Failure analysis of the water-wall tube in KIVCET waste heat boiler

Through methods, such as microscope analysis, mechanical analysis, chemical analysis, metallography examination etc, the causes resulting in water wall tube bursting of 300MW station boiler have been analyzed. The raw material defects is the primarily inducement of bursting failure. In welding tube, the measures of reducing residual stress, such as lower welding heat input, reducing thickness of welding layer and so on, were taken. The welding repair succeeded greatly.

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Failure analysis of a water wall tube

Journal of Physics Conference Series ◽

10.1088/1742-6596/1635/1/012072 ◽

2020 ◽

Vol 1635 ◽

pp. 012072

Author(s):

Facai Ren ◽

Jinsha Xu ◽

Jun Si

Keyword(s):

Failure Analysis ◽

Water Wall ◽

Water Wall Tube

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Leakage failure analysis of water wall tube in circulating fluidized bed boiler

Journal of Physics Conference Series ◽

10.1088/1742-6596/1653/1/012007 ◽

2020 ◽

Vol 1653 ◽

pp. 012007

Author(s):

Facai Ren ◽

Jinsha Xu ◽

Jun Si

Keyword(s):

Failure Analysis ◽

Fluidized Bed ◽

Circulating Fluidized Bed ◽

Circulating Fluidized Bed Boiler ◽

Water Wall ◽

Leakage Failure ◽

Water Wall Tube

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Failure Analysis of Spiral Water Wall Tube Cracking in Ultra-Supercritical Power Plant Boiler

Volume 1B: Codes and Standards ◽

10.1115/pvp2016-63260 ◽

2016 ◽

Author(s):

Jun Si ◽

Zhenrong Yan ◽

Jianjun Chen

Keyword(s):

Residual Stress ◽

High Temperature ◽

Power Plant ◽

Failure Analysis ◽

Power Plants ◽

Composition Analysis ◽

Element Analysis ◽

Water Wall ◽

Water Wall Tube ◽

Weld Heat

The efficiency of conventional boiler/steam turbine fossil power plants has strong relationship to the steam temperature and pressure. At present, steam temperatures of the most efficient fossil power plants are now in the 600°C range. Higher-strength materials are needed for upper water wall tube of boilers with steam pressure above 24 MPa. A high-strength 2.5%Cr steel recently approved by ASME code as T23 is the preferred candidate material for this application. Due to its superior properties, T23 steel is typically not post-weld heat treated. However, after several years running there are a lot of incident reports for T23 tubes especially the breakage of weldment in the ultra-supercritical power plant. This is cause for concern for T23 tubes weldment used under high temperature environments. Previous studies showed that the residual stress may play an important role to the performance of spiral water wall tube. In this paper, the distribution of residual stress in T23 tube weldment has been investigated in detail. Inner wall cracks were found at the butt-jointed seam region of spiral water wall tubes by radiographic testing after one year’s operation. Failure analysis of the spiral water wall tube cracking was conducted by chemical composition analysis, mechanical testing and finite element analysis in this paper. It was found that localized residual stress after the weld process caused concentrated stress, which is the primary reason for failure. Our studies illustrate the necessity of post weld heat treatment for the T23 tubes used under high temperature.

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