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BS EN 12953-3:2016:2024 Edition

BS EN 12953-3:2016:2024 Edition

$165.47

Shell boilers – Design and calculation for pressure parts

Published By Publication Date Number of Pages
BSI 2024 114
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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.

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PDF Pages PDF Title
2 undefined
6 Contents Page
9 European foreword
11 1 Scope
2 Normative references
3 Terms and definitions
12 4 Symbols and abbreviations
5 General
5.1 Boilers
5.2 Hot-water boilers
5.3 Main welds
13 5.4 Weld factor
5.5 Thermal design of furnaces tubes
5.5.1 Design conditions
14 Figure 1 — Relation between heat input and inside diameter of the furnace di
15 Figure 2 — Relation between heat input and length of the furnace L
5.5.2 Furnace dimensions
5.5.3 Heat input
16 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
17 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
18 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
19 6.2 Nominal design stress
7 Cylindrical shells
7.1 Shell thickness
7.1.1 Requirements
20 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
21 Figure 3 — Calculation dimensions for elliptical openings
22 8.1.3 Effective lengths lrs for calculation of efficiencies and of compensations
23 Figure 4 — Cylindrical shell with fillet welded branch (no additional reinforcement)
Figure 5 —Cylindrical shell with full penetration welded branch (set-through)
24 Figure 6 — Cylindrical shell with welded-on branch
Figure 7 — Opening with reinforcing pad
25 Figure 8 — Opening with reinforcing pad and full penetration branch
Figure 9 — Opening with reinforcing ring (flange)
26 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
27 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
28 8.2.2 Allowable efficiency and maximum diameter of an unreinforced opening
8.2.3 Isolated openings
29 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
30 8.3.2 Requirements for application
8.3.2.1 Openings
8.3.2.2 Minimum thickness of nozzles and branch connections
31 Figure 12 — Load diagram for cylindrical shell with oblique branch and reinforcing pad
32 Figure 13 — Load diagram for cylindrical shell with non-radial branch
33 Figure 14 — Load diagram for cylindrical shell with adjacent branches, arranged with an angle Φ to the axis of the shell
34 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
35 8.3.3.2 Isolated opening with a radial branch
8.3.3.3 Isolated opening with an oblique branch and additional reinforcing pad
36 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
37 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
39 Figure 16 — Shape factor C for unstayed dished heads without openings
9.1.3 Unstayed dished heads under external pressure
40 9.2 Flat unstayed removable closures
Table 1 — Values for C1
41 Figure 17 — Flat unstayed removable closures
9.3 Unstayed flat plates
42 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
43 Table 3 — Breathing space between furnace and shell when the thickness of the end plates exceeds 25 mm
44 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
45 Figure 19 — Point of support of a flanged end
10.2.4 Thickness
47 Figure 20 — Example for main and sub-circles / rectangular areas
Figure 21 — Example for main and sub-circles (single furnace boiler)
48 Figure 22 — Determination of factor y
10.2.5 Values of constant C4
49 Table 4— Values for constant C4
50 Figure 23 — Example for pressure loaded areas
51 Figure 24 — Permitted weld details of bar stays without washers
52 Figure 25 — Permitted weld details of bar stays with washers (unheated)
53 Figure 26 — Permitted weld details of stay tubes without washers
54 Figure 27 — Permitted weld details of stay tubes with washers (unheated)
55 Figure 28 — Access opening for wet back boilers
58 Figure 30 — Distances from manhole reinforcing ring
10.2.6 Stays for wet back reversal chambers
59 Figure 31 — Location of stays in reversal chamber back plates
60 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
61 Figure 32 — Details of welded gusset stays
62 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
63 Table 5 — Design parameters for set-in end plates
64 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
66 Figure 33 — Compensation of branch in flat end plate
11.3 Manholes, headholes and handholes
67 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
68 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
69 Figure 35 — Limits of departure from circularity for single operation bending
Figure 36 — Limits of departure from circularity for double operation bending
70 Figure 37 — Notation used for tube bends
Figure 38 — Design factors Ci and Co
12.4 Smoke tubes
72 Table 8 — Permitted methods of attaching smoke tubes
74 12.5 Pitch of tubes
12.6 Thickness of the tube plates within tube nests
75 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
76 13.1.3 Safety factors
13.1.4 Furnace components
13.1.5 Reversal chambers
77 Figure 39 — Cross sectional area for Fox type corrugated tube
13.2 Calculation length of composite furnaces tubes
78 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
79 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
82 Figure 42 — Bowling hoops
14 Access and inspection openings
14.1 General requirements
83 14.2 Types and minimum dimensions of access and inspection openings
84 Figure 43 — Openings for access and inspection
85 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
86 Annex A (informative) Calculation form for “Walker”-type reverse curve sections or corrugations
88 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
89 Figure B.2 — Free length of the furnace
Table B.1 — Emission-coefficient – Theoretic flame temperature
90 Table B.2 — Thermal conductivity λ in W/mm K as function of the temperature
91 Annex C (informative) Calculation of tube plate temperatures
C.1 General
C.2 Symbols
92 Table C.1 — Symbols
C.3 Calculation method
C.3.1 Radiation coefficients
93 Figure C.1 — Radiation coefficient h’R for black exchange (F = 1)
94 Figure C.2 — Determination of overall exchange factor F
95 Figure C.3 — AR/AC for a cylindrical chamber with diameter D and length L
96 C.3.2 Convection coefficients
97 Figure C.4 — Basis convection coefficient h’CO
98 Figure C.5 — Determination of correction factor
99 Figure C.6 — Determination of correction factor
C.3.3 Weighted average gas-side heat transfer coefficient
100 Figure C.7 — Non-dimensional tube area
101 Figure C.8 — Non-dimensional plate area
C.3.4 Tube plate thermal conductance
102 C.3.5 Water side heat transfer
C.3.6 Tube plate temperatures
Figure C.9 — Tube/plate area ratio
103 Figure C.10 — Factor η
104 Figure C.11 — Factor Φ
105 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
106 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
107 C.4.6 Calculation of tube plate temperatures
108 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
110 Annex E (informative) Significant technical changes between this European Standard and the previous edition
111 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
112 Bibliography

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BS EN 12953-3:2016
$165.47