Failure Analysis of a Low-Temperature Carbon Steel Pipe from a Nuclear Power Station Cooling Water System
This paper presents the results of a failure examination on an ASTM A106 carbon steel pipe from component cooling water system at a nuclear power station. The pipe was associated with a large motor air cooler. Through-wall cracking occurred after over three decades of total service and approximately one decade following a refurbishment. The pipe was filled with demineralized water and operated at a temperature <40 °C. Sections of the failed pipe along with a similar non-leaking section were examined with light optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, mass spectrometry, a gas analyzing furnace, and a microhardness indenter to provide data about the failure mechanism and the base material. The results of the study showed that the failure was the result of outside diameter initiated, intergranular stress corrosion cracking. The failure occurred in the vicinity of a weld in the heat-affected zone (HAZ) of the pipe. Other areas of non-through-wall cracking were also observed in the pipes outside of the HAZ.
KeywordsSteel Stress corrosion cracking Heat-affected zone Failure analysis Cracking EDS Electron fractography
The author is grateful for the support of the following individuals who supported this investigation: R. Rees, D. Love, C. McGuire, A. Sutton, and B. Lisowyj.
- 3.P. Muthuswami, Corrosion in steam systems. Steam Fuel Users J. 32, 9–11 (1982)Google Scholar
- 4.M. Kowaka, K. Yamanaka, S. Nagata, Y. Fujii, Stress corrosion cracking of carbon steel for hot blast stoves. Iron Steel Eng. 57(5), 25–30 (1980)Google Scholar
- 5.M.S. de Santa Maria, J. Verdeja, J. Perosanz, Failure analysis of low-carbon steel structure: a stress-corrosion problem. Microstruct. Sci. 9, 399–405 (1987)Google Scholar
- 6.M. Wright, Stress corrosion-cracking of carbon and low-alloy steels in nuclear power plant pressure vessels and piping, assessment methodologies for preventing failure: 2000, in ASME Pressure Vessels and Piping Conference, Vol 2, 2000, pp. 147–162Google Scholar
- 8.G. Nakayama, M. Akashi, Effects of test temperature and hardness of material on the intergranular stress-corrosion cracking behavior of carbon steel in simulated BWR environment, environmental degradation of materials in nuclear power systems—water reactors, in Proceedings of the International Symposium, 8th, 1997, pp. 947–951Google Scholar
- 9.J. Slade, T. Gendron, Flow accelerated corrosion and cracking of carbon steel piping in primary water—operating experience at the point Lepreau generating station, environmental degradation of materials in nuclear power systems—water reactors, in Proceedings of the International Symposium, 12th, 2005, pp. 773–782Google Scholar
- 10.O. Jonas, J. Mancini, A. McGehee, SCC of carbon steel in nuclear component cooling water systems—Part 1. Mater. Perform. 44(6), 52–56 (2005)Google Scholar
- 11.ASTM, Standard Specifications for Seamless Carbon Steel Pipe for High-Temperature Service, A 106-67, Annual Book of ASTM Standards (ASTM), pp. 29–39Google Scholar
- 13.H. Boyer, T. Gall (eds.) ASM Metals Handbook (ASM, Metals Park, 1985), pp. 1–60Google Scholar
- 14.A. Ikeda, Strength and environmental embrittlement of carbon steel. Sumitomo Search 48, 59–78 (1992)Google Scholar
- 18.B. Choi, A. Chudnovsky, Understanding and Modelling Stress Corrosion Cracking (SCC). Key Eng. Mater. 452–453, 801–804 (2011)Google Scholar
- 19.W. Bamford, G. Rao, J Houtman, Investigation of service induced degradation of steam generator shell materials, environmental degradation of materials in nuclear power systems—water reactors, in Proceedings of the 5th International Symposium, 1991, pp. 588–595Google Scholar