{"title":"Leg weld fatigue cracks in anhydrous ammonia nurse tanks","authors":"A.M. Russell , A.T. Becker , L.S. Chumbley , D.A. Enyart","doi":"10.1016/j.csefa.2015.03.002","DOIUrl":"10.1016/j.csefa.2015.03.002","url":null,"abstract":"<div><p>In an accident in southwest Iowa, USA in 2012, an anhydrous ammonia nurse tank vented its entire cargo of 5500<!--> <!-->L (1500<!--> <!-->gallons) of liquid ammonia to the atmosphere. Follow-up study of the failed tank revealed a through-crack along a weld used to connect the tank to its running gear. Side-angle ultrasound examinations were performed on 532 used anhydrous ammonia nurse tanks to measure the locations, sizes, and orientations of flaw indications. The tanks examined had manufacture dates ranging from 1952 to 2011. A total of 83 indications were found in or near the leg welds of 50 of these 532 tanks. Several factors suggest that these indications are fatigue cracks, not the stress corrosion cracks more commonly detected in nurse tanks. These findings suggest that roughly 9% of the 200,000 nurse tanks in the U.S. nurse tank fleet may contain leg-weld fatigue cracks. Nurse tanks are the only large, pressurized packages for hazardous cargo that do not contain manways; thus, their interior walls cannot be inspected for flaws with magnetic particle or fluorescent dye penetrant methods. Since the tank interior is inaccessible, side-angle ultrasound is the only detection method capable of detecting cracks in nurse tanks initiating at both interior and exterior tank surfaces. For this reason, the authors recommend that side-angle ultrasound be considered for use in periodic nurse tank inspections.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"3 ","pages":"Pages 73-79"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2015.03.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54177001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Srđan M. Bošnjak , Nebojša B. Gnjatović , Dejan B. Momčilović , Ivan L.J. Milenović , Vlada M. Gašić
{"title":"Failure analysis of the mobile elevating work platform","authors":"Srđan M. Bošnjak , Nebojša B. Gnjatović , Dejan B. Momčilović , Ivan L.J. Milenović , Vlada M. Gašić","doi":"10.1016/j.csefa.2015.03.005","DOIUrl":"10.1016/j.csefa.2015.03.005","url":null,"abstract":"<div><p>This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the ‘operating-in’ defect (the malfunction of the limit switch) and the ‘manufacturing-in’ defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"3 ","pages":"Pages 80-87"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2015.03.005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54177033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Statistical tools applied for the reduction of the defect rate of coffee degassing valves","authors":"Giorgio Olmi","doi":"10.1016/j.csefa.2014.10.002","DOIUrl":"10.1016/j.csefa.2014.10.002","url":null,"abstract":"<div><p>Coffee is a very common beverage exported all over the world: just after roasting, coffee beans are packed in plastic or paper bags, which then experience long transfers with long storage times. Fresh roasted coffee emits large amounts of CO<sub>2</sub> for several weeks. This gas must be gradually released, to prevent package over-inflation and to preserve aroma, moreover beans must be protected from oxygen coming from outside. Therefore, one-way degassing valves are applied to each package: their correct functionality is strictly related to the interference coupling between their bodies and covers and to the correct assembly of the other involved parts. This work takes inspiration from an industrial problem: a company that assembles valve components, supplied by different manufacturers, observed a high level of defect rate, affecting its valve production. An integrated approach, consisting in the adoption of quality charts, in an experimental campaign for the dimensional analysis of the mating parts and in the statistical processing of the data, was necessary to tackle the question. In particular, a simple statistical tool was made available to predict the defect rate and to individuate the best strategy for its reduction. The outcome was that requiring a strict protocol, regarding the combinations of parts from different manufacturers for assembly, would have been almost ineffective. Conversely, this study led to the individuation of the weak point in the manufacturing process of the mating components and to the suggestion of a slight improvement to be performed, with the final result of a significant (one order of magnitude) decrease of the defect rate.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"3 ","pages":"Pages 17-24"},"PeriodicalIF":0.0,"publicationDate":"2015-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.10.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Grooving corrosion of seam welded oil pipelines","authors":"Mohamed Hanafy El-Sayed","doi":"10.1016/j.csefa.2014.05.002","DOIUrl":"10.1016/j.csefa.2014.05.002","url":null,"abstract":"<div><p>24” pipeline carrying oil was failed in the form of longitudinal crack at the 6 O’clock position resulting in oil spill. The failed pipe was investigated to reveal the main cause of its failure. The procedure of investigation was built on studying the intact pipe, rupture area, parent material, and intact weld. Results of chemical analysis, mechanical properties, and microstructure of the pipe material were confirmed with the specified standard. Cracks were originated from weld defected sites, initiated by grooving corrosion, propagated by inertia at the normal designed pressure condition, and stopped when stress relief is attained. It is recommended to use high quality ERW pipe, with its seam weld line positioned around the 12 O’clock during installation, to minimize and decelerate grooving corrosion. It is also important to perform regular or routine inspection, on suitable intervals, determined by past experience.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 84-90"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.05.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis of cracks generated in the spinning-mandrel teeth","authors":"M. Haghshenas, R.J. Klassen","doi":"10.1016/j.csefa.2014.06.004","DOIUrl":"10.1016/j.csefa.2014.06.004","url":null,"abstract":"<div><p>The spinning process, using a splined mandrel, is always prone to premature failure of the splined mandrels. Such a failure is thought to be related to the magnitude of the forming forces exerted on the mandrel by the forming rollers during the spinning process. In the present paper, the characteristic of corner cracks in the mandrel teeth (made of S7 tool steel) of a spinning process has been investigated. The rotational speed of the mandrel is about 300<!--> <!-->rpm during spinning process and the sheet metal (<em>i.e.</em> AISI 1020) is in contact with mandrel teeth to get the mandrel shape at the end of process. During this process, the mandrel teeth eventually break away. Fractography analyses using scanning electron microscopy (SEM) clearly confirm “<em>fatigue</em>” as being the main reason for the failure.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 118-126"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.06.004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saud Al Subai , Keshab Barai, Esteban Morales Murillo
{"title":"Failure analysis of firewater pipeline","authors":"Saud Al Subai , Keshab Barai, Esteban Morales Murillo","doi":"10.1016/j.csefa.2014.07.002","DOIUrl":"10.1016/j.csefa.2014.07.002","url":null,"abstract":"<div><p>This paper presents the failure analysis of a fire water pipe line from a petrochemical industry. Leakages were noticed at the top portion of the pipeline. Severe deep pits were observed at the top inner surface and deposits found at the bottom inner surface of the pipe line. Visual inspection, microscopic examination, chemical and water analyses were employed in the present failure analysis. The analysis results showed that the failure occurred due to the severe oxygen corrosion attack at the top portion of the pipe while the bottom surface of the pipe suffered from under deposit corrosion. The fire water pipe line was made of low carbon steel.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 144-149"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.07.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Failure analysis of the impellers of coke plant","authors":"Souvik Das, Goutam Mukhopadhyay, Sandip Bhattacharyya","doi":"10.1016/j.csefa.2014.09.002","DOIUrl":"10.1016/j.csefa.2014.09.002","url":null,"abstract":"<div><p>Premature failure of the impeller blade of coke plant has been investigated. The component functioned during the CGC gas intake cycle. The component rotates at 1480<!--> <!-->rpm with a volumetric flow of 720<!--> <!-->m<sup>3</sup>/min of flue gas with temperature about 200–300<!--> <!-->°C. The failed component reveals exposed surface of a crack that extended slightly beyond the assembly weld. From macro-structural observation under-filled region in welding is observed which is detrimental because it acts as a stress concentration site. The microstructure from the weld zone showed severe intergranular corrosion degradation. Micro cracks and cracks have been observed at several locations, mostly originating from the weld zone. From the EDS analysis of the failed sample it is observed that there is a deposition of Cr along the grain boundary. From the mode of failure it indicates that probable reason for the premature failure is due to sensitization of the component. In this case, the precipitation of chromium carbides may be occurred during welding operation when the heat affected zone (HAZ) experiences a particular temperature range (550–850<!--> <!-->°C). From the microstructure it is observed that the welding operation was not proper and there is every chance that there is heat generation in around sensitization range leading to precipitation of chromium carbides consumed the alloying element – chromium from a narrow band along the grain boundary and this makes the zone anodic to the unaffected grains. The chromium depleted zone becomes the preferential path for corrosion attack or crack propagation if under tensile stress. Thus it leads to premature failure of the component during service.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 157-161"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.09.002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An investigation into failure analysis of interfering part of a steam turbine journal bearing","authors":"M. Mehdizadeh , F. Khodabakhshi","doi":"10.1016/j.csefa.2014.04.001","DOIUrl":"10.1016/j.csefa.2014.04.001","url":null,"abstract":"<div><p>Journal bearings as so sensitive parts of steam turbines are very susceptible to failure through different mechanisms of wear, fatigue and crush during service conditions. Failure occurring through these mechanisms lead to turbine completely shut down as a result of interfering in working conditions of bearing different parts. In this research, failed interfered part of a journal bearing related to a 320,000<!--> <!-->kW steam turbine was examined. Failure analysis investigations were performed by utilizing of stereographic, optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) analysis and hardness test. Surface crush, large amounts of surface cracks, no noticeable changes of failed surface chemical composition and microstructure with significant hardness improvement were the main obtained results. The studies were revealed that the bearing part loosing and inappropriate clearance can produce relative displacements under cyclic gradient loading. This condition was detrimental for the service life of turbine journal bearing via failure through fretting fatigue mechanism.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 61-68"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.04.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Reduction in diversion due to coil break in CRNO grades of coils","authors":"S.K. Thakur , B. Sarkar , B. Ghosh , Ramen Datta","doi":"10.1016/j.csefa.2014.04.005","DOIUrl":"10.1016/j.csefa.2014.04.005","url":null,"abstract":"<div><p>Diversion due to coil break in cold rolled non oriented (CRNO) grades of coils showed an increasing trend during Jan–May’12 at Silicon Steel Mill (SSM), Rourkela Steel Plant (RSP). Coil break increased from a level of less than 1% during to a level of 30% in May’12. Samples from hot rolled coils and finished coils were taken and detailed metallurgical investigation was carried out to ascertain the genesis of such defects. Further studies were carried out in the processing lines and material flow was tracked from steel making to final product. The probable reasons were identified and corrective measures were taken leading to reduction in diversion due to coil break less than 2%.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 76-83"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.04.005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Weld failure analysis of 2205 duplex stainless steel nozzle","authors":"Jingqiang Yang, Qiongqi Wang, Zhongkun Wei, Kaishu Guan","doi":"10.1016/j.csefa.2014.05.001","DOIUrl":"10.1016/j.csefa.2014.05.001","url":null,"abstract":"<div><p>Failure analyses of weld joint between the nozzle and the head of the reactor made of 2205 duplex stainless steel was performed by optical microscopy (OM) and scanning electron microscopy (SEM). Cracks were found in HAZ of the weld. The depth of the cracks is equal to the thickness of the inner weld. Localized uneven distribution of ferrite/austenite with 80–90% ferrite in weld is found. Results show that the cracks occurred along columnar granular with cleavage fracture. Poor weld process probably results in these cracks.</p></div>","PeriodicalId":91224,"journal":{"name":"Case studies in engineering failure analysis","volume":"2 2","pages":"Pages 69-75"},"PeriodicalIF":0.0,"publicationDate":"2014-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.csefa.2014.05.001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54176631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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