BELT CONVEYORS FOR BULK MATERIALS, 7th edition
Chapter 14 – Operation, Maintenance, and Safety Excerpt
Index of Chapter
- Maintenance, Maintenance Staffing for Conveyors
- Guidelines for Safe Operation and Maintenance: Safety Labels, Codes & Standards
- Guarding: Conveyor Guard Construction, Types of Conveyor Guarding, Strength of Guards, Labeling and Identifying, the Hazard, Return Rolls, Troughing Idlers, Head and Tail Pulley Guarding, Takeup and Bend Pulleys, Bearings, Other Components, and Accessories, Guarding Resources
- Risk Assessment: Acceptable Risk, MIL-STD 882, Examples of Hazards and Hazardous, Situations in Bulk
Materials, Example: Severity vs. Probability, ALARP Matrix
- Trouble Shooting Conveyor Problems
The preceding chapters of this book have provided engineering information that can form the basis for the proper application and design of high-quality belt conveyors and conveyor systems. To acquire optimum performance, dependability, and cost economy, equal importance and consideration must be given to the installation, safe operation, and proper maintenance of the system and all related equipment.
Each conveyor system is installed in a different location and facility and will have unique performance requirements, design features, and operating environment. All of these special considerations must be studied and evaluated when developing the best operating procedures and the safest workplace.
Because of the number and range of these variables, this chapter can provide only a brief overview of some of the most important and generally applied practices. Conveyor manufacturers are often able to offer assistance in establishing the best operating maintenance and safety programs.
Operation, maintenance, and safety are closely linked functions. Too often management of these functions is in conflict because the budgets for operation, maintenance and safety are controlled by different departments. For the safe and efficient operation of conveyor systems, it is critical that these primary functions are communicating and working together as a team.
Well designed conveyors are very robust and reliable machines. These inherent features of belt conveyors can lead to complacency where standard procedures are ignored and attitudes about the dangers of conveyors become lackadaisical. Conveyors can be abused by overloading, improper operation, or lack of maintenance and still perform. Spillage and dust hazards become accepted. The conveyor belt and the rotating components create numerous nip points and potential for stored energy hazards that may not be obvious to new personnel or may be ignored by experienced personnel due to familiarity.
Characteristically, the operation of truck and rail haulage systems for bulk materials requires a relatively large number of trained personnel. Operators are needed for scheduling and master control of the system, as well as to dispatch individual units and drive large vehicles. Employees are also required for such additional operations as loading, discharge, and weighing of the material.
Many belt conveyors, when appropriately designed, installed, and operated, will perform continuously and dependably with as few as one or two operators. One basic requisite is that the material being handled by the conveyor has the originally specified physical properties and is fed uniformly at the design rate.
Performance of a system can be continuously monitored by a combination of modern electrical controls, built-in safety sensors and devices, closed circuit TV, and other signal systems. A central control panel can be equipped so that an operator can monitor performance even at remote areas.
Depending on the length and complexity of a system, one or perhaps two trained mechanics should patrol the system at regular intervals to detect any conditions or components that need attention. On a 5.5 mile (9 km) overland system, two mechanics, and a supervisor can usually perform such inspections.
At the time of installation and during trial runs of a large and complex conveyor system, it is advantageous to offer a program of instruction and discussion for all personnel who will be involved in operation, safety, and maintenance of the system. At this time an operating procedure should be developed; the procedure should detail the sequence of operation of the system. Such programs should be repeated and the procedures reviewed at sufficiently frequent intervals so that trained personnel can update their knowledge and new employees can be trained.
It is important that belt conveyor maintenance be performed only by well trained and competent personnel who are provided with proper test equipment and tools. They should receive training in the value and conduct of a comprehensive preventive and predictive maintenance program done safely.
There are three types of maintenance: Breakdown Maintenance where the equipment is run to failure and then repaired, usually, on an emergency basis; Preventive Maintenance where the equipment is serviced regularly and rebuilds are performed on a planned schedule before the equipment is run to failure; and Predictive Maintenance where planned inspections are performed to determine the health of a machine and repairs accomplished only when the inspections indicate that the equipment is beginning to go into the failure mode.
Preventive maintenance includes lubrication programs and planned rebuild programs, where predictive maintenance includes vibration analysis trending on bearings, motors, reducers, and oil analysis in engines, reducers etc. A combination of preventative and predictive maintenance programs will help ensure maximum availability and component life. A well-maintained conveyor system should be able to consistently operate with 90% mechanical availability.
The conveyor belt often represents a high proportion of the total conveyor cost. Since the composition and construction of the belting makes it vulnerable to accidental damage and/or accelerated wear, belt operation and maintenance deserve special attention in a good training program to minimize replacement and repair cost. Refer to Chapter 7 for information on conveyor belting.
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