Failure Analysis & Characterization: Fatigue & Failure I
Program Organizers: Andrew Havics, PH2 LLC; James Lane, Rimkus Consulting Group Inc; Burak Akyuz, Applied Technical Services Inc; Pierre Dupont, UMONS, Faculté Polytechnique de MONS (FPMs)
Monday 2:00 PM
September 30, 2019
Location: Oregon Convention Center
Session Chair: Erhan Ulvan , Acuren Group Inc.; Robert O'Shea , Engineering Systems Inc; Daniel Baker , General Motors; Pierre Dupont , Schaeffler Belgium Sprl/bvba
2:00 PM Invited
Case Study Invoving Failure Sequence Determination of Machinery: Ronald Parrington1; Steven Counts1; 1Engineering Systems Inc.
Several failures of newly-designed, automated-packaging machinery occurred within two million cycles or less of operation. One unit with two fractured plain carbon steel pushrods, a fractured low alloy steel pushrod, and a cracked aluminum air cylinder was submitted for failure analysis. If possible, the primary objective was to determine which component(s) failed first. The broken components included fatigue and monotonic overload failures. Determination of the sequence of the failure events was complicated by the somewhat unique way that the machinery was operated. The machinery could continue to operate for thousands of cycles after certain component failures. The causative and consequential component failures were able to be determined through a combination of metallurgical failure analysis and fact gathering.
Rolling Contact Fatigue Failure Analysis of Ball Bearing in Gear Box: Piyas Palit1; 1Tata Steel Ltd
Bearing is an important machinery part in industry. When bearings fail to meet their expected life the consequences are increased down time, loss of revenue and missed delivery. This article describes failure of a gear box bearing in rolling contact fatigue. The investigation consists of visual observation, chemical analysis, characterization of microstructures using optical microscopes and hardness test. Present study also considers bearing life as well as operational condition of bearings. Surface initiated rolling contact fatigue, leading to a surface failure known as pitting, is a life limiting failure mode in many modern machine elements, particularly rolling element bearings. Metallography analysis of crack propagation, crack morphology was also described. Indication of fatigue spalling in ferrography test was also discussed. Analysis suggested the probable reasons of such kind of failure in operation.
Failure Analysis of a Separator Shaft: Emily Bardugon1; 1Applied Technical Services Inc
In-service fracture of a drive shaft was experienced in the same system, which was used in the separation and milling operation of raw cement materials. The failure was detected by a drop off in power. It was unknown if the shaft had any previous overlay repairs. Scanning electron microscopy and metallographic examinations determined that the separator shaft failed due to rotating bending fatigue initiating at the overlay interface. Several factors contributed to the failure, but primarily improper welding practice or procedure. An extensive analysis of actual failed sample as well as a process of elimination methodology will be discussed during the presentation. Welding procedures and stress risers caused by the weld defects and geometrical effects will also be discussed.
Failure Analysis of Racing Engine Components in Large Displacement V-8 Engines: Kyle Ventura1; Hugo Ortega1; Kathryn Harris1; David Rule1; Michael Pulver1; Gerhard Fuchs1; 1University of Florida
Large Displacement (i.e., >8 liter) V-8 engines are used in a variety of racing applications including drag racing, tractor-pulls and off-shore boat racing. Often times, these engines include power adders, such as nitrous oxide injection, supercharging or turbocharging and can produce from several hundred horsepower, up to close to 1000 horsepower, per liter displacement. The loads experienced by the components in these engines during a race can result in failures; however, determining the cause of the failure may be difficult due to the damage to the component and collateral damage that occurs during the failure event. The analysis of failures of several components in these large displacement V-8 racing engines, including, engine blocks, crankshafts, connecting rods, valves and pushrods, will be discussed.
3:20 PM Break
Faulty Metallurgy and Maintenance Causing Bolt Failures in Oil and Gas Industry: Waleed Khalifa1; Iman El-Mahallawi1; 1Cairo University
In this paper we present cases of bolt failure analysis. The first case was for an offshore drilling station. The causes of such failure included faulty material (bolt class 10.9 in place of class 8.8), and faulty fabrication (existence of nonmetallic inclusions and the improper heat treatment resulting in several quench cracks). These are indicative of faulty metallurgy. It was also believed that the rule of poor installation/maintenance procedures is highly evident. The second case was also a fatigue failure of bolts located near a check valve in fuel terminal. The root cause was improper maintenance: these bolts were used in for 5 years. The third case was for Monel K500 bolts in an Artificial Lift Electrical Submersible Pump (ESP) Assembly. The composition of the failed bolts showed excessive levels of additions such as aluminum and carbon that cause grain boundary embrittlement that lead to a final failure.
The Root Cause of a Plant Fire: Bearing Defects and Pump Cavitation: Michael Hoerner1; Linda Robinson1; Pooja Sheth1; Farzam Mortazavi1; 1KnightHawk Engineering
A fire occurred at a lubricants mixing plant, originating in a centrifugal pump. As with any situation involving the potential for loss of life, understanding the cause of the incident and preventing future occurrences is of the utmost importance. To ensure that the correct root cause was identified, a multidisciplinary analysis of the incident was employed. Examination of the debris showed that the fire originated when the pump impeller came into contact with the pump shroud. Mechanical analysis of the pump operation revealed that at times the pump was operated in the cavitation regime. Metallurgical analysis of the debris revealed cavitation of the pump shroud and rolling contact fatigue of the pump bearings that was exacerbated by the presence of aluminum oxides in the bearing steel. The combination of bearing fatigue and the high loads caused by the off-design operation of the pump ultimately led to the fire.
Initiation and Propagation of Rolling Contact Fatigue Cracks Observed by Laminography Using Ultra-bright Synchrotron Radiation X-ray: Yoshikazu Nakai1; Daiki Shiozawa1; Shoichi Kikuchi2; Takashi Nishina1; Hiroshi Kobayashi1; Masanori Kurahashi1; Taizo Makino3; Yutaka Neishi3; 1Kobe University; 2Shizuoka University; 3Nippon Steel & Sumitomo Metal Corporation
The flaking failure in rolling contact fatigue (RCF) has been believed to originate from non-metallic inclusions located beneath the surface. With conventional microscopies, however, damage process in the internal region of materials could not be observed, then they were observed by computed laminography using ultra-bright synchrotron radiation X-ray, and the effects of the shape and the orientation on the RCF crack initiation and propagation behaviors were examined. In every case, cracks were first initiated from surface inclusion, and they propagated to the surface and the thickness direction. After the crack reached a critical distance, horizontal cracks were formed from the vertical cracks, where the normal of the horizontal cracks were perpendicular to the surface, and those of the vertical cracks were parallel to the surface. However, the propagation direction just after the initiation from inclusions depended on the orientation of inclusions relative to the rolling direction.
4:40 PM Cancelled
Combatting Failures of Grate Bar in Sinter Plant and Pellet Plant: Ankita Roy1; 1Tata STeel
Grate bars are structural and functional units of pallet cars of sinter and pellet plant responsible for carrying base mixture into induration furnace for agglomeration. Failed grate bars were characterised via metallographic characterisations using stereo, optical, SEM and EDS, structural characterisation using XRD and mechanical characterisations using hardness, tensile, impact and wear tests on failed grate bars after 9 months and 1 year of service respectively of sinter and pellet plant. Characterisations revealed that sinter grate bar failed in wear while pellet grate bars failed in creep mode. Root cause of these differences in mode of failures were traced back to difference in composition, operating temperature, morphology of agglomerates. Metallographic changes occurring in service were simulated in lab scale and stark difference in evolved phases were noticed for the two different grades. Quenching and tempering of the as-cast samples were recommended as a preventive measure for material degradation.