Bsi bs en 50068 1991 (1999)

BRITISH STANDARD BS EN 50068:1991 Incorporating Amendment No Specification for Wrought steel enclosures for gas-filled high-voltage switchgear and controlgear This European Standard EN 50068:1991 has the status of a British Standard BS EN 50068:1991 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the National Committees of the following countries: Austria Luxemburg Belgium Netherlands Denmark Norway Finland Portugal France Spain Germany Sweden Greece Switzerland Iceland United Kingdom Ireland Italy This British Standard, having been prepared under the direction of the Power Electrical Engineering Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 30 September 1991 Amendments issued since publication © BSI 12-1999 Amd No Date Comments The following BSI references relate to the work on this standard: Committee reference PEL/92 Draft announced in BSI News December 1988 8054 January 1994 Indicated by a sideline in the margin ISBN 580 19622 BS EN 50068:1991 Contents Cooperating organizations National foreword Foreword Text of EN 50068 National appendix NA (informative) National appendix NB (informative) © BSI 12-1999 Page Inside front cover ii Inside back cover Inside back cover i BS EN 50068:1991 National foreword This British Standard has been prepared under the direction of the Power Electrical Engineering Standards Policy Committee and is the English language version of EN 50068:1991 and its Amendment A1:1993 “Wrought steel enclosures for gas-filled high-voltage switchgear and controlgear” published by the European Committee for Electrotechnical Standardization (CENELEC) National appendix NA gives the constitution of the committees responsible for UK participation in the preparation of this standard National appendix NB gives details of International Standards quoted in this standard for which there is an identical or technically equivalent British Standard A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 70, an inside back cover and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front cover ii © BSI 12-1999 EUROPEAN STANDARD EN 50068 NORME EUROPÉENNE February 1991 + A1 August 1993 EUROPÄISCHE NORM UDC 621.316.54-213.34-034.14 Descriptors: Enclosure, high-voltage switching device, H.V metal enclosed switchgear and controlgear, pressurized closure, wrought steel English version Wrought steel enclosures for gas-filled high-voltage switchgear and controlgear (includes amendment A1:1993) Enveloppes en acier soudé pour l’appareillage haute tension sous pression de gaz (inclut l’amendment A1:1993) Kapselungen aus Schmiedestahl für gasgefüllte Hochspannungs- Schaltgeräte und -Schaltanlagen (enthält Änderungen A1:1993) This European Standard was approved by CENELEC on March 1990 CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels © 1991 Copyright reserved to CENELEC members Ref No EN 50068:1991 + A1:1993 E EN 50068:1991 Foreword At the request of CENELEC Technical Committee TC 17C, the text of the draft EN 50068 prepared by TC 17C was submitted to the Unique Acceptance Procedure (UAP) The text of the draft was approved by CENELEC as EN 50068 on March 1990 The following dates were fixed: — latest date of publication of an identical national standard (dop) 1991-06-01 — latest date of withdrawal of conflicting national standards (dow) 1991-06-01 For products which have complied with the relevant national standard before 1991-06-01, as shown by the manufacturer or by a certification body, this previous standard may continue to apply for production until 1996-06-01 This document forms a supplement to EN 50052 (1986): “Cast aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear” and EN 50064 (1989): “Wrought aluminium and aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear”, concerning welded enclosures for the same type of switchgear and controlgear but composed of parts made of wrought steel It is based on the general specifications given in HD 358 S2 (IEC 517 (1986) ed 2) which are however not sufficient to satisfy the conditions for the service allowance of pressurized high-voltage switchgear and controlgear.) These specifications are appropriate for pressurized switchgear enclosures allowing an economic production without sacrificing aspects of safety For unusual shapes dictated by electrical conditions they permit the verification of sound design by proof tests instead of calculations Nevertheless this European Standard makes use of many internationally well acknowledged calculation rules and the Technical Committee will in addition pursue the progress in standardization in CEN/TC 121 and ISO/TC 44 on welding and allied processes For the time being reference can only be made to published International Standards as far as they are appropriate for the purpose of production of enclosures to be used in gas-filled switchgear and controlgear The present EN has been established as an international specification for the design, construction, testing, inspection and certification of pressurized enclosures used in high-voltage switchgear and controlgear This standard follows to that extent also Article of the Directive 76/767/EEC The European Standard contains two normative and one informative technical annexes: Annex A: Welding procedure and welder performance tests Annex B: Sample of record form Annex C: National deviations List of standards referred to in this standard: HD 358 S2 Gas-insulated (IEC 517 (1986) ed 2) metal-enclosed switchgear for rated voltages of 72,5 kV and above ISO 6213:1983 Welding: Items to be considered to ensure quality in welding structures ISO 9000:1987 Guidelines for selection and use of the standards on quality management, quality system elements and quality assurance ISO/IEC General terms and their Guide 2:1986 definitions concerning standardization and related activities ISO 6520:1982 Classification of imperfections in metallic fusion welds, with explanations ISO/R 373:1964 General principles for fatigue testing of metals Foreword to Amendment A1 This amendment was prepared by CENELEC Technical Committee TC17C, High-voltage enclosed switchgear and controlgear The text of the draft was submitted to the voting procedure in March 1993 and was approved by CENELEC as amendment A1 to EN 50068:1991 on July 6, 1993 The following dates were accepted: — latest date of publication of an identical national standard — latest date of withdrawal of conflicting national standards (dop) 1994-10-01 (dow) 1994-10-01 © BSI 12-1999 EN 50068:1991 Text of amendment 2.1 Type of equipment (page 5) The first paragraph has to be changed as follows (new text in bold letters); of high-voltage switchgear and controlgear, where the gas is used principally for its dielectric and/or arc-quenching properties, with rated voltages — kV and up to and including 52 kV and with gas-filled compartments with design pressure greater than bar (gauge); — and with rated voltage 72,5 kV and above Annex C (page 67) — only English version Clause 7.5.3.2, Italy: The formula for “B” has to be corrected as follows: K B = -4,8 © BSI 12-1999 Contents Foreword Introduction Scope and field of application Definitions Materials Design Manufacture and workmanship Inspection and testing Pressure relief devices Certification and marking Annex A Welding procedure and welder performance tests Annex B Sample of record form Annex C (informative) National deviations Figure to Figure — Typical connections between cylindrical and conical shells Figure — Design factor ¶ and numerical factor 1/cos Ỵ Figure — Dished end Figure — Dished end with branch Figure — Dished end with knuckle and crown of unequal wall thickness Figure — Welded joint outside 0,6Da: v = 0,75 resp 1,0 Figure 10 — Welded joint inside 0,6Da: v = 1,0 Figure 11 — Welded dished end from crown and knuckle components inside 0,6Da: v = 1,0 Figure 12 — Welded dished end from crown and knuckle components outside 0,6Da: v = 0,75 resp 1,0 Figure 13 — Design factor ¶ for dished ends of the Klöpper type Figure 14 — Design factor ¶ for dished ends of the Korbbogen type Figure 15 — Determination of the buckling pressure Figure 16 — Increased thickness of a cylindrical shell Figure 17 — Increased thickness of a conical shell Figure 18 — Local increase by reinforcement rings Figure 19 — Pad reinforcement Figure 20 — Branch reinforcement Page 5 7 40 46 53 53 55 65 67 11 13 15 15 15 16 16 17 17 19 19 20 21 21 21 21 22 EN 50068:1991 Figure 21 — Necked out opening Figure 22 — Calculation scheme for cylindrical shells Figure 23 — Calculation scheme for spherical shells Figure 24 — Calculation scheme for adjacent branches in longitudinal direction of a cylinder Figure 25 — Calculation scheme for adjacent branches in a sphere or in circumferential direction of a cylinder Figure 26 — Branch and pad reinforcement Figure 27 — Weakening factor vA for openings and branches perpendicular to cylindrical and conical shells Figure 28 — Weakening factor vA for openings and branches perpendicular to spherical shells Figure 29 — Circular flange joint Figure 30 — Examples of different flange types Figure 31 — Forces and moment arms for flanges with O-ring seal Figure 32 — Hubless flange sections for stress calculation Figure 33 — Flange with untapered hub section for stress calculation Figure 34 — The factor “A” as a function of K1 and K2 Figure 35 — Graph showing in (Dy/Di) as a function of m = Dy/Di Figure 36 — Forces and moment arms for flanges with O-ring seal Figure 37 — Flange with large fillet radius sections for stress calculation Figure 38 — Flange with tapered hub sections for stress calculation Figure 39 — Flange with flat circular cover and O-ring seal Figure 40 — Butt welds in plates of unequal thickness with approximately coincident middle lines Figure 41 — Butt welds in plates of unequal thickness with offset of middle lines Figure A.1 — Test piece for butt weld in plate Figure A.2 — Test piece for butt weld in pipe Page 22 23 24 24 25 26 27 28 29 31 32 32 Page Figure A.3 — Test piece for fillet weld in plate Figure A.4 — Test piece for branch connection in pipe Figure A.5 — Dimensions of tensile test specimen from pipe of outside diameter greater than 35 mm Table — Examples of materials (not exhaustive; other steels may be used from national standards) Table — Design factor ả for conical shells and numerical factors cos ẻ and 1/cos Ỵ Table — The factor “A” as a function of K1 and K2 Table — Values of “ln m” as function of “m” Table — Circumferential tolerances Table — Circularity tolerances for shells Table — Acceptance levels for imperfections Table A.1 Table A.2 — Number of test specimens required 61 63 64 13 35 36 43 43 50 57 60 33 35 36 37 38 39 40 47 48 59 59 © BSI 12-1999 EN 50068:1991 Introduction This standard covers the requirements for the design, construction, testing, inspection and certification of gas-filled enclosures for use specifically in high-voltage switchgear and controlgear or for associated gas-filled equipment Special consideration is given to these enclosures for the following reasons a) The enclosures usually form the containment of electrical equipment, thus their shape is determined by electrical rather than mechanical considerations b) The enclosures are installed in restricted access areas and the equipment is operated by experts and instructed persons only c) As the thorough drying of the inert, non-corrosive gas-filling medium is fundamental to the satisfactory operation of the electrical equipment it is periodically checked For this reason, no internal corrosion allowance is required on the wall thickness of these enclosures d) The enclosures are subjected to only small fluctuations of pressure as the gas-filling density shall be maintained within close limits to ensure satisfactory insulating and arc-quenching properties Therefore, the enclosures are not liable to fatigue due to pressure cycling e) The operating pressure is relatively low For the foregoing reasons, and to ensure the minimum disturbance hence reducing the risk of moisture and dust entering the enclosures which would prevent correct electrical operation of the switchgear, no pressure tests shall be carried out after installation and before placing in service and no periodic inspection of the enclosure interiors or pressure tests shall be carried out after the equipment is placed in service Scope and field of application 2.1 Type of equipment This standard applies to fusion welded wrought steel enclosures pressurized with dry air, inert gases, for example sulphur hexafluoride or nitrogen or a mixture of such gases, used in indoor or outdoor installations of high-voltage switchgear and controlgear with rated voltages 72,5 kV and above, where the gas is used principally for its dielectric and/or arc-quenching properties The enclosures comprise parts of electrical equipment not necessarily limited to the following examples: Circuit-breakers Switch-disconnectors Disconnectors Earthing switches Current transformers Voltage transformers Surge arrestors Busbars and connections The scope also covers pressurized components such as the centre chamber of live tank switchgear, gas-insulated current transformers, etc 2.2 Production The production of the enclosures shall be in accordance with documented welding procedures which shall be carried out by well trained and supervised welding personnel Where International Standards (ISO or CEN) are not available national standards may be used NOTE The standard will be revised as soon as possible when ISO or CEN standards covering the various aspects are available 2.3 Quality assurance It is the intention of this standard that the switchgear manufacturer shall be responsible for achieving and maintaining a consistent and adequate quality of product Sufficient examinations shall be made by the enclosure manufacturer to ensure that the materials, production and testing comply in all respects with the requirements of this standard and ISO 6213:1983 Inspection by user’s inspectors shall not absolve the switchgear manufacturer from this responsibility to exercise such quality assurance procedures as to ensure that the requirements and intent of this standard are satisfied NOTE Reference should be made to the ISO 9000 series of standards for quality systems © BSI 12-1999 EN 50068:1991 Definitions 3.1 national standard a technical specification established by general agreement with the important part of the concerned interests, approved by a recognized national standards organization and made available to the public (ISO/IEC Guide 2:1986) 3.2 enclosure a part of gas-insulated metal-enclosed switchgear retaining the insulated gas under the prescribed conditions necessary to maintain safely the rated insulation level, protecting the equipment against external influences and providing a high degree of protection to personnel HD 358 S2 = IEC 517 (1986) ed 3.3 manufacturer individual or body responsible for designing and producing the enclosure In this standard this is the switchgear manufacturer 3.4 designer individual or body who determines the shape, dimensions and thickness of the enclosure and selects the materials and method of construction and testing 3.5 design pressure (of an enclosure) pressure used to determine the thickness of the enclosure It is at least the upper limit of pressure reached within the enclosure at the design temperature HD 358 S2 = IEC 517 (1986) ed 3.6 design temperature (of an enclosure) highest temperature reached by the enclosure which can occur under service conditions This is generally the upper limit of ambient air temperature increased by the temperature rise due to the flow of rated normal current HD 358 S2 = IEC 517 (1986) ed NOTE Solar radiation should be taken into account when it has a significant effect on the temperature of the gas and on the mechanical properties of some materials Similarly, the effects of low temperatures on the properties of some materials should be considered 3.7 Weld imperfections 3.7.1 lack of fusion lack of union between weld metal and parent metal or weld metal and weld metal ISO 6520:1982, No 400 3.7.2 overlap excess of weld metal at the toe of a weld covering the parent metal surface but not fused to it ISO 6520:1982, No 506 3.7.3 undercut a groove at the toe(s) (or at the root) of a weld run due to welding ISO 6520:1982, No 5012 3.8 heat treatment process in which the metal or the alloy in the solid state is subjected to one or more temperature cycles, to confer certain desired properties © BSI 12-1999 EN 50068:1991 If the test piece fails to comply with any of the requirements for visual inspection or non-destructive testing specified in A.7.2.2, one further test piece shall be welded and subjected to the same test If this additional test piece does not comply with the relevant requirements, the procedure shall be regarded as not capable of complying with the requirements of this standard without modification If any test specimen fails to comply with the relevant requirements of A.7.3.3, two further test specimens shall be prepared for each one that failed, and subjected to the same test These new test specimens are obtained either from the same test piece, if there is sufficient material available, or from a new test piece If either of these additional test specimens or the new test piece not comply with the relevant requirements, the weld procedure shall be regarded as not capable of complying with the requirements of this standard without modification When any further test piece or test specimen fails to comply with the requirements of this standard for non-destructive testing, the cause of failure shall be established Dependent upon the results of the investigation, either the procedure shall be modified necessitating a new welding procedure test (see clause A.4) or a new procedure shall be developed A.7.2 Non-destructive testing A.7.2.1 Examination Prior to the cutting of test specimens, all test pieces shall be examined visually, followed by: a) magnetic particle testing or penetrant testing, and b) ultrasonic examination, or c) radiographic examination A.7.2.2 Minimum level of acceptance Imperfections that are detected by visual inspection and the other relevant methods of non-destructive testing shall be assessed in accordance with the details specified in Table The existence of any imperfections greater than the maximum permitted by Table shall be sufficient cause for rejection Minor local imperfections except cracks, which can be established as being due solely to the welder’s workmanship need not be cause for rejection A.7.3 Destructive tests A.7.3.1 Test specimens The number of specimens to be tested shall be as given in Table A.2 It is permissible to take the test specimens from locations that avoid areas showing imperfections, although such imperfections are acceptable according to the requirement of A.7.2.2 When the size and thickness of a pipe butt joint are such that the specified test specimens cannot be obtained from one test piece, see clause A.6, and when the size and thickness of a pipe butt joint are such that it is impossible to take the specified test specimens (e.g transverse tensile), then some other methods of test shall be used, e.g a full-size tensile test or a hydraulic pressure test NOTE It may be useful and advantageous to carry out more comprehensive testing than is required by this clause (e.g Charpy V-notch impact test, chemical analysis, microexamination, delta ferrite determination in austenitic stainless steels) in order to gain more information and to avoid having to repeat the welding procedure test at a later date just to obtain additional test data The dimensions of the test piece would probably have to be increased, if additional tests were made 58 © BSI 12-1999 EN 50068:1991 Figure A.1 — Test piece for butt weld in plate (see clause A.6) Figure A.2 — Test piece for butt weld in pipe (see clause A.6) © BSI 12-1999 59 EN 50068:1991 Table A.2 — Number of test specimens required (see note 1) Test specimen Butt joint in plate of thickness Butt joint in pipe of thickness less than 10 mm less than 10 mm 10 mm over Fillet weld in plate Branch connection where branch is of outside diameter or dimension up to and including 88.9 mm 10 mm over over 88.9 mm Macro-examination 1 2 (note 5) (note 5) Hardness survey (note 2) 1 1 1 Transverse tensile 1 — — — Root bend (note 3) — (note 4) — — — — Face bend (note 3) — — — — — Side bend (note 3) — — — — — Fillet weld fracture (for test piece with only single side weld) — — — — — — NOTE When more than one specimen of a particular type is required, the specimens shall be taken as far apart as possible, with one specimen for macro-examination taken from that part of the joint considered to have been welded in the most difficult welding position or from a stop/start position NOTE The hardness survey shall be made on a macro-examination test specimen NOTE For a butt joint in plate when the weld metal and parent metal differ markedly in bending properties, either between dissimilar parent metals or between weld metal and parent metal, one longitudinal bend test specimen may be used instead of root and face or side bend tests, in which case the side to be placed in tension shall be agreed and recorded NOTE For a butt joint in plate made from one side only, one root bend test specimen is required NOTE For purely structural applications the number of specimens may be reduced to and respectively A.7.3.2 Preparation and testing A.7.3.2.1 Except as specified in A.7.3.2.2 the preparation, shape and dimensions of test specimens and the methods of testing them, except the hardness survey, shall be as specified in national standards The method of hardness testing shall be in accordance with national standards and the survey shall include at least two traverses of the weld section covering the parent metal and heat affected zones on each side of the weld, as well as the weld metal If backing material forms part of a butt joint, it shall be removed prior to tensile or bend testing For small diameter pipes, the transverse tensile test may be made on the welded pipe as a whole, in which case, if a backing ring is part of the joint, it shall not be removed prior to testing Each bend test specimen shall be bent through at least 90° round a former of diameter 4t, where t is the thickness of the specimen, or of diameter 1t greater than that required to test the parent metal of the same thickness, whichever is greater 60 © BSI 12-1999 EN 50068:1991 A.7.3.2.2 Each transverse tensile test specimen from a butt joint in pipe shall be of a shape similar to that given in Figure A.5 Each root and face bend test specimen from a butt joint in pipe shall be a strip of parallel width: D t + -10 for pipes up to and including 60.3 mm outside diameter, and D t + -20 with a maximum of 40 mm for pipes over 60.3 mm outside diameter, where: t is the pipe thickness and D is the outside diameter Figure A.3 — Test piece for fillet weld in plate (see clause A.6) © BSI 12-1999 61 EN 50068:1991 A.7.3.3 Test results A.7.3.3.1 Macro-examination and fillet weld fracture test The etched face for macro-examination and the fracture surface from the fillet weld fracture test shall be assessed in accordance with the requirements of A.7.2.2 A.7.3.3.2 Hardness survey The results from the hardness survey shall be recorded A.7.3.3.3 Transverse tensile test The minimum tensile strength shall be not less than the corresponding specified minimum value for the parent material The location of the fracture shall be recorded NOTE Consideration should be given to the effect of postweld heat treatment on parent material properties The minimum tensile strength of a weld joint between dissimilar materials shall be not less than that of the weaker parent metal in the as-welded condition A.7.3.3.4 All-weld tensile test The tensile strength and yield strength (or 0.2 % proof stress) shall be recorded Depending on which parameter the design criteria are based the tensile strength and/or the yield strength shall be not less than the corresponding specified minimum values for the parent metal Due account shall be taken of special cases where undermatching weld metal has to be employed The elongation shall be not less than 10 % or 0.8 times the minimum value for the parent metal, whichever is the greater A.7.3.3.5 Bend tests On completion of bending, no crack or other imperfection on the tension surface shall have a dimension greater than mm Slight tearing at the edges of the test specimen shall not be cause for rejection A.8 Statement of results A statement of the results of assessing each test piece, including repeat tests, shall be made for each welding procedure The items listed under clause A.3 shall be included together with details of any features that would be rejected by the requirements of A.7.2.2 and of the test results in accordance with A.7.3.3 If no rejectable features or test results are found, a statement that the test piece made according to the particular welding procedure satisfied the requirements of this standard in respect of that type of test piece shall be signed by the person conducting the test NOTE It is recommended, that the form given in Annex B be used to record details of the welding procedure and the test results, in order to facilitate uniform presentation and assessment of the data 62 © BSI 12-1999 EN 50068:1991 The same essential dimensions apply for rectangular hollow sections Figure A.4 — Test piece for branch connection in pipe (see clause A.6) © BSI 12-1999 63 EN 50068:1991 Figure A.5 — Dimensions of tensile test specimen from pipe of outside diameter greater than 35 mm 64 © BSI 12-1999 EN 50068:1991 Annex B Sample of record form (Organization’s symbol or logo) Record of approval test of welding procedure Test record no and welder performance test Procedure details Manufacturer’s name Location of test shop or site Manufacturer’s procedure no (and revision no.) Welding process(es) Parent material(s) Joint type Specification(s) Welding position(s) Material group(s) Test piece position Dimensions of test piece Weld preparation (dimensioned sketch) Run sequence and completed weld dimensions (sketch) Method of preparation and cleaning Welding conditions Run no Welding consumables Size(s) Current Filler material Voltage Make and type Polarity Composition Travel speed-Run out length (R.O.L.) Shielding gas/flux Wire feed speed Make and type Gas flow rate Composition Shield Baking treatment Purge Post-weld heat treatment Second side treatment Specification Method Temperature Method Control Control Preheat Soak temperature Interpass Soak time Other information See 3.2 and 3.3 Use supplementary sheets if necessary Originator Extent of approval Date Welder’s identity Name Mark Remarks (if any) Range of materials Range of thickness(es) Range of diameters © BSI 12-1999 65 EN 50068:1991 66 © BSI 12-1999 EN 50068:1991 Annex C (informative) National deviations ANational deviations due to regulations or requirements, the alteration of which is, at least deviations: for the time being, outside the competence of the National Committee of CENELEC The National Committee should, however, contact the authorities concerned with regard to the removal of these deviations Clause Member (regulation) Austria (Dampfkesselverordnung (Fire Vessel Code) BGB1 Nr 510/1986, Clause V and decree Nr 143, GZ 43010/2-IV/3/81) The regulations for pressure vessels include specifications for tests which — are the responsibility of the manufacturer only; — have to be carried out in connection with a type approval (type test); — have to be carried out by independent experts NOTE This principle is in accordance with the EC Directive 87/404/EEC and the Policy Statement of the EC Commission Doc 74/88 France (Ministerial Decree of July 23rd, 1943, Clause 17) An internal and external inspection of the enclosure is mandatory every years, and the renewal of the pressure test every years (in case of SF6 gas) Italy (Rule for the design, construction and service of pressure vessels, issued by I.S.P.E.S.L = Instituto Superiore per la Prevenzione e la Sicurezza del Lavore (former A.N.C.C.) A pressure test is required during the installation at 1,1 times the rated pressure Austria (Werkstoff - und Bauvorschriften (Material and Construction Rules) BGB1 Nr 524/73, Clause IV) The material characteristics are defined exactly (e.g elongation > 14 %) and the materials appropriate for the construction of pressure vessels are specified mandatorily Sweden (Applied practice in accordance with the Work Environmental Act SFS 1977:1169) Rimming steels are not permissible France (Ministerial Decree of July 23rd, 1943) The total elongation A (in %) and the minimum ultimate strength of the steel (in MPa) have to fulfil the following equations: R × A U 10 500 and A U 12 per bolting A U 14 per other cases 5.6 Italy (Rules of I.S.P.E.S.L (former A.N.C.C.), clauses VSR.5 and VSR.1 of the collection VSR) The permissible design stress (B) at the design pressure is: K K B = = -4 × 1,2 4,8 Sweden (Applied practice in accordance with the Work Environmental Act SFS 1977:1169) The safety factor (S) shall be 1,7 instead of 1,5 © BSI 12-1999 67 EN 50068:1991 Clause 5.7 Member (regulation) (Rules of I.S.P.E.S.L (former A.N.C.C.), collection VSR) Italy Only the calculation method as specified in Collection VSR is accepted Austria (Werkstoff- und Bauvorschriften (Material and Construction Rules) BGB1 Nr 67/1979, Clause III/1) The welding regulations include precise instructions on welding procedures and welding personnel (welder, welding supervisor) Austria (Werkstoff- und Bauvorschriften (Material and Construction Rules) BGB1 Nr 67/1979, Clause III/5) The range of weld seam test is greater, in particular for longitudinal seams France (Ministerial Decree of March 24th, 1978, clauses and 17) The weld joint factor may only have the values 0,7 – 0,85 or 1,0 The value 1.0 may only be used with steels satisfying the requirements of a limited number of AFNOR-standards namely given in Appendix II of the Ministerial Decree (Rules of I.S.P.E.S.L (former A.N.C.C.) Italy Inspections, testing and certification are only carried out under authoritative supervision 7.5.2 France (Ministerial Decree of July 23rd, 1943, Clause 15) The test pressure at the routine pressure test shall be equal to 1,5 times the design pressure 7.5.3.1 (Rules of I.S.P.E.S.L (former A.N.C.C.), clause VSR.6.A.2, collection VSR) Italy The design pressure p shall be calculated by the following equation: where v = weld joint factor (if any) pR = burst pressure S1 = minimum wall thickness of the enclosure S2 = wall thickness of the enclosure tested 7.5.3.2 Italy (Rules of I.S.P.E.S.L (former A.N.C.C.), clause VSR.7.A.3, collection VSR) The maximum stress fM at the design pressure shall be lower than the permissible design stress B fM k B where K B = 4488 68 © BSI 12-1999 EN 50068:1991 Clause Member (regulation) Austria (Dampfkesselverordnung (Fire Vessel Code) BGB1 Nr 510/1986, §30, paragraph 2) Pressure relief devices shall be provided mandatorily Italy (Rules of I.S.P.E.S.L (former A.N.C.C.), clauses E.1.D.2 and E.1.D.4, collection VSR) The bursting discs and pressure relief valves shall be designed to limit the overpressure to 1,1 times the design pressure The rated rupture pressure of the burst discs and the nominal opening pressure of the valves shall be equal or lower than the design pressure of the enclosure Table 8, Sweden Item 2024 (Applied practice in accordance with the Work Environmental Act SFS 1977:1169) Crater pipes are not permitted A.7.3.3.3 (Annex A) Sweden (Applied practice in accordance with the Work Environmental Act SFS 1977:1169) The yield and tensile strength shall not be less than the corresponding specified minimum value for the parent material © BSI 12-1999 69 70 blank BS EN 50068:1991 National appendix NA (informative) The United Kingdom participation in the preparation of this European Standard was entrusted by the Power Electrical Engineering Standards Policy Committee (PEL/-) to Technical Committee PEL/92, upon which the following bodies were represented: ASTA Certification Services Association of Manufacturers Allied to the Electrical and Electronic Industry (BEAMA Ltd.) British Railways Board Department of the Environment (Property Services Agency) ERA Technology Ltd Electricity Supply Industry in England and Wales GAMBICA (BEAMA Ltd.) Health and Safety Executive Transmission and Distribution Association (BEAMA Ltd.) The following bodies were also represented in the drafting of the standard, through subcommittees Association of Consulting Engineers British Cable Makers’ Confederation Engineering Equipment and Materials Users’ Association National appendix NB (informative) The British Standards corresponding to the International Publications referred to in EN 50068 are as follows: International Standard British Standard (content identical) EN 50052 BS 6878:1988 Specification for high-voltage switchgear and controlgear for industrial use Cast aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear EN 50064 BS 7315:1990 Specification for wrought aluminium and aluminium alloy enclosures for gas-filled high-voltage switchgear and controlgear HD 358S2 BS 5524:1987 Specification for gas-insulated metal-enclosed switchgear for rated voltages of 72.5 kV and above ISO 9000:1987 BS 5750 Quality Systems Part 0-0.1:1987 Guide to selection and use A related British Standard to ISO/IEC Guide is BS 7501:1989 “General criteria for the operation of testing laboratories ISO/R 373:1964 has been withdrawn and will be superseded by a new revision of ISO 1099 when it is published There are no corresponding British Standards to ISO 6213 and ISO 6520 © BSI 12-1999 BS EN 50068:1991 BSI — British Standards Institution BSI is the independent national body responsible for preparing British Standards It presents the UK view on standards in Europe and at the international level It is incorporated by Royal Charter Revisions British Standards are updated by amendment or revision Users of British Standards should make sure that they possess the latest amendments or editions It is the constant aim of BSI to improve the quality of our products and services We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover Tel: 020 8996 9000 Fax: 020 8996 7400 BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services Tel: 020 8996 9001 Fax: 020 8996 7001 In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical Help to Exporters Service Various BSI electronic information services are also available which give details on all its products and services Contact the Information Centre Tel: 020 8996 7111 Fax: 020 8996 7048 Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase price of standards For details of these and other benefits contact Membership Administration Tel: 020 8996 7002 Fax: 020 8996 7001 Copyright Copyright subsists in all BSI publications BSI also holds the copyright, in the UK, of the publications of the international standardization bodies Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained BSI 389 Chiswick High Road London W4 4AL If permission is granted, the terms may include royalty payments or a licensing agreement Details and advice can be obtained from the Copyright Manager Tel: 020 8996 7070