Journal of Failure Analysis and Prevention

, Volume 8, Issue 1, pp 41–47 | Cite as

Damage and Residual Life Assessment of Bends for X20CrMoV12.1 Main Steam Pipe after Long-Term Service

  • Zheng-Fei Hu
  • Zheng-Guo Yang
  • Guo-Qiu He
  • Cheng-Shu Chen
Case History---Peer-Reviewed


The bent sections from a main steam pipe in a thermal power plant in Shanghai were examined after 165,000 h service at 550 °C under 13.73 MPa pressure. The residual life of the bend sections is determined by evaluation of the service stresses and testing to obtain creep rupture data. Metallographic analysis and tensile, impact, and hardness tests are also conducted. These combined tests show that the properties of the steel deteriorated during service, displaying embrittlement tendencies; the corresponding microstructures exhibit grain boundary weakening and creep damage characteristics. However, considering no evidence of localized damage in the form of creep cavitation or surface cracks was observed in the examined parts, considering the residual life of the bends at service condition, they are adequate for an additional 44,000 h of operation. It is recommended that a health assessment should be taken after 25,000 h service exposure for safety reasons.


Main steam pipe Microstructure Finite element analysis Residual life assessment 



This work was supported by the National Natural Science Foundation of China under contract no. 50771073 and National Basic Research Program of China under contract no. 2007CB714705.


  1. 1.
    Masuyama, F., Nishimura, N., Sasada, A.: CAMP-ISIJ, 11, 614 (1998).Google Scholar
  2. 2.
    Ennis, J.P.: Creep strengthening mechanisms in high chromium steels. In: Bakker, W.T., Parker, J.D. (editors). Proceedings of the Third Conference on Advances in Materials. Technology for Fossil Power Plants. London (UK): The Institute of Materials, pp. 187–194 (2001).Google Scholar
  3. 3.
    Sawada, K., Maruyama, K., Hasegawa, Y., Muraki, T.: Creep life assessment of high chromium ferritic steels by recovery of martensitic lath structure. Proceedings of Eighth International Conf. on Creep and Fracture of Engineering Materials and Structures, Tsukuba, Japan, Nov. 1–5, 1999.Google Scholar
  4. 4.
    Hu, Z.F., Wu, X.F., Wang, C.X.: HRTEM study on precipitates in high CoNi steel. J. Mater. Sci. & Tech. 20, 425/528 (2004).Google Scholar
  5. 5.
    Vodarek, V., Strang, A.: Effect of nickel on the precipitation processes in 12CrMoV steels during creep at 550 °C. Scr. Mater. 38, 101 (1998).CrossRefGoogle Scholar
  6. 6.
    Ennis, P.J., Zielinska-Lipiec, A., Filemonowicz, A.: Quantitative comparison of the microstructure of high chromium steels for advanced power stations. In: Strang, A., Cawley, J., Greenwoof, G.W. (editors): Microstructure of High Temperature Materials, No. 2, The Institute of Materials, London, U.K., pp. 135–143 (1998).Google Scholar
  7. 7.
    Hu, Z.F., Yang, Z.G.: An investigation of the embrittlement in X20CrMoV12.1 power plant steel after long-term service exposure at elevated temperature. Mater. Sci. Eng. A, 383, 224–228 (2004).CrossRefGoogle Scholar
  8. 8.
    Chan, R.W., Haasen, P.: Physical Metallurgy, part 2 [M], North-Holland Physics Publishing, Netherlands (1983).Google Scholar
  9. 9.
    Hu, Z.F., Yang, Z.G.: Identification of the precipitates by TEM and EDS in X20CrMoV12.1 for long-term service at elevated temperature. J. Mater. Eng. Perform. 12(1), 106–111 (2003).CrossRefGoogle Scholar
  10. 10.
    European Standard: EN10216-2, Seamless steel tubes for pressure purpose—Technical delivery conditions, Part 2: Non alloy and alloy steel tubes with specified elevated temperature properties.Google Scholar
  11. 11.
    Weber, J., Klenk, A., Rieke, M.A.: new method of strength calculation and lifetime prediction of pipe bends operating in the creep range. Int. J. Pressure Vessels Piping 82, 77–84 (2005).CrossRefGoogle Scholar

Copyright information

© ASM International 2008

Authors and Affiliations

  • Zheng-Fei Hu
    • 1
  • Zheng-Guo Yang
    • 2
  • Guo-Qiu He
    • 1
  • Cheng-Shu Chen
    • 1
  1. 1.School of Materials Science and EngineeringTongji UniversityShanghaiChina
  2. 2.Department of Materials ScienceFudan UniversityShanghaiChina

Personalised recommendations