CGA-V-9-2005.pdf

CGA V-92005 COMPRESSED GAS ASSOCIATION STANDARD FOR COMPRESSED GAS CYLINDER VALVES FIFTH EDITION COMPRESSED GAS ASSOCIATION, INC. 4221 Walney Road, 5th Floor Chantilly, VA 20151 Phone: 703-788-2700 Fax: 703-961-1831 E-mail: cgacganet.com PAGE ii COMPRESSED GAS ASSOCIATION, INC. CGA V-92005 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 Association, 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 commodity 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 latest 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 via the Internet at our web site, www.cganet.com. 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 others, 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 www.cganet.com. For more information contact CGA at Phone: 703-788-2700, ext. 799. E-mail: customerservicecganet.com. Docket 03-42 Cylinder Valve Committee NOTETechnical changes from the previous edition are underlined. NOTEAppendices C and D (Normative) are requirements. NOTEAppendices A, B, and E (Informative) are for information only. FIFTH EDITION: 2005 FOURTH EDITION: 2004 THIRD EDITION: 2002 SECOND EDITION: 1997 © 2005 BY THE COMPRESSED GAS ASSOCIATION, INC. ALL RIGHTS RESERVED. 4221 WALNEY ROAD, 5TH FLOOR, CHANTILLY, VA 20151 Printed in U.S.A. CGA V-92005 COMPRESSED GAS ASSOCIATION, INC. PAGE iii Contents Page 1 Introduction.1 2 Scope .1 3 Definitions.1 4 Design considerations5 4.1 Valve connection.5 4.2 Temperatures6 4.3 Leak rate7 4.4 Materials7 4.5 Cleaning 9 4.6 Markings10 4.7 Pressure relief devices10 4.8 Specific valves.11 4.9 Other valve components/devices 11 4.10 Valve closure.12 5 Valve types and descriptions13 5.1 Packed valves .13 5.2 Pressure seal valves .13 5.3 Diaphragm valves13 5.4 Post-type medical valves.14 5.5 Reverse seated valves14 5.6 Remotely operated valves.15 5.7 Additional valve types15 6 Valve qualification and documentation.16 6.1 General16 6.2 Documentation 16 6.3 Valve qualification test procedure16 7 Valve qualification tests16 7.1 Performance and qualifying test16 7.2 Conditional qualifying tests22 8 Testing of production valves.25 9 Maintenance.25 9.1 Inspectiongeneral requirements.26 9.2 Inspection procedure.26 10 References.29 11 Related standards and regulations.31 12 Other related materials.31 Tables Table 1Opening and closing torque, in-lb (Nm).7 Table 2Test pressure.7 Table 3Sequence of tests for valve qualification .17 -,-,- PAGE iv COMPRESSED GAS ASSOCIATION, INC. CGA V-92005 Appendices Appendix A Valve selection guidelines (Informative).32 Appendix BDOs and DONTs relative to valve use and abuse (Informative).33 Appendix CPerformance standard for cylinder valve protection caps (Normative) .35 Appendix DOxygen pressure surge test (Normative)38 Appendix ECompressed gas cylinder valve figures (Informative) .41 Appendices Table Table D1Test sequence (ISO 10297, Table 3)39 Appendices Figures Figure D1Example of an ignition test installation (ISO 10297, Figure 4).39 Figure D2Pressure cycle specification (ISO 10297, Figure 5).40 Figure E1Packed valve41 Figure E2Packed valve41 Figure E3Pressure seal valve42 Figure E4Pressure seal valve42 Figure E5Diaphragm packless valve.43 Figure E6Post-type medical valve.43 Figure E7Reverse seated valve 44 Figure E8Impact testing.44 -,-,- CGA V-92005 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction The Compressed Gas Association, Inc. (CGA) has long recognized the need to promote public safety in the use of cylinder valves. This standard defines factors that contribute to the safe use of cylinder valves for com- pressed gases. Compressed gases supplied in cylinders are diverse in their chemical composition and properties. Some are oxidizers, some are flammables, some are inert, etc. Gases vary in degrees of corrosivity, toxicity, and pres- sure and exist not only in the pure state but also in a variety of mixtures. Thus it becomes a primary safety re- quirement of the cylinder valve that it must be appropriate for its intended use. The intended use must be iden- tified, and the cylinder valve must incorporate proper pressure capability as well as functional reliability for safe operation. This standard serves to inform cylinder valve users, buyers, sellers, manufacturers, and others in the safe and proper use of cylinder valves. It includes requirements for maintenance, reconditioning, and testing as needed to ensure that valves are maintained in a safe working condition. Standards incorporated by reference in this standard include the referenced standards procedures, criteria, and other requirements unless otherwise noted. 2 Scope This standard applies to valves for compressed gases in noncryogenic services packaged in U.S. Department of Transportation (DOT) and Transport Canada (TC) cylinders. This standard covers general cylinder valve design and includes performance requirements such as operating temperature limits, pressure range, and flow capabilities. It also includes mechanical requirements such as ma- terials, inlet and outlet connections, cleaning, testing, and maintenance. This standard covers valve selection, valve use guidelines, the minimum requirements for valve protection caps, and an oxygen pressure surge test (see Appendices A-D). This standard does not apply to cylinder valves used with nonrefillable cylinders whose valves, inlet connec- tions, or both are permanently attached to the cylinders by means of welding or brazing; or cylinder valves on DOT cylinders (tubes) that are horizontally mounted to a chassis or framework for road transportation. 3 Definitions For the purpose of this standard, the following definitions apply. 3.1 General 3.1.1 Cylinder valve Mechanical device attached to a compressed gas cylinder that permits flow into or out of the cylinder when the device is in the open position and prevents flow when it is in the closed position. 3.1.2 General purpose valves Valves used for industrial compressed gases (air, inerts, etc.). 3.1.3 Highly oxidizing gas Gas or gas mixture with an oxidizing potential greater than 23.5% oxygen at atmospheric pressure (i.e., FTSC Code with F=4). NOTEAir has an oxygen concentration not greater than 23.5% by volume and shall not be considered a highly oxidizing gas. -,-,- PAGE 2 COMPRESSED GAS ASSOCIATION, INC. CGA V-92005 3.1.4 Highly oxidizing gas service valve Valves used for compressed gases containing oxygen-enriched gases (over 23.5% oxygen) and other highly oxidizing gases such as nitrous oxide. 3.2 Valve parts See Figures E1 through E7 in Appendix E. 3.2.1 Backcheck device Device that permits flow out of the valve but does not permit flow into the valve without special tooling to over- come the device. 3.2.2 Bonnet Threaded member tightened onto or into the valve body over the valve stem to clamp and compress the pack- ing, diaphragm(s), or some other sealing member(s). 3.2.3 Diaphragm(s) Formed, flexible disk(s) clamped between the valve bonnet and the ledge in the valve body in diaphragm-type valves that provide(s) a seal or pressure barrier between the wetted parts of the valve and the exterior. 3.2.4 Dust cap/plug Cap or plug that only serves as a protective covering against contamination of the valve from external sources. 3.2.5 Eductor tube Tube that is attached to the valve inlet to withdraw liquid or vapor from the cylinder. 3.2.6 Excess flow valve Device designed to close when the fluid passing through it exceeds a prescribed flow rate as determined by pressure drop. 3.2.7 Flow restrictor Flow limiting feature provided in the valve outlet to greatly reduce flow out of the valve. 3.2.8 Fusible plug Nonreclosing pressure relief device (PRD) designed to function by the yielding or melting of a fusible alloy within a predetermined temperature range. 3.2.9 Handwheel Manually operated device attached to the valve stem that is used to open and close the valve. 3.2.10 Lower stem (also known as a seat insert holder, seat plug, lower plug) Lower member of a two-piece stem actuated by the upper stem. 3.2.11 Outlet seal cap/plug Cap or plug that serves as a protective covering against contamination of the valve from external sources and serves as a pressure barrier against leakage out of the valve outlet. NOTEThis device is also referred to as a gas-tight outlet seal cap/plug. 3.2.12 Packing Nonmetallic seal rings installed over the stem in a packed valve that create a seal around the stem when com- pressed. 3.2.13 Packing follower (also known as a packing gland) Ring, usually metal, often installed on top of the packing in a packed-type valve so the packing nut is not torqued directly against the packing. 3.2.14 Packing nut Threaded member tightened onto or into the body of a packed-type valve over the valve stem to clamp and compress the packing. -,-,- CGA V-92005 COMPRESSED GAS ASSOCIATION, INC. PAGE 3 3.2.15 Packing ring (also known as a packing gland) Ring installed in a packed-type valve to provide a suitable seat for the packing. 3.2.16 Pressure relief device Pressure and/or temperature activated device used to prevent the pressure from rising above a predetermined maximum and thereby preventing the rupture of a normally charged cylinder when subjected to a standard fire test as required by Title 49 of the U.S. Code of Federal Regulations (49 CFR) Part 173.301(f) or CSA B340, Selection and Use of Cylinders, Spheres, Tubes and Other Containers for the Transportation of Dangerous Goods, Class 2 1, 2. 1 3.2.17 Pressure relief nut (also known as a cap) Rupture disk holder threaded onto the valve body that incorporates a precisely machined edge around a relief device discharge port against which the disk is designed to rupture. 3.2.18 Pressure relief plug Rupture disk holder threaded into the valve body that retains a rupture disk in place and incorporates a pre- cisely machined edge around a relief device discharge port against which the disk is designed to rupture. 3.2.19 Pressure relief valve Type of PRD that is designed to relieve excessive pressure and to reclose and reseal to prevent further flow of fluid from the cylinder after the reseating pressure has been achieved. 3.2.20 Relief device gasket/washer Seal ring located between the rupture disk and the relief device discharge port in the valve body. 3.2.21 Residual pressure device Mechanism that leaves a positive pressure in the cylinder. NOTEThere are two types of these devices, either with or without a nonreturn feature. A nonreturn feature prevents back- flow into the cylinder from a higher pressure source. It also requires either an adapter or a manual adjustment to overcome this feature. 3.2.22 Rupture disk Operating part of a PRD that, when installed in the device, is designed to rupture at a predetermined pressure to permit the discharge of the cylinder contents. 3.2.23 Seat insert Element mechanically contained in or on the lower stem (sometimes on a one-piece stem) usually made of a soft material to facilitate sealing against the valve seat. 3.2.24 Tang Member or extension projecting from either the lower end of an upper stem or the upper end of a lower stem, mechanically attached or integral to the stem, through which torque is transmitted in a two-piece stem. 3.2.25 Thrust bearing Disk-like part sometimes inserted between the upper stem and the metal diaphragms to reduce friction. 3.2.26 Upper stem Upper member of a two-piece stem that when operated causes the lower stem to move. 3.2.27 Valve actuator Manually or remotely operated device that is used to open and close the valve. 3.2.28 Valve body Major portion of the valve (normally one piece) that contains the inlet and outlet connections and is machined to accept the component parts to create a valve assembly. 1 References are shown by bracketed numbers and are listed in order of appearance in the reference section. -,-,- PAGE 4 COMPRESSED GAS ASSOCIATION, INC. CGA V-92005 3.2.29 Valve inlet Portion of the valve body that connects to the cylinder. 3.2.30 Valve outlet Portion of the valve body through which product is introduced into or discharged from the valve. 3.2.31 Valve seat Sealing surface surrounding the orifice in the valve body. 3.2.32 Valve stem, one-piece (also known as a spindle or poppet) Movable member designed to seal against the valve seat. 3.2.33 Valve stem, two-piece Arrangement consisting of an upper stem and lower stem that work together to open and close the valve. 3.3 Valve functions 3.3.1 Backseat To back off the stem in the valve opening direction until it is physically stopped by some other valve component such as the packing, packing ring, bonnet, etc. NOTEIn some designs backseating acts as a secondary stem seal. 3.3.2 Closing off pressure Differential pressure between upstream and downstream pressures at which a residual pressure device closes. 3.3.3 Cracking Act of slightly opening the valve to permit a very small amount of flow. 3.3.4 External leakage Leakage to atmosphere when the valve is open and the outlet is sealed. 3.3.5 Full flow Valves open position when maximum flow capacity is achieved. 3.3.6 Full open Valves open position when the stem is backseated. 3.3.7 Internal leakage Leakage across the valve seat, when the valve is closed. 3.3.8 Shutoff Closed, no-flow condition of the valve. 3.4 Valve characteristics 3.4.1 Flow coefficient Numeric constant (Cv) used to calculate the flow capacity of the valve in its full flow position. 3.4.2 Maximum service pressure Maximum pressure at which the valve has been designed to operate, which is defined