Major Causes of Crane Accidents
Contact with power lines
Overturns
Falls
Mechanical failures
How Do Accidents Occur?
•Instability – unsecured load, load capacity exceeded, or ground not level or too soft
•Lack of communication - the point of operation is a distance from the crane operator or not in full view of the operator
•Lack of training
•
Inadequate maintenance or inspection
Who is at Risk
-Operators -Persons at Crane Site
Definitions
Crane – Consists of a rotating structure for lifting and lowering horizontally on rubber tires or crawler treads
Hoist - Used to lift and lower load.
Boom – An inclined spar, strut, or other long member supporting the hoisting tackle
Boom stops – A device used to limit the angle of the boom at its highest position
Brake – To slow or stop motion by friction or power
Block – Sheaves or grooved pulleys in a frame with hook, eye and strap
Jib – Extension attached to the boom point to provide added boom length for lifting specified loads.
Crane Parts
Types of Cranes
Mobile
Hydraulic
Overhead
Gantry
Tower
Crane Hazards
Planning Before Start-Up
Level the crane and ensure support surface is firm and able to support the load
Contact power line owners and determine precautions. Know the location and voltage of overhead power lines.
Know the basic crane capacities, limitations, and job site restrictions, such as the location of power lines, unstable soil, or high winds.
Make other personnel aware of hoisting activities.
Barricade areas within swing radius.
Ensure proper maintenance and inspections.
Determine safe areas to store materials and place machinery.
competent person
The competent person must inspect all machinery and equipment prior to each use, and during use, to make sure it is in safe operating condition.
If it needs fixing, take it out of service and don’t use it until it is fixed
Know the Weight of the Load
Refer to shipping ticket or other documentation
Ensure lift calculations are correct
Ensure load is within load chart rating for boom length and load radius of crane
Crane is rated by the maximum weight it will lift at a minimum radius and minimum boom length – the further from its centerpoint, the less it will lift
Load Limiting Factors
Not level
Wind
Side loads
On its wheels
Lifting over the side
Use of extensions, jibs and other attachments
Limits of wire rope, slings and lifting devices
Mobile Cranes – Lifting Principles
Center of Gravity
Leverage
Stability
Structural Integrity
Load Example – 30 ton crane
Will lift 60,000 pounds at 10 feet from the center pin of the crane
Based on level surface, no wind, and outriggers fully extended
At 25 feet from the center pin with an 80 foot boom, the capacity is only 14,950 pounds
At 74 feet from the center pin, the capacity is only 4,800 pounds
Improper Load
This crane overturned while performing loading operations on a pier. The crane was attempting to remove a metal container from a barge when it tipped and slid into the water. The wind caused the load to swing violently causing the load to go outside the swing radius, at that point the load dropped into the water and took the crane with it.
The crane overturned when it attempted to lift heavy pieces of metal chain in excess of its load rating. In addition it was side loading which was not part of the load calculation. Even though the outriggers were out, the weight of the load caused the crane to overturn.
the equipment clearance shall be a minimum of 4 feet for voltages less than 50 kV., and 10 feet for voltages over 50 kV., up to and including 345 kV., and 16 feet for voltages up to and including 750 kV.
Hand Signals
Hand signals to crane and derrick operators shall be those prescribed by the applicable ANSI standard for the type of crane in use. An illustration of the signals shall be posted at the job site.
These charts are available in other languages.
Swing Radius
determined that the preferred way to protect employees in these situations is to completely barricade the entire swing radius of the equipment and prevent employee access to the area.
Accessible areas within the swing radius of the rear of the rotating superstructure of the crane, either permanently or temporarily mounted, shall be barricaded in such a manner as to prevent an employee from being struck or crushed by the crane.
Operator Visibility
All windows in cabs shall be of safety glass, or equivalent, that introduces no visible distortion that will interfere with the safe operation of the machine.
ladders
(i)-Where necessary for rigging or service requirements, a ladder, or steps, shall be provided to give access to a cab roof.
- Guardrails, handholds, and steps shall be provided on cranes for easy access to the car and cab, conforming to American National Standards Institute B30.5.
- Platforms and walkways shall have anti-skid surfaces.
Guardrails
Guardrails, handholds, and steps shall be provided on cranes for easy access to
the car and cab, conforming to American National Standards Institute B30.5.
Platforms and walkways shall have anti-skid surfaces
suspended loads.
All employees shall be kept clear of loads about to be lifted and of suspended loads.
The boom angle indicator
The boom angle indicator is an accessory device that measures the angle of the boom base section centerline to horizontal.
Supporting surface
The crane shall be uniformly level within one percent of level grade and located on firm footing. Cranes equipped with outriggers shall have them all fully deployed following manufacturer's specifications, insofar as applicable, when hoisting employees.
Be mindful of asphalt which easily becomes a shifting, soft surface under a concentrated load.
Sheaves
The grooves must be smooth and free from surface defects which could cause rope damage
Rigging Equipment Slings
This section applies to slings used in conjunction with other material handling equipment for the movement of material by hoisting.
The types of slings covered are those made from alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope (conventional three strand construction), and synthetic web (nylon, polyester, and polypropylene).
Annual Inspection
The employer shall maintain a record of the dates and results of inspections for each hoisting machine and piece of equipment.
What to Inspect
Correct air pressure and no leaks
Tires properly inflated
Clearance for tail swing
Wire rope wear
Physical damage to crane
Loose or missing hardware, nuts, or bolts
Fluid leaks
Training
•-Operators:
Ømust qualify on specific crane type
ØMust include on-the-job training
•-Supervisor / competent person
Summary
• An unstable load, lack of communication, lack of training, and inadequate maintenance or inspection are major contributors to crane accidents.
• Operators or others working in the area can be victims to “struck by" and "caught in" injuries.
• Contact with power lines causes many accidents.
• A competent person must inspect a crane regularly to insure it is in proper order.
• Planning and training reduces accidents.
