Failure analysis of the left waterwall tube of boiler furnace in the steam power plant based on thickness changes and pressure

Purpose The purpose of this paper is to analyze the failure of the left waterwall tube of a boiler furnace in the steam power plant which led to cracks and rupture. Macro visual observation showed the rupture like a fish mouth with slag adhering at the outer surface of the tube. Magnetite as a protective layer was peeled off. Changes in the thickness were analyzed through dimensional measurement. In this research, an analysis to find the cause and determine the fracture mechanism is presented. Design/methodology/approach A physical analysis was performed through visual observation of changes in the thickness. Micro visual testing with a metallography test provided the data required to measure the change of grain size. The mechanical analysis used Von Mises criteria and API 530 standard and provided the pressure limits data. Findings The thickness of the tube decreased at the peak curvature of the tube. The smallest thickness at the peak curvature of the tube was 0.108 inches. The working pressure was 40.74 percent from permit limits with Von Mises calculations. The percentage of pressure calculated by the API standard was 48.42 percent from permit limits. Larger crystal grains occurred only in the nearby area of the oxide layer and at the end of the crack tip. It indicated that part of the inner surface had a relatively high temperature and plastic deformation occurred because of the pressure from inside the tube. Combining all these factors ruptured the tube at this location because the cross-section could not hold up the pressure. Originality/value The analysis of this discussion focuses on the combined effect of those factors causing the ability to decrease stress being received. It restricts the tube from holding up the stress and furthermore it will generate fractures.

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Shaft Failure Sea Water Pumps At the Steam Power Plant Units

International Journal of Engineering and Advanced Technology - Regular Issue ◽

10.35940/ijeat.a9977.109119 ◽

2019 ◽

Vol 9 (1) ◽

pp. 7008-7012

Keyword(s):

Power Plant ◽

Sea Water ◽

Visual Observation ◽

Composition Analysis ◽

Water Pump ◽

Steam Power ◽

Steam Power Plant ◽

Pump Shaft ◽

Aisi 316 ◽

Water Pumps

The water pump used to suck and drain seawater to the heat exchanger unit at a Steam Power Plant (PLTU), is damaged. To find out the causal factors of this damaging phenomenon, the fractured shaft is tested which includes visual observation, fractography testing, metallography, hardness testing and chemical composition analysis on a fractured shaft. By knowing the type and cause of damage to the water pump shaft, steps of prevention or prevention can be formulated so that the same damage can be avoided. From the test results, it was found that the average carbon content was lower than the AISI 316 standard. While the average hardness was lower than the standard hardness. The damage that occurs to the CWP water pump shaft is basically caused by fatigue fracture due to excessive workload in the form of dynamic loading

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Process capability – a surrogate measure of process robustness: a case study

International Journal of Quality & Reliability Management ◽

10.1108/ijqrm-12-2013-0202 ◽

2015 ◽

Vol 33 (1) ◽

pp. 90-106 ◽

Cited By ~ 2

Author(s):

S. C. Mondal

Keyword(s):

Power Plant ◽

Random Noise ◽

Process Capability ◽

The Body ◽

Steam Power ◽

Content Type ◽

Steam Power Plant ◽

Process Robustness ◽

Surrogate Measure ◽

Tempering Process

Purpose – The purpose of this paper is to obtain a better understanding on robust performance of a hardening and tempering process producing component worm shaft used in the steam power plant. This research is capable to explaining the variation of process capability in terms of robustness. Design/methodology/approach – This paper proposed a methodology (a combination of simulation, regression modelling and robust design technique) to study robustness of a hardening and tempering process producing component worm shaft used in the steam power plant and process capability acts as a surrogate measure of robustness. In each experimental run, the values of responses and the corresponding multivariate process capability indices across the outer array are determined. The variation of process performance (process capability values) due to random noise variation is studied using a general purpose process control chart (R-chart). Findings – The results provide useful information in term of insensitiveness of the process against the noise (raw material and process noise) variation where the process capability acts as a surrogate measure of process robustness and explains the variation of process capability in term of robustness. Practical implications – This paper adds to the body of knowledge on robustness of a manufacturing process. This paper may be of particular interest to practicing engineers as it suggests what factors should be more emphasis to achieve robust (consistent) performance from the process. Originality/value – The originality of this paper lies within the context in which this study is to address key relationships between process robustness and process capability in a manufacturing industry.

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