《CGA-G-14-2003.pdf》由会员分享，可在线阅读，更多相关《CGA-G-14-2003.pdf（30页珍藏版）》请在三一文库上搜索。
1、 CGA G-142003 (EIGA DOC 92/03) CODE OF PRACTICE FOR NITROGEN TRIFLUORIDE FIRST EDITION COMPRESSED GAS ASSOCIATION, INC. 4221 Walney Road, 5th Floor Chantilly, VA 20151 Phone: 703-788-2700 Fax: 703-961-1831 E-mail: PAGE ii COMPRESSED GAS ASSOCIATION, INC. CGA G-142003 PREFACE As a part of a program
2、of harmonization of industry standards, the European Industrial Gases Association (EIGA) with the participation of the Compressed Gas Association (CGA) and the Japanese Industrial Gases Association (JIGA) has produced CGA G-142003, Code of Practice for Nitrogen Trifluoride. This standard is intended
3、 as a joint EIGA/CGA/JIGA international harmonized standard for the worldwide use and application by all members of EIGA, CGA and JIGA. The CGA edition has the same technical content as the EIGA edition, however, there are editorial changes primarily in formatting and spelling and references to regi
4、onal regulatory requirements. CGA G-142003 COMPRESSED GAS ASSOCIATION, INC. PAGE iii PLEASE NOTE: The information contained in this document was obtained from sources believed to be reliable and is based on technical information and experience currently available from members of the Compressed Gas A
5、ssociation, Inc. and others. However, the Association or its members, jointly or severally, make no guarantee of the results and assume no liability or responsibility in connection with the information or suggestions herein contained. Moreover, it should not be assumed that every acceptable commodit
6、y grade, test or safety procedure or method, precaution, equipment or device is contained within, or that abnormal or unusual circumstances may not warrant or suggest further requirements or additional procedure. This document is subject to periodic review, and users are cautioned to obtain the late
7、st edition. The Associa- tion invites comments and suggestions for consideration. In connection with such review, any such comments or suggestions will be fully reviewed by the Association after giving the party, upon request, a reasonable op- portunity to be heard. Proposed changes may be submitted
8、 via the Internet at our web site, . This document should not be confused with Federal, state, provincial, or municipal specifications or regulations; insurance requirements; or national safety codes. While the Association recommends reference to or use of this document by government agencies and ot
9、hers, this document is purely voluntary and not binding. A listing of all publications, audiovisual programs, safety and technical bulletins, and safety posters is available via the Internet at our website at . For more information contact CGA at Phone: 703-788-2700, ext. 799. E-mail: Docket 01-54
10、Specialty Gases Committee NOTEAppendices A and B (Informative) are for information only. FIRST EDITION: 2003 2003 BY THE COMPRESSED GAS ASSOCIATION, INC. ALL RIGHTS RESERVED. 4221 WALNEY ROAD, 5TH FLOOR, CHANTILLY, VA 20151 Printed in U.S.A. PAGE iv COMPRESSED GAS ASSOCIATION, INC. CGA G-142003 Cont
11、ents Page 1 Introduction.1 2 Scope and purpose1 3 Definitions.1 4 Gas properties2 4.1 Gas identification.2 4.2 Physical properties3 4.3 Chemical properties.4 4.4 Toxicology .4 4.5 Environmental issues 4 5 Gas major hazards.4 5.1 Introduction to fire and explosion hazards.4 5.2 Factors influencing co
12、mbustionnitrogen trifluoride considerations 5 5.3 Factors influencing combustionmaterial considerations 6 5.4 Other factors influencing combustionenergy source8 6 Gas handling equipmentgeneral considerations.9 6.1 Design principles.9 6.2 Materials of construction9 6.3 Gas velocities9 6.4 Cleaning an
13、d passivation after installation and maintenance10 6.5 Valves10 6.6 Filters.10 6.7 Operating procedures and personnel10 6.8 Maintenance procedures.10 6.9 Separation from flammable gases.11 6.10 Heat dissipation.11 6.11 Compression .11 7 Gas cylinder filling 11 7.1 Filling facility considerations11 7
14、.2 Gas containers and associated equipment .12 7.3 Cylinder filling equipment 13 8 Gas supply to point-of-use .14 8.1 Facility considerations.14 8.2 Gas supply manifolds14 8.3 Operating procedures and personnel15 9 Gas abatement systems.15 9.1 Basic principles of abatement15 9.2 Abatementsemiconduct
15、or process tool exhaust system15 9.3 Abatement at a cylinder filling facility.16 10 Emergency response .16 11 References.16 12 Additional references17 Tables Table 1Physical properties of nitrogen trifluoride 3 Table 2Table of conversion factors .3 -,-,- CGA G-142003 COMPRESSED GAS ASSOCIATION, INC.
16、 PAGE v Figures Figure 1Vapor pressure curve.3 Figure 2Triangle of fire 5 Appendices Appendix AEIGA Material Safety Data Sheet (Informative) 18 Appendix BAudit checklist (Informative)22 -,-,- -,-,- This page is intentionally blank. CGA G-142003 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction
17、Nitrogen trifluoride is an oxidizing compressed gas that has gained acceptance in a number of applications as a fluorinating agent. It is this property that makes it valuable as a nonreactive source of fluorine for etching and cleaning applications. The active fluorine is released only if sufficient
18、 energy is applied. Once initiated, the reac- tion is self propagating and presents a hazard for a material that is incompatible with fluorine (e.g., flammable gas, metals). Nitrogen trifluoride can be safely handled if equipment is properly designed and appropriate handling precau- tions are taken.
19、 This document has been prepared by the European Industrial Gas Association with the assistance of the Com- pressed Gas Association a combustible material in contact with the oxidizer; and a source of ignition energy. For each of these elements, several factors influencing the combustion must be con
20、sidered. They are given in 5.2, 5.3, and 5.4. -,-,- CGA G-142003 COMPRESSED GAS ASSOCIATION, INC. PAGE 5 Figure 2Triangle of fire 5.2 Factors influencing combustionnitrogen trifluoride considerations The following factors influence the combustion of materials: 5.2.1 Nitrogen trifluoride pressure Nit
21、rogen trifluoride is relatively inert at atmospheric pressure and ambient temperature. The autoignition tem- perature of some combustible materials in nitrogen trifluoride can decrease with increasing nitrogen trifluoride pressure, making the material more susceptible to ignition. Likewise, operatin
22、g at high pressures increases the chance for adiabatic compression (see 5.4.3) in the system, which would create high temperature from the heat of compression (see 5.2.2). 5.2.2 Nitrogen trifluoride decomposition temperature The primary concern with nitrogen trifluoride and higher temperatures (300
23、C and may depend upon catalyz- ing effect of certain materials) is the dissociation of nitrogen trifluoride into reactive fluorine species that will react with most materials. These reactive species can lead to uncontrolled reactions with polymers or certain metals, liberating heat and causing furth
24、er dissociation of nitrogen trifluoride. Therefore, precautions must be taken to prevent conditions or mechanisms that could lead to inadvertent heating of nitrogen trifluoride. At higher temperatures, nitrogen trifluoride loses its inherent chemical stability. The autoignition temperature of a mate
25、rial in contact with nitrogen trifluoride is more easily reached as the tem- perature of nitrogen trifluoride increases. Nitrogen trifluoride systems should operate at as low a temperature as is practical. 5.2.3 Nitrogen trifluoride velocity in pipelines The nitrogen trifluoride velocity will create
26、 heat by particle impacts (see 5.4.1) or flow friction (see 5.4.4) on the material, particularly in areas with tortuous passages and/or small crevices. This creation of heat can initiate a local combustion if the autoignition temperature of the material in contact with nitrogen trifluoride is reache
27、d. The nitrogen trifluoride velocity must therefore be limited to avoid the risk of this temperature being achieved. The risk of a particle and the resulting energy imparted by the high velocity in an oxidizing environment can lead to an ignition. This highlights the need to properly clean nitrogen
28、trifluoride systems for oxidizing service. The oxipotential of nitrogen trifluoride is greater than that of oxygen (NF3 = 1.6, where oxygen = 1), however in the absence of other data, the following velocity limits should be applied (by analogy with the EIGA Doc 13/02 and CGA G-4.4, section 4.4) 3, 4
29、: -,-,- PAGE 6 COMPRESSED GAS ASSOCIATION, INC. CGA G-142003 For pressures above 15 bar, the maximum nitrogen trifluoride velocity in pipelines is limited so the product of velocity and pressure does not exceed 450 bar m/s. i.e., PV 450 bar m/s where: V = NF3 velocity in pipeline (m/s) P = the press
30、ure in the pipeline (bar) For pressures below 15 bar, the maximum velocity in pipelines is less of a concern, however it is recom- mended that every effort is made to control this to less than 30 m/s. For equipment other than pipelines, recommendations are contained in other sections (such as 7.2.2
31、of this standard). 5.3 Factors influencing combustionmaterial considerations The most oxidant-compatible materials shall be used with nitrogen trifluoride. In all cases, the materials shall be thoroughly cleaned and free from oils, grease, dirt, and particles. Even compatible lubricants should be us
32、ed sparingly. Materials of concern when in contact with nitrogen trifluoride are: parts of the nitrogen trifluoride handling equipment such as some metals, polymers, plastics, lubricants, etc.; and contamination present in the equipment such as particles, swarf, dirt, grease, insects, etc. Factors i
33、nfluencing the combustion of these materials are as follows: 5.3.1 Autoignition temperature of materials The autoignition temperature is an important factor, which needs to be considered when choosing materials to resist combustion in nitrogen trifluoride. The risk of combustion is higher when the a
34、utoignition temperature is low since the energy required to reach this temperature is lower. Methods to determine the autoignition temperatures of materials in oxygen such as those described in ISO 11114-3 may also be used for nitrogen trifluoride 12. 5.3.1.1 Metals The autoignition temperatures of
35、three common metals in nitrogen trifluoride at 1 bar and 7 bar are given in 4.3. In the incidents mentioned in Section 5, the accidental combustion of a metal is initiated by the combustion of another material having a lower autoignition temperature than the metal, such as polymers, plastics, lubric
36、ants or contaminants in the nitrogen trifluoride handling equipment, more commonly known as the “kindling effect.” 5.3.1.2 Nonmetals Autoignition tests of plastics and lubricants have been conducted with nitrogen trifluoride at 70 bar. Highly fluorinated polymers such as Teflon, including glass and
37、bronze-filled types, Kalrez, Kel-F, and Neoflon are common plastic materials used for nitrogen trifluoride applications and exhibit a high resistance to ignition at high temperatures ( 400 C). Less fluorinated polymers, such as Halar and Viton demonstrate a tendency to autoignite in nitrogen trifluo
38、ride at temperatures less than 400 C with some as low as 240 C. Halocarbon or perfluorinated lubricants such as Krytox 240AC and Fomblin appear to be the most commonly appropriate for nitrogen trifluoride service, exhibiting a similar high resistance to ignition at temperatures in ex- cess of 400 C.
39、 Some halocarbon greases can dissolve in nitrogen trifluoride. -,-,- CGA G-142003 COMPRESSED GAS ASSOCIATION, INC. PAGE 7 5.3.2 Self-propagation of ignition of metals The self-propagation of metals ignited in nitrogen trifluoride is also an important factor that needs to be consid- ered when selecti
40、ng metal equipment components, in particular when they are in contact with materials having a lower autoignition temperature such as plastics. The consequences of the autoignition of sensitive materials (e.g., plastics) are aggravated when a metal can self-propagate from ignition under nitrogen trif
41、luoride pres- sure. The degree of self-propagation is a function of the nitrogen trifluoride pressure. Recent promoted combustion tests of metal rods have shown Monel 400, Nickel 200, and aluminum to exhibit the least potential to self-propagate at pressures in excess of 70 bar. Hastelloy C276 and H
42、astelloy C22 have demonstrated self-propagation at pressures between 5 bar and 50 bar, while most of the stainless and carbon steels will self-propagate at pressures lower than 5 bar. However, the value of threshold pressures cannot be used alone to determine a metals resistance to propagation since
43、 there are several other combustion proper- ties that can impact the selection of a metal for specific nitrogen trifluoride service conditions. NOTEAlthough aluminum has a relatively high nitrogen trifluoride threshold pressure, it is not recommended due to its high specific heat of combustion and l
44、ow melting point (see 5.3.5). Critical metal components that are in contact with plastic parts or used in severe nitrogen trifluoride conditions should be selected to minimize self-propagation from ignition under nitrogen trifluoride pressure. When it is im- practical to select the best metal materi
45、als, a risk assessment shall be undertaken to determine if any preven- tive measures are required (e.g., fire resistant barrier with remote access to isolate personnel or the wearing of fire-resistant personal protective equipment). 5.3.3 Specific heat of materials Metals have a significantly higher
46、 specific heat than nonmetals and therefore absorb significantly more heat with a lower temperature increase. Hence, the preferred materials are metals, which should be used instead of plastics or polymers wherever practical. 5.3.4 Thermal conductivity of materials The higher the thermal conductivit
47、y of a material, the greater the rate of heat dissipation and the lower the tem- perature will be at any point of localized heating. As metals have a higher thermal conductivity than nonmetals, metals are the preferred materials. Copper and its alloys such as brass, nickel and Monel have a better th
48、ermal conductivity than stainless steel and therefore may be preferred in particular for critical components such as valve seat supports and filters. NOTEThere may be other considerations such as chemical reactivity and heat of combustion, etc. (e.g., aluminum and its alloys, which have a good thermal conductivity, are not recommended for other reasons, see 5.3.5). 5.3.5 Heat of combustion of materials Heat of combustion of materials is the energy produce