INFORMATION BULLETIN

Construction Safety Association of Ontario

CONVEYORS

 

Background

Conveyors are standard equipment in the mining and aggregates industries. They are also widely used in construction -- for aggregates and other applications. For example, concrete forming machines, such as curb machines and pavers, use conveyors to transport concrete from the delivery truck up into hoppers or placers on the equipment. Similarly, aggregate delivery trucks are often equipped with conveyors to place stone in basements or hard-to-reach locations. Asphalt paving and road milling equipment also uses conveyors extensively.

Conveyors are essential to mining, construction, quarry, pit, and aggregate operations. But they are also a source of some well-recognized hazards.

Hazards

The main hazards involve belts. This moving component can catch body parts in pinch points and lead to entanglement and crushing.

Accident Types

Common types of accidents with conveyors involve personnel struck by objects or caught in equipment. The majority of these accidents occur when workers attempt to do repairs, installation or clean-up while the conveyor system is active.

Lockout

Procedures for tagging and lockout can prevent many conveyor accidents. Workers repairing conveyors, adjusting belt tracking, cleaning residues from parts, or applying belt lubrication have been caught by moving parts and badly injured or killed when equipment was inadvertently activated. This can't happen if lockout procedures are consistently applied. Section 93(2) of the construction regulation (213/91) states that "No vehicle, machine, tool or equipment shall be used...while it is being repaired or serviced."

Lockout begins with determining the equipment or components to be worked on, turning off and isolating all energy sources, drawing off stored energy or potentially dangerous product, and installing tags and locks.

Equipment must be turned off and isolated even for short-duration adjustments or repairs.

Procedures must be specified for each workplace and each piece of equipment to ensure, for instance, that all energy sources (electric, hydraulic, pneumatic, etc.) involved in powering or controlling the equipment are properly isolated or locked out.

Audits conducted by supervisors can be used to ensure that procedures have been communicated and understood by the workforce and followed as required.

Machine Guarding

The use of guards on a conveyor system is not a recommendation -- it is a requirement. Section 109 of the construction regulation states that "Every gear, pulley, belt, chain, shaft, flywheel, saw and mechanically-operated part of a machine to which a worker has access shall be guarded or fenced so that it will not endanger a worker."

Guards on moving conveyor parts are often non-existent, inadequate, improperly positioned, or not replaced after repairs. In addition to making sure that guards are in place, operators should consider painting them in bright contrasting colours. This helps draw attention to their absence when they get lost or aren't replaced.

Legal Requirements

In addition to the general equipment requirements from the construction regulation cited above, there are specific requirements for conveyors set out in the Regulation for Mines and Mining Plants under the Occupational Health and Safety Act.

Among other points, Section 196 of the regulation requires that a conveyor have

• pull cords at accessible locations for stopping the conveyor in emergencies
• a means of applying belt dressing while the conveyor is in motion
• a start-up warning device when the conveyor is started automatically or by remote control or where portions of the conveyor are not visible to the operator
• pulleys guarded at pinch points that are or may become accessible to workers.

Guards must also be provided beneath a conveyor that passes over workers or from which falling materials or parts may endanger workers.

Checklist

For inspection and maintenance purposes, a conveyor checklist is recommended. This can be used periodically to identify components that are working properly or in need of attention. Points to check include

• emergency stop pull cords
• start-up warning device (audible/visible)
• guards on head, tail, drive, deflection, and tension pulleys
• guards on accessible pinch points
• guards protecting workers from overhead material
• means of safely applying belt dressing and lubrication to a moving conveyor
• fire suppression system
• guardrails
• access equipment (walkways, ramps, stairs, platforms, etc.)
• noise control.

Inspection guidelines and checklist are available from the Mines and Aggregates Safety and Health Association at (705) 474-7233 or fax (705) 472-5800.

Belt Alignment

Conditions such as misalignment at loading points, sidewinds, rain, snow, and buildup of product can interfere with the alignment or "train" of conveyor belts.

Realigning belts is one of the highest-risk activities involving conveyors. Too often the job is done without shutting down and locking out the conveyor.

To align a conveyor belt that has shifted, workers loosen bolts on the idler framework and hammer the belt back into position.

When alignment is attempted on a moving belt, workers can get hands, tools, or clothing caught in machinery, be struck by components, or be pulled into pinch points where they may lose a limb or be crushed.

Systems such as conveyor belt conductors and self-training idlers are available to keep the belt on track. With training idlers, a manual preliminary alignment is necessary. But after that any factors causing the belt to wander are automatically corrected.

Self-tracking systems reduce the risk of injury to operators and damage to equipment. The systems also cut maintenance requirements.

This bulletin is based on information reprinted with permission from Safety Focus (March 1999), published by the Mines and Aggregates Safety and Health Association.

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