Journal of Failure Analysis and Prevention

, Volume 18, Issue 2, pp 322–329 | Cite as

Failure Analysis and Remedy Procedure for Cracking of Fuel Nozzles in a Gas Turbine

  • Seyed Ebrahim Moussavi Torshizi
  • Pedram Safarpour
Technical Article---Peer-Reviewed
  • 44 Downloads

Abstract

A common failure in a certain type of gas turbine, observed during the first periodic inspection, is radial cracks in the tip plate of gas fuel nozzles. Here, each gas turbine has 18 nozzles. In all nozzles and in all similar units, these cracks of lengths ranging from 1 mm to a maximum of 14.5 mm are observed. As prescribed by the manufacturer, the defective part must be removed and replaced by welding and machining of a new one. But this problem is repeated and observed in the next periodic visits, and in all units. Depending on the number of nozzles in each gas turbine unit and the number of units in total, these repairs are very expensive and time-consuming. In this paper, the failure is analyzed and the causes of the cracks in the nozzles are investigated. Studies show that the main causes of nozzle failure are residual stresses caused by welding and thermal stresses caused by the start-up and shutdown processes. According to results, a solution has been proposed to release these residual and thermal stresses. After the implementation of this method in 1998, no more failure has been reported by the repair team, which proves the effectiveness of this solution. Since this paper has been prepared based on technical reports from the years between 1996 and 1998, the cited references of this paper are these technical reports.

Keywords

Fuel nozzle Gas turbine Residual stresses Thermal fatigue Failure analysis 

Notes

Acknowledgments

This research has been done with financial support of Tehran Electricity Research Committee and with cooperation of Qom and Ray power plants.

References

  1. 1.
    S.E. Moussavi, et al., Report of the First Phase of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1998)Google Scholar
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    S.E. Moussavi, S. Miri, Report of the Second Phase of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1998)Google Scholar
  3. 3.
    S.E. Moussavi, P. Safarpour, M.J. Mousa Miali, Report of the Third Phase of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1999)Google Scholar
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    S.E. Moussavi, P. Safarpour, Report of the Fourth Phase of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1999)Google Scholar
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    S.E. Moussavi, P. Safarpour, Report of the Fifth Phase of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1999)Google Scholar
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    S.E. Moussavi, P. Safarpour, Final Report of Failure Analysis Project of Qom Power Plant Nozzles (Power and Water University Technology, Tehran, Iran, 1999Google Scholar

Copyright information

© ASM International 2018

Authors and Affiliations

  • Seyed Ebrahim Moussavi Torshizi
    • 1
  • Pedram Safarpour
    • 1
  1. 1.Faculty of Mechanical and Energy EngineeringShahid Beheshti University, A.C.TehranIran

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