.2.3 fractional evaporation, vthe continuous evaporationof a quantity of liquid that results in a progressive increase inthe concentration of a less-volatile constituent(s).4. Summary of Guide4.1 Fol
22、lowing a fire incident in an oxygen-enriched atmo-sphere, the equipment, operating procedures, and area areconsidered in light of other incidents, potential contributingfactors, suggested analytical strategies, and demonstrated labo-ratory results. The goal is to determine direct cause(s) of theinci
23、dent in order to prevent a recurrence.5. Significance and Use5.1 This guide helps those studying oxygen system inci-dents to select a direct cause hypothesis and to avoid conclu-sions based on hypotheses, however plausible, that haveproven faulty in the past.6. Abstract6.1 A series of possible cause
24、s and common scenarios aredescribed to assist those seeking to understand incidents inoxygen-enriched atmospheres. Many easily misinterpreted fac-tors are described to help avoid faulty conclusions. Severalsuspected but unproven incident scenarios are described. Selectlaboratory data are presented t
25、o support assertions about directcauses of incidents.7. Direct-Cause Analysis7.1 In this guide, the direct cause of an incident is themechanical or thermodynamic event (such as breakage of acomponent or near-adiabatic compression), the physicochemi-cal property (such as heat of combustion), the proc
26、edure (suchas a valve opening rate), or any departure(s) from the intendedstate of any of these items, that leads directly to ignition or fire,or both. A fire might also be the result of a financial decision,worker skill, or manufacturing processall of which can beviewed as causesbut such factors ar
27、e addressed more prop-erly in a system hazard review. Note that some fires areanticipated and the risks (whether human or economic) areaddressed by such things as shielding (for example to controlhuman risk) or acceptance (for example to address economicrisk). In these cases, a fire is not an “incid
28、ent” unless someaspect of the event exceeded the initial parameters (forexample, the shielding did not provide the expected contain-ment, or the cost exceeded projections). This guide seeks toidentify the material choice, equipment design, assemblyprocedure, or other factor that led directly to the
29、fireandmore specifically, to distinguish the physical object or actionthat caused the fire to start, to continue, or to be injurious ordestructive. Remedial actions are found in other documentssuch as Guides G 63, G 88, and G 94, and Practice G 93, aswell as publications NFPA 53, CGA G-4.4, and G-4.
30、8, OSHAProcess Safety Management Compliance Manual, and others.7.2 ExampleThe direct cause of an incident may beconcluded to be the use of an incompatible material, because apolyacetyl component was installed when a material such asPTFE or CTFE was preferred. The direct cause was not that thebudget
31、was inadequate to cover the cost of PTFE; nor thatspecific frictional properties of polyacetyl were required formechanical purposes; nor that an incorrect part was installed inerror. Note that in this example, PTFE and CTFE might beneeded to prevent or cope with ignition and fire, but that theymight
32、 introduce non-fire-related issues such as loss of me-chanical strength or production of toxic decomposition prod-ucts when exposed to heat of compression.8. Elements of a Study8.1 OverviewThe study of an oxygen incident typicallybegins (preferably promptly) after the event has concluded.The fire is
33、 extinguished and any safety requirements orimmediate needs are addressed (treating injuries, returningsystems to a safe state, and so forth). Then the investigator canbegin to document the event, to preserve the artifacts, and todetect how they may have been altered or compromised by theevent and f
34、ollow-up activities. Although many of these stepsare itemized here, the intent of this guide is not to specify howor in what order they should be conducted. Rather, informationis offered about certain procedures that have been effective inthe past, as well as some that have led to faulty conclusions
35、.Typically, good scientific and laboratory skills are useful andadequate. Forensic skills and procedures can be helpful inmany cases, but may not be practical in all. For example, theforensic Guide E 1459 can assist with managing post-incidentartifacts, and related Practices E 1492, E 620, E 678, E
36、860,E 1020, and E 1188, as well as Terminology E 1138, may haveother uses. However, when a forensic approach is neededbecause a legal action is involved, the insights in this guidemay effectively supplement it.7Available from Occupational Safety and Health Administration, 1825 K Street,NW Washington
37、, DC 20006.G 14528.2 DocumentationAmong the urgent post-incident ef-forts are: photographing or videotaping the site and anydamaged equipment; obtaining system drawings, supportingdesign analysis, process hazards analysis, and any otherhazard-evaluation materials; interviewing persons knowledge-able
38、 about the system, operating procedures and the eventsbefore, during, and after the fire; collecting specimens, oper-ating logs, and related information; and preliminary formula-tion and testing of hypotheses.8.3 AnalysisThe principal effort in a study will be analy-sis of the data and artifacts. Th
39、is may require further exami-nation of the equipment and records, laboratory study ofselected items, and perhaps even laboratory simulation of theincident.8.4 Completion of StudyAn incident study is completedwhen the qualified technical personnel involved in the studyconclude that the event is under
40、stood.8.4.1 An incident might be understood adequately when aconclusion has been drawn about the direct cause of the event.The following examples show the distinction between directcauses and causes that are not physicochemical or thermody-namic events.8.4.1.1 Example 1A substantial amount of hydroc
41、arbonoil was introduced into a system just before an incident. Thissingle factor may be identified as the direct cause of the fire.Any reasons for introducing the lubricant may be important toa new hazard review, but are not the direct cause of the fire.Prevention can focus on cleanliness. Initiatin
42、g Event: ignitionof an incompatible oil. Direct Cause: contamination of thesystem.8.4.1.2 Example 2Records may show that a componentbroke and produced a rub in a piece of machinery just beforean incident. This factor alone can ignite a fire and could beidentified as the direct cause. If the componen
43、t broke becauseit contained a flaw, the flaw might be determined to be thedirect cause. However, if the part was selected because itoffered economy, then the direct cause remains the inadequatepartnot a misguided effort to economize. Prevention in thiscase can focus on component quality. Initiating
44、Event: frictionduring the rub. Direct Cause: Mechanical failure.8.4.1.3 Example 3Deviation from an important operatingpractice, such as first equalizing downstream pressure with abypass valve before opening a quick-opening valve, may beestablished as the direct cause of a fire. The reasons fordepart
45、ing from mandated practice are important, but they arenot the direct cause. Here, prevention can focus on followingstandard operating procedures. Initiating Event: approximatelyadiabatic compression. Direct Cause: incorrect operation.8.4.2 An incident might be understood adequately when aconservativ
46、e tactic has been identified that would have pre-vented or safely managed the event.8.4.2.1 Example 1If an item of machinery cannot employoxygen-compatible materials because they compromise itsoperating economy, and it becomes the site of a fire and injuressomeone, then the event may be understood a
47、dequately (re-garding preventing recurrence of injury rather than fire) wheninadequate shielding or inadequate mechanical design or othercomparable factor is identified singly or in combination as thedirect cause.8.4.3 The study is complete when the direct cause has beendetermined. Preventing the re
48、petition of an event is thefunction of a hazard review using well-established techniques,including the use of related standards from ASTM CommitteeG-4. The hazard review may be integral to the incident studyand may involve some or all of the same people, but it is aseparate activity for the purpose
49、of this guide.9. Factors Affecting an Incident Study9.1 Missing ComponentsFollowing some oxygen inci-dents, components have appeared to be absent, leading tospeculation that the component was not installed or that itsmechanical failure and passage through the system were atfault. Sometimes, the damage is so negligible that the possi-bility that there was no fire is considered. These conclusionscan be in error. In an oxygen-enriched atmosphere, combustioncan be remarkably clean. A simple polymer may be convertedtotally into carbon dioxide and water, leaving no trace
