NFPA 329-2015 Recommended Practice for Handling Releases of Flammable and Combustible Liquids and Gases (Effective Date 12 1 2014).pdf

1、Copyright 2014 National Fire Protection Association. All Rights Reserved.NFPA329Recommended Practice forHandling Releases of Flammable and CombustibleLiquids and Gases2015 EditionThis edition of NFPA 329, Recommended Practice for Handling Releases of Flammable and Com-bustible Liquids and Gases, was

2、 prepared by the Technical Committee on Tank Leakage andRepair Safeguards. It was issued by the Standards Council on November 11, 2014, with aneffective date of December 1, 2014, and supersedes all previous editions.This edition of NFPA 329 was approved as an American National Standard on December 1

3、,2014.Origin and Development of NFPA 329This recommended practice began as a report (NFPA 30B), which was published until1950. A manual on this subject was published in 1959. The manual was rewritten as a recom-mended practice in 1964, with subsequent revisions in 1965, 1972, 1977, 1983, 1987, 1992,

4、and 1999.The 1999 edition of this recommended practice combined the relevant and updated ma-terial contained in earlier editions of NFPA 329 and of NFPA 328, Recommended Practice for theControl of Flammable and Combustible Liquids and Gases in Manholes, Sewers, and Similar Under-ground Structures, i

5、nto a single document. NFPA 328 was withdrawn in May 1999.The 2005 edition of NFPA 329 was the result of a major rewrite effort to comply with theManual of Style for NFPA Technical Committee Documents and also incorporated amendments toseveral defined terms in order to use preferred NFPA definitions

6、.The 2010 edition of NFPA 329 was amended to ensure that all referenced documents werecorrectly listed as pertains to title and edition date. In addition, Figure 5.4.7.1 was revised toshow a grounding connection for the air eductor; an Annex item was added to Section 9.1 tocross-reference requiremen

7、ts for control of ignition sources, as set forth in NFPA 326, Stan-dard for the Safeguarding of Tanks and Containers for Entry, Cleaning, or Repair; and errors in theheadings of Table A.4.1.11 were corrected.In the 2015 edition of NFPA 329, referenced publications have been updated to currentrevisio

8、n dates. In addition, definitions have been revised to better describe the terminologyused in the standard and, where appropriate, to use the preferred definition found in otherNFPA publications.3291NFPA and National Fire Protection Association are registered trademarks of the National Fire Protecti

9、on Association, Quincy, Massachusetts 02169.Technical Committee on Tank Leakage and Repair SafeguardsJames R. Rocco, ChairSage Risk Solutions, LLC, OH ERep. Petroleum Underground Storage Tank Release Compensation BoardJohn H. Bagnall, Burns including, but not limited to,safeguarding, repair, hot wor

10、k, cleaning, change of service,maintenance, inspection, and transportation.Chapter 4 Flammable and CombustibleLiquids and Gases4.1 General.4.1.1 Releases of flammable and combustible liquids andgases can result from leaks in tanks, containers, or pipelines,from surface spills, or from human error.4.

11、1.2 In most cases, the amount of liquid or gas that is lost issmall and can be dissipated by evaporation or otherwise as-similated into the environment.4.1.3 Because of the physical and chemical characteristics ofmany flammable and combustible liquids and gases, it is pos-sible that a release can fi

12、nd its way into a subsurface structure,such as a basement, utility conduit, sewer, or well.4.1.4 Whether or not an immediate hazard exists depends ona number of factors, such as the amount of liquid or gas re-leased, where it is found, how it is confined, and possiblesources of ignition.4.1.5 Becaus

13、e a flammable or combustible liquid that is un-confined in the subsurface can move from place to place, anyindication that such liquids have escaped into the subsurfacemust be considered as a potential, if not immediate, hazard.4.1.6 Flammable vapors in subsurface structures can resultfrom a release

14、 of a flammable or combustible liquid.4.1.6.1 Examples of these releases include cleaning solventsand compounds washed down drains by industrial and domes-tic users or a surface release that enters a sewer or drain.4.1.6.2 A release can also result from damage to tanks, con-tainers, and pipelines fr

15、om corrosion, structural failure, exca-vation in the area, or fire.4.1.7 If a flammable or combustible liquid or gas is present inthe soil, as might be produced by decaying organic matter,there is a likelihood that it will penetrate an adjacent subsur-face structure.4.1.8 Particular attention should

16、 be paid to landfill sites. Gasfrom decomposing material in landfills, primarily methane,might not have an odor.4.1.9 Flammable gases or vapors can enter conduits, sewers,drains, or basements because subsurface structures con-structed of cement, concrete, brick, or vitreous tile typicallyare not bui

17、lt to be impervious to gases or vapors.4.1.10 Gases or vapors can enter the subsurface sections ofbuildings through cracks or around any underground con-duits that penetrate the subsurface walls or floors.3296 HANDLING RELEASES OF FLAMMABLE AND COMBUSTIBLE LIQUIDS AND GASES2015 Edition4.1.11* The co

18、ndition created by the releases of liquids andvapors in subsurface structures can be grouped into the fol-lowing two classes:(1) Flammable(2) Injurious to life4.1.11.1 The condition of “injurious to life” specified in4.1.11(2) results from the toxic or suffocating properties ofthe gases or vapors. S

19、ome of these liquids and gases fall intoboth classes. While this publication deals primarily with theflammable limits associated with liquids and gases, some ofwhich are listed in Table A.4.1.11, additional precautionsmight be required to protect against health hazards. An ex-ample is benzene; its d

20、angerous breathing concentration isonly a small fraction of the lower flammable limit (LFL).4.1.12 Flammable and combustible liquids and gases arecommonly stored and handled in locations that are immedi-ately adjacent to structures, facilities, and people.4.1.13 Flammable and combustible liquids inc

21、lude but arenot limited to, chemicals, cleaning fluids, gasoline, alternativefuels, diesel fuel, and heating oil.4.1.14 Gasoline is the most widely used of these liquids and iscommonly stored aboveground and underground at motorfuel dispensing facilities and service stations.4.1.15 Flammable and com

22、bustible gases include natural gas,propane, sewage gases, and refrigerant gases.4.2 Fires and Explosions.4.2.1 The probability of an explosion or fire within a subsur-face space depends on the following two factors:(1) The atmosphere must contain a mixture of flammablevapor and air within the flamma

23、ble range.(2) There must be a coincident source of ignition.4.2.2 The severity of an individual explosion or fire and itsconsequences depend on various other factors and the possi-bility that any one explosion might result in a major catastro-phe is always present.4.3 Sources of Ignition.4.3.1 The p

24、ossibility of ignition of flammable gases or vaporsthat collect in subsurface structures is limited by the followingconditions:(1) The vapor must be mixed with sufficient air to make aflammable mixture or it must escape into the air at a pointwhere a flammable mixture can be created.(2) Heat of suff

25、icient intensity to ignite the particular airvapor mixture involved must be present at the placewhere the flammable mixture exists.4.3.2 Flammable mixtures are formed when the concentra-tion of these gases and vapors in air is between the lower andupper flammability limits.4.3.3 Flammable limits of

26、some gases and vapors that have beenfound in subsurface structures are listed in Table A.4.1.11.4.3.4 Potential sources of ignition can be encountered in ev-eryday operations and include open flames, furnace pilotlights, automotive and other internal combustion engines, tarpots, and smoking. Little

27、control can be exerted over thesesources of ignition where flammable vapors are escaping fromor into subsurface structures.4.3.5 Static electricity can be a source of ignition when itaccumulates to the extent that an ignition-capable spark dis-charge occurs.4.3.5.1 The accumulation of a static elect

28、ric charge is easiestand greatest in an atmosphere of low humidity.4.3.5.2 Static electricity can be generated when a liquid un-der pressure escapes at high velocity from a pipe. Particles ofdust, scale, or rust or liquid droplets inside the pipe can be-come heavily charged when blown out by gas or

29、vapor and, ifthey impinge on an electrically isolated body, that body willaccumulate the charge and a spark discharge can occur.Chapter 5 Initial Response5.1 Indicators of a Release. The release of a flammable orcombustible liquid or gas can be indicated by physical discov-ery of an actual release o

30、r by indication of a potential release.5.1.1 Physical discovery of an actual release of a flammable orcombustible liquid or gas can be indicated by the presence ofthe liquid or gas in any of the following:(1) Normally inhabited subsurface structures, such as base-ments, subways, or tunnels(2) Subsur

31、face structures not normally inhabited, such asmanholes, sewers, utility conduits, utility vaults, or obser-vation wells(3) Groundwater(4) Drinking water supplies(5) Surface water(6) Seepage from the soil5.1.2 Potential release of a flammable or combustible liquid,gas, or vapor can be detected by th

32、e following:(1) Evidence of a spill(2) Failure of a tightness test(3) Monitoring equipment(4) Loss of inventory(5) Presence of water in a tank(6) Odor5.2 Initial Response to Physical Discovery.5.2.1 Depending on the circumstances of physical discovery,conditions might exist where a potential hazard

33、to life orproperty exists, in which case immediate steps should be takento protect the public from the danger of an explosion or fire.5.2.2* For uninhabited structures, those directly responsiblefor the facility should be contacted, such as a municipal sani-tary, highway, or street department for se

34、wers or the electrical,telephone, or gas companys engineering department for util-ity conduit.5.2.3 Police should be asked to keep the public clear of anydanger areas.5.2.4 If necessary, the fire department should assist in firecontrol and purging.5.2.5 Those involved with facilities that store and

35、handleflammable and combustible liquids that might be the sourceof the problem should offer all possible assistance.5.2.6 Although the presence of flammable gases or vapors ina building or subsurface structure is typically reported becauseof an odor, smell cannot be relied on to determine the type o

36、f3297INITIAL RESPONSE2015 Editiongas or vapor or its concentration. A properly calibrated and ad-justed instrument such as a combustible gas indicator or photo-ionization detector should be used to determine the presenceand extent of a flammable gas or vapor concentration.5.2.7 No one should enter a

37、reas where flammable or com-bustible liquids, gases, or vapors have been discovered, exceptas described in Section 5.4.5.2.7.1 If liquids, gases, or vapors within or above the flam-mable range are found in a building, the building should notbe entered.5.2.7.2 Evacuation of building occupants, at lea

38、st in areasthat are exposed, should be ordered.5.2.7.3 Building construction, building layout, and buildingoccupancy are factors that should be considered in orderingevacuation.5.2.8 If liquids, gases, or vapors are found in tunnels orsubways, traffic should be stopped until qualified personneldeter

39、mine that there is no danger of explosion, fire, orhealth hazards.5.3 Eliminating Sources of Ignition.5.3.1 Smoking or other sources of ignition should not bepermitted in areas where flammable or combustible liquids,gases, or vapors have been discovered.5.3.2* Lights and other electrical switches sh

40、ould not beturned on or off. Power cords should not be removed fromoutlets. Only those switches located well away from the areashould be used to disconnect electrical power.5.3.3* After the presence of flammable or combustible liq-uids, gases, or vapors has been verified in a building orsubsurface s

41、tructure, the electrical and gas services to thebuilding or structure should be disconnected or shut offoutside the structure.5.4 Entering the Area.5.4.1 Due to the risk of toxic exposure, fire, or explosion,personnel should use caution when entering an area wherethere is an undetermined concentrati

42、on of an unknown gas orvapor.5.4.2 Flammable gases or vapors in a sewer or conduit mightnot originate from flammable liquids but might be vaporsfrom overheated insulation, sewer-generated gases, fuel gases,or industrial gases. In these cases, special instruments, equip-ment, skills, and procedures (

43、confined space entry) should beused, as necessary.5.4.3 The guidance of the owner or operator of the facilityshould be solicited and should be followed. Entry should notbe made until the gas or vapor concentration has beenchecked by instrument. (See 5.2.6.)5.4.4 An additional hazard might exist beca

44、use of the pres-ence of toxic gases or vapors or because of insufficient oxygen.If these conditions are suspected, a properly calibrated andadjusted instrument appropriate to the suspected hazardshould be used to determine the nature and extent of thehazard.5.4.5 The gas or vapor concentrations in t

45、he affected areashould be checked continuously or at intervals determined bya qualified person.5.4.5.1 Where gas or vapor concentrations are above 50 percentof the LFL, everyone in the affected area should be evacuated.5.4.5.2 The affected area should be ventilated to remove orreduce the flammable g

46、as or vapor concentration and thusreduce the fire or explosion hazard.5.4.5.3 As soon as the flammable gas or vapor has been re-duced below 50 percent of the LFL, entry can be made tolocate and eliminate the source.5.4.5.4 Personnel should wear self-contained breathing appa-ratus when entering the a

47、ffected area.5.4.6 Natural ventilation provided by opening doors and win-dows and removing manhole covers or other access closuresmight be sufficient to remove vapors from the affected areaand should be used.5.4.7 Where natural ventilation is not capable of removingvapors from all areas, particularl

48、y from low, confined spaces,grounded and bonded mechanical exhaust ventilating equip-ment should be used.5.4.7.1 Fans driven by electric motors that are approved forClass I, Group D locations, Division 1 or Zone 0 or Zone 1hand-driven fans, or air eductors should be used to removevapors, as shown in

49、 Figure 5.4.7.1.5.4.7.2 Sources of ignition close to the exhaust outlets shouldbe eliminated.5.4.7.3 Openings for free entry of fresh air should be pro-vided, but air should never be forced into the area.5.4.8 The generation of sewer gas might be stopped or sig-nificantly reduced by slowly flushing the sewer or conduit withwater.5.4.9 When the area has been tested and determined to besafe for entry, entry can be made to remove or control thesource of the flammable or combustible liquids, gases, orvapors.Eliminate sources of ignition.Provide fresh air inlets elsewhere.Window opening