Abstract

Engineering critical assessment (ECA) is an evaluation procedure for structures with flaws and has been widely applied for assessing pipeline integrity. The standards for structural integrity assessment, including BS 7910, involve stress-based ECA, and they are known to produce overly conservative results. Therefore, strain-based ECA has been recently developed as an alternative approach. One of the effective methods for improving the accuracy of strain-based ECA is the reference strain method. However, only a limited number of studies have applied this method to welded pipelines. Therefore, a numerical analysis based on strain-based ECA was performed for girth-welded joints with a circumferentially oriented internal surface crack. Particular attention was given to the strength mismatch effects. The equivalent stress–strain curve in BS7910 was used to reflect the strength mismatch effects in the reference strain. The results of the proposed method were validated with the results of a finite element analysis (FEA) in terms of the J-integral. Previous methods and the proposed method exhibit a reasonable correlation of the J-integral in the case of over-matching (OM). In the under-matching (UM) cases, while the previous procedures tended to underestimate or excessively overestimate the elastic-plastic energy release rate in comparison with the FEA, the proposed method evaluated the J-integral of pipelines with sufficient accuracy.

References

1.
British Standards Institution
,
2013
, “
BS 7910:2013—Guide to Methods for Assessing the Acceptability of Flaws in Metallic Structures
,”
London, UK
.
2.
British Energy
,
2001
, “
R6:2001—Assessment of the Integrity of Structures Containing Defects
,”
London, UK
.
3.
Det Norske Veritas
,
2013
, “
DNV-OS-F101—Submarine Pipeline Systems
,”
Hovik, Norway
.
4.
Wu
,
G.
, and
Wang
,
L.
,
2018
, “
An Overview of Strain-Based Fracture Assessment of Pipelines
,”
Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering
,
Madrid, Spain
,
June 17–22
.
5.
Rice
,
J. R.
,
1968
, “
A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks
,”
ASME J. Appl. Mech.
,
35
(
2
), pp.
379
386
. 10.1115/1.3601206
6.
Budden
,
P. J.
,
2006
, “
Failure Assessment Diagram Methods for Strain-Based Fracture
,”
Eng. Fract. Mech.
,
73
(
5
), pp.
537
552
. 10.1016/j.engfracmech.2005.09.008
7.
Budden
,
P. J.
, and
Ainsworth
,
R. A.
,
2012
, “
The Shape of a Strain-Based Failure Assessment Diagram
,”
Int. J. Press. Vessels Pip.
,
89
, pp.
59
66
. 10.1016/j.ijpvp.2011.09.004
8.
Cheaitani
,
M.
, and
He
,
W.
,
2011
, “
Strain-Based Driving Force Estimates for Circumferential Cracks in Pipe Girth Welds
,”
TWI Member Report, Report No. 1000/2011
.
9.
Kumar
,
V.
, and
Shih
,
V.
,
1980
, “
Fully Plastic Crack Solutions, Estimation Scheme and Stability Analyses for the Compact Specimen
,”
Fracture Mechanics: Twelfth Conference, ASTM 700, American Society for Testing and Materials
,
Saint Louis
,
May 21–23
, pp.
406
438
.
10.
Ainsworth
,
R. A.
,
1984
, “
The Assessment of Defects in Structures of Strain Hardening Material
,”
Eng. Fract. Mech.
,
19
(
4
), pp.
633
642
. 10.1016/0013-7944(84)90096-1
11.
Milne
,
I.
,
Ainsworth
,
R. A.
,
Dowling
,
A. R.
, and
Stewart
,
A. T.
,
1988
, “
Background to and Validation of CEGB Report R/H/R6-Revision 3
,”
Int. J. Press. Vessels Pip.
,
32
(
1-4
), pp.
105
196
. 10.1016/0308-0161(88)90072-5Get
12.
Kim
,
J. S.
,
Song
,
T. K.
,
Kim
,
Y. J.
, and
Jin
,
T. E.
,
2009
, “
Strength Mis-Match Effect on Limit Loads for Circumferential Surface Cracked Pipes
,”
Eng. Fract. Mech.
,
76
(
8
), pp.
1074
1086
. 10.1016/j.engfracmech.2009.01.008
13.
Dassault Systèmes Simulia Corp.
,
2017
,
SIMULIA User Assisstance 2018
.
You do not currently have access to this content.