Section 334.61. Hoisting of platforms.

 

(1)   Application. This section applies to movable platforms that are raised and lowered from the structure.

(2)   Operational criteria.

(a) Hoisting of the platform shall be performed in a slow, controlled, cautious manner with no sudden movements of the platform.

(b) Load and boom hoist drum brakes, swing brakes and locking devices such as pawls or dogs shall be engaged when the occupied platform is in a stationary working position.

(c) Portable towers shall be uniformly level within one percent of level grade and located on firm footing. Portable towers shall be equipped with outriggers. The outriggers shall be fully deployed following manufacturer's specifications when hoisting.

(d) The total weight of the loaded platform and related rigging shall not exceed 50 percent of the rated load capacity for the radius and configuration of the portable tower.

(e) The use of a machine having a boom in which lowering is controlled by a brake without aid from other devices which slow the lowering speed is prohibited.

(3)   Instruments and components.

(a) Portable towers with variable angle booms shall be equipped with a boom angle indicator, readily visible to the operator.

(b) A positive-acting device, such as an anti-two-blocking device, shall be used to prevent contact between the load block or overhaul ball and the boom tip, or a system shall be used to deactivate the hoisting action before damage occurs in the event of a two-blocking situation.

(c) The load-line hoist drum shall have a controlled-load lowering system or device on the power train, other than the load hoist brake, which regulates the lowering rate of speed of the hoist mechanism. Free fall is prohibited.

(4)   Design criteria.

(a) The hoisting mechanism shall be equipped with a dual cable suspension system. The platform and dual suspension system shall be designed by a qualified engineer or a qualified person competent in structural design.

(b) The dual cable suspension system shall be designed to minimize tipping of the platform due to movement of persons occupying the platform.

(5)   Rigging.

(a) If a wire rope bridle is used to connect the platform to the load line, each bridle leg shall be connected to a master link or shackle to ensure that the load is evenly divided among the bridle legs.

(b) Hooks on overhaul ball assemblies, lower load blocks or other attachment assemblies shall be of a type that can be closed and locked, eliminating the hook throat opening, except that an alloy anchor type shackle with a bolt, nut and retaining pin may be used.

(c) Wire rope, shackles, rings, master links and other rigging hardware shall be capable of supporting at least 5 times the maximum intended load applied or transmitted to that component. Where rotation resistant rope is used, the rope and hardware shall be capable of supporting without failure at least 10 times the maximum intended load.

(d) All eyes in the wire rope slings shall be fabricated with thimbles.

(e) Bridles and associated rigging for attaching the platform to the hoist line shall be used only for that purpose.

(6)   Trial lift, inspection and proof testing.

(a) A trial lift with the unoccupied platform loaded at least to the anticipated liftweight shall be made from ground level, or any other location where persons will enter the platform, to each location at which the platform is to be hoisted and positioned. The trial lift shall be performed immediately prior to placing personnel on the platform. The operator shall determine that all systems, controls and safety devices are activated and functioning properly, that no interferences exist, and that all configurations necessary to reach each location will allow the operator to remain under the 50 percent limit of the hoist's rated load capacity. A single trial lift may be performed at one time for all locations that are to be reached from a single set up position.

(b) The trial lift shall be repeated daily, or when the portable tower is moved and set up in a new location or returned to a previously used location.

(c) Persons shall not be hoisted unless:

1. Hoist ropes are free of kinks;

2. Multiple part lines are not twisted around each other; and

3. The primary attachment is centered over the platform.

(d) The hoisting system shall be inspected if the load rope is slack to ensure all ropes are properly seated on drums and in sheaves.

(e) A visual inspection of the portable tower, rigging, platform and the tower base support or ground shall be conducted by a person designated by the jump master immediately after the trial lift to determine whether the testing has exposed any defect or produced any adverse effect upon any component or structure.

(f) Any defects found during inspections which create a safety hazard shall be corrected before hoisting personnel.

(g) Documentation of the trial lift and daily pre-operational lift shall be made available to the department.

(7)   Jump practices.

(a) Persons shall keep all parts of the body inside the platform during raising, lowering and positioning.

(b) Tag lines shall be used unless their use creates an unsafe condition.

(c) The portable tower operator shall remain at the controls at all times when the tower engine is running and the platform is occupied.

History: Cr. Register, January, 1994, No. 457 , eff. 2-1-94.

Note

This type of prohibited boom is commonly called a live boom. Microsoft Windows NT 6.1.7601 Service Pack 1