Failure Analysis of a Structural Sub-assembly From a Slimes Filter Press
- PDF / 2,502,754 Bytes
- 7 Pages / 595.276 x 790.866 pts Page_size
- 76 Downloads / 191 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Failure Analysis of a Structural Sub-assembly From a Slimes Filter Press Jessica Lynn Buckner • Ngozi Ochoa Alejandro Hinojos • Matthew Garcia Stephen William Stafford
• •
Submitted: 19 September 2014 / in revised form: 27 October 2014 / Published online: 8 November 2014 ASM International 2014
Abstract This paper presents results from a failure analysis investigation of a structural I-beam and supporting bolt of a slimes filter press. Metallurgical failure analysis techniques were employed to investigate the sequence of events leading up to final fracture. From analysis of the micrographs, it is concluded that the cyclic loading operating conditions of the filter press caused an initial fatigue crack on the bolt that propagated until the surrounding bolts failed, causing the last bolt to fracture by overload. Once this final bolt failed, a crack initiated at the weld interface where defects were observed and was the cause for final failure of the filter press. Keywords Cyclic loading Failure analysis Low carbon steel
Background During the electrorefining process, the insoluble components, called slimes, settle to the bottom of the refining tank; these slimes contain precious metals including gold, silver, and selenium that can be recovered and utilized for other applications with the use of a filter press [1]. The focus of this analysis is on a failed washing slimes filter press operating by a diaphragm pump with pressure applied by a hydraulic cylinder. A schematic of the failed portion
J. L. Buckner (&) N. Ochoa A. Hinojos M. Garcia S. W. Stafford University of Texas at El Paso - Metallurgy, 500 W University Ave El Paso, Texas 79968, USA e-mail: [email protected]
123
of the filter press is provided in Fig. 1, with the fracture surface outlined. There were three separate I-beams utilized on this filter press, with the inner surface of the topmost I-beam failing, after the last of four supportive bolts failed on the right side of the I-beam, referencing the orientation shown in Fig. 2a. The bottom flange of the I-beam had four threaded bolts total securing it to the press with two on each side of the web, and the I-beam was secured on both ends in the same fashion, with a total of 8 threaded bolts between both sides. The left side of the I-beam remained secured by four bolts at the time of failure when the last bolt on the right side fractured. The bottom flange of the I-beam is connected by a corner weld to a support base, which the bolts support. The bolts and I-beam were loaded and unloaded on average, two times per day, five days per week and exposed to a dilute sulfuric acid environment. The load produced a flexural state on both the final failed bolt and the I-beam. Initial chemical compositions as well as time in service are unknown, and the company was no longer in possession of the other three failed bolts at the time of this analysis. These I-beams were coated with a corrosion protective paint. It is theorized that the unrecovered bolts failed by
Data Loading...
