IMPEX 2009 – Improving the European pressure vessel standard EN13445-2 by means of pre-normative research

Dr. Peter LangenbergIWTprojects Ltd

7th Dillinger Pressure Vessel ColloquiumSeptember 2012

-80 -60 -40 -20 0 20

-120

-100

-80

-60

-40

-20

0

20

355 M P a, 27 J, PW HT

110110

57

90

48

70

35

50

17

40

4

30

-12

20

-30

10

-48

eBME T HO D 2

T R, °

C

TKV, °C

© www.i-w-t.de

Overview

1. Overview on actual status of European Standardisation of pressurised components

2. Principles of the European method for selecting steels to avoid brittle fracture

3. What is IMPEX 2009 project about?

4. Ways, Means and Achievements

5. Conclusions

© www.i-w-t.de

Development of European Standards for pressurised Components

1990: Harmonisation process started. CENTC 54: pressure vessels; CENTC 267: Piping

1997: PED 97/23/EC was published by EU as legal frameAim: Harmonisation of European markets CE marking

2002: First publication of EN13445 (PV) and EN13480 (Piping)

2009: Consolidated Version published of EN13445Containing all corrections and ammendments, published in issues 1 to 32.New Issues are published every year.

2012: Consolidated Version of EN13480 will be published

2013: EN13445: Issue 4 will contain results from IMPEX pre-normative research

© www.i-w-t.de

Impact of pre-normative research projects for standardisation

Major changes of EN13445-2 (Materials) from 2002 to 2009

1. Change in philosophy as concerns steels for warm and cold going vessels

2. Inclusion of High Strength Steel with Yield Strength up to 690 MPa and Duplex Stainless Steels (ECOPRESS European Research Project from 2000 to 2003)

3. Improved method 2 (ECOPRESS)

4. Improved method 1 (ECOPRESS)

© www.i-w-t.de

Overview

1. Overview on actual status of European Standardisation of pressurised components

2. Principles of the European method for selecting steels to avoid brittle fracture

3. What is IMPEX 2009 project about?

4. Ways, Means and Achievements

5. Conclusions

© www.i-w-t.de

General approach: Requierement on Charpy toughness

0

27J

Ker

bsch

laga

rbei

t A [J

]V

Temperatur [K]

Hochlage

TieflageÜbergangs-

bereich

AVmax/2

TÜ27JTÜAVmax/2

Lower shelf

Upper shelf

Transition

Cha

rpy

toug

hnes

in J

© www.i-w-t.de

The Fracture Mechanics approach

0

10

20

30

40

50

60

70

80

0 20 40 60 80 100

120

140

160

180

200

220

240

Failure depth a, mm

thickness t, mm

EN13445:2009ASMEEurocode 3

ASMElimited @ 7 inch

EN13445limit @ 110 mm

EN1993 (EC3)limit @ 200 mm

ad

2cd

Comparison of EN13445-ASME-Eurocode 3

1. Crack assumption2. Quantification of toughness requierments in terms of fracture toughness.3. Contradiction to practical situation of charpy requirements ?????

© www.i-w-t.de

Practical Solution: FAD plus Master Curve Concept

CEGB R6 Option 2KR=

KIKmat

LR=σBruttoσFließ

Kmat= KR

KI

LIMIT STATEnot safe

safe

MASTER CURVE[MPa m]

CORRELATION

Loads

Resistance

Limit Condition

FAD: Failure Assessment Diagram, e.g. in BS7910

© www.i-w-t.de

Result: Toughness requirements in EN13445/EN 13480

Des

ign

Ref

eren

ce T

empe

ratu

re, T

R

Charpy Test Temperature TKV

Method 2Method 1

Condition: TR = T KV

Limiting max. thicknessfor EN steel grades

given in tables

Method 3

Individual Fracture Mechanics Analysis

© www.i-w-t.de

Main achievements

1. The new and practical handling of steels from Harmonised European Standard

2. The reduction of test efforts on working plates.

3. The full revision of method 2 and method 1 including a new fracture mechanics based calculation model and extending to higher strength and austenitic-ferritic steels.

4. The consideration and acceptance of operation experienceinstead of the calculation model where appropriate.

5. The differentiation after materials for warm and cold goingvessels, where for warmgoing vessels no extra low temperature testing is required anymore.

© www.i-w-t.de

But !!!!!!, Still industrial need for improvements in 2009

1. Extension of Nomograms to plate thickness higher than 110 mm (Ferritic) up to 200 mm.

2. Temperature benefit factor TS for consideration of lower pressure utilisation is treated rather conservative in the EN standard.

3. The calibration of the calculation model to experience for low strength grades required (overcome dotted line for Steels with Re ≤ 355 MPa)

Consequence:3 new Work Items introduced on TC54 level in 2009.

Target dates depend on results from pre-normative research.

© www.i-w-t.de

The solution: pre-normative Research IMPEX 2009

No. Name Industry area Country

1 Arcelor Mittal (Industeel)

Steel France

2 Voest Alpine Steel Austria

3 Sandvick Steel Sweden

4 Otokumpu Steel Sweden

5 Dillinger Huette Steel Germany

6 Thyssen Krupp Steel Germany

7 Linde AG Engineering Germany

8 BASF End user Germany

Start of the project: 01.01.2009Duration: 12 monthWorking group: KTH (Sandstroem), RWTH (Muenstermann), IWT(Langenberg)Coordination: IWTprojects Ltd

© www.i-w-t.de

Work Items Overview

1. Extension of thickness limitations (tmax = 200 mm)2. Improvement of design benefit for Vessels with

reduced stress utilisation (TS –factor in EN 13445)3. Calibration of experience with low strength steels to

the design model

© www.i-w-t.de

Parameters to be considered

Input:

A. Material• Strength: f (TD)• Toughness f(T27J, T40J)

B. Stresses and Temperature• Primary Stresses σp• Secondary Stresses σs• Interaction rules• Design Temperature TD

C. Geometry• Failure assumption a/c = 0,33

and a = 0,25 t (>30 mm)• Thickness t (Weibull, Constraint)

-80 -60 -40 -20 0 20

-120

-100

-80

-60

-40

-20

0

20

355 M P a,

27 J, PW HT

110110

57

90

48

70

35

50

17

40

4

30

-12

20

-30

10

-48

e BME T HO D 2

T R, °

C

TKV, °C

D. FAD• Stress intensity factor• Limit Load

© www.i-w-t.de

Comparison of failure assumptions in different codes

© www.i-w-t.de

New crack assumption

Crack depth a for EN13445 calculation model

0

10

20

30

40

50

60

0 20 40 60 80 100 120 140 160 180 200 220thickness t, mm

crac

k de

pth

a, m

m

alim = 15alim =20alim = 25a = 1/4t

EN13445:2009

NEW

© www.i-w-t.de

Verification by FEM calculations: effect of crack depth

Stress Triaxility

J-Integral

t = 60 – 200 mm

©and info: www.i-w-t.de

Result:for a/t < 0,22 no effect of thickness on crack driving force

© www.i-w-t.de

Effect on toughness requirements

P355 Comparison NEW with EN13445:2009

-100

-80

-60

-40

-20

0

20

40

60

0 20 40 60 80 100 120 140 160 180 200 220thicknes t, mm

TD

EN13445-2:2009NEW proposal

55 mm, 40 J for t up to 110 mm

©and info: www.i-w-t.de

ΔT = 2 K

© www.i-w-t.de

Result WI 1: Practical proposal for EN13445-2

©and info: www.i-w-t.de

355 Mpa, EN

< 450 MPa,ASME

235 Mpa, EN

< 550 MPa, ASME

< 550 MPa, EN

© www.i-w-t.de

TRANSFER: New Design Table B2.15 in EN13445 included in Method 1

Specified minimum yield strength of base material

Required Impact energy KV (on 10x10 mm specimen) at

TR

max. thickness

MPa J mm

Re ≤ 275 MPa 27 200

Re ≤ 355 MPa 40 70 - 200

Re ≤ 460 MPa 60 65 - 200

Re ≤ 500 MPa 60 60 - 200

P355 : no dotted line P460

©and info: www.i-w-t.de

Simplified steel selection within wide range of thickness

© www.i-w-t.de

WI 2: Improvement of design benefit or Vessels with reduced stress utilisation

Ratio of pressure induced principal membrane stress andmaximum allowable design stress

Membrane stress b

Condition > 75 % > 50 % ≤ 75 % ≤ 50 % ≤ 50 N/mm2

Non welded,post-weld heat treatedcondition a

0 °C + 10 °C + 25 °C + 50 °C

As welded conditionand reference thickness< 30 mm

0 °C 0 °C 0 °C + 40 °C

a Also applicable for equipment where all nozzles and non-temporary welded attachments are first welded to vessel components and these sub-assemblies are post-weld heat treated before being assembled into the equipment by butt-welding, but the main seams are not subsequently post-weld heat treated.b The membrane stress shall take account of internal and external pressure and dead weight. For walls and pipes of heat exchangers the restraint of free end displacement of the heat exchanger pipes should also be taken into account.

Table B2.12EN13445:2009

1. Background for stress reduction, what are the relevant parameters?2. Comparison among different codes, philosophies?3. Change of model to calculate effect of stress reduction?4. Role of secondary stresses?5. Performance of tests?

Hypothesis: With the help of the model the stress utilisation can be optimised.

© www.i-w-t.de

WI2: Comparison of TS in EN with other Standards

TS in °C 10 20 25 30 40 50 60 70 80

EN 13445 PWHT

Stress between 50% and

75%

---- Stress <

50%

---- ---- Membrane Stress

< 50MPa

---- ---- ----

EN 13445 AW ---- ---- ---- ---- Membrane Stress < 50MPa

---- ---- ---- ----

ASME VIII /1 0.82 0.64 0.57 0.52 0.44 0.41 0.38 0.36 0.35

PD 5500 2fn/3 ---- ---- ---- ---- Membrane Stress

< 50MPa

ADM W10 ---- ---- ---- ---- ---- Pressure < 75% or Pressure < 50%

---- ---- Pressure < 25%

© www.i-w-t.de

TS: comparison of standards, PWHT

0

10

20

30

40

50

60

0 0,25 0,5 0,75 1 1,25Stress Ratio [-]

Del

ta T

s

EN13445 PWHT, ≤ 50 MPaEN13445 PWHT, > 50 MPaASME, PWHTAD > 20 mm, with PWHTPD 5500, PWHT, ≤ 50 MPaPD 5500, PWHT, > 50 MPaAD > 10 mm, with PWHT

© www.i-w-t.de

Application of new calculation model

IWT, P355GH PWHTEffect of stress Reduction

-140

-120

-100

-80

-60

-40

-20

0

20

0 20 40 60 80 100 120 140 160 180 200 220t, mm

TD, °

C

100%

75%

50%

25%

Change from T27 J to T40J

20 K

40 K

© www.i-w-t.de

NEW and TRANSFER: Proposal for change of TS for PWHT

© www.i-w-t.de

Conclusions

1. European Pressure vessel standards contain latest technology in design and material requierments !!

2. Active standardisation development requires support from industry !!!

3. Pre-normative research allows a fast transfer of new technologies into the standard.

4. Joint Industry Projects are an optimal instrument to improve standards on the fast track.

So, become part of the team.Join us and help us to make

standards economical, safe and sustainable.

© www.i-w-t.de

Thank you for your attention

IWTprojects Ltd and IWT Aachen (Ingenieurbuero)Mail: peter.langenberg@i-w-t.deWeb: www.i-w-t.deWeb: www.bruchmechanik.infoPhone: +49 (0) 241 16 82 859

For further information, discussion and questions please contact me.