Original scientific paper

Integrity assessment of bucket wheel excavator welded structures by using the single selection method

Marko Rakin orcid.org/0000-0002-3965-0380 ; University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, 11000 Belgrade, Serbia
Miodrag Arsić ; University of Belgrade, Institute for Material Testing, Bulevar Vojvode Mišića 43, Belgrade, Serbia
Srđan Bošnjak ; University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, Serbia
Nebojša Gnjatović ; University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, Serbia
Bojan Međo ; University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, 11000 Belgrade, Serbia

Abstract

In order to reduce the testing costs for structural welded joints and production losses due to excavator standstill, a new method for integrity and reliability assessment of welded joints during exploitation of bucket wheel excavators has been developed. In this paper, a part of non-destructive testing results for the butt welded joints on bucket wheel boom, counterweight boom and discharging boom is presented, prior to the repair of the collapsed bucket wheel excavator SchRs 1760×32/5. It has been in operational mode for 17 years prior to the collapse, in other words it has been subjected to aproximatelly 2 125 000 cycles of variable loading. Hypergeometric distribution has been used for calculation of probability that x welded joints, which comprise n welded joints with defects, would be selected for testing out of overall number of joints Q. The integrity assessment for welded structures of bucket wheel excavators has been performed on the basis of defect analysis and probabilistic assessment of the fatigue crack growth in welded joints. By using this method, the testing costs have been reduced by 70 % through optimized scope of the inspections and time periods between them.

Keywords

bucket wheel excavator; fatigue; integrity assessment; non-destructive tests; single selection method; welded structure

Hrčak ID:

109789

URI

https://hrcak.srce.hr/109789

Publication date:

25.10.2013.

Article data in other languages: croatian

Visits: 2.964 *