Power plant piping operating at elevated temperatures is subject to several types of service aging-related degradation, such as softening, spheroidization, embrittlement, and creep. When cracks are found in these components, weld repair is often employed to ensure continued operation. The efficacy of the weld repairs in terms of extending the life of the aged components has, however, not been documented quantitatively. The Electric Power Research Institute (EPRI) has recently undertaken a comprehensive study to evaluate weld repairs performed to aged piping. In connection with this study, results from other worldwide activities have been reviewed, leading to significant conclusions regarding weld repair. This review of results from several worldwide studies has confirmed that aged high-temperature piping can be successfully weld repaired to gain additional lives in excess of several decades. The key aspects of successful weld repair include excavation and removal of all prior creep cavitation damage, elimination of external bending stresses, and implementation of good welding practice. From merely a creep rupture point of view, postweld heat treatment (PWHT) has been concluded to be superfluous by several authors. Temperbead repairs appear to offer a promising alternative to PWHT repairs from a creep, tensile, and toughness standpoint. Choice of the repair process ultimately is dictated by many considerations such as toughness, notch sensitivity, residual stresses and hydrogen embrittlement susceptibility. Several reports suggest that gas tungsten arc welding (GTAW) repairs may outperform shielded metal arc welding (SMAW) repairs with or without PWHT. [S0094-9930(00)02001-1]

Issue Section:
Technical Papers
Keywords:
reviews, pressure vessels, creep fracture, embrittlement, ageing, welding, fatigue cracks
Topics:
Creep, Maintenance, Pipes, Rupture, Steel, Stress, Base metals, Welded joints, Temperature, Cavitation
1.
Viswanathan, R., 1996, “Weldment Related Issues in U.S. Power Plants.” Proceedings of the Symposium on Joining of Metals, Welding Research Institute, Tiruchy, India, pp. 1–23.
2.
Gandy, D. W., and Viswanathan, R., 1999, “Weld Repair of Casings and Piping—An Industry Survey,” ASME J. Pressure Vessel Technol., to be published.
3.
Viswanathan, R., Gandy, D. W., and Findlan, S., 1997, “Performance of Repair Welds on Service-Aged 2-1/4Cr-1Mo Girth Weldments,” ASME J. Pressure Vessel Technol., Nov., pp. 2–9.
4.
Viswanathan
,
R.
,
Gandy
,
D. W.
, and
Findlan
,
S.
,
1999
, “
Weld Repair of 2-1/4Cr-1Mo Service-Aged Header Welds
,”
ASME J. Pressure Vessel Technol.
,
121
, pp.
345
–
352
.
5.
Viswanathan, R., Gandy, D. W., and Findlan, S., 1999, “Weld Repair of 1-1/4Cr-1/2Mo Steel Piping Girth Welds,” ASME J. Pressure Vessel Technol., to be published..
6.
Viswanathan, R., June 1998, Weld Repair of Aged Piping—A Literature Review, EPRI Report, TR-103592-Vol. 7, EPRI. Palo Alto.
7.
Etienne, C. F., Heerings, J. H., and Van Wortel, J. C., 1992, “Weldability and Assessment of Residual Life of Repair Welds in Thick Walled Headers,” VGB Conference, Residual Service Life 1992, Mannheim, 2, July.
8.
Smith, G. V., 1971, Supplemental Report on the Elevated Temperature Properties of Chromium-Molybdenum Steels, ASTM DS652, American Society for Testing Materials, Philadelphia, PA.
9.
DeWitte, M., and Coussement, C., 1992, “Behavior of 2-1/4C-1Mo Base Material and (Repair) Weldments at High Temperatures,” Creep Characterization, Damage and Life Assessment, D. A. Woodford, C. H. A. Townley and M. Ohnami, eds., ASM International, Metals Park, OH.
10.
Lundin, C. D., and Wang, T., 1989, “Repair Welding of Service Exposed CrMo Steel Weldments,” Weld. Res. Council Bull. 348, Nov.
11.
Croker, A. B. L., et al., 1997, “Repair Welding of Creep Damaged Steels,” IMMA Conference on Operating Pressure Equipment, Brisbane, Australia, April 7–11, Institute of Metals and Materials Australasia, pp. 209–215.
12.
Arnswald, W., Blum, R., Neubauer, B., and Poulsen, K. E., 1992, “Remaining Life Affected by Repair Welds,” VGB Conference, Residual Service Life, Mannheim, 2, July.
13.
Westwood, H. J., 1995, “Axial Creep Tests on 1.25Cr-0.5Mo Steam Pipe Weldments, in Materials Aging and Component Life Extension,” V. Bicego, A. Nitta, and R. Viswanathan, eds., Engineering Materials Advisory Services Ltd., West Midlands, UK, pp. 733–743.
14.
Wu
,
R.
,
Storesund
,
J.
, and
Sandstrom
,
R.
,
1993
, “
Influence of Postweld Heat Treatment on Creep Properties of 1Cr-0.5Mo Welded Joints
,”
J. Mater. Sci. Technol.
,
9
, pp.
773
–
780
.
15.
Lundin, C. D., 1996, “Overview of Results from PVRC Programs on Half-Bead/Temper-Bead/Controlled Deposition Techniques for Improvement of Fabrication and Service Performance of Cr-Mo Steels,” Challenges and Solutions in Repair Welding for Power and Process Plants, Proceedings of a Workshop January 31-February 1, WRC Bulletin, 412, June, pp. 16–26.
16.
Shkylyarov, M. J., Schtromberg, Y. Y., and Viswanathan, R., 1997, Rejuvenation of Main Streamline Piping by Reheat Treatment—A Review of Russian Experience, Report TR-106610, Electric Power Research Institute, Palo Alto, CA.
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