Corrosion-provoked collapse of the inclined belt conveyor bridge

This paper presents the results of the holistic failure-based root cause analysis of a sudden collapse of the inclined belt conveyor bridge (IBCB), which is a vital subsystem of a steel mill raw material handling system. Through a comprehensive analysis of the set of possible causes ('design-in' defects, 'manufacturing-in' defects, 'exploitation-in' defects and 'environmental-in' defects), by the method of elimination it has been determined that the inadequate maintenance of the anti-corrosion coating was the root cause of collapse of the IBCB. Due to inadequate maintenance of the anti-corrosion coating of the IBCB structure, heavy and uniform corrosion, provoked by increased acidity of precipitations in the area of the steel mill, had led to disintegration of structural elements and, ultimately, collapse of the IBCB structure. Additionally, based on the appearance and position of the collapsed remains of the IBCB, as well as state of the objects connected by it before the breakdown, the structural collapse scenario was established. Results of the presented investigation underline the importance of the corrosion inspection and monitoring, especially in cases of facilities exposed to chemically aggressive environments. The expenses of planned standstills for the purpose of corrosion inspection and potential repairs on the structural elements damaged by corrosion are significantly lower than direct and indirect expenses of by accidental destruction.