EPERC Presentation Baylac

1
Introduction to European Standard EN 13445 on
Advanced Design of Pressure Vessels
Guy BAYLAC Consultant for Pressure
Equipment Technical Advisor of EPERC IIW Annual
Assembly 11-16 July 2002 Paper XI-800-04
2
Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

3
The European standard EN 13445Unfired pressure
vessels

• After 10 years of discussion of European experts
  a consensus was reached
• Publication and Harmonisation in May 2002
• First step of continuous process of development

4
Part 3Design

• Very innovative
• Limit Analysis
• Design by Analysis Direct Route

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Publication of the book
BACKGROUND TO THE DESIGN RULES www.unm.fr/en/gene
ral/en13445 Editors Guy BAYLAC Danielle KOPLEWICZ
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Contents
7
Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

8
Design Methods

• Design by Formulae (DBF)
• Design by Analysis (DBA)
• Annex C stress partitioning
• Annex B Design by Analysis Direct Route

9
The concept of testing group

• One of the four groups designed to specify the
  extent of non destructive and destructive testing
  in association with
• Material grouping
• Welding process
• Maximum thickness
• Service temperature range

10
Testing groups of steel pressure vessels
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Fatigue and NDT
Only testing groups 1, 2 and 3
yes
no
neq ? 500
Fatigue analysis
All testing groups
yes
D ? Dmax
no
NDT Level C
NDT Level C
NDT Level B
12
Number of equivalent full pressure cycles
3
is the maximum permissible pressure based on the
analysis thickness
13
Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

14
A high level of nominal design stress
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EN 13445-3 Nominal design stress
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Methodology
In ordinate
Nominal design stress at t C
Safety factor S

Yield strength at t C
In abscissa
Yield strength at t C
Ratio

Tensile strength at 20 C
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Give an example
Rp0,2/t
S 1,5 for
? 0,625
Rm/20
DBF Nominal design stress
Rp0,2/t
S gt 1,5 for
gt 0,625
Rm/20
1,5
0,625
2,4
18
2,5
1,5/2,4 0,625
1,5
0,8
0
1
0,3
0,6
0,8
0,4
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Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

20
Testing group 4 vessels

• Large number of vessels built without NDT
• Easy-to-weld materials (groups 1.1 and 8.1)
• With a nominal design stress equal to 90 of the
  current nominal design stress

21
Testing group 4 vessels - Equivalent safety

• Reduction of manufacturing tolerances
• Peaking
• Excess weld
• Increasing the test pressure (about 2 times Ps)
• To reduce residual stresses
• Obtain crack blunting
• Correct shape imperfection

22
Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

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General

• All structures
• All loadings
• Similar to EUROCODE 3

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If it can be shown that any lower bound limit
value of the action or combination of actions,
determined with the design model specified in the
principle, is reached without violation of the
strain limit, the principle is fulfilled if the
design value of the action or combination of
actions does not exceed that lower bound limit
value. Partial safety factors on actions are
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I.E. THE MATERIAL TERM EQUALS THE MEAN CREEP
RUPTURE STRENGTH DIVIDED BY 1,25 BUT IS NEVER
GREATER THAN THE MEAN STRENGTH FOR 1 CREEP
STRAIN.
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Layout

• Introduction
• A novel architecture
• A high level of nominal design stress
• Testing group 4 vessels
• Annex B
• Conclusion

27
Original design methods

• New rules for the design of heat exchanger
  tubesheets (identical to CODAP and ASME Code
  Mr. Osweiller)
• Alternative methods based on limit analysis for
  flanges and tubesheets (based on TGL and
  theoretical work of Dr. Wölfel)
• New rules for non-pressure loads (Mr. Decock)

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Alternative method for the design of flanges (EN
1591-1)
Balance of deformations
Balance of forces
Axisymmetric model
Laws of rheology
The behaviour of the complete Flanges-bolts-gasket
system is considered
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29
Gasket tightening
7 MPa
700 MPa
-MPa
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Alternative method for the design of tubesheets
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Loads in tubes where tubesheet is supported by
the tubes
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Fatigue of welded zones
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LOCAL LOADS
Lifting lugs
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Major advances

• Extension of limit analysis
• Deletion of elastic shakedown when unecessary
• Annex B
• Fatigue of weldments

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Future developments

• DBA-Direct Route
• Creep
• Design by Experiment

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EN 13445 is a modern standard

• Maintenance performed by a Help Desk with
  permanent site
• www.unm.fr/en/general/en13445
• Remarks on Background to the design rules to be
  sent to the same address

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Thank you for attention!