Water-tube boilers and auxiliary installations - Part 3: Design and calculation for pressure parts of the boiler

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.

Wasserrohrkessel und Anlagenkomponenten - Teil 3: Konstruktion und Berechnung für drucktragende Kesselteile

Dieses Dokument legt Anforderungen an die Konstruktion und Berechnung von Wasserrohrkesseln nach der Definition in EN 12952 1 fest.
Durch die sachgemäße Konstruktion nach diesem Teil des Dokuments EN 12952 wird sichergestellt, dass die Gefährdungen, die mit Wasserrohrkesseln einhergehen auf ein Minimum reduziert werden.

Chaudière à tubes d'eau et installations auxiliaires - Partie 3 : Conception et calcul des parties sous pression de la chaudière

Le présent document spécifie les règles de conception et de calcul des chaudières à tubes d'eau telles que définies dans l'EN 12952-1.
L’objet du présent Document est d’assurer que les phénomènes dangereux associés aux chaudières à tubes d’eau sont réduits au minimum par l’application appropriée des exigences de conception de la présente partie de l’EN 12952.

Vodocevni kotli in pomožne napeljave - 3. del: Konstruiranje in izračun tlačno obremenjenih delov kotla

General Information

Status
Published
Publication Date
01-Nov-2022
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
02-Nov-2022
Due Date
26-Jul-2022
Completion Date
02-Nov-2022

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SLOVENSKI STANDARD
oSIST prEN 12952-3:2021
01-julij-2021
Vodocevni kotli in pomožne napeljave - 3. del: Konstruiranje in izračun tlačno
obremenjenih delov kotla

Water-tube boilers and auxiliary installations - Part 3: Design and calculation for pressure

parts of the boiler

Wasserrohrkessel und Anlagenkomponenten - Teil 3: Konstruktion und Berechnung für

drucktragende Kesselteile

Chaudières à tubes d'eau et installations auxiliaires - Partie 3 : Conception et calcul des

parties sous pression
Ta slovenski standard je istoveten z: prEN 12952-3
ICS:
27.060.30 Grelniki vode in prenosniki Boilers and heat exchangers
toplote
oSIST prEN 12952-3:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 12952-3:2021
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oSIST prEN 12952-3:2021
DRAFT
EUROPEAN STANDARD
prEN 12952-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2021
ICS 27.040 Will supersede EN 12952-3:2011
English Version
Water-tube boilers and auxiliary installations - Part 3:
Design and calculation for pressure parts of the boiler

Chaudières à tubes d'eau et installations auxiliaires - Wasserrohrkessel und Anlagenkomponenten - Teil 3:

Partie 3 : Conception et calcul des parties sous pression Konstruktion und Berechnung für drucktragende

Kesselteile

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 269.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations

which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC

Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12952-3:2021 E

worldwide for CEN national Members.
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oSIST prEN 12952-3:2021
prEN 12952-3:2021 (E)
Contents Page

European foreword ...................................................................................................................................................... 8

1 Scope .................................................................................................................................................................. 10

2 Normative references .................................................................................................................................. 10

3 Terms and definitions ................................................................................................................................. 11

4 Symbols and abbreviations ....................................................................................................................... 11

5 General.............................................................................................................................................................. 11

5.1 Purpose ............................................................................................................................................................. 11

5.2 Dimensions of pressure parts .................................................................................................................. 11

5.3 Strength of pressure parts ......................................................................................................................... 12

5.4 Design by analysis ........................................................................................................................................ 12

5.5 Cyclic loading .................................................................................................................................................. 12

5.6 Other design requirements ....................................................................................................................... 13

5.6.1 General.............................................................................................................................................................. 13

5.6.2 Access ................................................................................................................................................................ 14

5.6.3 Drainage and venting .................................................................................................................................. 14

5.7 Design, calculation and test pressures .................................................................................................. 14

5.7.1 Design pressure ............................................................................................................................................. 14

5.7.2 Calculation pressure .................................................................................................................................... 14

5.7.3 Calculation pressure for pressure differences ................................................................................... 15

5.7.4 Hydrostatic test ............................................................................................................................................. 15

5.8 Metal wastage ................................................................................................................................................. 16

5.8.1 Internal wastage ............................................................................................................................................ 16

5.8.2 External wastage ........................................................................................................................................... 16

5.8.3 Requirements ................................................................................................................................................. 17

5.8.4 Stress corrosion ............................................................................................................................................. 17

5.8.5 Mechanical requirements .......................................................................................................................... 17

5.9 Attachment on pressure parts ................................................................................................................. 17

5.9.1 Load carrying attachments ........................................................................................................................ 17

5.9.2 Non load carrying attachments ................................................................................................................ 17

6 Calculation temperature and nominal design stress ....................................................................... 18

6.1 Calculation temperature ............................................................................................................................ 18

6.1.1 General.............................................................................................................................................................. 18

6.1.2 Circulation boilers ........................................................................................................................................ 18

6.1.3 Once-through boilers, superheaters and reheaters ......................................................................... 19

6.1.4 Hot water generators .................................................................................................................................. 19

6.1.5 Temperature allowances for unheated components ....................................................................... 19

6.1.6 Headers ............................................................................................................................................................. 19

6.1.7 Unheated components ................................................................................................................................ 19

6.1.8 Components protected against radiation ............................................................................................ 20

6.1.9 Components heated by convection ......................................................................................................... 20

6.1.10 Components heated by radiation ............................................................................................................ 20

6.2 Maximum through-the-wall temperature difference and maximum flue gas

temperature for heated drums and headers ...................................................................................... 22

6.2.1 Maximum through-the-wall temperature difference ...................................................................... 22

6.2.2 Headers exposed to flue gas ...................................................................................................................... 22

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6.2.3 Allowable deviations ................................................................................................................................... 22

6.3 Design stress................................................................................................................................................... 22

6.3.1 General ............................................................................................................................................................. 22

6.3.2 Rolled and forged steels ............................................................................................................................. 24

6.3.3 Austenitic steels ............................................................................................................................................ 25

6.3.4 Cast steel .......................................................................................................................................................... 25

6.3.5 Nodular graphite cast iron ........................................................................................................................ 26

6.3.6 Design stress for welded connections operating under creep condition ................................. 26

6.3.7 Design stress for test pressure ................................................................................................................ 26

7 Cylindrical shells of drums and headers under internal pressure ............................................. 27

7.1 Shell thickness ............................................................................................................................................... 27

7.1.1 Requirements ................................................................................................................................................. 27

7.1.2 Required wall thickness including allowances .................................................................................. 27

7.2 Basic calculation ........................................................................................................................................... 27

7.2.1 Required wall thickness without allowances ..................................................................................... 27

7.2.2 Different thickness ....................................................................................................................................... 28

7.2.3 Fabrication tolerances ................................................................................................................................ 28

7.3 Combined stress in drum or header shells .......................................................................................... 28

7.3.1 General ............................................................................................................................................................. 28

7.3.2 Stress from longitudinal loads ................................................................................................................. 28

7.3.3 Longitudinal bending stress ..................................................................................................................... 29

7.3.4 Evaluation of ligament stress for inclined ligaments in drums ................................................... 30

7.4 Boiler drum supports .................................................................................................................................. 32

7.5 Other stresses in cylindrical shells ........................................................................................................ 32

8 Openings and branches in cylindrical shells of drums and headers and integral tubes .... 32

8.1 General ............................................................................................................................................................. 32

8.1.1 Requirements for the ligament efficiency of the main body with openings and

branches ........................................................................................................................................................... 32

8.1.2 Effective lengths for calculation of efficiencies of components ................................................... 38

8.1.3 Conditions for isolated openings ............................................................................................................ 38

8.1.4 Requirements for design of branches ................................................................................................... 38

8.1.5 Requirements for the design of reinforcing pads ............................................................................. 39

8.2 Efficiency factor, calculation by way of approximation, and maximum diameter of

unreinforced openings ............................................................................................................................... 40

8.2.1 General ............................................................................................................................................................. 40

8.2.2 Allowable efficiency and maximum diameter of unreinforced opening .................................. 40

8.2.3 Isolated openings .......................................................................................................................................... 40

8.2.4 Adjacent openings ........................................................................................................................................ 43

8.3 Design of openings and branches in cylindrical shells (efficiency and reinforcement) ..... 43

8.3.1 Symbols and abbreviations ....................................................................................................................... 43

8.3.2 Requirements for application .................................................................................................................. 44

8.3.3 Design of isolated openings and branch connections ..................................................................... 49

8.3.4 Design of adjacent openings and branch connections .................................................................... 52

8.4 Bolted connections ....................................................................................................................................... 53

8.4.1 General ............................................................................................................................................................. 53

8.4.2 Symbols and abbreviations ....................................................................................................................... 54

8.4.3 Calculation of bolt diameter ..................................................................................................................... 55

8.4.4 Calculation of bolt load ............................................................................................................................... 56

8.4.5 Calculation temperature t ....................................................................................................................... 58

8.4.6 Design strength value K .............................................................................................................................. 59

8.4.7 Safety factor S ................................................................................................................................................. 59

8.4.8 Quality factor q .............................................................................................................................................. 59

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8.5 Screwed and socket welded connections ............................................................................................. 60

8.5.1 Screwed connections into the belt .......................................................................................................... 60

8.5.2 Screwed socket connections ..................................................................................................................... 60

8.5.3 Socket welded connections ....................................................................................................................... 61

9 Headers and plain tubes of rectangular section ................................................................................ 62

9.1 General.............................................................................................................................................................. 62

9.2 Symbols and abbreviations ....................................................................................................................... 63

9.3 Required wall thickness ............................................................................................................................. 65

9.3.1 General.............................................................................................................................................................. 65

9.3.2 Minimum wall thickness at the centre of one side ........................................................................... 66

9.3.3 Minimum wall thickness at the corners ............................................................................................... 66

9.3.4 Minimum thickness at a line of openings ............................................................................................. 66

9.3.5 Minimum wall thickness at staggered opening arrangement (diagonal pitch) ..................... 67

9.3.6 Minimum wall thickness at isolated openings ................................................................................... 67

10 Ends and spherical shells ........................................................................................................................... 68

10.1 Symbols and abbreviations ....................................................................................................................... 68

10.2 Spherical shells and dished heads .......................................................................................................... 68

10.2.1 General.............................................................................................................................................................. 68

10.2.2 Calculation formula ...................................................................................................................................... 70

10.2.3 Openings in dished ends and spherical ends ...................................................................................... 73

10.3 Unstayed flat ends ........................................................................................................................................ 77

10.3.1 General.............................................................................................................................................................. 77

10.3.2 Thickness of circular unstayed flat ends .............................................................................................. 79

10.3.3 Thickness of non-circular and rectangular unstayed flat ends.................................................... 80

10.4 Flat unstayed closures ................................................................................................................................ 83

11 Tubes ................................................................................................................................................................. 85

11.1 Symbols and abbreviations ....................................................................................................................... 85

11.2 Thickness of straight boiler tubes .......................................................................................................... 85

11.2.1 Required wall thickness with allowances ............................................................................................ 85

11.2.2 Required wall thickness without allowances ..................................................................................... 86

11.2.3 Minimum thickness ...................................................................................................................................... 86

11.2.4 Circumferentially butt welded tubes ..................................................................................................... 87

11.3 Thickness of tube bends and elbows ..................................................................................................... 87

11.3.1 General.............................................................................................................................................................. 87

11.3.2 Required wall thickness with allowances ............................................................................................ 87

11.3.3 Required wall thickness without allowances ..................................................................................... 88

11.3.4 Departure from circularity of tube bends ............................................................................................ 88

11.4 Flexibility of integral tubing systems .................................................................................................... 89

11.4.1 General.............................................................................................................................................................. 89

11.4.2 Analysis ............................................................................................................................................................ 89

11.5 Structural attachments to tubes .............................................................................................................. 89

11.5.1 General.............................................................................................................................................................. 89

11.5.2 Attachments welded on tube bends ....................................................................................................... 91

11.5.3 Length of attachments ................................................................................................................................. 91

11.5.4 Limit of intensity in the case of radial loading ................................................................................... 91

11.5.5 Calculation of intensity in the case of radial loading ....................................................................... 91

11.5.6 Strength of welds .......................................................................................................................................... 93

11.6 Fitting and joining of heated tubes ......................................................................................................... 94

11.6.1 Fitting of tubes ............................................................................................................................................... 94

11.6.2 Joining of heated tubes ............................................................................................................................... 94

11.7 Joining of unheated tubes .......................................................................................................................... 94

11.7.1 General.............................................................................................................................................................. 94

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11.7.2 Flanges and bolting ...................................................................................................................................... 94

11.7.3 Butt welded joints ........................................................................................................................................ 94

11.7.4 Screwed or screwed and seal welded joints ....................................................................................... 94

11.8 Standardized fittings ................................................................................................................................... 94

12 Pressure parts of irregular shape ........................................................................................................... 95

12.1 Hydrostatic test for determining the allowable internal pressure ............................................ 95

12.1.1 General ............................................................................................................................................................. 95

12.1.2 Proof test to produce yielding .................................................................................................................. 95

12.1.3 Proof test to destruction ............................................................................................................................ 96

12.2 Numerical methods ...................................................................................................................................... 97

12.2.1 General ............................................................................................................................................................. 97

12.2.2 Methods ............................................................................................................................................................ 97

12.2.3 Evaluation of stress ...................................................................................................................................... 97

13 Fatigue .............................................................................................................................................................. 97

13.1 General ............................................................................................................................................................. 97

13.1.1 Procedure ........................................................................................................................................................ 97

13.1.2 Fatigue loading .............................................................................................................................................. 97

13.1.3 Calculation of fluctuating stress .............................................................................................................. 98

13.1.4 Fatigue assessment ...................................................................................................................................... 98

13.2 Symbols and abbreviations ....................................................................................................................... 98

13.3 Exemption rule for fatigue analysis .................................................................................................... 100

13.3.1 General .............................
...

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