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1、 CGA C-6.42007 METHODS FOR EXTERNAL VISUAL INSPECTION OF NATURAL GAS VEHICLE (NGV) AND HYDROGEN VEHICLE (HV) FUEL CONTAINERS AND THEIR INSTALLATIONS THIRD 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 C
2、OMPRESSED GAS ASSOCIATION, INC. CGA C-6.42007 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, t
3、he 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 me
4、thod, 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 c
5、omments 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, . Th
6、is 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
7、 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: Work Item 06-055 Cylinder Specifications Committee N
8、OTETechnical changes from the previous edition are underlined. NOTEAppendices A, B, and C (Informative) are for information only. THIRD EDITION: 2007 SECOND EDITION: 2003 FIRST EDITION: 1998 2007 BY THE COMPRESSED GAS ASSOCIATION, INC. ALL RIGHTS RESERVED. All materials contained in this work are pr
9、otected by United States and international copyright laws. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording, or any informa- tion storage and retrieval system without permission in writing from The Compresse
10、d Gas Association, Inc. All requests for permission to reproduce material from this work should be directed to The Compressed Gas Association, Inc., 4221 Walney Road, Suite 500, Chantilly VA 20151. You may not alter or remove any trademark, copyright or other notice from this work. -,-,- CGA C-6.420
11、07 COMPRESSED GAS ASSOCIATION, INC. PAGE iii Contents Page 1 Introduction.1 2 Scope and purpose 1 2.1 Scope 1 2.2 Purpose.1 3 Definitions.2 4 General design information 5 4.1 Design types and descriptions.5 4.2 Installation and mounting of NGV fuel containers .6 4.3 Labeling information6 5 Qualifica
12、tions of inspector 7 5.1 Container and installation knowledge7 5.2 Resources .7 5.3 Inspection knowledge7 5.4 Gas and technical knowledge7 5.5 Literacy8 5.6 Supervisory ability .8 6 Inspection equipment .8 6.1 Inspection of mounting 8 6.2 Inspection of container 8 7 Inspection and examination10 7.1
13、Inspection interval10 7.2 Conditions requiring immediate inspection10 7.3 Preparation for inspectionall types.11 7.4 Examination of installationall container types11 7.5 Container examinationall container types13 7.6 Additional inspection of metal containersType 1 and metallic portions of Type 215 7
14、.7 Additional inspection composite containers (Types 2, 3, and 4) .17 7.8 Examination of valves and relief devicesall container types19 7.9 Labelingall container types 20 7.10 Inspection record/check listall container types.21 7.11 Final dispositionall container types21 7.12 Final dispositionall equ
15、ipment22 8 Alternatives to visual inspection (nondestructive inspection) .22 8.1 In-situ acoustic emission testing22 8.2 Traditional nondestructive testing methods.22 9 Disposition of condemned containers 23 10 References.24 11 Additional references25 Tables Table 1Container inspection criteria limi
16、ts.9 Table 2Installation equipment criteria10 -,-,- PAGE iv COMPRESSED GAS ASSOCIATION, INC. CGA C-6.42007 Figures Figure 1Full-wrapped cylinder with one port3 Figure 2Dent to all metal cylinder16 Figure 3Abrasion level 217 Figure 4Impact damage.18 Figure 5Cut with delamination.18 Figure 6Crazing.19
17、 Figure 7Stress corrosion cracking.19 Appendices Appendix AFrequency of inspection (Informative).26 Appendix BSample inspection form (Informative)27 Appendix CDepressurizing containers, an example procedure (Informative)29 -,-,- CGA C-6.42007 COMPRESSED GAS ASSOCIATION, INC. PAGE 1 1 Introduction Th
18、is document provides information and procedures for the periodic visual examination and inspection of natu- ral gas and hydrogen fuel containers and the condition of the installation. These containers are installed in ve- hicles certified by the manufacturer to meet the following U.S. or Canadian st
19、andards: ANSI NGV2, American National Standard for Natural Gas Vehicle Containers 1;1 U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) FMVSS, Standard No. 304, Compressed Natural Gas Fuel Container Integrity 2; Canadian Motor Vehicle Safety Regulations,
20、Standard 301.2, CNG Fuel System Integrity 3; and Canadian Standards Association (CSA) B51, Boiler, Pressure Vessel, and Pressure Piping Code 4. This document may be used for the inspection of other natural gas and hydrogen fuel containers that are certi- fied to meet other specifications and standar
21、ds (see Section 4). These containers are designed to store natural gas and hydrogen at high pressures. It is critical that this document be carefully read and completely under- stood before initiating either the examination or inspection of a container and that all applicable sections of the documen
22、t be followed during the examination/inspection process. This document requires that appropriate in- formation, such as an installation and maintenance manual from the container manufacturer, be reviewed and used during the examination/inspection together with all current container manufacturers rec
23、ommendations and guidance documents. The examinations/inspections covered in this document are intended to be carried out only by qualified indi- viduals as defined in Section 5. When preparing to conduct an inspection, the inspector should have the equipment described in Section 6 available and wit
24、hin easy access during the inspection. The vehicle to be inspected should be positioned so access to the surface of the container is unimpeded or positioned according to the vehicle manufacturer. If the examination, conducted as described in Section 7, reveals areas that require additional inspectio
25、n or testing of the container, the container label is not visible, or the container surfaces are not all sufficiently visible to the inspector, the container shall be depressurized (following this document and the manufacturers instructions) and removed from the vehicle. See Section 8 for alternativ
26、e and ancillary inspec- tion methods. 2 Scope and purpose 2.1 Scope This document addresses containers manufactured to generally accepted codes and standards for fuel gas vehicle (FGV) service (see Section 4) 1, 2. 2.2 Purpose The purpose of this document is to provide guidance for the visual inspec
27、tion of these containers and to pro- vide criteria for the acceptance or rejection (in the absence of guidance from the manufacturer) with subse- quent disposal or repair as necessary. In the event of a difference between this document and the manufac- turers instructions, the manufacturers instruct
28、ions shall be used. The continued safe use of acceptable containers and the removal from service of unsafe, damaged containers that do not pass the visual inspection criteria are important to the safety and well being of all who come into contact with natural gas vehicle (NGVs). This document is dir
29、ected to all who perform periodic inspections of compressed natural gas containers. The recommended minimum visual inspection frequency is once every 3 years for the life of the container 1. Manufacturers recommendations, harsh or abusive conditions (as outlined in Appendix A), or federal, state, pr
30、ovincial/territorial, or local regulations can warrant more frequent inspections. Whatever the frequency of in- 1 References are shown by bracketed numbers and are listed in order of appearance in the reference section. -,-,- PAGE 2 COMPRESSED GAS ASSOCIATION, INC. CGA C-6.42007 spection for the fue
31、l gas (FG) container, the inspector needs to know what to look for, how to visually inspect, and how to make the determination whether the container meets the criteria for continued safe service. 3 Definitions For the purpose of this document, the following definitions apply. 3.1 Abrasion damage Dam
32、age to a container caused by wearing, grinding, or rubbing away of the container material by friction. 3.2 Aramid fiber Type of reinforcement fiber used in composite overwrap. 3.3 Carbon fiber Type of reinforcement fiber used in composite overwrap. 3.4 Composite Structural material composed of load-
33、bearing fibers embedded in a protective resin matrix. 3.5 Condemned container Cylinder no longer fit for service and for which repair is not allowed. 3.6 Crazing Hairline cracking of the resin giving it an opaque “frosty” appearance. 3.7 Cut damage Damage caused by a sharp object coming in contact w
34、ith a composite surface. 3.8 Delamination Form of composite damage in which a separation develops between layers of the composite. NOTEThis type of damage usually results from excessive localized loading that is normal to the surface of the laminate. 3.9 Destroyed Alteration of a fuel container to m
35、ake it physically unusable. NOTEDrilling a hole 1 in (25.4 mm) diameter or larger completely through the wall is an acceptable means of destroying a container. 3.10 External/exterior coating Clear or colored surface treatment applied to the container for environmental protection and improved appear-
36、 ance. 3.11 Fiberglass Type of reinforcement fiber used in composite overwrap. 3.12 Filament winding Automated process used for orienting strands of high strength fibers and plastic resin to construct composite containers. 3.13 Fuel gas (FG) Compressed natural gas, hydrogen gas, or mixtures thereof,
37、 suitable for vehicle fuel. 3.14 Fuel gas vehicle (FGV) Vehicle that uses compressed natural gas, hydrogen gas, or mixtures thereof as fuel. CGA C-6.42007 COMPRESSED GAS ASSOCIATION, INC. PAGE 3 3.15 Helical wrap Layers in the composite overwrap filament wound to provide primarily longitudinal stren
38、gth and some hoop strength for the cylindrical region of the container. NOTEThe strands of reinforcing fibers are oriented at an angle to the longitudinal axis of the container (see Figure 1). 3.16 Hoop wrap Composite reinforcement wound at a nominal angle of 90 degrees to the longitudinal axis that
39、 generally carries the major portion of the load in the hoop direction and little load in the longitudinal direction (see Figure 1). Figure 1Full-wrapped cylinder with one port 3.17 Impact damage Damage caused by dropping or by a blow from another object. NOTEImpact damage can be at the surface, int
40、ernal to the structure, or both. 3.18 Inspection mark Mark, label, or tag placed by an inspector on the container indicating acceptance of the container. NOTEThe mark shall at least identify the inspecting agency and the date of inspection (month and year). 3.19 Level 1 damage Minor damage that can
41、occur during normal use. NOTESuch damage should have no adverse effects on the safety of the cylinder and its continued use. Such items as scratched paint, nicks, or dings that have no appreciable depth or no significant quantity of frayed fibers are considered to be in this category. 3.20 Level 2 d
42、amage More severe damage than Level 1 but keeps open the possibility of repair and the container being returned to service based on the recommendations of the manufacturer or their literature. NOTELevel 2 damage can be cuts or gouges that are deeper or longer than those of Level 1. Level 2 damage ca
43、nnot remain at that level after inspection. It shall be repaired to an acceptable condition or moved to Level 3 and condemned. 3.21 Level 3 damage Damage that renders the cylinder unfit for continued service and cannot be repaired. NOTEContainers with Level 3 damage shall be condemned. 3.22 Liner In
44、ternal component of the container that prevents leakage of gas through the composite container structure. -,-,- PAGE 4 COMPRESSED GAS ASSOCIATION, INC. CGA C-6.42007 3.23 Manufacturer Container manufacturer. 3.24 Manufacturers marks Required official markings that are stamped on the exposed metal en
45、ds or neck, printed on permanent labels, or a combination of stamping and labels. 3.25 Manufacturers recommendations/guidelines Recommendations or guidelines from the manufacturer to direct and/or advise the inspector on Level 2 dam- age issues. 3.26 Mounting brackets and/or straps Devices used to s
46、ecure fuel containers in a vehicle. 3.27 Overpressurization Pressures exceeding those allowed during filling procedures specified in the standards referenced in this document. 3.28 Ports Openings at the ends of the container where valves (manual or solenoid), pressure relief devices, and blank plugs
47、 are installed. 3.29 Pressure relief device (PRD) Device installed in the container or integrated with a valve that will release the contained gas in specific emer- gency conditions. NOTEPRDs can be activated by excessive temperature, excessive internal pressure, or both. 3.30 Reinforcing fibers Con
48、tinuous fibrous strands in the composite that withstand loads caused by pressurization. 3.31 Rejected container Container that shall be removed from service and evaluated further before final disposition. 3.32 Resin Plastic material in the composite overwrap that fills the space between individual reinforcing fibers. 3.33 Scuff Minor abrasion damage to the protective coating, paint, or resin-rich composite surface. 3.34 Service pressure Authorized pressure marking on the cylinder. 3.35 Standard When used and not otherwise qualif