PART 18: DEMOLITION BALL OPERATIONS

The incorrect use of a demolition ball is hard on the machine. Crane operators shall be conversant with demolition balling, and the work shall be supervised by an experienced person.

18.1 Machines

Not all machines are robust enough to withstand the rigours of demolition ball work. Large capacity strut boom crawler cranes are the most suitable. Hydraulic boom cranes shall not be used for this type of work, as overstressing at the sliding points can occur.

Because an uncontrolled demolition ball swings in all directions, slackness in the boom and slewing machinery will reduce control of the ball and make operating uncomfortable.

Precautions shall be taken to prevent the hoist rope from leaving the boom point sheave, as the slack rope condition, when the ball has fallen, allows the rope to jump off the sheave unless heavy duty rope guards are fitted. Damage is likely where the ball is attached to the hoist rope. Hoist ropes should not be fixed directly to the demolition ball.

These should be joined by at least 2 metres of chain which must have a minimum breaking load capacity no less than 10 times the weight of the ball.

18.2 Operator Protective Structures

(1) Falling Object Protective Structure (FOPS): Cranes used specifically for demolition balling should be fitted with a CPEng-certified FOPS cab to meet or exceed the requirements of ISO 8083:2006 Machinery for Forestry - Falling-Object Protective Structures (FOPS) - Laboratory Tests and Performance Requirements, and be adequate and safe for the purpose intended.

(2) Side or roof intrusion: Operators are to be protected from debris by a CPEng-certified protective structure to meet or exceed the requirements of ISO 8084:2003 Machinery for Forestry - Operator Protective Structures - Laboratory Tests and Performance Requirements and be adequate and safe for the purpose intended.

18.3 Demolition Balls

Safety rules for demolition balling:

(1) All demolition is to be supervised by a competent person. Operators shall be competent and experienced.

(2) The boom angle when balling should not be more than 60° to the horizontal.

(3) The top of the boom should not be less than 3 metres above the wall being knocked down.

(4) The static weight of the demolition ball is to be not more than 33% of the machine's maximum rated safe working load.

(5) The weight of the ball is not to exceed 10% of the hoist rope's minimum breaking load.

(6) The boom and hoist rope are to be as short as possible.

(7) The ball is to be securely attached to the chains from the hoist and drag ropes with a swivel coupling, and inspected hourly.

(8) Arrestors are to be fitted to prevent the boom whipping back over the machine should a rope or coupling fail, or an entangled ball break free.

(9) The machine shall be in proper working order while in use. When the demolition ball is suspended, the operator shall be at the controls.

(10) Machine fatigue shall be watched for, and particular attention should be paid to fatigue failure at pendant rope sockets.

For further information on safe demolition practices, refer to the Approved Code of Practice for Demolition (published by the Department of Labour).