CONDITION MONITORING
talk
Condition monitoring of belt conveyors Steve Davis explains the ins and outs of conveyor condition monitoring and how it can be deployed to save operators time and money. 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.
A ONE-KILOMETRE-LONG conveyor will have 4000 plus components: belt, pulleys, bearings, idlers, drives, cleaners, chutes etc. These components all wear out at different rates. Damage is common and component life becomes difficult to predict. What options are there for getting the best life from your conveyors? Firstly, what should we be looking at on typical conveyors to maximise uptime and component life? Belting and all aspects of the conveyor that cause damage to the belt, as this is the most expensive to replace: belt cost, labour cost and lost opportunity. In the worst case, a failed belt or splice will lead to potentially fatal outcomes as the belt and load run away and the take up falls. Belt tracking causes, and there are many, are usually the result of other
It is difficult to assess internal components visually, so often operators rely on noise, visible bearing collapse, and seizure to identify failure or near onset failure.
54 І Australian Bulk Handling Review: September/October 2021
condition issues. The result can be extreme belt damage, spillage, and structure damage. Pulley condition, as poor
cause belt cover damage and can cause belt tracking. Idlers that are buried in spillage will fail early as the bearing seals are penetrated.
lagging and entrapped material create uneven stress distribution across the belt and lead to carcass and splice failure and bottom cover wear, sometimes puncturing through the belt. Seized or collapsed pulley bearings, excessive shell wear, loose connections have many impacts and can lead to serious collateral damage. Allowing pulley bearings to run with incorrect lubrication or buried in spillage encourages early failure. Loading zone problems will cause belt tracking through off centre loading, incorrect skirts set up and adjustment can wear through the carry cover or allow spillage and dust escape. Worn or maladjusted belt cleaner systems allow excess carry back and may damage splices. Ploughs and safety attachments, as they prevent rocks getting trapped in the pulley nip point and damaging the belt and pulley; even worse if they come loose and run into the pulley. Seized idlers can fail producing the ‘potato peeler’ and ‘pizza cutter’ effects, cutting through
Spillage increases idler drag and energy consumption and is a cause of belt tracking. Spillage can initiate corrosion leading to shell failure. Check drive components and maintain. Brakes and holdbacks are safety devices and must be functional. Couplings may need lubrication. Gearboxes need oil. Check the drive set up, as incorrect fluid coupling fill or variable frequency drive set up can limit starting ability or increase acceleration time such that dangerous problems results. Guards should be visually assessed for condition and attachment. Any part of the guard that allows access to a danger zone or is a danger from corrosion or damage, snags or sharp edges must be fixed.
the bottom cover and can heat up and cause fires as they grind to a halt. Watch for idlers that have come out of the frame, as they can damage and injure. Buildup of carry back on idlers will
for visible damage or unusual noise, temperature, operation. This option is viable for smaller installations where manpower with sufficient knowledge to determine condition is available.
What do we do to monitor condition of our conveyors? There is the run it until it breaks and then repair philosophy. The only condition monitoring is by inspection. Failure or wear is determined through walking the machine and checking
