A coal terminal had three ship loaders in service. The telechutes on these ship loaders were programmed for change-out after a minimum of 125 million tonnes in service, depending on wear; and the business currently stocked one spare telechute onsite.
The business sought to investigate the risks associated with the current spare stock level and, if warranted, develop a business case to justify the purchase of an additional telechute to act as a spare for the ship loaders.
On more than one occasion, one of the operating telechutes became faulty or damaged and became inoperable before it was scheduled for changeout. The most common reason for this damage was wear and tear to the bottom segment rotating frame.
With three ship loaders in service, only one spare available and a repair time of approximately two months for a damaged telechute, the risk of unavailability to the business was significant. This could result in a potential throughput loss of 4,735,160 tonnes or 8.27 million dollars in the two months required to source and repair the telechute.
The coal terminal thus sought to determine the optimum number of spares to hold onsite.
ARMS Reliability was engaged to perform a Spares Optimization Analysis on the ship loader telechute. The goal was to determine an acceptable risk mitigation strategy based on spares holding levels, and identify the optimum number of spare telechutes to hold onsite.
Two studies were conducted as part of the analysis - Availability Modeling and a Failure Modes, Effects and Criticality Analysis (FMECA) study.
First, to measure the cost impact of failures, a FMECA study was performed for key pieces of equipment.
The modeling revealed the costs and plant availability over a 10 year lifetime for each scenario. From this it was predicted that the optimal number of spare telechutes for the business was two (Refer to Chart 1). With two spares held onsite, there would be an optimum increase in availability of all three ship loaders as well as a significant decrease in the unavailability of the ship loaders due to telechute issues.
Following completion of the project, the results of the report were used as a key element of a business case to support the purchase of a second telechute.