THE THERMAL HISTORY AND STRESS STATE OF A FRESH STEAM-PIPELINE INFLUENCING ITS REMAINING SERVICE LIFE

Abstract

The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and re-heated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service- and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a ∅324×36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160 000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.

Keywords

Dates

  • Submission Date2011-05-09
  • Revision Date2011-05-11
  • Acceptance Date2011-05-13

DOI Reference

10.2298/TSCI110509050B

References

  1. R.Viswanathan, Damage mechanisms and life assessment of high temperature components, ASM International, 1989
  2. Бугай Н.В., Березина Т.Г., Трунин И.И., Serviceability and longtime behaviour of metal at Thermal Power Plants (Работоспособность и долговечность металла энергетического оборудования), Энергоатомиздат, Москва, 1994, p.120,
  3. Крутасова Е. И., Metal Reliability at Thermal Power Plants (Надежность металла энергетического оборудования), Энергoaтoмиздат, Москва, 1981
  4. Inherently Reliable Boiler Component Design, EPRI, Palo Alto, CA:2003. 1004324
  5. V.Sijacki, G.Bakic, M. Đukić, B. Rajičić, A. Sedmak, et al, Evaluation of microstructural degradation, metal damage and remaining life assessment of thermal power plant components of Electric Power Industry of Serbia (Procedure and application), Int.Rep.EPS, Fac. of Mech. Eng. Un. of Belgrade, 309p. 2008.god.
  6. Comprehensive Structural Integrity, Vol. 5: Creep and High Temperature Failure (ed A. Saxena), Elsevier Pergamon, London, 2003, pp 309-359
  7. TRD 508, Inspection and testing, with Annex 1: Additional tests on components - Methods for the calculation of components having time-dependent design strength values, Edition July 1986
  8. ASME: Boiler and Pressure Vessel Code, Part III, Division 1, Subsection NH - Class 1 Components in Elevated Temperature Service, ASME, New York, 2004
  9. ECCC Recommendations -Vol.6 (Issue 1), Edited by: S. Concari, UK, 2005, www.ommi.co.uk/etd/eccc/advancedcreep/V6i1x.pdf
  10. [10
  11. ] B.Wilshire, Creep and Fracture of Engineering Materials and Structures, Ashgate Publishing, London, 1993, Thermal Science 11;
  12. Bakić G., Žeravčić V.Š., Radović M., Estimation of the failure time for low-carbon CrMoV steels in creep condition using modified kinetic theory based on microstructural parameters, Proceedings - ECCC Creep Conference: Creep and Fracture in High Temperature Components - Design and Life Assessment Issues, London, (2005) pp 235-243
  13. G. Bakić, V. Šijački-Žeravčić, Determination of Time-to-Fracture of Low Alloyed Steels Under Creep Conditions as a Function of Microstructural Parameters Second Part: Determination of time-to-fracture DIVK Vol. 3, No 2, 2003
  14. Carl E. Jask And Brian E. Shannon, Inspection and Remaining Life Evaluation of Process Plant Equipment Process & Power Plant Reliability Conference Houston, Texas November 13-14, 2002 Organized by Clarion Technical Conferences
  15. Jaske, C. E., and Simonen, F. A., 1991, Creep-Rupture Properties for Use in the Life Assessment of Fired Heater Tubes, Proc., First International Conference on Heat-Resistant Materials, ASM International Materials Park, OH, pp. 485-493.
  16. M. Zuo, S. Chiovelli, Y. Nonaka, Fitting Creep-Rupture LifeDistribution Using Accelerated Life Testing Data, Journal of Pressure Vessel Technology, doi:10.1115/1.1310164 J. Pressure Vessel Technol., November 2000, Vol. 122, Issue 4, 482 (6 pages)
  17. J.Chadek, Creep of Metallic Materials, Mir, Moscow, 1981
  18. Arūnas Baltušnikas, et.al, Analysis of Heat Resistant Steel State by Changes of Lattices Parameters of Carbides Phases ISSN 1392-1320 Materials Science (Medžiagotyra). Vol. 14, No. 3. 2008
  19. A. Jakovljević, Numerical stress analysis of high pressure steam lines in power plants DIVK Vol. 7, No 1, 2007
  20. S. Damnjanović, A. Sedmak, H. A. Anyiam, et al, Određivanje C* integrala primenom EPRI procedure C* Integral Evaluation by Using EPRI Procedure DIVK, Vol. 2, No 1-2, 2002
Volume 15, Issue 3, Pages691 -704