Toolbox Talk: “CRANE SAFETY”
A worker was struck and injured when the load line on an articulating boom crane broke and the crane’s load fell about 6 metres (20 feet) to the ground.
The load line broke because the crane “two-blocked”, meaning that its travelling lower block (the hook block) and its stationary upper block (the tip sheave) came into contact.
This contact can put extreme stress on the load line and other parts of a crane.
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Two-blocking can happen for various reasons.
In this case, the crane was fitted with a winch on the underside of its boom.
The crane operator extended the boom to place the load, but did not spool the load line off the winch’s drum at the same time.
This caused the crane’s travelling lower block (the hook block) to rise and contact its stationary upper block (the tip sheave).
When the crane operator continued to extend the boom after this two-blocking occurred, the load line broke.
The crane lacked the required two-blocking damage-prevention feature, which would have stopped this from happening.
When a crane two-blocks, a two-blocking damage-prevention feature will stall whatever actions the crane is performing so that the load applied by those actions doesn’t damage the crane’s
machinery or load line.
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Safe Work Practice
• Ensure that articulating boom cranes that are equipped with a winch are also equipped with a feature to prevent damage from two-blocking
• Ensure that cranes are inspected, tested, repaired, and maintained according to the manufacturer’s instructions, the Occupational Health and Safety Regulation, and the applicable standards.
• Operators must be familiar with operating manuals for respective equipment.
• We must establish and enforce written safe work procedures for rigging and lifting loads to include:
o Isolation of work zone to prevent loads being passed over workers.
o Warning for authorized workers not to stand or walk under loads.
• Provide workers with the information, training, and supervision necessary to ensure their health and safety when working with or around cranes.
• Unauthorized personnel must avoid areas where lifting activity is taking place.
• Know the rated load limitations of your crane and the weight of the load to be lifted and moved. Do not move the load if the weight is uncertain.
• When calculating the weight of the load, consider internal fluids or objects within the load that could increase the weight.
• Understand the reach and travel limits of the crane before moving the load to avoid extra handling, sudden stops and uncontrolled load swings.
• If required, ensure rigging and cribbing is adequate to support the load. Attach eye-bolts or other latching devices to the loads’ strongest structural members.
• Avoid lifting the load from the side to prevent sudden impacts on the crane.
• Ensure the load is in static and not dynamic state. That is, inspect the load for additional forces applied to it other than the vertical upward force of the crane.
Unforeseen forces on the load could create a sudden jerk or impact on the crane and introduce more safety hazards or damage.
• Never use the crane to pull or drag the load across the ground or floor. This introduces frictional forces that could exceed the rated crane load capacity.
• When using mobile cranes, ensure it is stable enough to move the load without tipping or over-turning.
This is one of the most hazardous conditions when using mobile cranes. If required, use stabilizing bars or outriggers to provide the necessary resistance.
• For heavy and awkwardly-shaped loads, use tag lines to help guide the load.
• Always wear the proper PPE before using cranes, including eye protection and steel-toed shoes.
“What you allow you teach what you teach is your standard” Unknown
