MAINTENANCE
talk
Maintaining belt conveyors STEVE DAVIS In his regular BULKtalk column, Steve Davis considers the basics of bulk handling that sites often struggle with. Steve has worked in bulk handling for 30 years, for both resource companies and professional engineering firms, in Australia, South Africa, the Middle East and Canada. His experience encompasses such commodities as iron ore, coal, potash, phosphates, petcoke, sulphur, sands and grain.
In the September edition of ABHR, Steve Davis considered the many different types of condition monitoring equipment for conveyors. In this edition of BULKtalk, he examines how the industry can make conveyors more maintainable. CONDITION MONITORING SYSTEMS can be installed on existing conveyors to observe, predict, and indicate potential equipment failures. Predictive maintenance and planned repair are possible and provide the opportunity to get the best possible productivity from these machines. So far, the only automated online replacement is for idler rolls. This technology seems to be a real possibility, but there are limitations and from review will likely be most effective if the conveyor system is designed specifically to match the replacement method. In most situations, idlers and all other components will need to be replaced using traditional manual methods. Although some components have been known to last for many years, this is not the norm. Most conveyors will need to be regularly shut down to allow Covers bolted in place no access to idlers.
38 І Australian Bulk Handling Review: November/December 2021
component change. The prime consideration should be safety and environment. This results from a combination of initial design and work processes. The better the initial design, the easier the work processes and generally quicker repairs can be made, costing less, and getting conveyors back in service quickly. Unfortunately, I still see many new conveyor designs that have scant consideration for maintenance. Is this because knowledgeable Operational Readiness (OR) and maintenance personnel are not engaged early enough or do not have sufficient authority? Is it because the concepts are not embedded in the projects from the onset and require additional time and engineering budget to change when identified in workshops? We are certainly improving but there is a long way to go. Rotability of components, especially in chutes, seems to be widespread but having a rotable component that is unsafe or very difficult to exchange is an incomplete concept. Given that shutdown time is always premium time, additional pressure from complex methods and poor access and extended time increases the likelihood of accidents. As examples: • We can monitor the condition of conveyor pulley bearings such that planned change is implemented before failure, but
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long after a scheduled change based on operating hours. - If the plan is to change bearing in-situ and there is poor man access needing scaffold, no consideration of how to remove the bearing, no spare bearing in the spares list we may have an extended and potentially unsafe and expensive bearing change. - If the plan is to rotate the entire pulley for shop repair, and design of the conveyor requires that the belt be cut, structure be modified and complete disassembly of a chute using a large mobile crane due to poor site access, is a four-day outage and an unnecessary resplice or two a good result? We can monitor idlers and identify when to change rather than waiting for failure. Idler change should be relatively fast with conveyor matched to a good belt lifter and easy access. - Idler change is more complex and time consuming if there is poor access, if roof/cover panels must be removed and the stringer section and arrangement doesn’t match any available belt lifter. The need for additional time and equipment can delay change until roll failure occurs and beyond to where belt damage occurs, and the benefit of monitoring has been lost.
