Cryogenic vessels - Static vacuum insulated vessels - Part 2: Design, fabrication, inspection and testing

This standard is applicable to the design, fabrication, inspection and testing of static vacuum insulated cryogenic vessels designed for a maximum allowable pressure of more than 0,5 bar. This standard applies to static vacuum insulated cryogenic vessels for fluids as specified in WI 00268006 and is not applicable to vessels designed for toxic fluids. For static vacuum insulated cryogenic vessels designed for a maximum allowable pressure of not more than 0,5 bar this standard may be used as a guide.

Kryo-Behälter - Ortsfeste vakuum-isolierte Behälter - Teil 2: Bemessung, Herstellung und Prüfung

Diese Europäische Norm gilt für die Bemessung, Herstellung und Prüfung von ortsfesten, vakuum-isolierten Kryo-Behältern, die für einen höchstzulässigen Betriebsdruck von über 0,5 bar bemessen sind.
Diese Norm gilt für ortsfeste, vakuum-isolierte Kryo-Behälter für Fluide, die in prEN 13458-1 festgelegt sind, und sie gilt nicht für giftige Fluide.
Für ortsfeste vakuum-isolierte Kryo-Behälter mit einem höchstzulässigen Betriebsdruck von weniger als 0,5 bar kann diese Norm als eine Richtlinie angewendet werden.

Récipients cryogéniques - Récipients fixes isolés sous vide - Partie 2: Conception, fabrication, inspection et essais

La présente Norme européenne spécifie des exigences de conception, fabrication, contrôle et essais des récipients cryogéniques fixes, isolés sous vide, conçus pour une pression maximale admissible supérieure a 0,5 bar.
La présente Norme européenne s'applique aux récipients cryogéniques fixes, isolés sous vide, pour les fluides, tels que spécifiés dans l'EN 13458-1 et ne s'applique pas aux récipients conçus pour contenir des fluides toxiques.
Pour les récipients cryogéniques fixes, isolés sous vide, conçus pour une pression maximale admissible inférieure ou égale a 0,5 bar, la présente Norme européenne peut servir de guide.

Kriogene posode - Stabilne, vakuumsko izolirane posode - 2. del: Načrtovanje, izdelava, nadzor in preskus

General Information

Status
Published
Publication Date
30-Nov-2003
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Dec-2003
Due Date
01-Dec-2003
Completion Date
01-Dec-2003

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Cryogenic vessels - Static vacuum insulated vessels - Part 2: Design, fabrication, inspection and testing1DþUWRYDQMHRécipients cryogéniques - Récipients fixes isolés sous vide - Partie 2: Conception, fabrication, inspection et essaisKryo-Behälter - Ortsfeste vakuum-isolierte Behälter - Teil 2: Bemessung, Herstellung und PrüfungTa slovenski standard je istoveten z:EN 13458-2:2002SIST EN 13458-2:2003en23.020.40ICS:SLOVENSKI

STANDARDSIST EN 13458-2:200301-december-2003

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 13458-2November 2002ICS 23.020.40English versionCryogenic vessels - Static vacuum insulated vessels - Part 2:Design, fabrication, inspection and testingRécipients cryogéniques - Récipients fixes isolés sous vide- Partie 2: Conception, fabrication, inspection et essaisKryo-Behälter - Ortsfeste vakuum-isolierte Behälter - Teil 2:Bemessung, Herstellung und PrüfungThis European Standard was approved by CEN on 12 August 2002.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 Management Centre 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 Management Centre has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36

B-1050 Brussels© 2002 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 13458-2:2002 E

EN 13458-2:2002 (E)2ContentspageForeword.......................................................................................................................................................................31Scope...............................................................................................................................................................42Normative references.......................................................................................................................................43Terms, definitions and symbols.......................................................................................................................64Design..............................................................................................................................................................85Fabrication.....................................................................................................................................................546Inspection and testing....................................................................................................................................61Annex A (normative)

Elastic stress analysis.............................................................................................................68Annex B (normative)

Additional requirements for 9 % Ni steel.................................................................................77Annex C (informative)

Pressure strengthening of vessels from austenitic stainless steels......................................79Annex D (normative)

Pressure limiting systems.......................................................................................................90Annex E (normative)

Further use of the material cold properties to resist pressure loads.......................................91Annex F (informative)

Specific weld details..............................................................................................................95Annex G (normative)

Additional requirements for flammable fluids.........................................................................99Annex H (informative)

Non-design requirements for flammable fluids...................................................................100Annex I (normative)

Outer jacket relief devices......................................................................................................101Annex J (informative)

Increased material property for austenitic stainless steel....................................................103Annex K (normative)

Base materials......................................................................................................................104Annex L (informative)

Other materials.....................................................................................................................105Annex ZA (informative)

Clauses of this European Standard addressing essential requirements or other provisionsof EU directives............................................................................................................................................106Bibliography..............................................................................................................................................................107

EN 13458-2:2002 (E)3ForewordThis document (EN 13458-2:2002) has been prepared by Technical Committee CEN/TC 268 "Cryogenic vessels",the secretariat of which is held by AFNOR.This European Standard shall be given the status of a national standard, either by publication of an identical text orby endorsement, at the latest by May 2003, and conflicting national standards shall be withdrawn at the latest byMay 2003.This document has been prepared under a mandate given to CEN by the European Commission and the EuropeanFree Trade Association, and supports essential requirements of EU Directive(s).For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document.In this European Standard the annexes A, B E, G, I and K are normative and the annexes C, D, F, H and J areinformative.EN 13458 consists of the following Parts under the general title, Cryogenic vessels – Static vacuum insulatedvessels¾ Part 1: Fundamental requirements¾ Part 2: Design, fabrication, inspection and testing¾ Part 3: Operational requirementsAccording to the CEN/CENELEC Internal Regulations, the national standards organizations of the followingcountries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland,France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,Sweden, Switzerland and the United Kingdom.

EN 13458-2:2002 (E)41 ScopeThis European Standard specifies requirements for the design, fabrication, inspection and testing of static vacuuminsulated cryogenic vessels designed for a maximum allowable pressure of more than 0,5 bar.This European Standard is applicable to static vacuum insulated cryogenic vessels for fluids as specified inEN 13458-1, and does not apply to vessels designed for toxic fluids.For static vacuum insulated cryogenic vessels designed for a maximum allowable pressure of not more than0,5 bar this standard can be used as a guide.2 Normative referencesThis European Standard incorporates by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the publications are listed hereafter. Fordated references, subsequent amendments to or revisions of any of these publications apply to this EuropeanStandard only when incorporated in it by amendment or revision. For undated references the latest edition of thepublication referred to applies (including amendments).EN 287-1, Approval testing of welders – Fusion welding – Part 1: Steels.EN 287-2, Approval testing of welders – Fusion welding – Part 2: Aluminium and aluminium alloys.EN 288-3:1992, Specification and approval of welding procedures for metallic materials – Part 3: Weldingprocedure tests for the arc welding of steels.EN 288-4:1992, Specification and approval of welding procedures for metallic materials – Part 4: Weldingprocedure tests for the arc welding of aluminium and its alloys.EN 288-8, Specification and approval of welding procedures for metallic materials – Part 8: Approval by a pre-production welding test.EN 473, Qualification and certification of NDT personnel – General principles.EN 875:1995, Destructive tests on welds in metallic materials – Impact tests – Test specimen location, notchorientation and examination.EN 895:1995, Destructive tests on welds in metallic materials – Transverse tensile test.EN 910:1996, Destructive tests on welds in metallic materials – Bend tests.EN 1252-1:1998, Cryogenic vessels – Materials – Part 1: Toughness requirements for temperatures below –80 °C.EN 1252-2, Cryogenic vessels – Materials – Part 2: Toughness requirements for temperatures between –80 °C and–20 °C.EN 1418, Welding personnel – Approval testing of welding operators for fusion welding and resistance weld settersfor fully mechanised and automatic welding of metallic materials.EN 1435, Non-destructive examination of welds – Radiographic examination of welded joints.EN 1626, Cryogenic vessels – Valves for cryogenic service.EN 1797, Cryogenic vessels – Gas/material compatibility.EN 10028-4, Flat products made of steels for pressure purposes – Part 4: Nickel alloy steels with specified lowtemperature properties.

EN 13458-2:2002 (E)5EN 10028-7:2000, Flat products made of steels for pressure purposes – Part 7: Stainless steels.prEN 10216-5, Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 5: Stainless steeltubes.prEN 10217-7, Welded steel tubes for pressure purposes - Technical delivery conditions - Part 7: Stainless steeltubes.EN 12300, Cryogenic vessels – Cleanliness for cryogenic service.EN 13068-3, Non-destructive testing – Radioscopic testing – Part 3: General principles of radioscopic testing ofmetallic materials by X- and gamma rays.EN 13133, Brazing – Brazer approval.EN 13134, Brazing – Procedure approval.EN 13445-3, Unfired pressure vessels – Part 3: Design.EN 13445-4, Unfired pressure vessels – Part 4: Fabrication.EN 13458-1:2002, Cryogenic vessels – Static vacuum insulated vessels - Part 1: Fundamental requirements.prEN 13458-3, Cryogenic vessels – Static vacuum insulated vessels – Part 3: Operational requirements.prEN 13648-1, Cryogenic vessels – Safety devices for protection against excessive pressure – Part 1:Fundamental requirementsprEN 13648-3, Cryogenic vessels – Safety devices for protection against excessive pressure – Part 3:Determination of required discharge – Capacity and sizing.prEN ISO 4126-2, Safety devices for protection against excessive pressure – Part 2: Bursting disc safety devices(ISO/DIS 4126-2:1996).EN ISO 6520-1:1998, Welding and allied processes – Classification of geometrical imperfections in metallicmaterials – Part 1: Fusion welding (ISO 6520-1:1998).ISO 1106-1, Recommended practice for radiographic examination of fusion welded joints - Part 1: Fusion weldedbutt joints in steel plates up to 50 mm thick.SA-353/A353M, Specification for pressure vessel plates, alloy steel, 9 percent nickel, double-normalized andtempered.SA-479/SA-479M, Specification for stainless steel bars and shapes for use in boilers and other pressure vessels.SA-522/SA-522M, Specification for forged or rolled 8 and 9% nickel alloy steel flanges, fittings, valves and parts forlow-temperature service.SA-553/SA-553M, Specification for pressure vessel plates, alloy steel quenched and tempered 8 and 9 percentnickel.

EN 13458-2:2002 (E)63 Terms, definitions and symbols3.1 Terms and definitionsFor the purposes of this European Standard, the following terms and definitions apply.3.1.1static vesselstationary unit capable of receiving, storing (under pressure) and dispensing cryogenic fluids. The vessel is notintended to be used for transporting liquid product3.1.2inner vesselpressure vessel proper intended to contain the cryogenic fluid3.1.3outer jacketgas-tight enclosure which contains the inner vessel and enables a vacuum to be established3.1.4automatic weldingwelding in which the parameters are automatically controlled. Some of these parameters may be adjusted to alimited extent, either manually or automatically, during welding to maintain the specified welding conditions3.1.5maximum allowable pressure, psmaximum pressure for which the equipment is designed, as specified by the manufacturer, defined at a locationspecified by the manufacturer, being the location of connection of protective or limiting devices or the top of theequipmentNOTEps is equivalent to PS used in article 1, 2.3 of the PED.3.1.6relief plate/plugplate or plug retained by atmospheric pressure only which allows relief of excess internal pressure3.1.7bursting disc devicenon-reclosing pressure relief device ruptured by differential pressure. It is the complete assembly of installedcomponents including where appropriate the bursting disc holder3.2 SymbolsNOTEThroughout this European Standard ps is equivalent to PS used in article 1, 2.3 of the PED and pT is equivalent toPT used in Annex I of the PED.For the purposes of this standard, the following symbols apply:callowancesmmdidiameter of openingmmdaoutside diameter of tube or nozzlemmfnarrow side of rectangular or elliptical platemmblbuckling lengthmm

EN 13458-2:2002 (E)7nnumber-pdesign pressure as defined by 4.2.3.2 j) and 4.3.3.2barpeallowable external pressure limited by elastic bucklingbarpkstrengthening pressurebarppallowable external pressure limited by plastic deformationbarpTpressure test (see 4.2.3.2 g))barrradius e.g. inside knuckle radius of dished end and conesmmsminimum wall thicknessmmseactual wall thicknessmmvfactor indicative of the utilisation of the permissible designstress in joints or factor allowing for weakenings-x(decay-length zone) distance over which governing stress is assumed to actmmAareamm2A5elongation at fractureCdesign factors-Dshell diametermmDaoutside diameter e.g. of a cylindrical shellmmDiinternal diameter e.g. of a cylindrical shellmmEYoung's modulusN/mm2Imoment of inertia of stiffening ringmm4Kmaterial property (see 4.3.2.3.1)N/mm2K20see 4.3.2.3.2Ktsee 4.3.2.3.3Kdesigna value defined by the manufacturer for a particular design caseRradius of curvature e.g. inside crown radius of dished endmmSsafety factor at design pressure-kSsafety factor against elastic buckling at design pressure-pSsafety factor against plastic deformation at design pressure-TSsafety factor against plastic deformation at proof test pressure-

EN 13458-2:2002 (E)8Zauxiliary value-vPoisson's ratio-uout of roundnessskdesign stress value N/mm24 Design4.1 Design options4.1.1 GeneralThe design shall be carried out in accordance with one of the options given in 4.1.2, 4.1.3 or 4.1.4.In the case of 9 % Ni steel, the additional requirements of annex B shall be satisfied.For carbon and low alloy steels the requirements of EN 1252-2 shall be satisfied.When further use of cold properties is considered the requirements of annex E shall be satisfied.4.1.2 Design by calculationCalculation of all pressure and load bearing components shall be carried out. The pressure part thicknesses of theinner vessel and outer jacket shall not be less than required by 4.3. Additional calculations may be required toensure the design is satisfactory for the operating conditions including an allowance for external loads (e.g.seismic).4.1.3 Design by calculation when adopting pressure strengtheningThe pressure retaining capability of inner vessels manufactured from austenitic stainless steel, strengthened bypressure, is calculated in accordance with the informative annex C.4.1.4 Design by calculation supplemented with experimental methodsWhere it is not possible to design by calculation alone planned and controlled experimental means may be usedproviding that the results confirm the standards of design required in 4.3. An example would be the application ofstrain gauges to assess stress levels.4.2 Common design requirements4.2.1 GeneralThe requirements of 4.2.2 to 4.2.8 are applicable to all vessels irrespective of the design option used.In the event of an increase in at least one of the following parameters:¾ maximum allowable pressure;¾ specific mass (density) of the densest gas for which the vessel is designed;¾ maximum tare weight of the inner vessel;¾ nominal length and/or diameter of the inner shell;

EN 13458-2:2002 (E)9or, in the event of any change relative:¾ to the type of material or grade (e.g. stainless steel to aluminium or change of stainless steel grade);¾ to the fundamental shape;¾ to the decrease in the minimum properties of material being used;¾ to the modification of the design of an assembly method concerning any part under stress, particularly as faras the support systems between the inner vessel and the outer jacket or the inner vessel itself or the protectiveframe, if any, are concerned;the initial design programme shall be repeated to take account of these modifications.4.2.2 Design specification and documentationTo enable the design to be prepared the following information shall be available:¾ maximum allowable pressure;¾ fluids intended to be used;¾ liquid capacity;¾ volume of the inner vessel;¾ configuration;¾ method of handling and securing during transit and site erection;¾ site conditions e.g. ambient temperatures, seismic etc.;¾ fill and withdrawal rates.A design document in the form of drawings with text if any shall be prepared, it shall contain the information givenabove plus the following where applicable:¾ definition of which components are designed by calculation, by pressure strengthening, by experiment and bysatisfactory in-service experience;¾ drawings with dimensions and thicknesses of load bearing components;¾ specification of all load bearing materials including grade, class, temper, testing etc. as relevant;¾ type of material test certificates;¾ location and details of welds and other joints, welding and other joining procedures, filler, joining materials etc.as relevant;¾ calculations to verify compliance with this standard;¾ design test programme;¾ non destructive testing requirements;¾ pressure test requirements;¾ piping configuration including type, size and location of all valves and relief devices;

EN 13458-2:2002 (E)10¾ details of lifting points and lifting procedure;¾ wind, seismic loads.4.2.3 Design loads4.2.3.1 GeneralStatic vessels are not considered to be in cyclic service, therefore fatigue analysis needs normally not to beperformed.The static cryogenic vessel shall be able to safely withstand the mechanical and thermal loads encountered duringnormal operation and pressure test, as specified in 4.2.3.2 to 4.2.3.7.4.2.3.2 Inner vesselThe following loads shall be considered to act in the combinations specified in 4.2.3.2 j):a) pressure during operation when the vessel contains cryogenic liquid productbarpppcLsL1++=wherepsmaximum allowable pressure (in bar);pLpressure (in bar) exerted by the weight of the liquid contents when the vessel is filled to capacity witheither:1) boiling liquid at atmospheric pressure; or2) cryogenic fluid at its equilibrium triple point or melting point temperature at atmospheric pressure.pLmay be neglected if less than 5 % of (ps + 1). Otherwise the pressure in excess of 5 % of (ps + 1) shallbe used;b) pressure during operation when the vessel contains only gaseous product at 20 °Cbarppc1sG+=c) reactions at the support points of the inner vessel during operation when the vessel contains cryogenic liquidproduct. The reactions shall be determined by the weight of the inner vessel, the weight of the maximumcontents of the cryogenic liquid and vapour and seismic loadings where appropriate. The seismic loadingsshall consider any forces exerted on the vessel by the insulation;d) reactions at the support points of the inner vessel during operation when the vessel contains only gaseousproduct at 20 °C. The reactions shall be determined by the weight of the inner vessel, its contents and seismicloadings where appropriate. The seismic loadings shall consider any forces exerted on the vessel by theinsulation;e) load imposed by the piping due to the differential thermal movement of the inner vessel, the piping and theouter jacket.The following cases shall be considered:¾ cool down(inner vessel warm - piping cold);¾ filling and withdrawal(inner vessel cold - piping cold); and

EN 13458-2:2002 (E)11¾ storage(inner vessel cold - piping warm);f) load imposed on the inner vessel at its support points when cooling from ambient to operating temperature.g) pressure test : the value used for design purposes shall be the higher of:()1431s+=ppT, or see 6.5.1 or()barKKpp,pdesignLsT201 251++=considered for each element of the vessel e.g. shell, courses, head, etc.The 1 bar is added to allow for the external vacuum;h) loads imposed during transit and site erection;i) load imposed by pressure in annular space equal to the set pressure of the outer jacket relief device andatmospheric pressure in inner vessel;j) the vessel shall be capable of withstanding the following combinations of loadings. The design pressure p isequal to pressure specified therein, in each combination 1, 2 and 3:1) operation at maximum allowable working pressure when vessel is filled with cryogenic liquid:a) + c) + e) + f);2) operation at maximum allowable working pressure when vessel is filled with warm gas: b) + d);3) pressure test: g);4) shipping and lifting: h);5) vessel subject to external pressure developed in the vacuum jacket: i).The inner vessel shall, in addition, be capable of holding the pressure test fluid without gross plastic deformation.4.2.3.3 Outer jacketThe following loads shall be considered to act in combination where relevant:a) an external pressure of 1 bar;b) an internal pressure equal to the set pressure of the outer jacket pressure relief device;c) load imposed by the supporting systems in the outer jacket taking into consideration site conditions, e.g. windand seismic loadings etc.;d) load imposed by piping as defined in 4.2.3.2 e);e) load imposed at the inner vessel support points in the outer jacket when the inner vessel cools from ambient tooperating temperature and during operation;f) loads imposed during transit and site erection;g) external loads from e.g. wind, seismic or other site conditions;h) gross mass.

EN 13458-2:2002 (E)124.2.3.4 Inner vessel supportsThe inner vessel supports shall be suitable for the load defined in 4.2.3.2 c) plus loads due to differential thermalmovements.4.2.3.5 Outer jacket supportsThe outer jacket supports shall be suitable for the load defined in 4.2.3.3.4.2.3.6 Lifting pointsLifting points shall be suitable for lifting the static cryogenic vessel when empty and lifted in accordance with thespecified procedure.4.2.3.7 Piping and accessoriesPiping including valves, fittings and supports shall be designed for the following loads. With the exception a) theloads shall be considered to act in combination where relevant:a) pressure test : in accordance with 6.5.4;b) pressure during operation : not less than the set pressure of the system pressure relief devices, e.g. setpressure of the thermal relief device;c) thermal loads defined in 4.2.3.2 e);d) loads generated during pressure relief discharge;e) a design pressure not less than the maximum allowable pressure ps of the inner vessel plus any appropriateliquid head. For piping inside the vacuum jacket a further 1 bar shall be added.4.2.4 Corrosion allowanceCorrosion allowance is not required on surfaces in contact with the operating fluid. Corrosion allowance is notrequired on other surfaces if they are adequately protected against corrosion.4.2.5 Inspection openingsInspection openings are not required in the inner vessel or the outer jacket, providing the requirements ofprEN 13458-3 are followed.NOTE 1Due to the combination of materials of construction and operating fluids, internal corrosion cannot occur.NOTE 2The inner vessel is inside the evacuated outer jacket and hence external corrosion of the inner vessel cannot occur.NOTE 3The elimination of inspection openings also assists in maintaining the integrity of the vacuum in the interspace.4.2.6 Pressure relief4.2.6.1 GeneralRelief devices for the inner vessel shall be in accordance with prEN 13648-1.Relief devices for the outer jacket shall be in accordance with annex I.

EN 13458-2:2002 (E)134.2.6.2 Inner vesselThe inner vessel shall be provided with a pressure limiting system to protect the vessel against excessive pressure.Examples of current practice are shown in annex D. The system shall:¾ be designed so that it is fit for purpose;¾ be independent of other functions, unless its safety function is not affected by such other functions;¾ limit the vessel pressure to 110 % maximum allowable pressure in a momentary surge;¾ fail safely;¾ contain redundant features;¾ contain non-common mode failure mechanisms (diversity).The capacity of the protection system shall be established by considering all of the probable conditions contributingtowards internal excess pressure. For example:a) normal vessel heat leak;b) heat leak with loss of vacuum;c) failure in the open position of the make-up pressure control valve;d) any other valve in a line connecting a high pressure source to the inner vessel;e) recycling of any possible combination of pumps;f) flash gas, plus liquid, from maximum plant capacity fed into a tank which is at operating temperature.The excess pressure created by any combination of conditions 'a' to 'f' shall be limited to not more than 110 % ofmaximum allowable pressure by at least one re-closable device. The required capacity of this re-closable devicemay be calculated in accordance with prEN 13648-3.NOTEWhere, in addition, a non re-closable, fail open device is fitted, its operating pressure should be chosen such that itsability to retain pressure is unaffected by the operation of the re-closable device at 110 % of maximum allowable pressure andis, in any case, not more than the top of vessel strength test pressure less 1 bar. The required capacity of any device providedfor redundancy should be equal to the required capacity of the primary device.An external fire condition only to be considered if determined by location of the cryogenic vessel.Shut off valves or equivalent may be installed upstream of pressure relief devices, provided that interlocks are fittedto ensure that the vessel has sufficient relief capacity at all times.The relief valve system piping shall be sized such that the pressure drops during discharge are fully taken intoaccount so that the vessel pressure is not excessive and also that the valve does not reseat instantly, i.e. chatter.The maximum pressure drop of the pipework to the pressure relief valve should not exceed that specified inprEN 13648-3.4.2.6.3 Outer jacketA pressure relief device shall be fitted to the outer jacket. The device shall be set to open at a pressure whichprevents collapse of the inner vessel and is not more than 0,5 bar. The discharge area of the pressure relief deviceshall be not less than 0,34 mm2/l capacity of the inner vessel and in any case need not exceed 5 000 mm2.

EN 13458-2:2002 (E)144.2.6.4 PipingAny section of pipework containing cryogenic fluid which can be isolated shall be protected by a relief valve or othersuitable relief device.4.2.7 Valves4.2.7.1 GeneralValves shall conform to EN 1626.4.2.7.2 Isolating valvesTo prevent any large spillage of liquid, a secondary means of isolation shall be provided for those lines emanatingfrom below the liquid level that are:¾ greater than 9 mm bore and exhausting to atmosphere; or¾ greater than 50 mm bore when forming part of a closed system.The secondary means of isolation may be within the user installation and shall provide an equivalent level ofprotection.The secondary means of isolation, where provided, may be achieved, for example, by the installation of a secondvalve, positioned so that it can be operated safely in emergency, an automatic fail-closed valve or a non-returnvalve or fixed or removable cap on the open end of the pipe.4.2.8 Filling ratioMeans shall be provided to ensure that the vessel is not filled to more than 98 % of its total volume with liquid at thefilling condition.4.3 Design by calculation4.3.1 GeneralWhen design is by calculation in accordance with 4.1.2, the dimensions of the inner vessel and outer jacket shallnot be less than that determined in accordance with this subclause.4.3.2 Inner vessel4.3.2.1 GeneralThe information in 4.3.2.2 to 4.3.2.6 shall be used to determine the pressure part thicknesses in conjunction withthe calculation formulae of 4.3.6.4.3.2.2 Design loads and allowable stressesa) In accordance with 4.2.3.2 j) 1)Material properties determined either in accordance with 4.3.2.3.2 or 4.3.2.3.3 shall be adopted at the discretion ofthe vessel manufacturer.b) In accordance with 4.2.3.2 j) 2), 3), 4) and 5)Material properties determined in accordance with 4.3.2.3.2 shall be adopted.

EN 13458-2:2002 (E)154.3.2.3 Material property K4.3.2.3.1 GeneralThe material property K to be used in the calculations shall be as follows:¾ for austenitic stainless steel and unalloyed aluminium, 1 % proof strength;¾ for all other metals the yield strength, and if not available 0,2 % proof strength.NOTEUpper yield strength can be used.4.3.2.3.2

K20K shall be the minimum value at 20 °C taken from the material standard, (see annex J).

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