Campaign life assessment and extension of melt shop cranes

Abstract

Operators of equipment which are critical to plant operations commonly require Fitness-For-Service (FFS) assessments to determine the necessary measures for continued operation. This paper presents the work performed by Hatch on several melt shop cranes which support operations at Gerdau’s integrated steel plant at Ouro Branco in Minas Gerais State, Brazil. Some of these cranes have shown signs of structural damage including cracking and local deformations to girders, end truck and trolley structures. Hatch was requested to perform a structural FFS assessment of some of the critical cranes which included two primary Hot Metal Charging cranes, a Basic Oxygen Furnace (BOF) slag crane and a Scrap Metal Charging crane.

Root Cause Analysis (RCA) and subsequent FFS assessments were performed, which included fatigue assessments to aid in the identification of cracking mechanisms for the observed damages to the crane structure. This work led to the development of a range of practical options for mitigation and monitoring, tailored to address the observed damages. These options included short-term local repairs and monitoring strategies that could be completed with minimum interruptions to overall production. This work also proposed possible long-term repairs, reinforcements, and local platework replacements to extend the operational life until a replacement crane is procured and installed. To date, many of the interventions have been successfully implemented, allowing for reliable continued operation of these cranes, resulting major benefits to the Melt Shop facility.