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BS EN 12952-3:2022

BS EN 12952-3:2022

$215.11

Water-tube boilers and auxiliary installations – Design and calculation for pressure parts of the boiler

Published By Publication Date Number of Pages
BSI 2022 170
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This document specifies the requirements for the design and calculation of water-tube boilers as defined in EN 12952-1. The purpose of this document is to ensure that the hazards associated with water-tube boilers are reduced to a minimum by the proper application of the design according to this part of EN 12952.

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PDF Pages PDF Title
2 undefined
14 1 Scope
2 Normative references
15 3 Terms and definitions
4 Symbols and abbreviations
5 General
5.1 Purpose
5.2 Dimensions of pressure parts
16 5.3 Strength of pressure parts
5.4 Design by analysis
5.5 Cyclic loading
17 5.6 Other design requirements
5.6.1 General
18 5.6.2 Access
5.6.3 Drainage and venting
5.7 Design, calculation and test pressures
5.7.1 Design pressure
5.7.2 Calculation pressure
19 5.7.3 Calculation pressure for pressure differences
5.7.4 Hydrostatic test
5.7.4.1 General
5.7.4.2 Test pressure
5.7.4.3 Calculation of hydrostatic test pressure
20 5.8 Metal wastage
5.8.1 Internal wastage
5.8.2 External wastage
5.8.3 Requirements
5.8.4 Stress corrosion
21 5.8.5 Mechanical requirements
5.9 Attachment on pressure parts
5.9.1 Load carrying attachments
5.9.2 Non load carrying attachments
6 Calculation temperature and nominal design stress
6.1 Calculation temperature
6.1.1 General
22 6.1.2 Circulation boilers
6.1.3 Once-through boilers, superheaters and reheaters
6.1.4 Hot water generators
6.1.5 Temperature allowances for unheated components
23 6.1.6 Headers
6.1.7 Unheated components
6.1.8 Components protected against radiation
6.1.9 Components heated by convection
24 6.1.10 Components heated by radiation
25 6.2 Maximum through-the-wall temperature difference and maximum flue gas temperature for heated drums and headers
6.2.1 Maximum through-the-wall temperature difference
6.2.2 Headers exposed to flue gas
26 6.2.3 Allowable deviations
6.3 Design stress
6.3.1 General
27 6.3.2 Rolled and forged steels
6.3.3 Austenitic steels
28 6.3.4 Non-alloy and low-alloy cast steel
6.3.5 Nodular graphite cast iron
29 6.3.6 Design stress for welded connections operating under creep condition
6.3.7 Design stress for test pressure
7 Cylindrical shells of drums and headers under internal pressure
7.1 Shell thickness
7.1.1 Requirements
30 7.1.2 Required wall thickness including allowances
7.2 Basic calculation
7.2.1 Required wall thickness without allowances
7.2.2 Different thickness
7.2.3 Fabrication tolerances
31 7.3 Combined stress in drum or header shells
7.3.1 General
7.3.2 Stress from longitudinal loads
32 7.3.3 Longitudinal bending stress
33 7.3.4 Evaluation of ligament stress for inclined ligaments in drums
34 7.4 Boiler drum supports
35 7.5 Other stresses in cylindrical shells
8 Openings and branches in cylindrical shells of drums and headers and integral tubes
8.1 General
8.1.1 Requirements for the ligament efficiency of the main body with openings and branches
8.1.1.1 Ligament efficiency of the main body
36 8.1.1.2 Special requirements
8.1.1.3 Extruded openings
8.1.1.4 Forged branches
37 8.1.1.5 Conical transitions
8.1.1.6 Set-through nozzles
40 8.1.2 Effective lengths for calculation of efficiencies of components
41 8.1.3 Conditions for isolated openings
8.1.4 Requirements for design of branches
8.1.4.1 Main body with lower design stress than the branches
8.1.4.2 Branches or reinforcing with lower design stress than the main body
8.1.4.3 Extruded branches
8.1.4.4 Extruded branches in creep region
8.1.4.5 Special case
42 8.1.5 Requirements for the design of reinforcing pads
8.1.5.1 General
8.1.5.2 Pressure considerations
8.1.5.3 Non-pressure considerations
8.1.5.4 Tell-tale holes
8.2 Efficiency factor, calculation by way of approximation, and maximum diameter of unreinforced openings
8.2.1 General
8.2.2 Allowable efficiency and maximum diameter of unreinforced opening
43 8.2.3 Isolated openings
45 8.2.4 Adjacent openings
46 8.3 Design of openings and branches in cylindrical shells (efficiency and reinforcement)
8.3.1 Symbols and abbreviations
8.3.2 Requirements for application
8.3.2.1 Openings
47 8.3.2.2 Branches
51 8.3.3 Design of isolated openings and branch connections
8.3.3.1 General
8.3.3.2 Isolated opening with a vertical branch
52 8.3.3.3 Isolated opening with an oblique branch and additional reinforcement
8.3.3.4 Cross-section vertical to the main body axis
53 8.3.3.5 Cylindrical shells with a branch not radially arranged
8.3.3.6 Y-shaped branches
8.3.3.7 Cylindrical shells as forged fitting (elbows)
54 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 Main body with lower design stress than the branches
55 8.3.4.4 Branches with equal or lower design stress than the main body
8.3.4.5 Adjacent branches in the circumferential direction
8.4 Bolted connections
8.4.1 General
56 8.4.2 Symbols and abbreviations
57 8.4.3 Calculation of bolt diameter
58 8.4.4 Calculation of bolt load
8.4.4.1 General
8.4.4.2 Operating condition
59 8.4.4.3 Test pressure
8.4.4.4 Bolting-up condition prior to application of pressure
60 8.4.5 Calculation temperature tc
8.4.5.1 General
8.4.5.2 Thermal insulated joints
61 8.4.5.3 Joints without thermal insulation
8.4.6 Design strength value K
8.4.7 Safety factor S
8.4.8 Quality factor q
62 8.5 Screwed and socket welded connections
8.5.1 Screwed connections into the belt
8.5.2 Screwed socket connections
63 8.5.3 Socket welded connections
64 9 Headers and plain tubes of rectangular section
9.1 General
66 9.2 Symbols and abbreviations
67 9.3 Required wall thickness
9.3.1 General
68 9.3.2 Minimum wall thickness at the centre of one side
9.3.3 Minimum wall thickness at the corners
9.3.4 Minimum thickness at a line of openings
69 9.3.5 Minimum wall thickness at staggered opening arrangement (diagonal pitch)
9.3.6 Minimum wall thickness at isolated openings
70 10 Ends and spherical shells
10.1 Symbols and abbreviations
10.2 Spherical shells and dished heads
10.2.1 General
72 10.2.2 Calculation formula
75 10.2.3 Openings in dished ends and spherical ends
79 10.3 Unstayed flat ends
10.3.1 General
82 10.3.2 Thickness of circular unstayed flat ends
10.3.3 Thickness of non-circular and rectangular unstayed flat ends
85 10.4 Flat unstayed closures
87 11 Tubes
11.1 Symbols and abbreviations
11.2 Thickness of straight boiler tubes
11.2.1 Required wall thickness with allowances
88 11.2.2 Required wall thickness without allowances
11.2.3 Minimum thickness
89 11.2.4 Circumferentially butt welded tubes
11.3 Thickness of tube bends and elbows
11.3.1 General
11.3.2 Required wall thickness with allowances
90 11.3.3 Required wall thickness without allowances
11.3.4 Departure from circularity of tube bends
91 11.4 Flexibility of integral tubing systems
11.4.1 General
11.4.2 Analysis
11.5 Structural attachments to tubes
11.5.1 General
93 11.5.2 Attachments welded on tube bends
11.5.3 Length of attachments
11.5.4 Limit of intensity in the case of radial loading
11.5.5 Calculation of intensity in the case of radial loading
95 11.5.6 Strength of welds
96 11.6 Fitting and joining of heated tubes
11.6.1 Fitting of tubes
11.6.2 Joining of heated tubes
11.7 Joining of unheated tubes
11.7.1 General
11.7.2 Flanges and bolting
11.7.3 Butt welded joints
11.7.4 Screwed or screwed and seal welded joints
11.8 Standardized fittings
97 12 Pressure parts of irregular shape
12.1 Hydrostatic test for determining the allowable internal pressure
12.1.1 General
12.1.2 Proof test to produce yielding
98 12.1.3 Proof test to destruction
12.2 Numerical methods
12.2.1 General
12.2.2 Methods
99 12.2.3 Evaluation of stress
13 Fatigue
13.1 General
13.1.1 Procedure
13.1.2 Fatigue loading
100 13.1.3 Calculation of fluctuating stress
13.1.4 Fatigue assessment
13.2 Symbols and abbreviations
102 13.3 Exemption rule for fatigue analysis
13.3.1 General
13.3.2 Materials
103 13.3.3 Loadings
104 13.3.4 Temperature differences during transient operating conditions
110 13.4 Stress analysis for fatigue calculation
13.4.1 Principal and equivalent stresses
13.4.2 Temperature of a load cycle
111 13.4.3 Protection of the magnetite layer
13.4.4 Allowable circumferential stress range at the inside corner of a bore
13.4.5 Circumferential stress caused by pressure at the inside corner of a bore
112 13.4.6 Stresses on the branch caused by external forces and moments
13.4.7 Thermal stresses
13.4.8 Upper and lower limit of the circumferential stress at the inside corner of a bore
116 13.4.9 Admissible through-the-wall temperature differences
117 13.4.10 Allowable temperature transients
13.4.11 Components with oblique and/or non-radial branches
13.5 Example calculations
121 Annex A (normative)Calculation of tube bends and elbows
A.1 General
A.2 Symbols and abbreviations
122 A.3 Calculation
A.3.1 Required wall thickness
A.3.2 Calculation of the wall thickness
124 A.3.3 Calculation of stress
A.3.3.1 The strength conditions for the intrados of the bend shall be:
A.3.3.2 The strength conditions for the extrados of the bend shall be:
131 Annex B (normative)Fatigue cracking – Design to allow for fluctuating stress
B.1 General
B.2 Conditions
133 B.3 Symbols and abbreviations
134 B.4 Cyclic stress range and mean cyclic stress in the case of uniaxial and multiaxial fluctuating stress
B.4.1 General
B.4.2 Uniaxial stress state
B.4.3 Multiaxial stress state with principal stress directions constant
136 B.5 Correction factors for taking into account the influences of surface finish and weldments
144 B.6 Controlling stress range
B.6.1 General
B.6.1.1 Controlling stress range
B.6.1.2 Elastic range
B.6.1.3 Partly elastic range
B.6.1.4 Fully plastic range
145 B.6.2 Correction factor
146 B.7 Permissible stress range with a known number of load cycles
147 Annex C (informative)Examples of calculating the effects of fatigue
C.1 General
C.2 Calculation of the admissible number of load cycles
150 C.3 Calculation of the admissible temperature gradient
154 Annex D (informative)Physical properties of steels
D.1 General
D.2 Symbols and abbreviations
D.3 Physical properties
D.3.1 Density
D.3.2 Differential coefficient of linear thermal expansion
155 D.3.3 Heat capacity
D.3.4 Thermal diffusivity
D.3.5 Poisson’s ratio
D.4 Physical properties of steels
D.4.1 Data sheet (tables)
157 D.4.2 Graphs
161 D.4.3 Polynomials
164 Annex E (informative)Consideration of external wastage due to flue gas exposure
E.1 General
E.2 Symbols and abbreviations
E.3 Wall thickness of straight tubes in accordance to Clause 11
E.3.1 Required wall thickness with allowance
E.3.2 Required wall thickness without allowances
E.3.3 Circumferentially butt welded tubes
165 E.4 Wall thickness of tube bends and elbows in accordance with Clause 11
E.4.1 Required wall thickness with allowance
E.4.2 Required wall thickness without allowances
E.5 Wall thickness of tube bends and elbows in accordance with Annex A
166 Annex F (informative)Significant technical changes between this European Standard and the previous edition
167 Annex ZA (informative)Clauses of this European Standard addressing essential safety requirements of the Pressure Equipment Directive 2014/68/EU

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BS EN 12952-3:2022
$215.11