Shell boilers - Part 3: Design and calculation for pressure parts

This standard applies to shell boilers as defined in prEN 12953-1. This Part of the standard specifies rules for the design and calculation of shell boilers.

Großwasserraumkessel - Teil 3: Konstruktion und Berechnung für drucktragende Teile

Diese Norm gilt für die in prEN 12953-1 definierten Großwasserraumkessel. Dieser Teil der Norm schreibt Regeln für die Konstruktion und Berechnung von Großwasserraumkessel vor.

Chaudières à tubes de fumée - Partie 3: Conception et calcul des parties sous pression

La présente partie de l'EN 12953 s'applique aux chaudières à tubes de fumée telles que définies dans le prEN 12953-1.
La présente partie de la norme européenne spécifie les règles de conception et de calcul des chaudières à tubes de fumée.

Mnogovodni kotli - 3. del: Konstruiranje in izračun tlačno obremenjenih delov

General Information

Status
Withdrawn
Publication Date
21-May-2002
Withdrawal Date
10-May-2016
Current Stage
9960 - Withdrawal effective - Withdrawal
Completion Date
11-May-2016

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Großwasserraumkessel - Teil 3: Konstruktion und Berechnung für drucktragende TeileChaudieres a tubes de fumée - Partie 3: Conception et calcul des parties sous pressionShell boilers - Part 3: Design and calculation for pressure parts27.060.30Grelniki vode in prenosniki toploteBoilers and heat exchangersICS:Ta slovenski standard je istoveten z:EN 12953-3:2002SIST EN 12953-3:2002en01-november-2002SIST EN 12953-3:2002SLOVENSKI

STANDARD
SIST EN 12953-3:2002

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 12953-3May 2002ICS 27.060.30; 27.100English versionShell boilers - Part 3: Design and calculation for pressure partsChaudières à tubes de fumée - Partie 3: Conception etcalcul des parties sous pressionGroßwasserraumkessel - Teil 3: Konstruktion undBerechnung für drucktragende TeileThis European Standard was approved by CEN on 15 May 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 12953-3:2002 ESIST EN 12953-3:2002

EN 12953-3:2002 (E)2ContentsPageForeword......................................................................................................................................................................41Scope..............................................................................................................................................................52Normative references....................................................................................................................................53Terms and definitions....................................................................................................................................54Symbols and abbreviations..........................................................................................................................55General............................................................................................................................................................55.1Boilers.............................................................................................................................................................55.2Hot-water generators.....................................................................................................................................55.3Design of principal welds..............................................................................................................................65.4Thermal design of furnaces tubes...............................................................................................................65.5Dimensions of pressure parts......................................................................................................................75.6Establishment of pressures..........................................................................................................................75.7Allowances.....................................................................................................................................................86Calculation temperature and nominal design stress.................................................................................96.1Calculation temperature................................................................................................................................96.2Nominal design stress.................................................................................................................................107Cylindrical shells under internal pressure................................................................................................107.1Shell thickness.............................................................................................................................................107.2Basic calculation..........................................................................................................................................117.3Boiler support...............................................................................................................................................117.4Reinforcing pads..........................................................................................................................................118Openings and branches in cylindrical shells............................................................................................118.1General..........................................................................................................................................................118.2Efficiency factor, calculation by way of approximation and maximum diameter of an unrein-forced opening.............................................................................................................................................178.3Design of openings and branches in cylindrical shells (efficiency and reinforcement)......................199Ends..............................................................................................................................................................269.1Unstayed dished heads without openings................................................................................................269.2Flat unstayed removable closures.............................................................................................................289.3Flange connections.....................................................................................................................................3010Supported flat plates, stays and stiffeners...............................................................................................3010.1Breathing spaces for flat plates.................................................................................................................3010.2Stayed flat surfaces.....................................................................................................................................3211Design of isolated openings in shell boiler flat end plates.....................................................................5211.1Unreinforced isolated openings.................................................................................................................5211.2Branch openings..........................................................................................................................................5211.3Manholes, headholes and handholes........................................................................................................5312Unpierced tubes and tube plates...............................................................................................................5412.1Thickness of straight tubes subject to external pressure.......................................................................5412.2Thickness of straight tubes subject to internal pressure........................................................................5512.3Wall thickness and ovality of elbows and tube bends.............................................................................5512.4Stay tubes.....................................................................................................................................................5612.5Smoke tubes.................................................................................................................................................5812.6Pitch of tubes...............................................................................................................................................5812.7Thickness of the tube plates within tube nests........................................................................................5813Furnaces tubes, furnace tube components and reversal chambers of cylindrical form subjectto external pressure.....................................................................................................................................5813.1Furnaces tubes.............................................................................................................................................5813.2Calculation length of composite furnaces tubes......................................................................................6013.3Tolerances of furnaces tubes.....................................................................................................................6113.4Stiffeners.......................................................................................................................................................61SIST EN 12953-3:2002

EN 12953-3:2002 (E)314Access and inspection openings...............................................................................................................6414.1General requirements..................................................................................................................................6414.2Types and minimum dimensions of access and inspection openings..................................................6414.3Minimum gasket bearing width and clearance for access and inspection doors................................6714.4Access and inspection openings in flat plates.........................................................................................6814.5Inspection requirements.............................................................................................................................6814.6Requirements for entry into boilers with a shell outside diameter greater than 1 400 mm.................6914.7Accessibility and arrangement of entry and inspection openings.........................................................69Annex A (normative)

Calculation of tube plate temperatures..............................................................................70Annex B (informative)

Calculation form for "Walker"-type reverse curve sections or corrugations...............87Annex ZA (informative)

Clauses of this European Standard addressing essential requirements or otherprovisions of the Pressure Equipment Directive.....................................................................................89Bibliography..............................................................................................................................................................90SIST EN 12953-3:2002

EN 12953-3:2002 (E)4ForewordThis document (EN 12953-3:2002) has been prepared by Technical Committee CEN/TC 269 "Shell and water-tubeboilers", the secretariat of which is held by DIN.This European Standard has been prepared under a mandate given to CEN by the European Commission and theEuropean Free 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 standard.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 November 2002, and conflicting national standards shall be withdrawn at the latestby November 2002.This European Standard EN 12953 concerning shell boilers consists of the following Parts:Part 1:General.Part 2:Materials for pressure parts of boilers and accessories.Part 3:Design and calculation for pressure parts.Part 4:Workmanship and construction of pressure parts of the boiler.Part 5:Inspection during construction, documentation and marking of pressure parts of the boiler.Part 6:Requirements for equipment for the boiler.Part 7:Requirements for firing systems for liquid and gaseous fuels for the boiler.Part 8:Requirements for safeguards against excessive pressure.Part 9:Requirements for limiting devices, and of the boiler and accessories.Part 10:Requirements for boiler feedwater and boiler water quality.Part 11:Acceptance tests.Part 12:Requirements for firing systems for solid fuels for the boiler.Part 13:Operational Instructions.CR 12953-14:Guidelines for the involvement of an inspection body independent of the manufacturer.Although these Parts can be obtained separately, it should be recognized that the Parts are inter-dependent. As such,the design and manufacture of shell boilers requires the application of more than one Part in order for the require-ments of the standard to be satisfactorily fulfilled.The Annex A

of this European Standard is informative.The Annex B of this European Standard is normative.According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following coun-tries 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, Swe-den, Switzerland and the United Kingdom.SIST EN 12953-3:2002

EN 12953-3:2002 (E)51 ScopeThis Part of this European Standard specifies requirements for the design and calculation of pressure parts of shellboilers as defined in EN 12953-1.2 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. For datedreferences, subsequent amendments to or revisions of any of these publications apply to this European Standard onlywhen incorporated in it by amendment or revision. For undated references the latest edition of the publication referredto applies (including amendments).EN 12953-1:2001, Shell boilers — Part 1: General.EN 12953-2, Shell boilers — Part 2: Materials for pressure parts of boilers and accessories.EN 12953-4, Shell boilers — Part 4: Workmanship and construction of pressure parts of the boiler.EN 12953-5:2002, Shell boilers — Part 5: Inspection during construction, documentation and marking of pressureparts of the boiler.EN 12953-8, Shell boilers — Part 8: Requirements for safeguards against excessive pressure.prEN 12953-10, Shell boilers — Part 10: Requirements for boiler feedwater and boiler water quality.EN 13445-3, Unfired pressure vessels - Part 3: Design.3 Terms and definitionsFor the purposes of this European Standard the terms and definitions given in EN 12953-1 apply.4 Symbols and abbreviationsFor the purposes of this Part of this European Standard, the symbols given in EN 12953-1:2002, Table 4-1 shallapply. Throughout this standard, additional terminology and symbols have been included where necessary to meetthe requirements of the specific text concerned. It should also be noted that in some clauses the same additionalsymbol is used in different formulae to represent different terms. However, in all such cases, the special meaning ofeach symbol is indicated for each formula.5 General5.1 BoilersThe requirements in this standard shall apply to boilers constructed throughout under the conditions specified hereinand which are to be operated under normal operating conditions, with feedwater and boiler water in accordance withprEN 12953-10, and under adequate supervision. Where the risk of abnormal working conditions is foreseen, such assevere cyclic service, the design shall be given special consideration.5.2 Hot-water generatorsFor directly fired hot-water generators the difference between the outlet temperature and the inlet temperature shouldnot exceed 50 K. If the difference between these two temperatures is greater than 50 K, either internal or externalmixing devices shall be used to limit the differential temperature within the boiler to 50 K.SIST EN 12953-3:2002

EN 12953-3:2002 (E)6The difference between the saturation temperature corresponding to the maximum working pressure, and the outlettemperature, should not exceed 80 K. If the difference is greater than 80 K, the distances in accordance with 10.1shall be increased by 50 %. Furthermore the maximum heat input in accordance with Figure 5.4-1 shall be reduced by20 %.The inlet water entering the boiler shall not impinge directly on the furnace tube.5.3 Design of principal weldsThe types of weld employed in the design of the boiler shall be in accordance with EN 12953-4. Welds which aresubjected to non-destructive examination (NDE) in accordance with the requirements of EN 12953-5 shall bedesigned so that the required NDE can be carried out.The value of the weld factor v used in the calculation for the shell thickness shall be either 0,85 or 1 depending on theextent of NDE to be carried out (see 7.2 and EN 12953-5).5.4 Thermal design of furnaces tubesIn order to ensure safe burner/boiler combinations, the heat input for a given furnace tube inside diameter shall notexceed the value given in Figure 5.4-1. Burners with a fixed firing rate (also called on/off or single stage burners) shallnot be used for heat inputs exceeding 1 MW per furnace tube. Combustion shall be completed in the furnace tube.NOTEExamples 1 and 2 show how Figure 5.4-1 is used.EXAMPLE 1Furnace tube inside diameter required for a given heat inputOil flow: 0,1 kg/sNet calorific value: 42,9 MJ/kgAir flow (with air excess 15 %): 1,76 kg/sAir temperature (with air preheater): 120 °CHeat input: 4 290

214 = 4 504 kWFurnace tube steel: P295 GHa) Minimum plain furnace tube inside diameter: 810 mmb) Minimum Fox 150

50 (Table 13.1-1) corrugated furnace tube inside diameter: 760 mm.EXAMPLE 2:Allowable heat input for a given furnace tube inside diametera) Plain furnace tube inside diameter: 1 500 mm P295 GH, oil firing:12,90 MW P295 GH, gas firing:16,77 MW P265 GH, oil firing:

8,00 MW P265 GH, gas firing:10,40 MWb) Fox 150

50 (Table 13.1-1) corrugated furnace tube inside diameter 1 000 mm P265 GH, gas firing:7,02 MW.The length of the refractory should not be larger than one third of the inside furnace tube diameter measured fromthe end of the burner.NOTEAttention is drawn to national regulations that for boilers with an inside furnace tube diameter greater than 1 400 mmor a heat input greater than 12 MW a temperature measurement consisting of at least three measurement points in the furnacecan be required.SIST EN 12953-3:2002

EN 12953-3:2002 (E)7Key1
Coal firing (grate) P 295 GH2
Oil firing P 265 GH3

Oil firing of P 295 GH, P 355 GHaMinimum furnace tube inside diameter [mm]bHeat input [MW]NOTE 1For corrugated furnaces tubes the minimum inside diameter di can be reduced by the depth of the corrugation.NOTE 2In the case of gas firing the heat input given for oil firing can be increased by 30 %.NOTE 3Heat input is the product of the fuel flow rate and the lower calorific value. Air preheating should be taken into ac-count if the air temperature is greater than 100 °C.Figure 5.4.1 — Relation between heat input and furnace tube inside diameter5.5 Dimensions of pressure partsThe wall thickness and other dimensions of pressure parts shall be sufficient to withstand the calculation pressure atcalculation temperature and shall be determined in accordance with this Part.5.6 Establishment of pressures5.6.1 Maximum allowable pressureThe maximum allowable pressure PS is the maximum pressure for which the boiler is designed and shall bemeasured at the highest point of the shell boiler.SIST EN 12953-3:2002

EN 12953-3:2002 (E)85.6.2 Calculation pressureThe calculation pressure shall be not less than the sum of the maximum allowable pressure and the hydrostatic head.If the latter is less than 3 % of the maximum allowable pressure, the effect of hydrostatic head shall be ignored.5.6.3 Safety valves set pressureThe safety valve(s) set pressure shall not exceed the maximum allowable pressure (see also EN 12953-8).5.6.4 Hydrostatic test pressureThe standard hydrostatic test pressure shall be not less than that obtained from the following:tc2,0p202,0pdt25,1RRpp(5.6-1)ordtpp43,1(5.6-2)which ever is the higher;whereRp0,2 20is the minimum value of the yield point at 20 °C.The value of Rp0,2 tc shall be taken for the boiler shell or ends at their calculation temperatures.In the case of boilers with expanded tubes, the values of pt = 1,43 pd may be taken.5.7 Allowances5.7.1 Allowances for fabrication tolerancesThe allowance c1 is to compensate for negative tolerances, and also any reduction in thickness as a result of theforming process.5.7.2 Corrosion allowanceFor the purpose of design, corrosion allowance c2 shall also include for erosion and abrasion if these effects areexpected to occur.For components with wall thickness: 30 mm and for all flat components, a corrosion allowance of 0 mm may be used; 30 mm a minimum corrosion allowance of 0,75 mm shall be taken.In the case of severe corrosion conditions an increased c2 value shall be chosen accordingly.SIST EN 12953-3:2002

EN 12953-3:2002 (E)96 Calculation temperature and nominal design stress6.1 Calculation temperatureThe calculation temperature tc shall be the mean metal temperature and shall be determined as specified in a) to e).a) For shells, drums and other components not subject to heat transfer, the calculation temperature shall be notless than the saturation temperature corresponding to the maximum allowable pressure or the maximum al-lowable temperature.b) For smoke tubes, the calculation temperature shall be determined in accordance with the following equations:tc = ts

2et(6.1-1)ortc = ts

25(6.1-2)whichever is the greater.c) The calculation temperature for areas of plate subject to heat transfer but not swept by flame, or for tube nestareas where the gas entry temperature is not greater than 800 °C, shall be determined in accordance with thefollowing equations:tc = ts

2eh(6.1-3)ortc = ts

50(6.1-4)whichever is the greater.The calculation temperature for flat walls in the flue gas pass with a flue gas temperature tG

400 °C shall be:tc = ts

20(6.1-5)d) For tube plates subject to gas entry temperatures exceeding 800 °C in fired boilers using fossil fuels, includingnatural gas, the calculation temperature shall be determined in accordance with Annex A, using the true gasentry temperature tG determined from the following equation:25,051AHtG(6.1-6)For fuels where the true gas entry temperature is higher than that obtained with natural gas, and for waste-heat boilers, the calculation temperature shall be determined in accordance with Annex A.The maximum metal temperature as determined in accordance with Annex A shall not exceed 420 °C.The condition for the calculation in accordance with Annex A is good contact between smoke tubes and tubesheet. Where this cannot be ensured, the method of attachment shown in Figure 12.4-1f) may be employedwith the following limitations:1) The depth of the connecting weld between smoke tubes and tube sheet shall be greater than or equal tothe wall thickness of the smoke tube plus 2 mm;2) The length of the gap, measured from the root of the weld, shall be less than or equal to four times thewall thickness of the smoke tube. If this dimension is exceeded, a cooling groove shall be provided.SIST EN 12953-3:2002

EN 12953-3:2002 (E)10If the above requirements are adhered to, the calculated temperature shall be determined in accordance withequation (6.1-4).For LPB, the calculation temperature for flat walls subject to a flue gas temperature

800 °C shall be given byequation (6.1-4).e) The calculation temperature for furnaces tubes shall be determined by the following equations:1) In the case of furnaces tubes subjected to the flame and a heat input

12 MWtc = ts
15(6.1-7)2) In the case of furnaces tubes subjected to flame and a heat input
12 MWfor oil firingtc = ts
3,5e
80(6.1-8)for gas firingtc = ts

65(6.1-9)NOTEEquations (6.1-8) and (6.1-9) are based on a maximum heat flux of 0,3 W/mm2 for oil firing and 0,24 W/mm2 forgas firing, taking into account an allowance of 0,25 mm for the thickness of scale with a conductivity of 1,2 W/m K.Where it can be shown that the heat flux is lower, e.g. low NOx firing, the calculations can be adjusted accordingly, but thevalue of tc should be not less than that given by equation (6.1-7).3) In the case of furnace tubes without flame the calculation temperature tc shall taken as being equal to thehighest of the two values given by the following equations:tc = ts

25(6.1-10)tc = ts

2e(6.1-11)6.2 Nominal design stressUnless otherwise stated in this Part of this European Standard, the nominal design stress f shall be the lower of thevalues obtained from the following ratios:4,2;5,1min2,0mtcpRRf(6.1-12)NOTEThe term "nominal design stress", designated by the symbol f, is the stress to be used in the equations herein forthe design of pressure parts. The detailed design rules in this Part will maintain the actual maximum stresses within acceptablelimits for the type of loading considered.7 Cylindrical shells under internal pressure7.1 Shell thickness7.1.1 RequirementsThe shell thickness after deduction of allowancesers = es-c1-c2 (7.1-1)of cylindrical shell shall be at least the greatest of those required by the following:SIST EN 12953-3:2002

EN 12953-3:2002 (E)11a) a minimum of 6 mm for cylindrical shells of outside diameter

1 000 mm except LPB. For outside diameter 1 000 mm and LPB a minimum of 4 mm shall be required;b) the requirements of 7.2;c) the requirements of 7.2 by applying 8.2 or 8.3.3 and 8.3.4.7.1.2 Required wall thickness including allowancesThe required wall thickness including allowances shall be derived from:esa = ecs

c2(7.1-2)7.2 Basic calculationThe required wall thickness without allowances ecs of a cylindrical shell shall be determined by either of the followingequationsvpfdpecsisccs2(7.2-1)if dis is given orccsosccspvpfdpe22(7.2-2)if dos is given.The equivalent value of the stress in the shell can be calculated by modifying

equations (7.2-1) or (7.2-2).7.3 Boiler supportExperience has shown that it shall not be necessary to carry out strength calculations in regard to boiler supports asfatigue is not normally encountered in this area.7.4 Reinforcing padsReinforcing pads may be used for the reinforcement of openings and branches and for the distribution of load atsupports and attachments. Such reinforcing pads shall be designed analogous to the requirements of 8.1.5.1.8 Openings and branches in cylindrical shellsNOTEThis clause specifies the design rules for openings and branches in cylindrical shells. All dimensions exclude allow-ances c1 and c2 for wall thickness.8.1 General8.1.1 Requirements for the efficiency of the main body with openings and branches8.1.1.1For cylindrical shells with openings the efficiency of the main body shall be satisfied by the following:a) by increasing the wall thickness of the main body compared with that of the cylindrical shell without openings.This wall thickness shall be available at least up to the length lrs measured from the edge of the opening (seeFigure 8.1-1; and for lrs see 8.1.2). Where there is a branch, the cylindrical length of the main body up to anyadjacent butt weld in it shall be lso

ers (see Figures 8.1-2 and 8.1-3).SIST EN 12953-3:2002

EN 12953-3:2002 (E)12b) by branches, measured on a length lb1 from the outside surface of the main body wall, which have been pro-vided with a wall thickness in excess of that required on account of the internal pressure, without or in connec-tion with an increase in main body wall thickness (see Figures 8.1-2 and -3). The welded joint between themain body and branch shall be a full-strength weld where in the case of branches in accordance with Fig-ure 8.1-3 a residual gap

1,5 mm may be present. A wall thickness ratio of erb/ers up to and including 2 shall bepermitted for dib

50 mm. This shall also apply to branches with dib
50 mm insofar as the diameter ratiodib/dis
0,2. For branches with dib
50 mm and a diameter ratio dib/dis

0,2, erb/ers shall not exceed unity. Theseconditions do not apply to access and inspection openings.Expanded or set-in and seal-welded-only branches (see Figure 8.1-1) or branches attached to the main body byfillet welds with a residual root gap

1,5 mm shall not be regarded as contributing to the reinforcement.The cylindrical length of branches up to the butt weld between tube and branch shall be lbo

erb (seeFigures 8.1-2 and 8.1-3).For branches with dib/dis

0,7 reference shall be made to 8.3.3.4.In general, special emphasis shall be placed on smooth wall thickness transitions. Wall thickness transitions shallbe made with an angle

30° (see Figure 8.1-2). The reinforcement of openings by inside reinforcing plates orpads shall not be permitted.c) reinforcement by reinforcing pads analogous to increasing the wall thickness as in a) (see Figures 8.1-4 to8.1-5).8.1.1.2Where there are elliptical access and inspection openings it shall be assumed that the ratio of major tominor axis does not exceed 1,5. For elliptical or obround openings in cylindrical shells the dime

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