GeregistreerdeBelgische normNBN EN 14015Voorschrift voor hetontwerpen en de vervaardiging van ter plekke gebouwde, verticale,cilindrische, bovengrondse, gelaste stalen tanks met vlakke bodemvoor de opslag van vloeistoffen bij omgevingstemperatuur enhogerSpcification pour la conception et la fabrication de rservoirsen acier, souds, ariens, fond plat, cylindriques, verticaux,construit sur site destins au stockage des liquides la tempratureambiante ou suprieure1e uitg., december 2004Normklasse: B03Specification for the design and manufacture of site built,vertical, cylindrical, flat-bottomed, above ground, welded, steeltanks for the storage of liquids at ambient temperature andaboveBelgisch instituut voor normalisatie (BIN), vereniging zonderwinstoogmerkBrabanonnelaan 29 - 1000 BRUSSEL - telefoon: 02 738 0112 - fax: 02 733 42 64e-mail: [email protected] - BIN Online: www.bin.be- prk. 000-0063310-66Prijsgroep: 36Toelating tot publicatie: 15december 2004Deze Europese norm EN 14015: 2004 heeft de status vaneen Belgische norm.Deze Europese norm bestaat in drie officileversies (Duits, Engels, Frans). BIN 2004ICS: 23.020.10 ICS:23.020.10norme belgeenregistreNBN EN 14015Spcification pour laconception et la fabrication de rservoirs en acier, souds, ariens,fond plat, cylindriques, verticaux, construit sur site destins austockage des liquides la temprature ambiante ousuprieureVoorschrift voor het ontwerpen en de vervaardiging van terplekke gebouwde, verticale, cilindrische, bovengrondse, gelastestalen tanks met vlakke bodem voor de opslag van vloeistoffen bijomgevingstemperatuur en hoger1e d., dcembre 2004Indice declassement: B 03Specification for the design and manufacture ofsite built, vertical, cylindrical, flat-bottomed, above ground,welded, steel tanks for the storage of liquids at ambienttemperature and aboveAutorisation de publication: 15 dcembre 2004Laprsente norme europenne EN 14015: 2004 a le statut d'une normebelge.La prsente norme europenne existe en trois versionsofficielles (allemand, anglais, franais).Prix: groupe 36 IBN2004Institut belge de normalisation (IBN), association sans butlucratifavenue de la Brabanonne 29 - 1000 BRUXELLES - tlphone: 02738 01 12 - fax: 02 733 42 64e-mail: [email protected] - IBN Online:www.ibn.be - CCP. 000-0063310-66EUROPEAN STANDARDNORMEEUROPENNEEUROPISCHE NORMEN 14015November 2004ICS 23.020.10EnglishversionSpecification for the design and manufacture of sitebuilt,vertical, cylindrical, flat-bottomed, above ground, welded,steeltanks for the storage of liquids at ambient temperatureandaboveSpcification pour la conception et la fabricationderservoirs en acier, souds, ariens, fond plat,cylindriques,verticaux, construit sur site destins austockage des liquides latemprature ambiante ousuprieureAuslegung und Herstellungstandortgefertigter,oberirdischer, stehender, zylindrischer,geschweiterFlachboden-Stahltanks fr die Lagerung vonFlssigkeitenbei Umgebungstemperatur und hheren TemperaturenThisEuropean Standard was approved by CEN on 2 February 2004.CENmembers are bound to comply with the CEN/CENELEC InternalRegulations which stipulate the conditions for giving thisEuropeanStandard the status of a national standard without anyalteration. Up-to-date lists and bibliographical referencesconcerning such nationalstandards may be obtained on application tothe Central Secretariat or to any CEN member.This European Standardexists in three official versions (English, French, German). Aversion in any other language made by translationunder theresponsibility of a CEN member into its own language and notifiedto the Central Secretariat has the same status as theofficialversions.CEN members are the national standards bodies ofAustria, Belgium, Cyprus, Czech Republic, Denmark, Estonia,Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy,Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and UnitedKingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMI T EUROPEN DENORMALI SATI ONEUROPI SCHES KOMI TEE FR NORMUNGManagement Centre:rue de Stassart, 36 B-1050 Brussels 2004 CEN All rights ofexploitation in any form and by any means reservedworldwide for CENnational Members.Ref. No. EN 14015:2004: EEN 14015:2004 (E) 2Contents pageForeword.......................................................................................................................................11 1Scope................................................................................................................................12 2 Normative references.....................................................................................................13 3 Terms, definitions, symbols and abbreviations.......................................................... 15 3.1Terms anddefinitions.....................................................................................................15 3.2 Symbols...........................................................................................................................19 3.3 Abbreviations..................................................................................................................21 4 Information and requirements to bedocumented.......................................................22 4.1 Information to be specified by thepurchaser..............................................................22 4.2 Information to be agreed between the purchaser and the tankmanufacturer ......... 22 4.3 Information to be supplied by thetank manufacturer.................................................22 4.4 Information to be supplied by the steelmanufacturer................................................ 22 4.5Information to be agreed between the steel manufacturer and thetank manufacturer...................................................................................................................22 4.6 Information to be agreed between the purchaser and the coversupplier................ 22 4.7 Information to be agreed betweenthe tank manufacturer and the cover supplier.. 22 4.8 Informationto be supplied by the cover supplier....................................................... 22 5Requirements..................................................................................................................22 5.1 Designpressure..............................................................................................................22 5.2 Design metaltemperature..............................................................................................23 5.2.1 Maximum design metaltemperature.............................................................................23 5.2.2 Minimum design metal temperature.............................................................................23 5.3 Designdensity.................................................................................................................24 5.4 Yield strength..................................................................................................................24 6Materials...........................................................................................................................24 6.1 Carbon and carbon manganesesteels.........................................................................24 6.1.1 Platematerials.................................................................................................................24 6.1.2 Structural steel sections................................................................................................30 6.1.3Forgings...........................................................................................................................30 6.1.4Pipes.................................................................................................................................31 6.1.5 Welding consumables....................................................................................................31 6.1.6 Charpy V-notch impact energy requirements of carbon andcarbon manganese steels................................................................................................................................31 6.1.7Mountings........................................................................................................................33 6.1.8 Thicknesstolerances......................................................................................................33 6.2 Stainless steels...............................................................................................................34 6.2.1 General.............................................................................................................................34 6.2.2 Platematerials.................................................................................................................36 6.2.3 Structural steel sections................................................................................................36 6.2.4Forgings...........................................................................................................................36 6.2.5Pipes.................................................................................................................................36 6.2.6 Welding consumables....................................................................................................37 7 Designloads....................................................................................................................37 7.1Loads................................................................................................................................37 7.2 Load values.....................................................................................................................38 7.2.1 Liquid induced loads......................................................................................................38 7.2.2 Internal pressureloads...................................................................................................38 EN 14015:2004 (E) 3 7.2.3 Thermally inducedloads................................................................................................38 7.2.4 Deadloads.......................................................................................................................38 7.2.5 Insulationloads...............................................................................................................38 7.2.6 Liveload...........................................................................................................................38 7.2.7 Concentrated liveload....................................................................................................38 7.2.8 Snow loads......................................................................................................................38 7.2.9 Rainfall.............................................................................................................................39 7.2.10Wind..................................................................................................................................39 7.2.11 Seismic loads..................................................................................................................39 7.2.12 Loads resulting from connected piping andattachments.......................................... 39 7.2.13Foundation settlementloads.........................................................................................39 7.2.14 Emergency loads............................................................................................................39 7.3 Load combinations.........................................................................................................39 8 Tankbottoms...................................................................................................................40 8.1 General.............................................................................................................................40 8.2Materials...........................................................................................................................40 8.3 Design..............................................................................................................................43 8.4Fabrication.......................................................................................................................43 9 Shelldesign.....................................................................................................................45 9.1 Design and teststress....................................................................................................45 9.2 Internalloads...................................................................................................................48 9.3 Wind and vacuumloads.................................................................................................49 9.3.1 Stiffeningrings................................................................................................................49 9.3.2 Primary stiffening ring (wind girder)design................................................................51 9.3.3 Secondary stiffening ring (wind girder)design...........................................................51 9.4 Shell plate arrangement.................................................................................................54 9.5 Shelljoints.......................................................................................................................54 10 Fixed roof design............................................................................................................54 10.1Loads................................................................................................................................54 10.2 Type of roof.....................................................................................................................54 10.3 Roof plating with supporting structure........................................................................54 10.4 Roof plating without supporting structure (membrane roofs)................................... 56 10.5 Compression area at thejunction of the shell and roof............................................. 56 10.6 Ventingrequirements.....................................................................................................59 10.6.1 General.............................................................................................................................59 10.6.2 Scope of ventingprovided.............................................................................................59 10.6.3 Ventingcapacity..............................................................................................................59 10.6.4 Accumulation of pressure andvacuum........................................................................59 10.7 Floatingcovers................................................................................................................59 11 Floating roofdesign........................................................................................................59 12 Tankanchorage...............................................................................................................60 12.1 General.............................................................................................................................60 12.2 Anchorage attachment...................................................................................................60 12.3 Holding down bolt or strap............................................................................................60 12.3.1 Allowable tensile stress.................................................................................................60 12.3.2 Cross-sectionalarea.......................................................................................................60 12.4 Resistance to uplift during test.....................................................................................61 13Mountings........................................................................................................................61 13.1 Shell nozzles O/D 80 mm andabove.............................................................................61 13.2 Shell nozzles less than O/D 80mm...............................................................................71 13.3 Roofnozzles....................................................................................................................71 13.4 Studded padconnections..............................................................................................73 13.5 Nozzle loads....................................................................................................................73 13.6 Flush type clean-out doors and water draw-off sumps.............................................. 73 13.6.1 General.............................................................................................................................73 13.6.2 Flush type clean-outdoors............................................................................................74 EN 14015:2004 (E) 4 13.6.3 Water draw-off sumps....................................................................................................74 13.6.4 Combined water draw-off and clean-outsump............................................................ 7413.7 Nozzle weldingdetails....................................................................................................74 13.8 Flangedrilling..................................................................................................................75 13.9 Post-weld heat treatment ofnozzles.............................................................................75 13.10 Heating and/or coolingsystems....................................................................................75 13.11 Stairways and walkways................................................................................................78 13.12 Handrailing......................................................................................................................78 13.13 Ladders............................................................................................................................79 13.14 Earthing connections.....................................................................................................79 13.15 Permanent attachments.................................................................................................79 13.16 Temporary attachments.................................................................................................79 14 Insulation.........................................................................................................................79 15 Shop fabrication of tank components..........................................................................79 15.1 General.............................................................................................................................79 15.2 Reception and identification ofmaterials.....................................................................79 15.3 Handling and storage ofmaterials................................................................................80 15.4 Materialmarkings............................................................................................................80 15.5 Plate preparation and tolerances..................................................................................81 15.6 Preparation of nozzle components...............................................................................81 15.7 Plate forming andtolerances.........................................................................................81 15.8Openings..........................................................................................................................81 15.8.1Nozzles.............................................................................................................................81 15.8.2 Inspectionwindows........................................................................................................82 15.8.3 Nozzles for mixers..........................................................................................................82 15.8.4 Clean-outdoors...............................................................................................................82 15.8.5 Reinforcementplates......................................................................................................82 15.8.6 Insertplates.....................................................................................................................82 15.9 Welding............................................................................................................................82 15.10 Surfacecondition............................................................................................................83 15.11 Marking for erection purposes......................................................................................83 15.12 Packing, handling and transport to site.......................................................................83 16 Site erection andtolerances..........................................................................................84 16.1 General.............................................................................................................................84 16.2Foundations.....................................................................................................................84 16.2.1 General.............................................................................................................................84 16.2.2 Peripheraltolerance........................................................................................................85 16.2.3 Foundation surfacetolerance........................................................................................85 16.3 Anchorpoints..................................................................................................................85 16.4 Handling and storage.....................................................................................................86 16.5 Rectification of parts damaged during transportation andhandling........................ 86 16.6 Bottom plates..................................................................................................................86 16.7 Shell to bottom, and shell..............................................................................................86 16.7.1 Assembly tolerances of first shell course on flatbottom........................................... 86 16.7.2Tolerance on shell geometry.........................................................................................87 16.7.3 Vertical tolerance............................................................................................................88 16.7.4 Tolerances on alignment ofplates................................................................................88 16.7.5 Tolerances on shape of weldedjoints..........................................................................88 16.7.6 Primary and secondary stiffening rings (wind girders).............................................. 89 16.8 Fixedroofs.......................................................................................................................89 16.8.1 General.............................................................................................................................89 16.8.2 Support framework.........................................................................................................89 16.8.3 Roofplates.......................................................................................................................89 16.8.4 Roof plating and roofstructure.....................................................................................90 16.8.5 Frangibleroofs................................................................................................................90 16.9Nozzles.............................................................................................................................90 16.10 Externalattachments......................................................................................................90 16.11 Internalattachments.......................................................................................................90 EN 14015:2004 (E) 5 16.12 Temporary attachments.................................................................................................90 17 Approval of welding procedures andwelders.............................................................91 17.1 General.............................................................................................................................91 17.2 Welding procedure approval.........................................................................................91 17.2.1 General.............................................................................................................................91 17.2.2 Welding of test pieces....................................................................................................91 17.2.3 Examination and testing of test pieces........................................................................91 17.3 Welding Procedure Approval Record(WPAR).............................................................92 17.3.1 Preparation......................................................................................................................92 17.3.2 Range of approval...........................................................................................................92 17.4 Welders and welding operatorsapproval.....................................................................92 17.5 Production control testplates.......................................................................................92 17.5.1 Horizontalwelds..............................................................................................................92 17.5.2 Vertical welds..................................................................................................................93 18 Welding............................................................................................................................93 18.1 General.............................................................................................................................93 18.2 Weldingsequences.........................................................................................................93 18.3 Welding ofbottoms.........................................................................................................93 18.3.1 Removal ofcoatings.......................................................................................................93 18.3.2 Annular ring plates.........................................................................................................93 18.3.3 Bottom plates..................................................................................................................94 18.4 Welding of shell tobottom.............................................................................................94 18.5 Welding ofshell...............................................................................................................94 18.6 Welding ofroof................................................................................................................94 18.7 Temporarywelds.............................................................................................................94 18.8 Atmosphericconditions.................................................................................................94 18.9Preheating........................................................................................................................95 18.10 Post-weld heat treatment...............................................................................................95 18.11 Repairwelding.................................................................................................................96 19 Testing andinspection...................................................................................................96 19.1 General.............................................................................................................................96 19.2 Qualification of NDT personnel.....................................................................................96 19.3 Test procedures..............................................................................................................97 19.4 Type of inspections andexaminations.........................................................................97 19.4.1 Inspection ofmaterials...................................................................................................97 19.4.2 Examinations of edges to be welded and jointpreparations..................................... 97 19.4.3 Visualexamination..........................................................................................................97 19.4.4 Type and extent of examination and test ofwelds...................................................... 9819.4.5 Additional examinations if imperfections arefound................................................. 102 19.5Vacuum box test...........................................................................................................103 19.6 Penetrant test................................................................................................................104 19.7 Magnetic particleexamination.....................................................................................104 19.8 Soap bubble examination............................................................................................104 19.8.1 Reinforcementplates....................................................................................................104 19.8.2 Fixed roof and roof toshell..........................................................................................104 19.8.3 Shell to bottom with double fillet weld.......................................................................105 19.9 Radiographicexamination...........................................................................................105 19.9.1 General procedure........................................................................................................105 19.9.2 Storage offilms.............................................................................................................105 19.10 Ultrasonicexamination.................................................................................................105 19.11 Acceptancecriteria.......................................................................................................106 19.11.1 Imperfection acceptancecriteria.................................................................................106 19.11.2 Acceptable thinning after grinding.............................................................................109 19.12 Dimensionalcheck........................................................................................................110 19.13 Hydrostatic and pneumatic tests................................................................................110 19.13.1 General...........................................................................................................................110 19.13.2 Hydrostatic test liquid level.........................................................................................110 19.13.3 Pneumatic test pressure..............................................................................................110 EN 14015:2004 (E) 6 19.13.4 Conditions of implementation.....................................................................................110 19.13.5 Examination duringfilling............................................................................................111 19.13.6Filling..............................................................................................................................112 19.13.7 Checking and testing of roof (over pressure)............................................................ 11219.13.8 Test for tank stability under negativepressure.........................................................113 19.14 Emptychecks................................................................................................................113 19.15Accessories...................................................................................................................113 19.15.1 External accessories....................................................................................................113 19.15.2 Internalaccessories......................................................................................................113 20 Documentation and name-plate..................................................................................114 20.1Documentation..............................................................................................................114 20.2Name-plate.....................................................................................................................116 Annex A (normative) Information and requirements to bedocumented ............................ 117 A.1 Information to besupplied by thepurchaser.............................................................117 A.2 Information agreed between the purchaser and themanufacturer ......................... 119 A.3 Information to besupplied by the manufacturer....................................................... 120 A.4Information to be supplied by the steelmanufacturer.............................................. 121 A.5Information to be agreed between the steel manufacturer and thetank manufacturer.................................................................................................................121 A.6 Information to be agreed between the purchaser and thecover supplier.............. 121 A.7 Information to be agreedbetween the tank manufacturer and the cover supplier 121 A.8Information to be supplied by the cover supplier..................................................... 121 Annex B(informative) Operational and safety considerations for storagetanks and storage installations.....................................................................................................122 B.1 General...........................................................................................................................122 B.2 Tank type.......................................................................................................................122 B.2.1 Stored product..............................................................................................................122 B.2.2 Local climatic and geologicalconditions...................................................................122 B.3 Health, safety and environmentalconsiderations.....................................................123 B.3.1 Containment..................................................................................................................123 B.3.2 Fireprotection...............................................................................................................123 B.4 Attachments to tanks for safety or firefighting facilities.......................................... 123 Annex C (normative)Requirements for floating covers....................................................... 124 C.1General...........................................................................................................................124 C.2 Types of floatingcovers...............................................................................................125 C.3 Design and constructionrequirements......................................................................128 C.3.1 Design............................................................................................................................128 C.3.2 Materials of construction.............................................................................................130 C.3.3 Coverfittings.................................................................................................................133 C.3.4 Tankfittings...................................................................................................................137 C.4 Installation.....................................................................................................................139 C.4.1 Tankexamination..........................................................................................................139 C.4.2 Examination and installation of thecover..................................................................139 C.4.3Tests...............................................................................................................................140 C.5Documentation..............................................................................................................140 Annex D (normative) Requirements for floatingroofs.......................................................... 141D.1 General...........................................................................................................................141 D.2 Rooftypes......................................................................................................................141 D.3 Design............................................................................................................................141 D.3.1 General...........................................................................................................................141 D.3.2Buoyancy.......................................................................................................................142 D.3.3 Structuraldesign...........................................................................................................144 D.3.4 Roof stability under windload.....................................................................................144 D.3.5 Pontoonmanholes........................................................................................................144 D.3.6 Roof manhole................................................................................................................144 D.3.7 Centering and anti-rotationdevices............................................................................144 D.3.8 Main roof drains............................................................................................................145 EN 14015:2004 (E) 7 D.3.9 Emergencydrains.........................................................................................................145 D.3.10 Drain plugs....................................................................................................................145 D.3.11Vents...............................................................................................................................146 D.3.12Seals...............................................................................................................................146 D.3.13 Support legs..................................................................................................................146 D.3.14 Gauging device.............................................................................................................147 D.3.15 Rolling ladder................................................................................................................147 D.3.16 Earthing cables.............................................................................................................147 D.3.17 Foamdam......................................................................................................................147 D.4 Prefabrication in the workshop...................................................................................147 D.5 Marking, packing, handling,transport........................................................................148 D.5.1 General...........................................................................................................................148 D.5.2 Repair after damage during handlingoperations......................................................148 D.6 Assembly.......................................................................................................................148 D.7 Welding..........................................................................................................................148 D.7.1 General...........................................................................................................................148 D.7.2 Support legs..................................................................................................................148 D.7.3Bulkheads......................................................................................................................148 D.8 Inspection andtesting..................................................................................................149 D.8.1Welds..............................................................................................................................149 D.8.2Pontoons........................................................................................................................149 D.8.3Checks............................................................................................................................149 D.8.4 Drains.............................................................................................................................149 D.9Documentation..............................................................................................................149 Annex E (normative) Requirements for rim seals for floatingroofs ................................... 150 E.1 General...........................................................................................................................150 E.2 Design............................................................................................................................150 E.3 Seal types......................................................................................................................151 E.4 Weathershields.............................................................................................................151 E.5 Application and technical details of rimseals...........................................................151 E.5.1 Mechanical shoe seals.................................................................................................151 E.5.2 Spring-forced lip primaryseals...................................................................................152 E.5.3 Liquid-filled primaryseals............................................................................................152 E.5.4 Foam-filled primaryseals.............................................................................................152 E.5.5 Spring-forced pad or lip secondary seals..................................................................152 E.5.6 Compression plate secondaryseals...........................................................................153 E.5.7 Wiper seals....................................................................................................................153 E.5.8 Integrated primary/secondary seals...........................................................................153 E.6 Installation.....................................................................................................................153 Annex F (normative) Selection of carbon and carbon manganesesteel plate to alternative specifications to those in6.1.......................................................................................156 F.1 Alternative national standards....................................................................................156 F.2 General...........................................................................................................................156 F.3 Chemicalcomposition..................................................................................................156 F.4 Mechanical properties..................................................................................................158 F.5 Impacttesting................................................................................................................158 F.5.1 General...........................................................................................................................158 F.5.2 Impactproperties..........................................................................................................159 Annex G (informative) Recommendations for seismic provisionsfor storage tanks ....... 161 G.1 General...........................................................................................................................161 G.2 Designloads..................................................................................................................161 G.2.1 Overturningmoment.....................................................................................................161 G.2.2 Effective mass of tankcontents..................................................................................162 G.2.3 Lateral forcecoefficients..............................................................................................163 G.3 Resistance tooverturning............................................................................................165 G.3.1 The tank contents.........................................................................................................165 G.3.2 The thickness of the bottomplate...............................................................................165 G.4 Shell compression........................................................................................................166 EN 14015:2004 (E) 8 G.4.1 Unanchoredtanks.........................................................................................................166 G.4.2 Anchoredtanks.............................................................................................................166 G.4.3 Maximum allowable shellcompression......................................................................167 G.4.4 Upper shellcourses......................................................................................................168 G.5 Anchorage oftanks.......................................................................................................168 G.5.1 Minimum anchoragerequired......................................................................................168 G.5.2 Design ofanchorage.....................................................................................................168 G.6 Piping.............................................................................................................................169 G.7 Sloshing height.............................................................................................................169 Annex H (informative) Recommendations for other types of tankbottoms (double bottoms, elevated bottoms etc.)..................................................................................170 H.1 Non-fully supportedbottoms.......................................................................................170 H.2 Doublebottoms.............................................................................................................171 H.2.1 General...........................................................................................................................171 H.2.2 Design............................................................................................................................171 H.2.3 Leakdetection...............................................................................................................174 H.3 Elevated or beam supported tanks.............................................................................174 H.4 Leaktest.........................................................................................................................175 Annex I (informative) Recommendations for tankfoundations........................................... 176 I.1General...........................................................................................................................176 I.2 Soil Investigation..........................................................................................................176 I.2.1 General...........................................................................................................................176 I.2.2 Watertables...................................................................................................................176 I.2.3 Seismic investigations.................................................................................................177 I.2.4 Sites to be avoided.......................................................................................................177 I.3 Foundationdesign........................................................................................................177 I.3.1 General...........................................................................................................................177 I.3.2 Loadingconditions.......................................................................................................177 I.3.3 Allowable soil loading..................................................................................................177 I.3.4 Settlement......................................................................................................................177 I.3.5 Soil improvement andpiling........................................................................................178 I.3.6Drainage.........................................................................................................................178 I.3.7 Resistance to uplift.......................................................................................................179 I.3.8 Membrane vapourbarrier.............................................................................................179 I.4 Types offoundations....................................................................................................179 I.4.1 General...........................................................................................................................179 I.4.2 Padfoundations............................................................................................................179 I.4.3 Ring beam foundations................................................................................................180 I.4.4 Surface raftfoundations...............................................................................................180 I.4.5 Pile supported raft........................................................................................................180 Annex J (informative) Example calculations of stiffening rings(wind girders) ................. 184 J.1 General...........................................................................................................................184 J.2 Section moduli..............................................................................................................184 J.3 Worked examples of design of secondary stiffening rings(wind girders)............. 184 J.4 Example 1......................................................................................................................186 J.5 Example 2......................................................................................................................187 Annex K (normative) Design rules for tanks with frangible roofto shell joints................. 188 K.1 General...........................................................................................................................188 K.2Construction..................................................................................................................189 K.3Materials.........................................................................................................................189 K.4 Designrules...................................................................................................................190 Annex L (normative) Requirements for ventingsystems..................................................... 194L.1 General...........................................................................................................................194 L.2 Types of vents and valves...........................................................................................195 L.2.1 General...........................................................................................................................195 L.2.2 Free vents for outbreathing andinbreathing.............................................................195 L.2.3 Pressure and vacuum reliefvalves.............................................................................195 EN 14015:2004 (E) 9 L.2.4 Ventpipes......................................................................................................................195 L.2.5 Emergency ventingvalves...........................................................................................195 L.2.6 Venting systems with flame arrestingcapability.......................................................195 L.3 Calculation of maximum flow rates for normal outbreathingand inbreathing ...... 196 L.3.1 General...........................................................................................................................196 L.3.2 Pumpcapacities............................................................................................................196 L.3.3 Thermal outbreathing andinbreathing.......................................................................196 L.4 Calculation of maximum flow rates for emergency pressureventing .................... 199 L.4.1 General...........................................................................................................................199 L.4.2Fire..................................................................................................................................199 L.4.3 Malfunction of blanketingsystem...............................................................................201 L.4.4 Other possiblecauses..................................................................................................201 L.5 Emergency vacuum venting........................................................................................201 L.6 Testing venting devices...............................................................................................201 L.6.1 General...........................................................................................................................201 L.6.2 Testapparatus...............................................................................................................202 L.6.3Method............................................................................................................................204 L.7 Manufacturers documentation and marking of venting devices............................. 205 L.7.1Documentation..............................................................................................................205 L.7.2 Marking..........................................................................................................................205 Annex M (informative) Tankanchorages................................................................................207 M.1 General...........................................................................................................................207 M.2 Holding downstrap.......................................................................................................207 M.3 Holding down bolt with individual chair.....................................................................207 M.4 Holding down bolt with continuous supportring...................................................... 207Annex N (informative) Weld details for the connection ofmounting.................................. 211 N.1 Set-throughmountings................................................................................................211 N.2 Set-onmountings..........................................................................................................215 N.3 Studded padconnections............................................................................................216 Annex O (informative) Flush-type clean-out doors and waterdraw-off sumps ................. 217 O.1 Flush-type clean-outdoors..........................................................................................217 O.1.1 General...........................................................................................................................217 O.1.2 Flush-type clean-out doors with insert platereinforcement. ................................... 217 O.1.3Flush-type clean-out doors with plate reinforcement............................................... 218 O.2Water-draw-offsumps..................................................................................................218 O.3 Combined water draw-off and clean-outsump.......................................................... 218Annex P (informative) Heating and/or cooling systems....................................................... 225 P.1General...........................................................................................................................225 P.2 Heat transfer fluid.........................................................................................................225 P.3 Type of heating or coolingdevices.............................................................................225 P.4 Installation.....................................................................................................................226 Annex Q (informative) Recommendations for the design andapplication of insulation.. 228 Q.1 General...........................................................................................................................228 Q.2 Designconsiderations..................................................................................................229 Q.2.1 General...........................................................................................................................229 Q.2.2 Deadload.......................................................................................................................229 Q.2.3 Windloads.....................................................................................................................229 Q.2.4 Thermal expansion.......................................................................................................230 Q.2.5 Movements due to hydrostaticpressure....................................................................230 Q.3 Mechanical support arrangement...............................................................................230 Q.3.1 General...........................................................................................................................230 Q.3.2 Supports attached bywelding.....................................................................................231 Q.3.3 Supports attached byadhesive...................................................................................231 Q.3.4 External structuralframe..............................................................................................233 Q.3.5 Secondary support members......................................................................................233 Q.3.6 Roofinsulation..............................................................................................................233 Q.4 Designdetails................................................................................................................234 EN 14015:2004 (E) 10 Q.4.1 Nozzles andmanholes..................................................................................................234 Q.4.2 Stairway connections...................................................................................................234 Q.4.3 Supports near stiffening rings (windgirders)............................................................235 Q.4.4 Roofprojection..............................................................................................................235 Q.4.5 Stiffening rings (wind girders).....................................................................................235 Q.4.6 External shell stiffening rings (wind girders) andbottom-to-shell insulation........ 235 Q.5 Corrosion protection....................................................................................................235 Q.6 Insulation.......................................................................................................................235 Q.6.1 General...........................................................................................................................235 Q.6.2 Nozzle connections and manholes.............................................................................237 Q.6.3 Stiffening rings (wind girders).....................................................................................239 Q.7Cladding.........................................................................................................................240 Q.7.1 General...........................................................................................................................240 Q.7.2 Side-wallcladding.........................................................................................................240 Q.7.3 Roofingcladding...........................................................................................................240 Q.8 Securing insulationmaterials......................................................................................241 Q.8.1 Slab or block insulation with metalcladding.............................................................241 Q.8.2 In situ foam behind metalcladding.............................................................................241 Q.8.3 Sprayfoam.....................................................................................................................242 Q.8.4Roofs..............................................................................................................................242 Q.9 Firehazard.....................................................................................................................242 Annex R (normative) Surfacefinish........................................................................................243 R.1 Internal surfaces in contact with the product............................................................ 243R.1.1 General...........................................................................................................................243 R.1.2 Carbon and carbon manganese steeltanks...............................................................243 R.1.3 Stainless steeltanks.....................................................................................................243 R.2 External surfaces..........................................................................................................246 R.2.1 General...........................................................................................................................246 R.2.2 Carbon and carbon manganese steeltanks...............................................................246 R.2.3 Stainless steeltanks.....................................................................................................246 Bibliography...............................................................................................................................247 EN 14015:2004 (E) 11 Foreword This document (EN 14015:2004) hasbeen prepared by Technical Committee CEN/TC 265 Site built metallictanks for the storage of liquids, the secretariat of which is heldby BSI. This European Standard shall be given the status of anational standard, either by publication of an identical text or byendorsement, at the latest by May 2005, and conflicting nationalstandards shall be withdrawn at the latest by May 2005. Accordingto the CEN/CENELEC Internal Regulations, the national standardsorganizations of the following countries are bound to implementthis 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, Slovakia, Slovenia, Spain,Sweden, Switzerland and United Kingdom. This European Standardreflects the current practice within the oil, petrochemical,chemical, food and general bulk liquid storage industry, bothEuropean and world-wide. The practice is based on the theory ofdesign stresses or allowable stresses. There is a parallelpre-standard, ENV 1993-4-2 Tanks. It is based on the Limit StateTheory (LST), which is being used more and more by the structuresteel and reinforced concrete industry. Experience in designingsteel storage tanks to LST is limited, and there is littleinformation on which to base the values for load factors, loadcombinations and serviceability. When sufficient experience hasbeen gained in designing tanks to, and credible values becomeavailable for load factors, etc., it is envisaged that there may bea gradual move towards the use of LST for the design of tankscovered by this European Standard. EN 14015:2004 (E) 12 1 Scope 1.1This document specifies the requirements for the materials, design,fabrication, erection, testing and inspection of site built,vertical, cylindrical, flat bottomed, above ground, welded, steeltanks for the storage of liquids at ambient temperatures and above,and the technical agreements that need to be reached (see Annex A).This document does not apply to tanks where the product isrefrigerated to maintain it as a liquid at atmospheric pressure(see prEN 14620). This document is concerned with the structuralintegrity of the basic tank structure and does not providerequirements for considering process design, operational issues,safety and firefighting facilities, in-service inspection,maintenance or repair. These aspects are covered in detail in otherCodes of Practice (see Annex B). 1.2 This document applies toclosed-top tanks, with and without internal floating covers (seeAnnex C) and open-top tanks, with and without floating roofs (seeAnnexes D and E). It does not apply to 'lift-type' gas holders. 1.3This document applies to storage tanks with the followingcharacteristics: a) design pressure less than 500 mbar1) and designinternal negative pressure not lower than 20 mbar (see 5.1 forpressure limitations); b) design metal temperature not lower than-40 C and not higher than +300 C (see 5.2.2); c) maximum designliquid level not higher than the top of the cylindrical shell. 1.4The limits of application of this document terminate at thefollowing locations. face of the first flange in a bolted flangeconnection; first threaded joint on the pipe or coupling outside ofthe tank shell, roof or bottom; first circumferential joint in apipe not having a flange connection. 1.5 This document isapplicable to steel tanks with a maximum design strength 260 N/mm2.1.6 In addition to the definitive requirements, this document alsorequires the items detailed in Annex A to be documented. Forcompliance with this document, both the definitive requirements andthose required in Clause 4 have to be satisfied. 1) All pressuresare in mbar gauge unless otherwise stated. EN 14015:2004 (E) 13 2Normative references The following referenced documents areindispensable for the application of this document. For datedreferences, only the edition cited applies. For undated references,the latest edition of the referenced document (including anyamendments) applies. EN 287-1: 2004, Qualification test of welders- Fusion welding - Part 1: Steels EN 288-2, Specification andapproval of welding procedures for metallic materials Part 2:Welding procedure specification for arc welding EN 444,Non-destructive testing- General principles for radiographicexamination of metallic material by X- and gamma- rays EN 462-1,Non-destructive testing Image quality of radiographs Part 1: Imagequality indicators (wire type). Determination of image qualityvalue EN 462-2, Non-destructive testing Image quality ofradiographs Part 2: Image quality indicators (step/hole type).Determination of image quality value EN 473, Non destructivetesting - Qualification and certification of NDT personnel -General principles EN 485 (all parts), Aluminium and aluminiumalloys Sheet, strip and plate EN 499, Welding consumables Coveredelectrodes for manual metal arc welding of non alloy and fine grainsteels Classification EN 571-1, Non destructive testing - Penetranttesting Part 1: General principles EN 754 (all parts), Aluminiumand aluminium alloys Cold drawn rod/bar and tube EN 755 (allparts), Aluminium and aluminium alloys Extruded rod/bar, tube andprofiles EN 970, Non-destructive examination of fusion welds -Visual examination EN 1092-1, Flanges and their joints - Circularflanges for pipes, valves, fittings and accessories, PN designatedPart 1: Steel flanges EN 1290, Non-destructive examination of welds- Magnetic partical examination of welds EN 1418, Welding personnel- Approval testing of welding operators for fusion welding andresistance weld setters for fully mechanized and automatic weldingof metallic materials EN 1435, Non-destructive examination of weldsRadiographic examination of welded joints EN 1593, Non-destructivetesting Leak testing Bubble emission techniques EN 1600, Weldingconsumables Covered electrodes for manual metal arc welding ofstainless and heat resisting steels Classification EN 1714,Non-destructive examination of welded joints - Ultrasonicexamination of welded joints prEN 1759-1: 2000, Flanges and theirjoints - Circular flanges for pipes, valves, fittings andaccessories, Class designated - Part 1: Steel flanges, NPS to 24 EN1991-1-3:2003, Eurocode 1 - Actions on structures - Part 1-3:General actions - Snow loads EN 14015:2004 (E) 14 EN 10025:1992,Hot rolled products of non-alloy structural steels Technicaldelivery conditions EN 10028-2: 1993, Flat products made of steelsfor pressure purposes Part 2: Non-alloy and alloy steels withspecified elevated temperature properties EN 10028-3: 1993, Flatproducts made of steels for pressure purposes Part 3: Weldable finegrain steels, normalized EN 10029: 1991, Hot rolled steel plates 3mm thick or above Tolerances on dimensions, shape and mass EN10045-1, Metallic materials Charpy impact test Part 1: Test methodEN 10088-1, Stainless steels Part 1: List of stainless steels EN10088-2: 1995, Stainless steels Part 2: Technical deliveryconditions for sheet/plate and strip for general purposes EN10088-3: 1995, Stainless steels Part 3: Technical deliveryconditions for semi-finished products, bars, rods and sections forgeneral purposes EN 10113-2: 1993, Hot-rolled products in weldablefine grain structural steels Part 2: Delivery conditions fornormalized/normalized rolled steels EN 10113-3: 1993, Hot-rolledproducts in weldable fine grain structural steels Part 3: Deliveryconditions for thermomechanical rolled steels EN 10204: 2004,Metallic products Types of inspection documents EN 10210-1: 1994,Hot finished structural hollow sections of non-alloy and fire grainstructural steels Part 1: Technical delivery requirements EN10216-1, Seamless steel tubes for pressure purposes Technicaldelivery conditions - Part 1: Non-alloy steel tubes with specifiedroom temperature properties EN 10216-2, Seamless steel tubes forpressure purposes - Technical delivery conditions - Part 2:Non-alloy and alloy steel tubes with specified elevated temperatureproperties EN 10216-3, Seamless steel tubes for pressure purposes -Technical delivery conditions - Part 3: Alloy fine grain steeltubes EN 10216-5, Seamless steel tubes for pressure purposesTechnical delivery conditions Part 5: Stainless steel tubes EN10217-1, Welded steel tubes for pressure purposes Technicaldelivery conditions - Part 1: Non-alloy steel tubes with specifiedroom temperature properties EN 10217-2, Welded steel tubes forpressure purposes - Technical delivery conditions - Part 2:Electric welded non-alloy and alloy steel tubes with specifiedelevated temperature properties EN 10217-3, Welded steel tubes forpressure purposes - Technical delivery conditions - Part 3: Alloyfine grain steel tubes EN 10217-5, Welded steel tubes for pressurepurposes - Technical delivery conditions - Part 5: Submerged arcwelded non-alloy and alloy steel tubes with specified elevatedtemperature properties prEN 10217-7, Welded steel tubes forpressure purposes Technical delivery conditions Part 7: Stainlesssteel tubes EN 14015:2004 (E) 15 EN 10222 (all parts), Steelforgings for pressure purposes EN 10250 (all parts), Open steel dieforgings for general engineering purposes EN 12874, Flame arresters- Performance requirements, test methods and limits for use ENV1991-2-1, Eurocode 1: Basis of design and actions on structuresPart 2-1: Actions on structures Densities, self-weight and imposedloads ENV 1993-1-1, Eurocode 3: Design of steel structures Part1-1: General rules and rules for buildings ENV 1993-4-2, Eurocode3: Design of steel structures Part 4-2: Silos, tanks and pipelinesTanks EN ISO 4063, Welding and allied processes Nomenclature ofprocesses and reference numbers (ISO 4063:1998) EN ISO 6520-1,Welding and allied processes Classification of geometricimperfections in metallic materials Part 1: Fusion welding (ISO6520-1: 1998) EN ISO 14122-1, Safety of machinery Permanent meansof access to machinery - Part 1: Choice of fixed means of accessbetween two levels (ISO 14122-1:2001) EN ISO 14122-2, Safety ofmachinery -- Permanent means of access to machinery -- Part 2:Working platforms and walkways (ISO 14122-2:2001) EN ISO 14122-3,Safety of machinery -- Permanent means of access to machinery --Part 3: Stairs, stepladders and guard-rails (ISO 14122-3:2001) ENISO 14122-4, Safety of machinery -- Permanent means of access tomachinery -- Part 4: Fixed ladders (ISO 14122-4:1996) EN ISO15607:2003, Specification and qualification of welding proceduresfor metallic materials - General rules (ISO 15607:2003) EN ISO15614-1:2004, Specification and qualification of welding proceduresfor metallic materials - Welding procedure test - Part 1: Arc andgas welding of steels and arc welding of nickel and nickel alloys(ISO 15614-1:2004) 3 Terms, definitions, symbols and abbreviations3.1 Terms and definitions For the purpose of this document, thefollowing terms and definitions apply: 3.1.1 design pressuremaximum permissible pressure in the space above the stored liquid3.1.2 design internal negative pressure maximum permissiblenegative pressure in the space above the stored liquid 3.1.3 setpressure pressure at which the pressure relief device first opensEN 14015:2004 (E) 16 3.1.4 set vacuum internal negative pressure atwhich a vacuum valve first opens 3.1.5 test pressure pressure inthe space above the test liquid during testing 3.1.6 maximum designmetal temperature temperature used for determining the maximumallowable stress for the material 3.1.7 minimum design metaltemperature temperature used for determining the material toughnessrequirements 3.1.8 LODMAT (lowest one day mean ambient temperature)lowest recorded average temperature based over any 24 hour periodNOTE The average temperature is half (maximum temperature plusminimum temperature). 3.1.9 purchaser company or its agent whichprepares and agrees a proposal with a contractor for the design,construction and testing of a storage tank 3.1.10 designer2) personor organization carrying out the engineering design of the tank3.1.11 contractor2) company with which the purchaser agrees aproposal for the design, construction and testing of a storage tank3.1.12 manufacturer2) organization carrying out the shopfabrication 3.1.13 erector2) organization carrying out theconstruction on site 3.1.14 inspector person or organizationcarrying out the inspection of the tank on behalf of the purchaser3.1.152) welding consumables manufacturer specific manufacturer ofwelding consumables 3.1.16 supplier company manufacturing andsupplying sub-assemblies 2) A single organization may cover two ormore of these activities. EN 14015:2004 (E) 17 3.1.17 oxygenatesoxygen compounds which may be added to fuels used for transport toenhance performance NOTE Most commonly used ones are methanol,ethanol, methyl tertiary butyl ether (MTBE) and tertiary butylalcohol (TBA). 3.1.18 static electricity build-up of an electricaldifference of potential or charge, through friction of dissimilarmaterials or substances e.g. product flow through a pipe 3.1.19operating basis earthquake (OBE) earthquake that the tank resistswithout any damage 3.1.20 safe shutdown earthquake (SSE) earthquakethat damages the tank without causing collapse or imposing seriousconsequential hazards 3.1.21 floating roof metallic structure whichfloats on the surface of a liquid inside an open top tank shell,and in complete contact with this surface 3.1.22 floating coverstructure which floats on the surface of a liquid inside a fixedroof tank, primarily to reduce vapour loss 3.1.23 contact typefloating cover cover which floats in direct contact with the liquidwith no space between the underside of the cover and the liquidsurface 3.1.24 non-contact type floating cover cover which issupported by buoyancy chambers or pontoons on the liquid surfacecausing the floating cover to be raised above the liquid surface,thus creating a void between the underside of the floating coverand the liquid surface 3.1.25 cover main load bearing structure towhich the peripheral (rim) seal is added 3.1.26 peripheral (rim)seal seal mounted around the periphery of the floating roof orfloating cover which contacts the tank shell and seals the annulargap 3.1.27 cover skirt lightweight structure fitted to theperiphery of a floating cover which protrudes above and ispartially submerged in the stored liquid who's purpose is toprevent vapour escape from the underside of a non-contact typefloating cover EN 14015:2004 (E) 18 3.1.28 floating suction devicesmechanical device, sometimes articulated, installed in some tanks,which floats on the liquid surface and only permits product to bewithdrawn from this point NOTE Commonly adopted for aviation fuelstorage tanks. 3.1.29 bleeder vent device incorporated in afloating cover to permit release of gas from under the floatingcover during tank filling, and to allow air to pass back throughthe floating cover when draining product when the floating cover isstationary on its support legs 3.1.30 buoyancy ability of astructure to float on liquid 3.1.31 inlet diffuser componentintended to join and extend the inlet pipe within the tank anddisperses the incoming product 3.1.32 maximum liquid operatingheight in tank with floating cover product height established in astorage tank after installing a floating cover and before allowingit to enter operational service 3.1.33 accumulation differentialpressure between the set pressure of the valve and the tankpressure at which the required flow rate is reached or the setvacuum of the valve and the tank internal negative pressure atwhich the required flow rate is reached 3.1.34 evaporation ventingoutbreathing depending on gas evaporation of the liquid product3.1.35 normal pressure venting outbreathing under normal operatingconditions (pumping product into the tank and thermal outbreathing)3.1.36 normal vacuum venting inbreathing under normal operatingconditions (pumping product out of the tank and thermalinbreathing) 3.1.37 emergency venting outbreathing in case of fire,or inbreathing and outbreathing in case of malfunction of tankequipment 3.1.38 thermal outbreathing pressure venting capacityinfluenced by atmospheric heating of the tank 3.1.39 thermalinbreathing vacuum venting capacity influenced by atmosphericcooling down of the tank EN 14015:2004 (E) 19 3.1.40 free ventsopen vents 3.1.41 pressure/vacuum valves valves used to reliefexcess pressure or internal negative pressure in the tank 3.1.42venting system with flame arresting capability free vents orpressure and/or vacuum valves combined with a flame arrester orwith integrated flame arresting elements 3.1.43 emergency ventingvalves pressure or vacuum relief valves for emergency venting3.1.44 pipe away valves pressure or vacuum valves to which a ventpipe may be connected 3.1.45 vent pipes pipes connected to pipeaway valves 3.2 Symbols For the purpose of this document, thesymbols given in Table 1 shall apply: EN 14015:2004 (E) 20 Table 1Symbols (continued) Symbol Description Unit c Corrosion allowancemm D Diameter of tank m d Diameter of hole mm dh Diameter of holein roof mm di Diameter (inside) of nozzle mm dn Diameter (outside)of nozzle mm do Diameter (outside) of manhole insert mm dr Diameter(outside) of reinforcement mm e Nominal thickness of plate mm eaNominal thickness of annular plate mm eb Thickness of bottom platemm ebr Thickness of bottom reinforcing plate (flush type clean outdoor) mm ec Calculated minimum thickness of plate includingcorrosion allowance mm ef Thickness of flange mm ei Thickness ofinsert plate mm en Thickness of nozzle mm ep Thickness of roofplate mm er Thickness of reinforcement plate mm es Thickness of anyshell plate mm et Thickness of shell plate for test conditions mme1 Thickness of first shell course mm F Overstress factor H Designliquid height m Hc Height from the bottom of the course underconsideration to design liquid level m hn Height of nozzle mm LrEffective roof length mm Ls Effective shell length mm EN 14015:2004(E) 21 Table 1 Symbols (concluded) Symbol Description Unit la Widthof the annular plate between the edge of the bottom plate and theinner surface of the shell mm ld Distance from the outer surface ofthe shell to the outer edge of the bottom plate or annular plate mmlw Lap of the bottom plates over the annular plate mm p Designpressure mbar pi Internal pressure minus pressure exerted by roofmbar pt Test pressure mbar R Radius of tank m R1 Radius ofcurvature of roof m ri Inside radius of nozzle mm rm Mean radiusfor nozzle mm ro Outside radius of nozzle mm S Allowable designstress N/mm2 Sc Allowable compressive stress N/mm2 St Allowabletest stress N/mm2 t Total thickness tolerance mm TDM Design metaltemperature C V Design wind speed m/s W Density of contained liquidkg/l Wt Density of test medium kg/l Z Section modulus cm3 3.3Abbreviations For the purpose of this document, the abbreviationsgiven in Table 2 shall apply. Table 2 Abbreviations AbbreviationDescription HAZ Heat affected zoneLODMAT Lowest one day meanambient temperatureNDE Non-destructive examinationNDTNon-destructive test(ing)PCD Pitch circle diameterPWHT Post-weldheat treatment EN 14015:2004 (E) 22 4 Information and requirementsto be documented 4.1 Information to be specified by the purchaserThe information to be specified by the purchaser, in accordancewith A.1, shall be fully documented. 4.2 Information to be agreedbetween the purchaser and the tank manufacturer The information tobe agreed between the purchaser and the tank manufacturer, inaccordance with A.2, shall be fully documented. 4.3 Information tobe supplied by the tank manufacturer The information to be suppliedby the tank manufacturer, in accordance with A.3, shall be fullydocumented. 4.4 Information to be supplied by the steelmanufacturer The information to be supplied by the steelmanufacturer, in accordance with A.4, shall be fully documented.4.5 Information to be agreed between the steel manufacturer and thetank manufacturer The information to be agreed between the steelmanufacturer and the tank manufacturer, in accordance with A.5,shall be fully documented. 4.6 Information to be agreed between thepurchaser and the cover supplier The information to be agreedbetween the purchaser and the cover supplier, in accordance withA.6, shall be fully documented. 4.7 Information to be agreedbetween the tank manufacturer and the cover supplier Theinformation to be agreed between the tank manufacturer and thecover supplier, in accordance with A.7, shall be fully documented.4.8 Information to be supplied by the cover supplier Theinformation to be supplied by the cover supplier, in accordancewith A.8, shall be fully documented. 5 Requirements 5.1 Designpressure The design pressure and the design internal negativepressure shall be within the limits specified in Table 3 for theparticular tank designation specified (see 10.6.4.1, 10.6.4.2, andA.1). The set pressure of the relief device plus the accumulationto permit the required throughput to be achieved shall not exceedthe design pressure. EN 14015:2004 (E) 23 The set vacuum of therelief device plus the accumulation to permit the requiredthroughput to be achieved shall not exceed the design internalnegative pressure. Table 3 Design pressure limits for tanks Tankdesignation Design pressure Design internal negative pressure p pvmbar (g) mbar (g) Open top tanks or floating roof tanks a 0 5Closed top tanks i) non-pressure tanks b 10 5 ii) low-pressuretanks b c 25 8,5 iii) high-pressure tanks b c 60 8,5 iv) veryhigh-pressure tanks b c d e 500 20 The requirements of thisdocument for roof plating and for roof nozzle reinforcement may notbe
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