Failure investigation into the boiler tubes of power plant

Badaruddin Soomro Badaruddin Soomro,Sumaira Nosheen Sumaira Nosheen,Hamza Butt Hamza Butt,Muhammad Irfan Muhammad Irfan,Bilal Waseem Bilal Waseem,Abdul Karim Aziz Abdul Karim Aziz

doi:10.30574/ijsra.2021.2.2.0048

Badaruddin Soomro Badaruddin Soomro, Sumaira Nosheen Sumaira Nosheen + Show 4 more

Open Access

https://doi.org/10.30574/ijsra.2021.2.2.0048

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Abstract

Failure of tubes is a very critical problem in boilers. The current study describes the detailed investigation for failure of boiler tubes in the power plants. Different characterization techniques like; metallography/microscopy, hardness, chemical analysis, SEM/EDS were utilized to find out the actual cause of failure. The tubes were failed within one year of its service. It was concluded that the brittle fracture (rupture) of tubes was occurred due to over-heating caused the formation of thermally insulating thick iron oxide scale on the inner surface of the boiler tube. Evidence of hydrogen embrittlement of the boiler tube in the rupture region was also found. Insights of this investigation might be helpful for the prevention of this type of failures in future.

Highlights

The role of boilers is to convert the water into superheated steam for power generation purposes
In water-tube boilers, water circulates inside the tubes and is heated externally by hot gases generated by the furnace
Fractography was performed via Optical Microscopes (Zoom Microscope, SZX7, Olympus, Japan; DM4000M Image Analyzer, Leica, Germany) [7]

Summary

Introduction

The role of boilers is to convert the water into superheated steam for power generation purposes. Two major types of tube boilers are used: water-tube and fire-tube boilers. In water-tube boilers, water circulates inside the tubes and is heated externally by hot gases generated by the furnace. With fire-tube boilers, hot gas passes through one or many tubes, which through thermal conduction, heats the water surrounding them [1]. Coal is the major and cheaper source of fuel for operation of boilers. These boilers are very critical and risky equipment for electricity generation. Two types of failure may occur in the tubes; the material failure and operational failure. Different damage mechanisms are responsible for such type of boiler failures. This includes failure due to corrosion, graphitization, erosion, creep, overheating and etc.

Method of Investigation

Sample Identification

Results and Discussion

C Mn P S Si Fe

Grain Size Measurement

Conclusion