DOCUMENT DESPATCH ADVICE Ref: MED 16 :3/T-45 Date:

DRAFT STANDARD UNDER WIDE CIRCULATION DOCUMENT DESPATCH ADVICE Ref: MED 16 :3/T-45 Date: 30-06-2015 Gas Cylinders, Sectional Committee, MED 16 TO: a) The interested members of Mechanical Engineering Division Council, MEDC b) All members of Gas Cylinders Sectional Committee, MED 16 and Valves and Fittings Gas Cylinders Sub Committee, MED 16:1, Low Pressure Gas Cylinders Subcommittee, MED 16:2 and Dissolved Acetylene Cylinders, Generators, Acetylene Pipe Lines And High Pressure Gas Cylinders Subcommittee, MED 16:3 c) All others interested Dear Sir(s), Please find enclosed the following document: Doc. No. TITLE MED 16 (1293) wc Draft Indian Standard Cylinders for On-Board Storage of Compressed Gaseous Hydrogen and Hydrogen Blends as a Fuel for Automotive Vehicles Specification (ICS 43.060.40) Kindly examine the Draft standard and forward your views stating any difficulties which you are likely to experience in your business or profession, if this is finally adopted. Last date for receipt of comments: 31-08-2015. Comments, if any, may please be made in the format as given overleaf and e-mailed to the undersigned at the above address. In case no comments are received or comments received are of editorial nature, you will kindly permit us to presume your approval for the above document as finalized. However, in case of comments of technical in nature are received then it may be finalized either in consultation with the Chairman, Sectional Committee or referred to the Sectional committee for further necessary action if so desired by the Chairman, Sectional Committee. The document is also hosted on BIS website www.bis.org.in. Thanking you, Yours faithfully (T.V Singh) Encl: As above Sc F & Head (MED), ROOM NO: 203 MANAK BHAVAN 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 TELEFAX 011-23232509 med@bis.org.in

DRAFT FOR COMMENTS ONLY Draft Indian Standard CYLINDERS FOR ON-BOARD STORAGE OF COMPRESSED GASEOUS HYDROGEN AND HYDROGEN BLENDS AS A FUEL FOR AUTOMOTIVE VEHICLES SPECIFICATION ICS 43.060.40 Not to be reproduced without the permission Last date for receipt of of BIS or used as an STANDARD comments is: 31/08/2015 FOREWORD Adoption clause will be added later on. Cylinders for on-board storage of compressed gaseous hydrogen and hydrogen blends as fuels for automotive vehicle service are required to maintain or improve the level of safety currently existing for automotive vehicle applications. These requirements are achieved by: a) specifying service conditions precisely and comprehensively as a firm basis for both cylinder design and use; b) using an appropriate method to assess cyclic pressure fatigue life and to establish allowable defect sizes in metal tanks or liners; c) requiring design qualification tests; d) requiring non-destructive testing and inspection of all production cylinders; e) requiring destructive tests on cylinders and tank material taken from each batch of cylinders produced; f) requiring manufacturers to specify the acceptable in-service damage levels for their design; and g) requiring manufacturers to specify as part of their design, the safe service conditions for their cylinders. Designs meeting the requirements of this Indian Standard: a) will have a fatigue life that exceeds the expected service; and b) will demonstrate appropriate strength and durability for expected service conditions. While implementing this standard, the manufacturer and the inspection agency shall ensure compliance with statutory regulations. In the Preparation of this standard, assistance has been derived from the ISO/TS 15869:2009 Gaseous hydrogen and hydrogen blends -- Land vehicle fuel tanks For the purpose of deciding whether a particular requirement of this standard is complied with the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2:1960 Rules for rounding off numerical values (revised). The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. 1

1 SCOPE This Indian Standard specifies the requirements for lightweight refillable cylinders of water capacity not exceeding 500 litres. intended only for the onboard storage of high-pressure compressed gaseous hydrogen or hydrogen blends on automotive vehicles. This Indian Standard is not intended as a specification for cylinders used for solid, liquid hydrogen or hybrid cryogenic high-pressure hydrogen storage applications. This Indian Standard is applicable for cylinders of steel, aluminium or non-metallic construction material, using any design or method of manufacture suitable for its specified service conditions. This Indian Standard applies to the following types of cylinder designs: 2 REFERENCES Type 1: metal cylinders; Type 2: hoop-wrapped composite cylinders with a metal liner; Type 3: fully wrapped composite cylinders with a metal liner; Type 4: fully wrapped composite cylinders with no metal liner. The following standards contain provisions which through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Standard No. IS 101:Part 3:Sec 2:1989 IS 101:Part 5:Sec 2:1988 IS 101 Part 8 Sec 2 : 1990 IS 1500 : 2005 IS 1608 : 2005 IS 1757 : 1988 Title Methods of sampling and test of paints, varnishes and related products Part 3 Tests on paint film formation Sec 2 Film thickness (Third Revision) Methods of sampling and test for paints, varnishes and related products Part 5 Mechanical test Sec 2 Flexibility and adhesion (Third Revision) Methods of sampling and test for paints, varnishes and related products Part 8 Tests for pigments and other solids Sec 2 Pigments and non-volatile matter (Third Revision) Method of Brinell Hardness Test for Metallic Materials (Third Revision) Metallic materials Tensile testing at ambient temperature (Third Revision) Methods for charpy impact test (V notch) for metallic material (Second Revision) IS 7285:Part 2:2004 Refillable seamless steel gas cylinders Specification Part 2 : Quenched and Tempered Steel Cylinders with Tensile Strength Less Than 1100 MPa (112 kgf/mm 2 ) (Third Revision) IS 13360:Part5:Sec 2:1996 Plastics Methods of Testing Part 5 : Mechanical Properties Sec 2 Determination of Tensile Properties Test Conditions for Moulding and Extrusion Plastics. IS 13360:Part 6:Sec 1:1999 Plastics Methods of testing : Part 6 Thermal Properties Sec 1 Determination of vicat softening temperature of thermoplastic materials. 2

IS 13411 : 1992 IS 15490 : 2004 Glass reinforced polyester dough moulding compounds (DMC) Cylinders for On Board Storage of Compressed Natural Gas As A Fuel For Automotive Vehicle Specification IS 15935 :2011 Draft Indian Standard on Composite Cylinders For On Board Storage of Compressed Natural Gas (CNG) As A Fuel For Automotive Vehicle Specification IS 15660 : 2006 Refillable Transportable Seamless Aluminium Alloy Gas Cylinders - Specification ISO 9809-2:2010 ISO 2409:2013 ISO 7225 : 2005 Gas cylinders Refillable seamless steel gas cylinders Design, construction and testing Part 2: Quenched and tempered steel cylinders with tensile strength greater than or equal to 1 100 MPa Paints and varnishes -- Cross-cut test Precautionary labels CSA HPRD-1:2007 Basic Requirements for Pressure Relief Devices for Compressed Hydrogen Vehicle Fuel Containers IS/ISO 11114-1 IS/ISO 11114-4:2005 IS 16061 (Part 1) :2013 ISO/TS 14687-2 :2012 ISO/TR 15916 :2004 ISO 9227 : 2012 ISO 20567-2:2005 ISO 1519:2011 IS 15643 : 2006 ISO 6272-2:2011 ISO 18373-2:2008 ISO DIS 4892-1 Transportable gas cylinders Compatibility of cylinder and valve materials with gas contents Part 1: Metallic materials Transportable gas cylinders Compatibility of cylinder and valve materials with gas contents Part 4: Test methods for selecting metallic materials resistant to hydrogen embrittlement Hydrogen fuel Product specification Part 1: All applications except proton exchange membrane (PEM) fuel cells for road vehicles Hydrogen fuel Product specification Part 2: Proton exchange membrane (PEM) fuel cell applications for road vehicles Basic considerations for the safety of hydrogen systems Corrosion tests in artificial atmospheres salt spray tests Paints and varnishes -- Determination of stone-chip resistance of coatings -- Part 2: Single-impact test with a guided impact body Paints and varnishes -- Bend test (cylindrical mandrel) Non-destructive examination of polymer based composite materials code of practice Paints and varnishes -- Rapid-deformation (impact resistance) tests -- Part 2: Falling-weight test, small-area indenter Rigid PVC pipes -- Differential scanning calorimetry (DSC) method -- Part 2: Measurement of the enthalpy of fusion of crystallites Plastics Methods of exposure to laboratory light sources Part 1 : General guidance 3 TERMINOLOGY For the purpose of this standard, the following terms and definitions shall apply. 3.1 Authorized Inspection Authority An inspection agency having qualification and wide experience in the field of design, manufacture and testing of gas cylinders and recognized by the Statutory Authority for inspection and certification of gas cylinders. 3

3.2 Autofrettage Pressure application procedure used in manufacturing composite cylinders with metal liners, which strains the liner past its yield point sufficient to cause permanent plastic deformation. This results in the liner having compressive stresses and the fibers having tensile stresses at zero internal pressure. Autofrettage is a part of the manufacturing operation and is conducted on the metal lined filament wound cylinders prior to hydrostatic pressure testing. 3.3 Auto-frettage Pressure Pressure within the over-wrapped cylinder at which the required distribution of stresses between the liner and the over-wrap is established. 3.4 Batch (of composite cylinders) Group of cylinders successively produced from qualified liners having the same size, design, specified material of construction and process of manufacture. A batch shall be a group of not more than 200 cylinders plus cylinders for destructive testing. 3.5 Batch (of metallic liners) Group of liners successively produced having the same heat number, nominal diameter, wall thickness, design, specified material of construction, process of manufacture, equipment for manufacture and heat treatment, and conditions of time, temperature and atmosphere during heat treatment. The batch shall be a group of not more than 200 liners plus liners for destructive testing 3.6 Batch (of non-metallic liners) Group of non-metallic liners successively produced having the same nominal diameter, wall thickness, design, specified material of construction, process of manufacture. A batch shall be a group of not more than 200 liners plus liners for destructive testing or one shift of successive production, whichever is greater. 3.7 Burst Pressure The highest pressure reached in a cylinder during a burst test. 3.8: Bursting Disc: A pressure relief device consisting of a disc that is in direct contact with the gas in cylinder and is designed to rupture between the pre-determined pressure limits. 3.9 Commercial Heavy-duty Vehicles Vehicles designed and constructed primarily for the carriage of goods etc. other than persons (for example trucks and trailers). 3.9 Composite Cylinder Cylinder made of resin-impregnated continuous filament wound over a metallic or non-metallic liner. NOTE Composite cylinders using non-metallic liners are referred to as all-composite cylinders. 3.10 Controlled Tension Winding Process used in manufacturing hoop-wrapped composite cylinders with metal liners by which compressive stresses in the liner and tensile stresses in the over-wrap at zero internal pressure are obtained by winding the reinforcing filaments under significant high tension. 3.11 Design Change Change in the selection of structural materials, pattern of winding in Type 2, Type 3 and Type 4 cylinders or dimensional changes exceeding the tolerances as on the design drawings. 3.12 Finished Cylinders Completed cylinders which are ready for use, typical of normal production, complete with identification marks and external insulation specified by the manufacturer, but free from non-integral insulation or protection. 3.13 Full Wrapped Cylinder Cylinder with an overwrap having filament wound reinforcement both in the circumferential and axial direction of the cylinder over the entire liner including the domes. 3.14 Gas Temperature Temperature of gas in a cylinder 3.15 Hoop-wrapped Composite Cylinder Cylinder with an over-wrap having a filament wound reinforcement in a substantially circumferential pattern over the cylindrical portion of the 4

liner such that the filament does not carry any significant load in a direction parallel to the longitudinal axis of the cylinder. 3.16 Hydrogen Blend A mixture of natural gas and more than 2 percent by volume of hydrogen. 3.17 Hydrogen and Hydrogen-blend Storage System System on an automotive vehicle comprised of the cylinder and all closure devices (for example, shut-off valves, check valves and pressure activated and thermal activated pressure relief devices), as well as piping that contains hydrogen and hydrogen-blend at the working pressure. The pressure relief device and thermal relief device should be activated independently. 3.18 Leakage Release of gas through a crack, pore, unbounded or similar defect. NOTE Permeation through the wall of a Type 4 cylinder that is less than the rates described in B.16 is not considered leakage. 3.19 Liner Gas-tight inner shell, on which reinforcing fibres are filament wound to reach the necessary strength. Two types of liner are described in this Standard; metallic and non-metallic liners. Metallic liners are designed to share the load with the reinforcement and non-metallic liners do not carry any part of the load. 3.20 Manufacturer Person or organization responsible for the design, fabrication and testing of the cylinders. 3.21 Overwrap Reinforcement system of filament and resin applied over the liner. 3.22 Passenger Vehicles Vehicles designed and constructed primarily for the carriage of persons (for example, cars and buses). 3.23 Pre-stress or Pre-stressing The process of applying auto-frettage or controlled tension winding. 3.24 Service Conditions Conditions that the cylinder will experience in service and that include on-road exposure to environmental factors (road salt, acids, alkalies, temperature extremes) and expected usage (gas composition, impurities in the gas and any odorizing agent added in the gas as well as pressure cycles associated with filling and discharge during service and driving, static pressure associated with vehicle parking, etc.) 3.25 Service Life Life, in years, during which the cylinders may safely be used in accordance with the standard service conditions. 3.26 Settled Pressure Gas pressure when a given settled temperature is reached. 3.27 Settled Temperature Uniform gas temperature after the dissipation of any change in temperature caused by filling. 3.28 Stress Ratio Stress in fiber at specified minimum burst pressure divided by stress in fiber at working pressure. 3.29 Test Pressure Test pressure means the internal pressure required for the hydrostatic test or hydrostatic stretch test of the cylinder. It shall be 1.5 x Working Pressure of cylinder except for Type 1 cylinders manufactured conforming to IS 7285 (Part 2). 3.30 Thermally Activated Pressure Relief Device Device that activates by temperature to release pressure and prevent a cylinder from bursting due to fire effects and that will activate regardless of cylinder pressure. 3.31 Working Pressure Settled pressure of 200 bar at a uniform temperature of 15 C. 5

4 SERVICE CONDITIONS 4.1 General The specified service conditions provide the basis for the design, manufacturing, inspection, and testing of cylinders that are to be mounted on automotive vehicles and used to store compressed gaseous hydrogen or hydrogen blends at ambient temperatures for use as a fuel for these vehicles. The specified service conditions are also intended to provide information on how cylinders made in accordance with this Indian Standard may safely be used, by: a) manufacturers of cylinders; b) owners of cylinders; c) users of cylinders. d) designers or contractors responsible for the installation of cylinders; e) designers or owners of equipment used to refuel automotive vehicle cylinders; f) suppliers of gaseous hydrogen and hydrogen blends; g) regulatory authorities that have jurisdiction over cylinder use; and h) Cylinder mounting arrangement considered by the manufacturer at the time of design. The service conditions do not cover external loading that may arise from vehicle collisions, etc. 4.2 Service life The service life for which cylinders are safe shall be specified by the cylinder manufacturer on the basis of use under service conditions specified therein. Recertification of cylinders to be done as per statutory requirements. Service life shall not be less than 15 years. The maximum service life shall be 20 years. For metal and metal-lined cylinders, the service life shall be based upon the rate of fatigue crack growth. The ultrasonic inspection, or equivalent, of each cylinder or liner shall ensure the absence of flaws which exceed the maximum allowable size. The method shall as per Annexure D. For all composite cylinders with non-metallic, non-load bearing liners the service life shall be demonstrated by appropriate design methods, design qualification testing and manufacturing controls. The requirements for periodic re-qualification by inspection or testing during the service life shall be specified by the cylinder manufacturer in consultation with statutory authority on the basis of use under service conditions specified herein. The manufacturer should clearly specify the user s obligation to observe the required cylinder inspection requirements. 4.3 Maximum Filling Pressure This Standard is based upon a working pressure of 200 bar settled at 15 C for hydrogen and hydrogen blends as a fuel with a maximum filling pressure of 250 bar. Other working pressures may be accommodated by adjusting the pressure by the appropriate factor (ratio); for example, a 250 bar working pressure system will require pressures to be multiplied by 1.25. Except where pressures have been adjusted in this way, the cylinder shall be designed to be suitable for the following pressure limits: a) A pressure that would settle to 200 bar at a settled temperature of 15 C; and b) The maximum pressure shall not exceed 250 bar regardless of filling conditions or temperature. 6

4.4 Filling Cycles 4.4.1 General Cylinders shall be designed for filling gas at least 1000 times per year of service. For more stringent duty the number of cycles per year to be decided between user and manufacturer. 4.5 Design Temperature Cylinders shall be designed to be suitable for use in the material temperature range -40 C to 85 C during filling and discharge. Charpy Impact test shall be conducted for steel cylinders and steel liners for cylinders, at -50 C. 4.6 Gas Composition Cylinders shall be designed to be filled with compressed gaseous hydrogen and/or hydrogen blends containing more than 2 percent hydrogen by volume, combined with dry natural gas. The gas composition shall comply with the following: a) compressed hydrogen gas shall comply with the composition specified in IS 16061 (Part 1) or ISO/TS 14687-2; b) compressed natural gas (CNG) used in hydrogen blends shall comply with the dry gas composition limits specified in IS 15490. 4.7 External Surfaces Cylinder external surfaces shall be designed to withstand mechanical and chemical exposure conditions as reflected in the type tests specified in 9. It shall also be designed to withstand inadvertent exposure to the following, consistent with installation being carried out in accordance with the instructions to be provided with the cylinder: a) Water, either by intermittent immersion or road spray; b) Salt, due to the operation of the vehicle near the ocean or where ice-melting salt used; c) Ultra-violet radiation from sunlight; d) Impact of gravel; e) Solvents, acids and alkalis, fertilizers; f) Automotive fluids, including petrol, hydraulic fluids, battery acid, glycol and oils; and g) Exhaust gases. 4.8 Fire Effects Cylinders shall be protected from fire effects using non-reclosing thermally activated pressure relief devices or non-reclosing pressure-activated relief device. Non-reclosing pressure-activated pressure relief devices shall only be used in parallel with thermally activated pressure relief devices. Under no circumstances shall a thermally activated pressure relief device require the operation of the pressure activated pressure relief device in order to function. The fire protection of cylinders may also be supplemented by the use of thermal insulation. This arrangement shall be such that bare cylinders are available for periodic inspection. 5 APPROVAL AND CERTIFICATION 5.1 Inspection and Testing In order to ensure that the cylinders are in compliance with this standard they shall be subjected to design approval in accordance with 5.2, and inspection and testing in accordance with 9.2 or 9.5 as appropriate. 7

5.2 Type Approval Procedure 5.2.1 General Type approval consists of 2 parts: a) The design submission comprising of information furnished by the manufacturer to the inspector for appraisal/scrutiny and further recommendations to the statutory authority for approval, as detailed in 5.2.2. b) Prototype testing, comprising testing carried out under the supervision of the inspector. The cylinder material, design, manufacture and examination shall be proved to be adequate for their intended service by meeting the requirements of the prototype tests specified in 9.2 or 9.5 as appropriate for the particular cylinder design. The test data shall also document the dimension, wall thicknesses and weights of each of the test cylinders. 5.2.2 Design Approval Cylinder designs shall be approved by the statutory authority. The following information shall be submitted by the manufacturer to the inspector for examination and further approval by statutory authority. a) Statement of service, in accordance with 5.2.3; b) Design data, in accordance with 5.2.4; c) Manufacturing data, in accordance with 5.2.5; d) Quality system, in accordance with 5.2.6; e) Fracture performance and NDE (non-destructive examination) defect size, in accordance with 5.2.7; f) Specification sheet, in accordance with 5.2.8; and g) Additional supporting data, in accordance with 5.2.9. 5.2.3 Statement of Service The purpose of this statement of service is to guide the user and the installer of cylinders as well as to inform the inspector. The statement of service shall include: a) the name and address of the cylinder manufacturer; b) a description of the cylinder design, including cylinder identification, working pressure (MPa), cylinder type, diameter (mm), length (mm), internal volume (l), empty weight (kg) and valve thread type; a statement that the cylinder design is suitable for use in the service conditions provided in 4; c) a statement of the maximum number of filling cycles for which the cylinder is designed; d) a statement of the service life; e) a specification for minimum in-service inspection and testing requirements; f) a specification for the pressure relief devices; g) a specification for the support methods, protective covering and any other items required but not provided; h) a description of the cylinder design; j) information regarding approval including date and approving agency. Periodic retesting interval; and k) any other information necessary to ensure the safe use and inspection of the cylinder. 5.2.4 Design Data 5.2.4.1 Drawings 8

Drawings shall show at least the following: a) Title, reference number, date of issue, and revision numbers with dates of issue if applicable; b) Reference to this Standard and the cylinder type reference as Type 1, Type 2, Type 3 or Type 4 design; c) All dimensions complete with tolerances, including details of end closure shapes with minimum thicknesses and of openings; d) Mass, complete with tolerance of cylinders; e) Material specifications, complete with minimum mechanical and chemical properties or tolerance ranges and, for metal liners, the specified hardness range; f) the gas or gas blends that the cylinder is designed to carry; g) the working pressure of the design and h) Other data such as, autofrettage pressure range, minimum test pressure details of the fire protection system and of any exterior protective coating. 5.2.4.2 Stress analysis report When a stress analysis is required to be carried out, the stress analysis report shall be kept on file and shall include a table summarizing the calculated stresses. NOTE Verification of the stress ratios shall be performed using strain gauges or an equivalent method. An example of an acceptable method is provided in Annex D. 5.2.4.3 Material property data A detailed description of the materials and tolerances of the materials properties used in the design shall be provided. Test data shall also be presented characterizing the mechanical properties and the suitability of the materials for service under the conditions specified in 4. 5.2.4.4 Fire protection The arrangement of the non-reclosing thermally activated pressure relief devices, and insulation if provided, that will protect the cylinder from sudden rupture when exposed to the fire conditions in B.9 shall be specified by the cylinder manufacturer. Test data shall substantiate the effectiveness of the specified fire protection system. 5.2.5 Manufacturing Data Details of all fabrication processes, tolerances, non-destructive examinations, type tests, batch tests and production tests shall be specified and kept on file by the cylinder manufacturer. The tolerances for all production process such as heat treatment, end forming resin-mix ratio, filament tension and speed for controlled tension winding, curing times and temperatures, and autofrettage procedures, surface finish, thread details, acceptance criteria for ultrasonic scanning (or equivalent) and maximum lot sizes for batch tests shall also be specified. The manufacturer shall specify the burst pressure range for the design. In no case shall the minimum specified burst pressure be less than the minimum burst pressure specified in this Indian Standard. 5.2.7 Fracture Performance and Non-destructive Examination (NDE) Defect Size) The manufacturer shall specify the maximum defect size for non-destructive examination which will ensure leak before break (LBB) fracture performance and will prevent failure of the cylinder during its service life due to fatigue, or failure of the cylinder by rupture. The maximum defect size shall be established by a method suitable to the design; an example of a suitable method is given in Annex E. 9

5.2.8 Specification Sheet A summary of the documents providing the information required in 5.2.2 shall be listed on a specification sheet for each cylinder design. The title, reference number, revision numbers and dates of original issue and version issues of each document shall be given. All documents shall be signed or initialled by the issuer. The specification sheet shall be given a number and revision numbers if applicable, that can be used to designate the cylinder design and shall carry the signature of the engineer responsible for the design. Space shall be provided on the specification sheet for a stamp indicating registration of the design. 5.2.9 Additional Supporting Data Additional data which would support the application, such as the service history of material proposed for use, or the use of a particular cylinder design in other service conditions shall be provided where applicable. 5.3 Type Approval Certificate If the results of the design approval according to 5.2 and the prototype testing according to 9.2 or 9.5 are satisfactory, the inspector shall foreword the test report for approval of the statutory authority (a typical example is given in the Annex G). 6 MATERIALS 6.1 Compatibility Materials used shall be suitable for the service conditions specified in 4. The design shall not have incompatible materials in contact with each other. All metallic materials in contact with hydrogen and hydrogen blends shall be compatible with hydrogen according to B.2. 6.2.1 Steel NOTE Guidance on hydrogen compatibility can be found in the documents listed in the Bibliography. Steels for cylinders and liners shall conform to the materials requirements of 5.1 to 5.7 of IS 15490 or 6.1 to 6.3 of ISO 9809-2, as appropriate. Stainless steels are not considered for cylinders and liners. 6.2.2 Aluminium Aluminium alloy shall conform to the material requirement of 5.1 of IS 15660. Aluminium alloys not covered by above may be used, provide that Hydrogen compatibility is demonstrated according to the method specified B.2 6.3 Resins The material for impregnation may be thermosetting or thermoplastic resins. Examples of suitable matrix materials are epoxy, modified epoxy, polyester and vinylester thermosetting plastics, as well as polyethylene and polyamide thermoplastic. The glass transition temperature of the resin material shall be determined in accordance with IS 15935 or ISO 18373-2.. 6.4 Fibers Structural reinforcing filament material types shall be glass fiber, aramid fiber or carbon fiber. If carbon fiber reinforcement is used, the design shall incorporate means to prevent galvanic 10

corrosion of metallic components of the cylinder. The cylinder manufacturer shall keep on file for the intended life of the cylinder design the published specifications for composite materials and the material manufacturer's recommendations for storage conditions and shelf life. The cylinder manufacturer shall keep on file, for the intended life of each batch of cylinders, the fiber manufacturer's certification that each shipment conforms to the manufacturer's specifications for the product. 6.5 Plastic liners The polymeric material used for plastic liners shall be compatible with the service conditions specified in 4. 6.6 Metal End Bosses The metal end bosses connected to a non-metallic liner shall be made of material compatible with the service conditions specified in 4. 7 DESIGN REQUIREMENTS 7.1 General This Indian Standard neither provides design formulae nor lists permissible stresses or strains, but requires the adequacy of the design to be established by appropriate calculations and demonstrated by cylinders being capable of consistently passing the materials, design qualification, production and batch tests specified in this standard. However, cylinders manufactured in conformance with IS 15490 and IS 15660 may be used as Type 1 cylinders, or as Metal Liners for Type 2 and Type 3 cylinders. During pressurization, this type of cylinder design exhibits behaviour in which the displacements of the composite overwrap and the metal liner are linearly superimposed. Due to different techniques of the manufacture, this standard does not give definite method for design. The design shall ensure a leakage-before-break failure mode under feasible degradation of pressure parts during normal services. If leakage of the metal liner occurs, it shall be only by the growth of a fatigue crack. 7.2 Test Pressure The minimum test pressure used during manufacturing shall be 1.5 times the working pressure. 7.3 Burst Pressure and Fiber Stress Ratio 7.3.1 Cylinder The minimum actual burst pressure of the finished cylinder shall not be less than the values given in Table 1. The composite overwrap shall be designed for high reliability under sustained loading and cyclic loading. This reliability shall be achieved by meeting or exceeding the composite reinforcement stress ratio values given in Table 1. Stress ratio is defined as the stress in the fibre at the specified minimum burst pressure divided by the stress in the fibre at working pressure. The burst ratio is defined as the actual burst pressure of the cylinder divided by the working pressure. Composite reinforcement used on cylinders shall also meet the minimum stress ratio requirements of 11

Table 1. Verification of the stress ratios may be done by calculation. When the calculation method is used, the stress ratio calculations shall include: a) An analysis method with capability for non-linear materials, such as a special purpose computer program or a finite element analysis program; b) Correct modeling of the elastic-plastic stress-strain curve for the liner material; c) Correct modeling of the mechanical properties of the composite materials; d) Calculations at autofrettage pressure, zero pressure after autofrettage, working pressure and minimum burst pressure; e) Account for the pre-stresses from the winding tension; f) Minimum burst pressure, chosen such that the calculated stress at minimum burst pressure divided by the calculated stress at the working pressure meets the stress ratio requirements for the fiber used and g) When analyzing cylinders with hybrid reinforcement (two or more different fibers), consideration of the load share between the different fibers based on the different elastic moduli of the fibers. The stress ratio requirements for each individual fiber type shall be in accordance with the values given in Table 1. Verification of the stress ratios may also be performed using strain gauges. An acceptable method is provided in Annex D. Table 1 Minimum Stress Ratios and Burst Pressures (Clause 7.3.1) Construction Minimum stress ratio Minimum actual burst pressure a Type 2 Type 3 Type 4 Type 1 Type 2 Type 3 Type 4 All-metal 2.25 Glass 2.65 3.5 3.5 2.4 3.4 3.5 Aramid 2.25 3.0 3.0 2.25 2.9 3.0 Carbon (working pressures less than 35 MPa) 2.25 2.25 2.25 2.25 2.25 2.25 Carbon (working pressures 2.0 2.0 2.0 2.0 2.0 2.0 greater than or equal to 35 MPa) Hybrid b a Burst pressures are expressed as a factor of the working pressure. b Stress ratios and burst pressures shall be calculated in accordance with 7.3.1 g). The stress ratio requirements for each individual fiber type shall be in accordance with the values given above. 7.3.2 Liner For Type 2 designs, the un-reinforced metal liner shall have a minimum burst pressure of 1.25 times the working pressure. 7.4 Stress Analysis A stress analysis shall be performed to justify the minimum design wall thickness. It shall include the determination of the stresses in the liners and fibers of composite designs for a given pattern of winding. For Type 2 and Type 3 designs, the stresses in the composite and in the liner after pre-stress shall be calculated at zero pressure, working pressure, test pressure and design burst pressure. The calculations shall use suitable analysis techniques taking account of non-linear material behaviour of the liner to establish the stress distributions. For Type 2 and Type 3 designs using autofrettage to provide pre-stress, the limits within which the autofrettage pressure shall fall shall be calculated and specified. For Type 2 and Type 3 designs 12

using controlled tension winding to provide pre-stress, the temperature at which it shall be performed, the tension required in each layer of the composite and the consequent pre-stress in the liner shall be calculated. For Type 3 and Type 4 designs, the stresses in the composite shall be calculated in the tangential and longitudinal direction of the cylinder. The pressures used for these calculations shall be zero pressure, working pressure, test pressure and design burst pressure. The calculations shall use suitable analysis techniques to establish the stress distribution throughout the cylinder. 7.5 Maximum Defect Size For Type 1, Type 2, Type 3 and Type 4 designs, the maximum defect size for non-destructive examinations (NDE) shall be established by a method suitable for the design. This method shall demonstrate that a cylinder with defects of the specified defect size will meet the ambient temperature pressure cycling requirements of B.7. The NDE method shall be capable of detecting the maximum defect size allowed. NOTE An example of a suitable method for establishing the maximum defect size is given in Annex E. 7.6 Fire Protection The cylinder design shall be protected with pressure relief devices. The cylinder, its materials, nonreclosing thermally activated pressure relief devices and any added insulation or protective material or non-reclosing pressure-activated pressure relief devices, shall be designed collectively to ensure adequate safety during fire conditions of the test specified in B.9. In no case shall a pressure relief device be composed of thermally activating and pressure-activating functions acting in series such that both functions are required to activate to prevent a cylinder from bursting due to fire effects. Provided that the finished cylinder with its fire protection system has passed the requirements of the bonfire test in B-9, alternative installation configurations for the fire protection system can be used if it can be demonstrated to provide the same or an improved level of safety. The final fire protection system used for vehicle installations involving multiple cylinders may require a different arrangement or number of non-reclosing thermally activated pressure relief devices. If the configuration of cylinders results in the possibility of multiple cylinders having to vent through one single pressure relief device (PRD), then the bonfire test shall flow that full amount of hydrogen through the PRD associated with the cylinder that is venting. It is not necessary to subject the extra cylinder(s) that contain this additional hydrogen to the bonfire, provided that a single cylinder has already passed the bonfire test with its own PRD. NOTES 1 The non-reclosing thermally activated pressure relief device that is part of the cylinder manufacturer specified fire protection system is not necessarily provided with the cylinder. It is, however, required that the effectiveness of this fire protection system be demonstrated by subjecting the same to the bonfire test with that cylinder model. 2 It should not be possible to isolate the non-reclosing thermally activated pressure relief device from the cylinder by the operation or failure of another component. 13

8 CONSTRUCTION AND WORKMANSHIP 8.1 Materials Type 1 designs and Type 2 liners shall be of seamless construction using steel that comply with the materials requirements in 6.2. Type 3 liners shall be constructed from steel that comply with the materials requirements in 6.2 or 6.3, as appropriate. 8.2 Type 3 Metal liner For Type 3 designs, the compressive stress in the liner at zero pressure and the design temperature range shall not cause the liner to buckle or crease. NOTE During pressurization, a Type 3 design has a behaviour in which the displacements of the composite overwrap and the metal liner are linearly superimposed. Due to different manufacturing techniques, this Indian Standard does not give a definite method for design. For Type 3 liners subjected to cold-forming or cryo-forming processes, heat treatment of the pre-form component is not required. Liners that have been cold-formed or cryo-formed shall not be subjected to any subsequent heat treatment or to additional heat application, such as welding. 8.3 Neck Threads The cylinder neck shall be threaded to suit the type of valves as given in IS 3224 or any other specification as approved by the statutory authority. The threads shall be full form, clean cut, even and without surface discontinuities, to gauge, and concentric with the axis of the cylinder. 8.4 Forming For Type 1 or Type 2 cylinders and liners, a forming process such as gas / arc welding shall not be used to fully close and seal the ends. The base ends of Type 1 steel cylinders that have been closed by forming shall be inspected using NDE, methods in 7.2 of IS 15490 or other equivalent techniques). Metal shall not be added in the process of closure at the end. Each cylinder shall be examined before end forming operations for thickness and surface finish. After end forming, the cylinders shall be heat treated to the hardness range specified for the design. Localized heat treatment shall not be used. 8.5 Fiber Winding Type 2, Type 3 and Type 4 cylinders shall be fabricated from a liner over-wrapped with continuous filament windings. Fiber winding operations shall be computer or mechanically controlled. The fibers shall be applied under controlled tension during winding. During winding, the significant variables shall be monitored to demonstrate that they remain within specified tolerances. The results shall be documented in a winding record that shall be retained by the cylinder manufacturer for the intended life of each batch of cylinders. These variables can include but are not limited to: a) Fiber type, including sizing; b) Manner of impregnation; c) Winding tension; d) Winding speed; e) Number of rovings; f) Band width; 14

g) Type of resin and composition; h) Temperature of the resin; j) Temperature of the liner; and k) Winding angle. l) Winding program reference number. 8.6 Curing of Thermosetting Resins If a thermosetting resin is used, the resin shall be cured after the fiber winding is complete. Thermosetting resins shall be cured by heating, using a predetermined and controlled timetemperature profile. During the curing, the curing cycle (that is the time-temperature history) shall be documented and retained by the cylinder manufacturer for the intended life of each batch of cylinders. The maximum curing time and temperature for cylinders with aluminium alloy liners shall not adversely affect metal, resin and fiber properties. 8.7 Autofrettage Autofrettage, if used, shall be carried out before the hydraulic test specified in 10.2 d). The autofrettage pressure shall be within the limits established in 7.4. The cylinder manufacturer shall establish the method to verify that the appropriate pressure is applied. Records of autofrettage pressure shall be retained by the cylinder manufacturer for the intended life of each batch of cylinders. 8.8 Exterior Environmental Protection Exterior protection may be provided by using any one of the following: a) A surface finishes giving adequate protection (for example, metal sprayed on aluminum, anodizing); b) A suitable fiber and matrix material (for example, carbon fiber in resin); and c) A protective coating (for example, organic coating, paint). If a protective coating is part of the design, the coatings shall be evaluated using the test methods in B.1. Any coatings applied to cylinders shall be such that neither the coating nor the application process adversely affects the mechanical properties of the cylinder. The coating shall be designed to facilitate subsequent in-service inspection, and the manufacturer shall provide guidance on coating treatment during such inspection to ensure the continued integrity of the cylinder. 9 TYPE APPROVAL PROCEDURE 9.1 Qualification of New Designs A technical specification of each new design of cylinder including design drawing, design calculations, material details and heal treatment, shall be submitted by the manufacturer to the statutory authority, through the inspection agency The test detailed in 9.2 shall be carried out on each new design under the supervision of the inspector. The cylinder manufacturer shall retain the proto type test results for the intended service life of the cylinder design. The test data shall also document the dimensions, wall thickness and weights of each of the tested cylinder. 15

9.2 Prototype Tests 9.2.1 General Requirement A minimum of 50 cylinders or liners which are guaranteed by the manufacturer to be representative of the new design shall be made available for prototype testing. However, if for special applications the total number of cylinders or liners required is less than 50, enough cylinders or liners shall be made to complete the prototype tests required, in addition to the production quantity. All cylinders subjected to prototype tests shall be made unserviceable after the tests. In the course of the type approval process, the inspector shall select the necessary cylinders or liners for testing and supervise the following tests on the cylinders or liners selected. Unless otherwise permitted by 9.3, Type 1, 2, 3 and 4 designs shall be subjected to the applicable prototype tests listed in Table 2. Table 2 Summary of Prototype tests (Clause 9.2.1) Test Number of cylinders required for testing Applicable to type 1 2 3 4 9.2.2 Material tests for metal cylinders and liners 1 Cylinder or liner 9.2.3 Material tests for plastic liners 1 liner 9.2.4 Resin properties composite samples 9.2.5 Hydrostatic burst pressure 3 plus 1 Liner 9.2.6 Ambient temperature pressure cycling 2 9.2.7 Leak-before-break (LBB) 3 9.2.8 Bonfire 1 or 2 9.2.9 Chemical exposure 1 9.2.10 Composite flaw tolerance 1 9.2.11 Accelerated stress rupture 1 9.2.12 Extreme temperature pressure cycling 1 9.2.13 Impact damage 1, 2 or 3 9.2.14 Permeation 1 9.2.15 Boss torque 1 9.2.16 Hydrogen gas cycling 1 Note : indicates that the test to be performed. 9.2.2 Material Tests for Steel Cylinders and Liners If the cylinder or liner is made of steel, appropriate material tests in accordance with 8.3 of IS 15490 or 10.2 to 10.4 of ISO 9809-2 shall be carried out on one liner. The tensile strength shall meet the manufacturer's design specifications. For Type 1 and Type 2 designs, the steel elongation shall be at least 14 percent. For Type 3 designs, the tensile strength and elongation shall meet the manufacturer's design specifications. The hydrogen compatibility of steels in contact with hydrogen shall be demonstrated in accordance with B-2. Steels that conform to 5.5 and 5.3 of IS 15490 are exempted from this test. 16

9.2.3 Material tests for aluminium alloy fuel tanks and liners For Type 1 fuel tanks and Type 2 liners using aluminium alloy, appropriate material tests as required in IS 15660, 10.2 and 10.3, as well as Annexes A and B shall be carried out on one cylinder or liner. The materials properties shall meet the manufacturer s design specifications. The elongation shall be at least 12 %. For Type 3 liners using aluminium alloy, materials tests as required in IS 15660 and Annex B shall be carried out on one liner. The materials properties, including elongation, shall meet the manufacturer s design specifications. as well as Annexes A and B, excluding B2.2 thereof. The hydrogen compatibility of aluminium alloys in contact with hydrogen shall be demonstrated in accordance with B.2. Aluminium alloys that conform to 6.1 and 6.2 of IS 15660 are exempted from this test. 9.2.3 Material Tests for Plastic Liners One liner shall be subjected to the following requirements: a) The tensile strength, yield strength and elongation shall be determined in accordance with B.3 and shall meet the requirements therein; and b) The softening temperature shall be determined in accordance with B.4 and shall meet the requirements therein. 9.2.4 Resin Properties Tests For Type 2, Type 3 and Type 4 designs, samples representative of the composite over-wrap shall be tested in accordance with B.5. Resin materials shall meet the requirements therein. 9.2.5 Hydrostatic Burst Pressure Test For Type 2 designs, one liner shall be hydrostatically pressurized to failure in accordance with B.6. The burst pressure shall exceed 1.25 times the working pressure. For all designs, three cylinders shall be hydrostatically pressurized to failure in accordance with B.6. For each cylinder, the burst pressure shall exceed the specified minimum burst pressure given in Table 1. In no case shall the burst pressure be less than the value necessary to meet the stress ratio requirements in Table 1. The average of the burst pressure results of the three cylinders shall be recorded for future reference. 9.2.6 Ambient Temperature Pressure Cycling Test For all designs, two cylinders shall be pressure cycled at ambient temperature in accordance with B.7 and meet the requirements therein. 9.2.7 Leak-before-break (LBB) Test For all designs, three cylinders shall be tested in accordance with B.8 and shall meet the requirements therein. 9.2.8 Bonfire Test For all designs, one or two cylinders as appropriate shall be tested in accordance with B.9 and meet the requirements therein. 9.2.9 Chemical Exposure Test For Type 2, Type 3 and Type 4 designs, one cylinder shall be tested in accordance with B.10 and meet the requirements therein. 17

9.2.10 Composite Flaw Tolerance Test For Type 2, Type 3 and Type 4 designs, one cylinder shall be tested in accordance with B.11 and meet the requirements therein. 9.2.11 Accelerated Stress Rupture Test For Type 2, Type 3 and Type 4 designs, one cylinder shall be tested in accordance with B.12 and meet the requirements therein. 9.2.12 Extreme Temperature Pressure Cycling Test For Type 2, Type 3 and Type 4 designs, one cylinder shall be tested in accordance with B.14 and meet the requirements therein. 9.2.13 Impact Damage Test For Type 3 and Type 4 designs, one or more finished cylinders shall be tested in accordance with B.15 and meet the requirements therein. 9.2.14 Permeation Test For Type 4 designs, one cylinder shall be tested for permeation in accordance with B.16 and meet the requirements therein. 9.2.15 Boss Torque Test For Type 4 designs, one cylinder shall be tested in accordance with B.17 and meet the requirements therein. 9.2.16 Hydrogen Gas Cycling Test For Type 4 designs, one cylinder shall be tested in accordance with B.18 and meet the requirements therein. 9.3 Exemptions to type tests As an alternative to the requirements in 9.2, Type 1 steel design meeting the requirements of IS 15490 and the additional requirements specified in 7.6 and 8.8 of this standard may only be subjected to the bonfire test in 9.2.8 and the hydrogen compatibility tests in B.2. As an alternative to the requirements in 9.2, Type 1 aluminium alloy design meeting the requirements of IS 15660 and the additional requirements specified in 7.6 and 8.8 of this Indian Standard may only be subjected to the bonfire test in 9.2.10 and the hydrogen compatibility tests in B.2. 9.4 Prototype Tests for Design Changes A cylinder shall be considered to be a new design, compared with an existing approved design, when: a) It is manufactured in a different factory; b) It is manufactured by a different process; c) It is manufactured from a steel of different specified chemical composition; d) It is given a different heat treatment beyond the stipulated limit; e) Ends or ends profile has changed for example convex, hemispherical, torispherical, ellipsoidal or also if there is a change in base thickness to cylinder diameter ratio; 18