부산대학교 도서관

During the coating of a natural gas pipeline, all 14 bolts securing the pedestal of a crane boom to a truck bed failed, causing the boom to fall and strike a worker in the head. The bolts exhibited excessive corrosion indicative of exposure to a harsh corrosive environment prior to the failure. Review of provided documents revealed that the crane was kept in an uncovered yardfor two years. Afterward, it was rented to petrochemical companies for use in heavy oil and gas industrial environments. The fracture surfaces of the bolts revealed signs of excessive fatigue, which were determined to be caused by loadings that the previous renters of the crane had subjected it to. Boltfatigue drastically reduced their strength, allowing them to fail under loads well below the recommended load capacity of the crane. Maintenance records indicated that the lessor failed to perform adequate inspection of the crane, allowing bolt corrosion and fatigue to go unnoticed. Had proper inspections and maintenance instructions been provided and performed, the incident would not have occurred. Keywords Fatigue, heat treatment for fasteners, hydrogen embrittlement, crane boom, periodic inspections, forensic engineering
Case Background A pipeline maintenance company was in the process of re-coating an excavated natural gas pipeline. Discovery documents describe their recoating procedure as follows: A heating ring is lowered [...]