In this study, a failure analysis on the water wall boiler tube in a district heating system was carried out. Not following stateoftheart practices lack of proper tube failure analysis wrong choice of correctivepreventive action. Tube failures in high pressure boilers bright hub engineering. Apr 04, 2014 what are 5 causes of steam boiler tube failure duration. Failure analysis of an electric resistance welded carbon steel boiler tube demonstrated that the mechanism of failure was longterm overheat due to heavy internal scaling, followed by shortterm overheat due to localized heating during boiler shutdown.
Failure analysis of a water wall boiler tube for power. Failure analysis of boiler economizer tubes at power house. Repeat failures are defined as multiple failures in a single boiler having the same failure mechanism and rootcause repeat boiler tube failures occur for the following reasons. Lack of proper failure analysis analysis of a tube failure incident should include. Aggressive localized boiler tube corrosion and loss of tube wall. A tube failure is usually a symptom of other problems. The thermal analysis is compared with previous studies on the cleanliness of boilers. Failure analysis of the boiler waterwall tube is presented in this work. Failure of super heater leads to breakdown of whole plant. As we collect, analyze, interpret and study our findings, ats indepth failure analysis experience plays a major contributing role in delivering accurate conclusions.
By measuring the tubes wall thicknesses far from failed region, nonuniformity was seen. To fully understand the cause of the failure, you must investigate all aspects of boiler operation leading to the failure in addition to evaluating the failure itself. Boiler tube failures boiler tube failures main cause of forced outages and availability in steam generating boilers one tube failure in a 500 mw unit rs. The nalco water guide to boiler failure analysis, second. Prevent boiler tube failures, one of the major causes of unplanned outages, by taking a proactive, costeffective approach to boiler tube management.
This volume examines more than 100 cases of failure and the process by which they were analyzed, diagnosed, and resolved. Several examples of boiler tube failures are given and explained using the thermal analysis. It provides expert analysis and insight on a variety of materials, failure modes, root causes, and analytical techniques. Boiler is a sealed vessel in which water is converted into steam. The current state of boiler tube failures in fossil plants introduction at the last international boiler tube failure conference in 1991 1, the conference participants ranked the following areas as being of the highest priority to improve the overall area of boiler tube failures btf. The failure mechanism of tube boiler is identified due to the shortterm overheating as result of the localized flue. Pdf failure analysis and retrofitting of superheater tubes. The primary issue appears to revolve around the rate of steam generation in the first few rows of. Good operating and maintenance practice reduces tube failures. Stress corrosion cracking scc hydrogen damage sulphur corrosion graphitization thermal fatigue waterside corrosion fatigue soot. Full text of boiler tube failure see other formats boilertube failer,prevention and control sundaraveerraju. Localized damage was observed on 70% of the ferrules. To get your boiler back on line and reduce or eliminate future forced outages due to tube failure, it is extremely important to.
A thinlipped rupture at failed region was observed in superheater tube. These include failures due to creep, corrosion, erosion, overheating and a host of other reasons. Boiler tube failure thermohydraulic analysis the boiler hopper tubes at an eskom power station suffer from continuous mechanical failures that lead to frequent unplanned maintenance. Meanwhile, the boiler water chemistry must be strictly controlled, as a delay of one or two years on a fouled boiler can result in major tube damage. Practical, uptodate techniques for identifying and eliminating common causes of boiler failure.
A detailed examination of the failure and associated operating data is usually helpful in identifying the mechanism of failure so that corrective action may be taken. Thematerialpresentedandtheviewsexpressedinthispaperaresolelythoseoftheauthors. Location wise boiler history further, it can be customized to suit the client specific requirement. Leakage failure analysis in a power plant boiler xiaoling luo, zhi zhang qingdao university of science and technology, qingdao, 266061, china abstract the boiler four tubes in a boiler occupies a very important position, according to incomplete statistics of a thermal. Look to the industry leader for comprehensive tube assessment. Boiler tube samples collected for failure analysis carried out by chandra, kain and dey 2010 on superheater tubes with carbon steel grade of sa2t22 2. Boiler tubes can undergo sudden failures by rupture or leakage and is usually detected while in operation rather than during a hydro test or other inspection activities. Critical failure analysis of superheater tubes of coalbased. This calls for immediate action as it can often cause a shutdown of the boiler, leading to loss of production and downtime. Type of boiler rb vs pb and use clean following major upgrade or rebuild as required 10% or more replacement. Procedures for boiler tube failure analysis at times, the cause of a failure cannot be readily determined, making it difficult to determine the appropriate corrective action. Understanding corrosion fatigue and developing solutions.
The boiler tube failure is occurring frequently in fertilizer plants, power plants, sugar manufacturing plants, paper manufacturing plants and all industries using boilers. Super heater is an inevitable component of any boiler system. Quite often they are related to dew point corrosion, an insidious condition that can penetrate up to 0. Metallurgical rootcause investigation helps narrow down the reasons for failure and provides inputs to take the right corrective action.
Hasseand hanke 30 concentrated on the analysis of economiser tube failure. Critical failure analysis of superheater tubes of coal. The previous failure analysis of similar boiler tube revealed that the hardness of the bulging tube is about 140 vhn which is the same as the hardness of the failed tube no. Failures due to caustic attack are caused by metal loss. Analysis of boiler tube failures union pacific rr steam. A petrochemical plant was shut down due to tubes leaks in a waste heat boiler whb. Learn from previous failures and our extensive experience of boiler plant worldwide to implement the right maintenance strategy and improve reliability and availability. Reduce boiler tube leakages in your power station role of mechwell industries ltd. It can occur during operation as a result of inleakage of air at pumps, or failure in operation of preboiler water. Failure analysis of the boiler waterwall tube sciencedirect. Following the incident, inspection activities revealed the following. This paper is aimed at thermal stress and creep damage analysis of secondary super heater tubes. Thermal stress and creep analysis of failed tube of. Xue, analysis of thermal power plant boiler heating surface leakage causes and prevention measures of, application of energy in,2011,4, p.
The fire tube boilers covered a steam production range of 120 thr at pressures from 10 to 20 bar. Workshop on boiler tube failures causes and remedial measures. The fire tube boilers covered a steam production range of. During periodic shutdowns of the boiler unit, tube failures can occur. Failure mode and effect aanalysis on power plant boiler. At the high temperatures found in a boiler, deposits are a serious problem, causing poor heat transfer and a potential for boiler tube failure. The failure analysis of boiler tubes and boiler reheater tubes due to fatigue has also been conducted by hu et al. Inspections to determine the extent of primary and secondary tube damage identification of the failure mechanism determination of the rootcause determination of residual lifepredictive maintenance 11 formalized boiler tube failure. Barry dooley the current state of boiler tube failures. The present study is related to the boiler tube failure analysis of three boilers which are under operation at national fertilizers limited naya nangal. Apr 16, 2019 corrosion failure of materials often exposed to the corrosive environment in district heating systems is critical for operation and maintenance of the facility. Boiler tube scale deposit measurement reduces energy cost. This comprehensive resource deals with the subject of failure investigation of boiler tubes from basic fundamentals to practical applications.
In their research, the formation of thick calcium sulphate deposited on the fireside tube wall and its spallation were the main cause of tube failure. Failure analysis of a boiler tube in usc coal power plant. The water flashed into steam, escaping the boiler mostly from the. Barry dooley the current state of boiler tube failures peter. Failures or forced shutdowns in power plants are often due to boilers, and particularly failure of boiler tubes. Computational fluid dynamic analysis of secondary super heater block is carried out which shows disturbed flue gas. Look to the industry leader for comprehensive tube assessment boiler tube failures continue to be the leading cause of forced outages in fossilfired boilers. Boiler feed pump failure root cause analysis duration. Boiler tube failures btfs in natural circulation high. Introduction in the normal operation of a steam generator, regardless of the temperature or pressure, steam or water will react with steel to form iron oxide. May 12, 20 boiler feed pump failure root cause analysis duration. Handbook of case histories in failure analysis failure. This void content is increased as the metal temperature goes up. Case study on premature failure of superheater tubes in.
Ats focus on boiler tube failure analysis begins with examining the conditions that resulted in the failed component and collecting the pertinent data for reliable information. Boilers tube failure analysis 2018 rev 0 free download as powerpoint presentation. Thin walled tubes that normally last 10 years can become badly pitted during shutdown, and replacement tubing becomes an unanticipated expense. The nalco guide to boiler failure analysis, second edition. Failure of tubes in boiler of the power plants may occur due to various reasons.
The failure investigated in this paper was caused by the presence of voids on the boundaries of the oxide layers. The damage progresses to failure when the tube wall thins to a point where rupture occurs locally. They can be analyzed and corrective and preventive action can taken. It is important to establish a prevention method from an accurate prognosis on the cause of the corrosion failure.
Xu, alkali corrosion diagnosis and mechanism of high pressure boiler water wall tube, chinese journal of rock mechanics and engineering, 2003,2, p. Boiler tube failure analysis applied technical services. How to use the handbook the visual appearance of a failed boiler or hrsg tube provides valuable information regarding the mechanism of failure. Look to the industry leader for comprehensive tube.
The statistics the statistics encompass a wide range of boiler inspection and failure analysis reports from all over subsaharan africa. A comprehensive assessment is the most effective method of determining the root cause of a failure. Boilers tube failure analysis 2018 rev 0 reliability. Failure mode effect analysis fmea on heat recovery steam. The failure analysis of a ruptured superheater tube after 20 years service in the oilfueled boiler, as the typical problems in power plants, was investigated.
The statistics encompass a wide range of boiler inspection and failure analysis reports from all over subsaharan africa. Boiler acts as a medium in which water is converted into steam by using the heat released in the process of combustion of coal in the presence of oxygen. Impact of boiler water chemistry on waterside tube failures. Paper open access failure analysis of superheater boiler tube. Remove sample tubes for dwd analysis and chemically clean based on analysis annual other interval maintain strict water chemistry controls a delay of one or two years on a dirty boiler can result in major tube damage. Kumarand sapra 28 and luo and zhang 29 discussed the leakage failure analysis of boiler tubes in a power plant. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy were carried out. Each type of failure is classified according to its location, general. Boiler boiler is the main part in the power generation. Program overview boiler tubes undergo abrupt failures by rupture or leakage. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical.
To get your boiler back on line and reduce or eliminate future forced outages due to tube failure, it is extremely important to determine and correct the root cause. The work described here presents the analysis of failure of economizer tubes to identify the root causes and to propose recommendations for prevention of such incidents. Failure analysis and retrofitting of superheater tubes in utility boiler. The exfoliation of tube s inner surface, which in followed by void formation and thermal expansion, might cause thermal barrier of the boiler tube. Failure analysis and retrofitting of superheater tubes in.
Schematic diagram of boiler operation and location of failure. Particles of metallic copper may also be embedded in the scale layer. Oxygen pitting occurs with the presence of excessive oxygen in boiler water. The failed whb has been in operation for about 20 years, without any previous failure. Pits can act as stressconcentration sites which can be initiation points for stressrelated corrosion mechanisms. When a failed tube section is removed from a boiler, care must be taken to. Contents boiler boiler accessories boiler tube failures case study on boiler tube failures. Additional chapters detailing the role of advanced material characterization techniques in failure investigation and the role of water chemistry in tube failures are key contributions to the book.
Determining the failure mechanism is the first step of the failure reductionelimination process. Tube failures during the initial operation period, the normal operation period, and after ten to fifteen years operation show different trends. A comprehensive discussion on different mechanisms of boiler tube failure is the heart of the book. Nigiscorcon20171720septembermumbai,india copyright2017bynigis. Numerical investigation of thermal analysis of boiler tube.
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