BS EN 12953-3:2016 – TC:2020 Edition
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Tracked Changes. Shell boilers – Design and calculation for pressure parts
| Published By | Publication Date | Number of Pages |
| BSI | 2020 | 277 |
This Part of this European Standard specifies requirements for the design and calculation of pressure parts of shell boilers as defined in EN 12953 1. NOTE For other components such as economisers, superheaters, tube walls, headers, reference should be made to EN 12952 series.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 167 | Contents Page |
| 170 | European foreword |
| 172 | 1 Scope 2 Normative references 3 Terms and definitions |
| 173 | 4 Symbols and abbreviations 5 General 5.1 Boilers 5.2 Hot-water boilers 5.3 Main welds |
| 174 | 5.4 Weld factor 5.5 Thermal design of furnaces tubes 5.5.1 Design conditions |
| 175 | Figure 1 — Relation between heat input and inside diameter of the furnace di |
| 176 | Figure 2 — Relation between heat input and length of the furnace L 5.5.2 Furnace dimensions 5.5.3 Heat input |
| 177 | 5.5.4 Additional operating conditions 5.6 Dimensions of pressure parts 5.7 Determination of pressures 5.7.1 Maximum allowable pressure 5.7.2 Calculation pressure 5.7.3 Safety valves set pressure |
| 178 | 5.7.4 Hydrostatic test pressure 5.8 Allowances 5.8.1 Allowance for material supply tolerances and forming processes 5.8.2 Allowance for metal wastage 5.9 Additional material requirements for plates |
| 179 | 5.10 Standardized fittings 5.11 Flanges 5.12 Design by analysis 5.13 Economizer and superheater 6 Calculation temperature and nominal design stress 6.1 Calculation temperature |
| 180 | 6.2 Nominal design stress 7 Cylindrical shells 7.1 Shell thickness 7.1.1 Requirements |
| 181 | 7.1.2 Required wall thickness including allowances 7.2 Basic calculation subjected to internal pressure 7.3 Boiler supports and lifting lugs 8 Openings and branches in cylindrical shells 8.1 General 8.1.1 Introduction 8.1.2 Requirements for the reinforcement of openings in shells |
| 182 | Figure 3 — Calculation dimensions for elliptical openings |
| 183 | 8.1.3 Effective lengths lrs for calculation of efficiencies and of compensations |
| 184 | Figure 4 — Cylindrical shell with fillet welded branch (no additional reinforcement) Figure 5 —Cylindrical shell with full penetration welded branch (set-through) |
| 185 | Figure 6 — Cylindrical shell with welded-on branch Figure 7 — Opening with reinforcing pad |
| 186 | Figure 8 — Opening with reinforcing pad and full penetration branch Figure 9 — Opening with reinforcing ring (flange) |
| 187 | 8.1.4 Condition of isolated openings 8.1.5 Requirements for design of branches 8.1.6 Requirements for design of reinforcing pads 8.1.6.1 General 8.1.6.2 Pressure considerations |
| 188 | Figure 10 — Welding of reinforcing pads by set-through and full penetration welded branch 8.1.7 General requirements for calculation of cross-sectional and pressure-loaded areas 8.2 Efficiency factor, alternative calculation method, maximum diameter of an un-reinforced opening 8.2.1 General |
| 189 | 8.2.2 Allowable efficiency and maximum diameter of an unreinforced opening 8.2.3 Isolated openings |
| 190 | Figure 11 — Tube attached to shell 8.2.4 Adjacent openings 8.3 Design of openings and branches in shells (efficiency and reinforcement) 8.3.1 Symbols and abbreviations |
| 191 | 8.3.2 Requirements for application 8.3.2.1 Openings 8.3.2.2 Minimum thickness of nozzles and branch connections |
| 192 | Figure 12 — Load diagram for cylindrical shell with oblique branch and reinforcing pad |
| 193 | Figure 13 — Load diagram for cylindrical shell with non-radial branch |
| 194 | Figure 14 — Load diagram for cylindrical shell with adjacent branches, arranged with an angle Φ to the axis of the shell |
| 195 | Figure 15 — Load diagram for cylindrical shell with non-radial adjacent branches, arranged on the circumference 8.3.3 Design of isolated openings and branch connections 8.3.3.1 General |
| 196 | 8.3.3.2 Isolated opening with a radial branch 8.3.3.3 Isolated opening with an oblique branch and additional reinforcing pad |
| 197 | 8.3.3.4 Cylindrical shells with a branch not radially arranged 8.3.4 Design of adjacent openings and branch connections 8.3.4.1 General 8.3.4.2 Condition of adjacent openings and branches 8.3.4.3 Shell with lower design stress than the branches 8.3.4.4 Branches with equal or lower design stress than the shell |
| 198 | 8.3.4.5 Adjacent branches in the circumferential direction 9 Ends 9.1 Unstayed dished heads without openings 9.1.1 Unstayed dished heads under internal pressure 9.1.2 Limiting conditions |
| 200 | Figure 16 — Shape factor C for unstayed dished heads without openings 9.1.3 Unstayed dished heads under external pressure |
| 201 | 9.2 Flat unstayed removable closures Table 1 — Values for C1 |
| 202 | Figure 17 — Flat unstayed removable closures 9.3 Unstayed flat plates |
| 203 | 10 Supported flat plates, stays and stiffeners 10.1 Breathing space for flat plates Table 2 — Breathing space between furnace and shell if eh ≤ 25 mm |
| 204 | Table 3 — Breathing space between furnace and shell when the thickness of the end plates exceeds 25 mm |
| 205 | Figure 18 — Examples for breathing spaces 10.2 Stayed flat surfaces 10.2.1 General 10.2.2 Radius of flange 10.2.3 Point of support |
| 206 | Figure 19 — Point of support of a flanged end 10.2.4 Thickness |
| 208 | Figure 20 — Example for main and sub-circles / rectangular areas Figure 21 — Example for main and sub-circles (single furnace boiler) |
| 209 | Figure 22 — Determination of factor y 10.2.5 Values of constant C4 |
| 210 | Table 4— Values for constant C4 |
| 211 | Figure 23 — Example for pressure loaded areas |
| 212 | Figure 24 — Permitted weld details of bar stays without washers |
| 213 | Figure 25 — Permitted weld details of bar stays with washers (unheated) |
| 214 | Figure 26 — Permitted weld details of stay tubes without washers |
| 215 | Figure 27 — Permitted weld details of stay tubes with washers (unheated) |
| 216 | Figure 28 — Access opening for wet back boilers |
| 219 | Figure 30 — Distances from manhole reinforcing ring 10.2.6 Stays for wet back reversal chambers |
| 220 | Figure 31 — Location of stays in reversal chamber back plates |
| 221 | 10.2.7 Stay tubes and bars 10.2.8 Loads on stay tubes and bar stays 10.2.9 Gusset stays 10.2.9.1 Principals for staying 10.2.9.2 Load on each stay 10.2.9.3 Calculation of gusset stays |
| 222 | Figure 32 — Details of welded gusset stays |
| 223 | 10.2.10 Weld attachments 10.2.11 Additional requirements for set-in end plates 10.2.11.1 General 10.2.11.2 Shell thickness local to the corner joint 10.2.11.3 Design parameters |
| 224 | Table 5 — Design parameters for set-in end plates |
| 225 | Table 6 — Conditions for omitting sections of fillet welds (back welds) from corner joints of flat end plates 10.2.12 Girder stays supporting the flat section of a reversal chamber 11 Design of isolated openings in boiler flat end plates 11.1 Unreinforced isolated openings 11.2 Branch openings |
| 227 | Figure 33 — Compensation of branch in flat end plate 11.3 Manholes, headholes and handholes |
| 228 | Figure 34 — Compensation for elliptical manholes or inspection openings in flat end plates 12 Unpierced tubes and tube plates 12.1 Thickness of straight tubes subject to external pressure Table 7 — Lowest nominal thickness of tubes |
| 229 | 12.2 Thickness of straight tubes subject to internal pressure 12.3 Wall thickness and ovality of elbows and tube bends 12.3.1 General 12.3.2 Departure from circularity of the tube bends |
| 230 | Figure 35 — Limits of departure from circularity for single operation bending Figure 36 — Limits of departure from circularity for double operation bending |
| 231 | Figure 37 — Notation used for tube bends Figure 38 — Design factors Ci and Co 12.4 Smoke tubes |
| 233 | Table 8 — Permitted methods of attaching smoke tubes |
| 235 | 12.5 Pitch of tubes 12.6 Thickness of the tube plates within tube nests |
| 236 | 13 Furnaces tubes, furnace components and reversal chambers of cylindrical form subject to external pressure 13.1 Furnaces tubes 13.1.1 Plain furnaces tubes 13.1.2 Corrugated furnaces tubes |
| 237 | 13.1.3 Safety factors 13.1.4 Furnace components 13.1.5 Reversal chambers |
| 238 | Figure 39 — Cross sectional area for Fox type corrugated tube 13.2 Calculation length of composite furnaces tubes |
| 239 | 13.3 Tolerances of furnaces tubes 13.4 Stiffeners 13.4.1 General Figure 40 — Furnace stiffeners up to and including 22 mm thick for plain and corrugated sections |
| 240 | Figure 41 — Furnace stiffeners thicker than 22 mm for plain and corrugated sections 13.4.2 Stiffener sections made from bar or plate 13.4.3 Stiffeners located within the zone of peak heat flux 13.4.4 Bowling hoops |
| 243 | Figure 42 — Bowling hoops 14 Access and inspection openings 14.1 General requirements |
| 244 | 14.2 Types and minimum dimensions of access and inspection openings |
| 245 | Figure 43 — Openings for access and inspection |
| 246 | Table 11 — Openings for access and inspection 14.3 Minimum gasket bearing width and clearance for access and inspection doors 14.4 Access and inspection openings in flat plates 14.5 Requirements for entry area into boilers with a shell outside diameter greater than 1 400 mm 14.6 Accessibility and arrangement of entry and inspection openings |
| 247 | Annex A (informative) Calculation form for “Walker”-type reverse curve sections or corrugations |
| 249 | Annex B (normative) Furnace calculation temperature B.1 Calculation of the maximum and the middle furnace wall temperature Figure B.1 — Calculation diameter of the furnace Dg = dOFR respectively Dg = (dOFR + dl) 0,5 |
| 250 | Figure B.2 — Free length of the furnace Table B.1 — Emission-coefficient – Theoretic flame temperature |
| 251 | Table B.2 — Thermal conductivity λ in W/mm K as function of the temperature |
| 252 | Annex C (informative) Calculation of tube plate temperatures C.1 General C.2 Symbols |
| 253 | Table C.1 — Symbols C.3 Calculation method C.3.1 Radiation coefficients |
| 254 | Figure C.1 — Radiation coefficient h’R for black exchange (F = 1) |
| 255 | Figure C.2 — Determination of overall exchange factor F |
| 256 | Figure C.3 — AR/AC for a cylindrical chamber with diameter D and length L |
| 257 | C.3.2 Convection coefficients |
| 258 | Figure C.4 — Basis convection coefficient h’CO |
| 259 | Figure C.5 — Determination of correction factor |
| 260 | Figure C.6 — Determination of correction factor C.3.3 Weighted average gas-side heat transfer coefficient |
| 261 | Figure C.7 — Non-dimensional tube area |
| 262 | Figure C.8 — Non-dimensional plate area C.3.4 Tube plate thermal conductance |
| 263 | C.3.5 Water side heat transfer C.3.6 Tube plate temperatures Figure C.9 — Tube/plate area ratio |
| 264 | Figure C.10 — Factor η |
| 265 | Figure C.11 — Factor Φ |
| 266 | Figure C.12 — Factor β C.4 Example of a calculation carried out using the method given in C.3 C.4.1 Design data assumed |
| 267 | C.4.2 Calculation of radiation coefficient C.4.3 Calculation of convection coefficients C.4.4 Calculation of weighted average gas-side heat transfer coefficient C.4.5 Calculation of tube plate thermal conductance |
| 268 | C.4.6 Calculation of tube plate temperatures |
| 269 | Annex D (normative) Economizer and superheater with water tube design connected to the shell boiler D.1 General Figure D.1 — Typical elements of an economizer or superheater D.2 Design of economizer and superheater connected to shell boilers |
| 271 | Annex E (informative) Significant technical changes between this European Standard and the previous edition |
| 272 | Annex ZA (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 2014/68/EU aimed to be covered Table ZA.1 — Correspondence between this European Standard and Directive 2014/68/EU on Pressure Equipment |
| 273 | Bibliography |
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