SIST EN 14638-1:2006
(Main)Transportable gas cylinders - Refillable welded receptacles of a capacity not exceeding 150 litres - Part 1: Welded austenitic stainless steel cylinders made to a design justified by experimental methods
Transportable gas cylinders - Refillable welded receptacles of a capacity not exceeding 150 litres - Part 1: Welded austenitic stainless steel cylinders made to a design justified by experimental methods
This European Standard gives minimum requirements concerning material, design, construction and workmanship, procedures and tests at manufacture of refillable transportable welded cylinders made of austenitic stainless steel, justified by experimental methods, of water capacities from 0,5 l up to and including 150 l for compressed or liquefied gases and of a test pressure up to 90 bar.
NOTE This European Standard may also be used as a guideline for cylinders less than 0,5 litres water capacity.
This European Standard is primarily for industrial gases other than LPG but may also be applied for LPG. However for dedicated LPG cylinders, see EN 14140, Transportable refillable welded steel cylinders for liquefied petroleum gas (LPG) Alternative design and construction prepared by CEN/TC 286 Liquefied petroleum gas equipment and accessories.
Ortsbewegliche Gasflaschen - Wiederbefüllbare geschweißte Gefäße mit einem Fassungsraum von nicht mehr als 150 Liter - Teil 1: Flaschen aus geschweißtem, austenitischen, nichtrostendem Stahl, ausgelegt nach experimentellen Verfahren
Diese Europäische Norm legt Mindestanforderungen an Werkstoff, Gestaltung, Konstruktion und Ausführung,
Verfahren und Prüfung bei der Herstellung wiederbefüllbarer, ortsbeweglicher, geschweißter Flaschen aus
austenitischem, nichtrostendem Stahl fest, ausgelegt nach dem experimentellen Verfahren, mit Fassungs-räumen
von 0,5 l bis einschließlich 150 l für unter Druck gesetzte Gase oder Flüssiggase (LPG, en.: liquefied
petroleum gas) und für einen Prüfdruck von bis zu 90 bar.
ANMERKUNG Diese Europäische Norm darf auch als Leitlinie für Flaschen mit einem Fassungsraum von weniger als
0,5 l angewendet werden.
Diese Europäische Norm gilt hauptsächlich für andere Gase für den industriellen Einsatz als LPG, darf jedoch
ebenfalls auf LPG angewendet werden. Für Flaschen, die für LPG vorgesehen sind, siehe EN 14140,
Ortsbewegliche, wiederbefüllbare, geschweißte Flaschen aus Stahl für Flüssiggas (LPG) - Alternative
Gestaltung und Konstruktion, die vom CEN/TC 286 "Flüssiggas-Geräte und Zubehörteile" erarbeitet wurde.
Bouteilles a gaz transportables - Récipients soudés rechargeables d'une capacité inférieure ou égale a 150 litres - Partie 1: Bouteilles en acier inoxydable austénitique soudées conçues par des méthodes expérimentales
La présente Norme européenne indique les exigences minimales concernant les matériaux, la conception, la fabrication et la mise en oeuvre, les modes opératoires et les essais lors de la fabrication des bouteilles soudées transportables et rechargeables, fabriquées en acier inoxydable austénitique et conçues par des méthodes expérimentales. Ces bouteilles ont une capacité en eau comprise entre 0,5 l et 150 l inclus, une pression d’épreuve jusqu'a 90 bar et sont destinées a contenir des gaz comprimés ou liquéfiés.
NOTE La présente Norme européenne peut également etre utilisée comme lignes directrices pour les bouteilles d’une capacité en eau inférieure a 0,5 l.
Bien que la présente Norme européenne porte principalement sur les gaz industriels autres que le GPL, elle peut également s’y appliquer. Toutefois, pour les bouteilles destinées a contenir du GPL, se reporter a l’EN 14140, Bouteilles en acier soudé transportables et rechargeables pour gaz de pétrole liquéfié (GPL) Autres solutions en matiere de conception et de construction élaborée par le CEN/TC 286 Équipements et accessoires pour gaz de pétrole liquéfié.
Premične plinske jeklenke – Ponovno polnljivi varjeni vsebniki s prostornino ne večjo kot 150 litrov – 1. del: Varjene jeklenke iz avstenitnega nerjavnega jekla, izdelane po eksperimentalno potrjeni metodi
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Transportable gas cylinders - Refillable welded receptacles of a capacity not exceeding 150 litres - Part 1: Welded austenitic stainless steel cylinders made to a design justified by experimental methodsBouteilles a gaz transportables - Récipients soudés rechargeables d'une capacité inférieure ou égale a 150 litres - Partie 1: Bouteilles en acier inoxydable austénitique soudées conçues par des méthodes expérimentalesOrtsbewegliche Gasflaschen - Wiederbefüllbare geschweißte Gefäße mit einem Fassungsraum von nicht mehr als 150 Liter - Teil 1: Flaschen aus geschweißtem, austenitischen, nichtrostendem Stahl, ausgelegt nach experimentellen VerfahrenTa slovenski standard je istoveten z:EN 14638-1:2006SIST EN 14638-1:2006en23.020.30MHNOHQNHPressure vessels, gas cylindersICS:SLOVENSKI
STANDARDSIST EN 14638-1:200601-oktober-2006
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14638-1May 2006ICS 23.020.30 English VersionTransportable gas cylinders - Refillable welded receptacles of acapacity not exceeding 150 litres - Part 1: Welded austeniticstainless steel cylinders made to a design justified byexperimental methodsBouteilles à gaz transportables - Récipients soudésrechargeables d'une capacité inférieure ou égale à 150litres - Partie 1: Bouteilles en acier inoxydable austénitiquesoudées, conçues selon des méthodes expérimentalesOrtsbewegliche Gasflaschen - Wiederbefüllbaregeschweißte Gefäße mit einem Fassungsraum von nichtmehr als 150 Liter - Teil 1: Flaschen aus geschweißtem,austenitischen, nichtrostendem Stahl, ausgelegt nachexperimentellen VerfahrenThis European Standard was approved by CEN on 23 March 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14638-1:2006: E
EN 14638-1:2006 (E) 2 Contents Page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms, definitions and symbols.6 4 Materials and heat treatment.8 5 Design.9 6 Construction and workmanship.10 7 New design tests.12 8 Marking.24 9 Conformity evaluation criteria.24 10 Records.24 Annex A (normative)
Non destructive examination (NDE) of welds.25 Annex B (normative)
Description, evaluation of manufacturing defects and conditions for rejection of welded stainless steel gas cylinders at time of final visual inspection by the manufacturer.27 Annex C (informative)
Model - Production certificate.30 Annex D (informative)
Recommendations to be applied in case of heat treatments on austenitic stainless steels.33 Bibliography.34
EN 14638-1:2006 (E) 3 Foreword This document (EN 14638-1:2006) has been prepared by Technical Committee CEN/TC 23 “Transportable gas cylinders”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2006, and conflicting national standards shall be withdrawn at the latest by November 2006. This document has been submitted for reference into the RID and/or in the technical annexes of the ADR. Therefore in this context the standards listed in the normative references and covering basic requirements of the RID/ADR not addressed within the present standard are normative only when the standards themselves are referred to in the RID and/or in the technical annexes of the ADR. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EN 14638-1:2006 (E) 4 Introduction The purpose of this European Standard is to provide a specification for the design, manufacture, inspection and approval of welded austenitic stainless steel gas cylinders for use in the countries of the CEN members. The specifications given in the present standard establish the methodology to be adopted in order to demonstrate that a cylinder conforms to the functional requirements demanded, based on the experience about materials, design prescriptions, manufacturing processes and controls manufacturing. This European Standard comprises experimental methods and appropriate stress analysis calculations. It does not cover methods exclusively by means of traditional calculation.
EN 14638-1:2006 (E) 5
1 Scope This European Standard gives minimum requirements concerning material, design, construction and workmanship, procedures and tests at manufacture of refillable transportable welded cylinders made of austenitic stainless steel, justified by experimental methods, of water capacities from 0,5 l up to and including 150 l for compressed or liquefied gases and of a test pressure up to 90 bar. NOTE This European Standard may also be used as a guideline for cylinders less than 0,5 litres water capacity. This European Standard is primarily for industrial gases other than LPG but may also be applied for LPG. However for dedicated LPG cylinders, see EN 14140, Transportable refillable welded steel cylinders for liquefied petroleum gas (LPG) – Alternative design and construction prepared by CEN/TC 286 Liquefied petroleum gas equipment and accessories. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 287-1, Qualification test of welders - Fusion welding - Part 1: Steels EN 473, Non destructive testing — Qualification and certification of NDT personnel — General principles EN 910, Destructive tests on welds in metallic materials — Bend tests EN 962, Transportable gas cylinders — Valve protection caps and valve guards for industrial and medical gas cylinders — Design, construction and tests EN 970, Non-destructive examination of fusion welds — Visual examination EN 1435, Non destructive examination of welds — Radiographic examination of welded joints EN 10002-1, Metallic materials — Tensile testing — Part 1: Method of test at ambient temperature EN 10028-7, Flat products made of steels for pressure purposes — Part 7: Stainless steels EN 10045-1, Metallic materials — Charpy impact test — Part1: Test method EN 10088-2, Stainless steels - Part 2: Technical delivery conditions for sheet/plate and strip of corrosion resisting steels for general purposes EN 13445-2, Unfired pressure vessels — Part 2: Materials EN ISO 3651-2, Determination of resistance to intergranular corrosion of stainless steels — Part 2: Ferritic, austenitic and ferritic-austenitic (duplex) stainless steels — Corrosion test in media containing sulfuric acid (ISO 3651-2:1998) EN ISO 5817, Welding — Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) — Quality levels for imperfections (ISO 5817:2003) EN ISO 7539-6, Corrosion of metals and alloys — Stress corrosion testing — Part 6: Preparation and use of pre-cracked specimens for tests under constant load or constant displacement (ISO 7539-6:2003)
EN 14638-1:2006 (E) 6 EN ISO 10692-2, Gas cylinders — Gas cylinder valve connections for use in the microelectronics industry — Part 2: Specification and type testing for valve to cylinder connections (ISO 10692-2:2001) EN ISO 11114-1, Transportable gas cylinders — Compatibility of cylinder and valve materials with gas contents — Part 1: Metallic materials (ISO 11114-1:1997) prEN ISO 13769: 2005, Gas cylinders — Stampmarking (ISO 13769:2002) EN ISO 15607, Specification and qualification of welding procedures for metallic materials — General rules (ISO 15607:2003) EN ISO 15614-1, Specification and qualification of welding procedures for metallic materials — Welding procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys (ISO 15614-1:2004) ISO 2504:1973, Radiography of welds and viewing conditions for films — Utilization of recommended patterns of image quality indicators (I.Q.I.) 3 Terms, definitions and symbols 3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 yield stress either the 0,2 % proof stress, Rp0,2, – or the 1,0 % proof stress, Rp1,0 where there is no apparent definite value for Rp0,2, as for example, is the case for austenitic steels 3.1.2 solution annealing heat treatment in which the steel is heated to a uniform temperature above the solid solubility temperature followed by rapid cooling 3.1.3 parent material material corresponding to the cylinder after finishing its manufacturing process and ready for service/operation NOTE The material characteristics may be variable at any point of the cylinder. 3.1.4 batch consists of finished cylinders made consecutively during the same or consecutive days to the same design, size and material specifications and from the same material supplier for each pressure containing parts on the same automatic welding machines and, if applicable, heat-treated under the same conditions of temperature and duration NOTE 1 In this context consecutively need not imply continuous production. NOTE 2 This definition allows different suppliers to be used for the different pressure containing parts within a batch, e.g. one supplier for heads, another for bases. 3.1.5 cylinder transportable pressure receptacle of a water capacity not exceeding 150 l
EN 14638-1:2006 (E) 7 3.1.6 finished cylinder cylinder which is fully assembled and appropriately stampmarked, but without any external coatings 3.1.7 cryoforming process where the cylinder is subjected to a controlled low temperature deformation treatment that results in a permanent increase in strength 3.1.8 coldforming final deformation treatment at ambient temperature given to the prefabricated cylinder, known as the preform, which results in a permanent increase in the material strength 3.1.9 valve boss or pad connection between valve and cylinder 3.2 Symbols a Minimum thickness, in millimetres, for calculation of weld clearance (see Figure 1); asi calculated minimum thickness, in millimetres, at a determined area “i” of the cylinder; abi minimum thickness, in millimetres, at a determined area “i” of the cylinder (including any corrosion allowance) guaranteed by the manufacturer; Ai percentage elongation after fracture, at a determined area “i” of the cylinder; i area of the cylinder used
for the calculation under consideration; L, original gauge length, in millimetres, in accordance with EN 10002-1; n ratio of diameter of bend test former to the thickness of the test piece; Ph test pressure, in bar, above atmospheric pressure; Pb minimum burst pressure, in bar; Pba actual burst pressure, in bar; Rpi1,0 minimum value of 1,0 % proof stress in MPa, guaranteed by the cylinder manufacturer for the finished cylinder, at a determined area “i” of the cylinder; Rgi minimum value of tensile stress, in MPa, guaranteed by the cylinder manufacturer for the finished cylinder, at a determined area “i” of the cylinder; Rmi actual value of tensile stress, in MPa, determined by tensile test specified in Clause 7, at a determined area “i” of the cylinder; Rei yield stress means the stress at which a permanent elongation of 1 % of the gauge length on the test-piece, has been produced, at a determined area “i” of the cylinder; Reai actual value of yield stress used for calculation, in MPa, at a determined area “i” of the cylinder;
EN 14638-1:2006 (E) 8 s nominal butt weld thickness. 4 Materials and heat treatment 4.1 General 4.1.1 The cylinder materials subject to pressure shall be of austenitic stainless steel according to EN 10088 or EN 10028-7 or other austenitic stainless steels standards, provided that they satisfy the requirements of this European Standard. NOTE These materials correspond to the materials received by the manufacturer, before having been submitted to any manufacturing process. 4.1.2 The welding consumables shall be such that they are capable of giving consistent welds. The material characteristics on the welds shall have to be considered by design. 4.1.3 Grades of steel used for the cylinder manufacture shall be compatible with the intended gas service, e.g. corrosive gases, embrittling gases according to EN ISO 11114-1. 4.1.4 There is a risk of sensitisation to inter-granular corrosion resulting from the hot processing of austenitic stainless steels. An inter-granular corrosion test in accordance with 7.5.4 shall be carried out on such stainless steels when intended to be used for corrosive applications. Corrosive gases are listed in EN 1968 and cylinders for such gases shall be marked as specified in prEN ISO 13769. 4.1.5 The manufacturer shall be able to guarantee cylinder steel casting traceability for each pressure retaining part. 4.1.6 All parts welded to, or in contact with, the cylinder shall be made of compatible material with the cylinder without harming its characteristics or favouring corrosion processes. 4.1.7 The cylinder manufacturer shall obtain and provide certificates of the ladle analysis of the steel supplied for the construction of the pressure retaining parts of the cylinder and of welding consumables. 4.1.8 The manufacturer shall demonstrate that the material is resistant to stress corrosion cracking. Where there is any doubt, tests shall be carried out on finished cylinders according to EN ISO 7539-6 or equivalent. The manufacturer shall assess the results according to the type of steel and the relevant environment under consideration. 4.2 Heat treatment There is no obligation to perform heat treatments. When the manufacturer considers the necessity of a heat treatment, it should be in accordance with Annex D. 4.3 Test requirements The material of the finished cylinders shall satisfy the requirements of Clause 7. 4.4 Failure to meet test requirements 4.4.1 In the event of failure to meet test requirements, retesting shall be carried out as given in 4.4.2 and 4.4.3. 4.4.2 If there is evidence of a fault in carrying out a test or an error of measurement, a further test shall be performed. If the result of the test is satisfactory, the first test shall be ignored. 4.4.3 If the test has been carried out in a satisfactory manner, the cause of test failure shall be identified.
EN 14638-1:2006 (E) 9 — If the failure is considered to be due to inappropriate heat treatment (if applied), the manufacturer may subject all the cylinders of the batch to a further heat treatment; — if the failure is not due to inappropriate heat treatment (if applied), all the identified defective cylinders shall be rejected or repaired by an approved method. The remaining cylinders are then considered as a new batch. In both cases the new batch shall be tested. All the relevant prototype or batch tests needed to prove the acceptability of the new batch shall be performed again and shall satisfy the requirements for batch or prototype testing. If one or more tests prove even partially unsatisfactory, all the cylinders of the batch shall be rejected. 5 Design 5.1 General For any new design, the concepts outlined in 5.2 and 5.3 shall be followed. It is recommended that an approximate calculation for the initial design be made. This initial calculated design may then be optimised if results from the experimental method exceed the minimum requirements. 5.2 Calculation Where a calculation is to be used as the basis for the design, the following conditions shall be considered. — the calculation of the wall thickness of the pressure containing parts “i” shall be related to the yield stress of the material, of the finished product in each area “i” to be considered; — for calculation purposes, the value of the yield stress Reai, is limited to a maximum of 0,85 Rgi; — The internal pressure upon which the calculation of gas cylinders is based, shall be the test pressure Ph. NOTE At the test pressure, the stress in the metal at the most severely stressed point of the cylinder shall not exceed 77 % of the guaranteed yield stress (Reai). This can be verified by for example, studying the stress analysis. 5.3 Experimental method An experimental method shall be used as the basis for the design. The following conditions shall be met. — the actual wall thickness, mechanical properties and the geometry of the cylinders submitted to the prototype tests shall be recorded; — the manufacturer shall take into account the requirements of 7.2 and ensure that the properties recorded represent the minimum values that would be used for production. 5.4 Openings 5.4.1 Each opening in the cylinder shall be reinforced, either by a valve boss or pad, of weldable and compatible steel, securely attached by welding and so designed as to be of adequate strength and to result in no harmful stress concentrations. This shall be confirmed by prototype testing. 5.4.2 When openings in the cylinder are reinforced, either by a valve boss or pad, they shall be of weldable and compatible steel, securely attached by welding and so designed as to be of adequate strength and to result in no harmful stress concentrations. This shall be confirmed by prototype test.
EN 14638-1:2006 (E) 10 5.4.3 Openings shall be clear of longitudinal and circumferential joints by a distance not less than 3a (see Figure 1). 6 Construction and workmanship 6.1 Manufacturing methods 6.1.1 The essential characteristics of the manufacturing processes applied and the corresponding parameters shall be defined in the technical specification of the cylinder (see 7.1). 6.1.2 The manufacturer shall have the technical capability, have at his disposal all appropriate means, and qualified personnel to carry out the manufacture of cylinders.
3
aa Figure 1 — Weld clearance 6.2 Welding procedures Each manufacturer, before proceeding with the production of a given design of cylinder, shall qualify the welding procedures and welders according to EN ISO 15614-1, EN ISO 15607 and EN 287-1. Records of such qualification shall be kept on file by the manufacturer. The welding procedure approval shall include a sensitisation test performed according to EN ISO 3651-2. 6.3 Plates and pressed parts Care shall be taken to avoid contamination from other manufacturing materials, e.g. potential of galvanic corrosion from carbon steel particles. 6.4 Welded pressure containing joints With exception of welds for openings, all welded joints shall be butt welded or joggle welded. When designing the welds, the cylinder manufacturer shall take into account the intended service, e.g. corrosive gases according to EN ISO 11114-1. 6.5 Non-pressure-containing attachments 6.5.1 Non pressure containing parts such as footrings, handles and neckrings which are not submitted to pressure shall be made in accordance with 4.1.6. 6.5.2 Each attachment shall be designed to permit inspection of the welds, which shall be clear of longitudinal and circumferential joints, and so designed as to avoid trapping water.
EN 14638-1:2006 (E) 11 6.5.3 A footring or other suitable supports shall be fitted when applicable to the cylinder to provide stability, and attached so as to permit inspection of the welds. The footring, if attached, shall be drained and the space enclosed by the footring shall be ventilated. 6.5.4 In case of cylinders subjected to a cold-forming or cryoforming process, the non-pressure retaining attachments shall be welded to the cylinder preform before cold-forming or cryoforming. 6.6 Valve protection 6.6.1 Valves of cylinders of more than 5 l water capacity shall be effectively protected from damage that could cause release of gas, either by the design of the cylinder (for example protective shroud) or by a valve protection device (see EN 962). 6.6.2 When a protective shroud is used, it shall fulfil the requirements of the drop test (see EN 962). 6.6.3 The requirements of 6.6.1 and 6.6.2 may be waived when the cylinders are used and conveyed in bundles or cradles, or when some other effective valve protection is provided. 6.7 Cylinder openings 6.7.1 Standard openings Cylinder openings shall conform to a recognized standard agreed between the parties to permit the use of a corresponding valve thus minimizing neck stresses following the valve torquing operation. Internal neck threads shall be checked using gauges corresponding to the agreed neck thread, or by an alternative method agreed between the parties. NOTE For example, where the neck thread is specified to be in accordance with EN 629-1, the corresponding gauges are specified in EN 629-2. Particular care shall be taken to ensure that neck threads are accurately cut, are of full form and free from any sharp profiles, e.g. burrs. 6.7.2 Special openings If a special valve/cylinder connection is used, it shall be checked that it conforms to EN ISO 10692-2. 6.8 Visual examination 6.8.1 Unacceptable defects Before assembly, the pressure containing parts of the cylinder shall be examined for uniform quality and freedom from unacceptable defects (see Annex C). 6.8.2 Welds 6.8.2.1 Before the cylinders are closed, the welds shall be visually examined from both sides. Permanent backing strips shall not be used with longitudinal welds. 6.8.2.2 All welds shall have a smooth finish without concavity and shall merge into the parent material without under-cutting or abrupt irregularity. 6.8.2.3 All welds shall have full penetration. 6.8.2.4 Radiographic examination, or radioscopic examination, or NDT examination carried out using another suitable method shall be as specified in Annex B.
EN 14638-1:2006 (E) 12 6.9 Dimensional tolerances 6.9.1 General The dimensional tolerances shall conform to the approved design drawing. In addition the following (6.9.2 to 6.9.4) shall apply for cylindrical shapes. 6.9.2 Out of roundness The out-of-roundness of the cylindrical shell shall be limited so that the difference between the maximum and the minimum outside diameter in the same cross-section is not more than 2 % of the mean of these diameters. 6.9.3 Straightness Unless otherwise agreed upon by the parties, the maximum deviation of the cylindrical part of the shell from a straight line shall not exceed 0,3 % of the cylindrical length. 6.9.4 Verticality When the cylinder is standing on its base, the cylindrical shell and top valve openings shall be vertical to within 1 % of the cylindrical length. 6.10 Stability If the cylinder is designed to be free standing when resting on its bottom, the centre of gravity of the cylinder shall stay approximately in the bottom centre, in order to obtain adequate stability. 6.11 Tightness Tests appropriate to the manufacturing process shall be carried out to ensure that there is no leakage from the cylinder in accordance with Clause 7. 7 New design tests 7.1 General requirements The requirements of this clause shall be used, as appropriate, in accordance with the methods of conformity assessment selected by the manufacturer. Each new cylinder design shall form the subject of a prototype test. A technical specification of the cylinder (or cylinder family), including design drawing, design calculation where appropriate, thicknesses and tolerances, specification for tests, material details, welding and manufacturing process and heat treatment, shall be made available by the manufacturer. 7.2 New designs A cylinder shall be considered to be of a new design compared with an existing approved design when: it is manufactured in a different factory, or it is manufactured by a different welding or manufacturing process or a radical change in an existing process, e.g. change in heat treatment, or
EN 14638-1:2006 (E) 13 it is manufactured from a steel of different specified composition range, or if there is a change in shape or curvature of the determined areas “i”, or the guaranteed minimum yield stress (Rpi1,0 and/or tensile strength (Rgi), and/or elongation (Ai) has been changed, or if the water capacity or gross weight have been increased, or if the guaranteed wall thickness have been decreased, or the hydraulic test pressure has been changed (where the cylinder is to be used for a lower pressure duty from that approved at the design approval stage, it shall not be deemed a new design). 7.3
Cylindrical walled cylinders For cylinders with cylindrical walls there is no need to repeat prototype testing for a family of cylinders, with the same diameter and shape, when the length of the cylindrical part of the cylinder has been reduced from the length of the prototype cylinder. 7.4 Valve protection If a change in the method of valve protection is made, only tests related to valves protection shall be repeated in accordance with EN 962. 7.5 Prototype tests 7.5.1 General For the purpose of these tests, a minimum of 50 cylinders, which are guaranteed by the manufacturer to be representative of new design, shall be made available for prototype testing. However, if the total production is less than 50 cylinders, enough cylinders shall be made to complete the prototype tests required, in addition to the production quantity. In this case the type approval validity is limited to the particular batch. 7.5.2 Verification and testing a) In the course of the type approval process, It shall be verified that:
the conditions specified in Clause 4 (materials) are fulfilled; the design conforms to the requirements of Clause 5; the thickness of the walls in all determined areas “i” of two cylinders meet the requirements of the agreed technical specification with respect to the guaranteed minimum thickness (abi). The measurements shall be taken on at least three locations for each determined area “i”. the requirements of Clause 6 (construction and workmanship) and Annex B (radiographic examination) are conformed to for all cylinders selected for the tests; the internal and external surfaces of the cylinders at warring stages of production are free of any defect which may make them unsafe (see Annex C); NOTE It may be necessary to section finished cylinders to undertake this inspection.
EN 14638-1:2006 (E) 14 b)
The following shall be performed on cylinders selected after the welds of the cylinders have been visually inspected: the tests specified in 7.5.3 - Fatigue testing. Two cylinders. The cylinders shall bear all representative markings. the tests specified in 7.5.4, when applicable. - Corrosion test. the tests specified in 7.5.5 - Drop test. Six cylinders. The cylinders shall bear all
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