Recent studies have shown that the crack growth of primary water stress corrosion cracking (PWSCC) is mainly driven by the weld residual stress (WRS) within the dissimilar metal weld. The existing stress intensity factor (K) solutions for surface cracks in pipe typically require a fourth order polynomial stress distribution through the pipe wall thickness. However, it is not always possible to accurately represent the through thickness WRS with a fourth order polynomial fit and it is necessary to investigate the effect of the WRS fitting on the calculated Ks. In this paper, two different methods were used to calculate the K for a semi-elliptical circumferential surface crack in a pipe under a given set of simulated WRS. The first method is the universal weight function method (UWFM) where the through thickness WRS distribution is represented as a piece-wise monotonic cubic fit. In the second method, the through thickness WRS profiles are represented as a fourth order polynomial curve fit (both using the entire wall thickness data and only using data up to the crack-tip). In addition, three-dimensional finite element (FE) analyses (using the simulated weld residual stress) were conducted to provide a reference solution. The results of this study demonstrate the potential sensitivity of Ks to fourth order polynomial fitting artifacts. The piece-wise WRS representations used in the UWFM were not sensitive to these fitting artifacts and the UWFM solutions were in good agreement with the FE results. In addition, in certain cases, it was demonstrated that more accurate crack growth calculations of PWSCC are made when the UWFM is used.

References

References
1.
Shim
,
D.-J.
,
Kalyanam
,
S.
,
Brust
,
F.
,
Wilkowski
,
G.
,
Smith
,
M.
, and
Goodfellow
,
A.
,
2012
, “
Natural Crack Growth Analyses for Circumferential and Axial PWSCC Defects in Dissimilar Metal Welds
,”
ASME J. Pressure Vessel Technol.
,
134
(
5
), p.
051402
.10.1115/1.4007040
2.
Rudland
,
D.
,
Csontos
,
A.
, and
Shim
,
D.-J.
,
2010
, “
Stress Corrosion Crack Shape Development Using AFEA
,”
ASME J. Pressure Vessel Technol.
,
132
(
1
), p.
011406
.10.1115/1.4000349
3.
Materials Reliability Program (MRP)
,
2007
, “
Advanced FEA Evaluation of Growth of Postulated Circumferential PWSCC Flaws in Pressurizer Nozzle Dissimilar Metal Welds
,” MRP-216, Rev. 1, EPRI, Palo Alto, CA.
4.
“Fitness-for-Service
,”
2000
,
API Recommend Practice 579
,
1st ed.
,
American Petroleum Institute
, Washington, DC.
5.
Glinka
,
G.
, and
Shen
,
G.
,
1991
, “
Universal Features of Weight Functions for Cracks in Mode I
,”
Eng. Fract. Mech.
,
40
(
6
), pp.
1135
1146
.10.1016/0013-7944(91)90177-3
6.
Zheng
,
X. J.
,
Kiciak
,
A.
, and
Glinka
,
G.
,
1997
, “
Weight Functions and Stress Intensity Factors for Internal Surface Semi-elliptical Crack in Thick-Walled Cylinder
,”
Eng. Fract. Mech.
,
58
(
3
), pp.
207
221
.10.1016/S0013-7944(97)00083-0
7.
ASME Boiler and Pressure Vessel Code, Section XI
,
2010
,
Rules for Inservice Inspection of Nuclear Power Plant Components
,
American Society of Mechanical Engineers
, New York.
8.
Xu
,
S. X.
,
Scarth
,
D. A.
, and
Cipolla
,
R. C.
,
2011
, “
Technical Basis for Proposed Weight Function Method for Calculation of Stress Intensity Facto for Surface Flaws in ASME Section XI Appendix A
,”
Proceedings of ASME-PVP 2011: 2011 ASME Pressure Vessels and Piping Division Conference
, July 17-21, 2011,
Baltimore, MD
, Paper No. PVP2011-57911.
9.
Xu
,
S. X.
,
Scarth
,
D. A.
, and
Cipolla
,
R. C.
,
2012
, “
Calculation of Stress Intensity Factor for Surface Flaws Using Universal Weight Functions With Piece-Wise Cubic Stress Interpolation
,”
Proceedings of ASME-PVP 2012: 2012 ASME Pressure Vessels and Piping Division Conference
, July 15-19, 2012,
Toronto, Ontario, Canada
, Paper No. PVP2012-78236.
10.
Fritsch
,
F. N.
, and
Carlson
,
R. E.
,
1980
, “
Monotone Piecewise Cubic Interpolation
,”
SIAM J. Numer. Anal.
,
17
(
2
), pp.
238
246
.10.1137/0717021
11.
Rathbun
,
H.
,
Fredette
,
L.
,
Scott
,
P.
,
Csontos
,
A.
, and
Rudland
,
D.
,
2011
, “
NRC Welding Residual Stress Validation Program International Round Robin Program and Findings
,”
Proceedings of ASME-PVP 2011: 2011 ASME Pressure Vessels and Piping Division Conference
, July 17-21, 2011,
Baltimore, Maryland
, Paper No. PVP2011-57642.
12.
ABAQUS Version 6.11
,
2012
, SIMULIA, Providence, RI.
13.
Unpublished work by K/WRS Subgroup of Models Group of xLPR,
2011
.
14.
Materials Reliability Program (MRP)
,
2004
, “
Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 82, 182, and 132 Welds
,” MRP-115, EPRI, Palo Alto, CA.
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