PROCEDURES AND PRECAUTIONS FOR LIFTING OPERATIONS The most important rigging precaution is to determine the weight of all loads before attempting to lift them, to make ample allowances for unknown factors, and to determine the available capacity of the equipment being used. In cases where the assessment of load weight is difficult, safe load indicators or weighing devices should be fitted. This chapter also includes a section dealing with the estimation of load weights.
It is equally important to rig the load so that it is stable. Unless the center of gravity of the load is below the hook, the load will shift.
The safety of personnel involved in rigging and hoisting operations largely depends upon care and common sense. Remember these safe practices.
Know the safe working load of the equipment and tackle being used. Never exceed this limit. Determine the load weight before rigging it. Examine all hardware, equipment, tackle, and slings before using them and survey defective components. Discarded equipment may be used by someone not aware of the hazards or defects. Never can-y out any rigging or hoisting operation when the weather conditions are such that hazards to personnel, property, or the public are created. You must carefully examine the size and shape of the loads being lifted to determine if a hazard exists during high wind speeds. Avoid handling loads that have large wind-catching surfaces that could cause loss of control of the load during high or gusty winds. The wind can critically affect the loading and load-landing operation and the safety of the personnel involved (fig. 1-16).
Figure 1-16.- Wind effects on load.
Figure 1-17.- Minimum safe distance for working around energized conductors. The primary killer of riggers and those persons handling loads is electrocution caused by the contact of the boom, load line, or load of a crane with electric power lines. When working with or around cranes that are within a boom's length of any power line, you must ensure that the power to that section of line is secured. If for some reason this cannot be accomplished, a competent signalman must be stationed at all times within view of the operator to warn him when any part of the machine or its load is approaching the minimum safe distance from the power line (fig. 1-17). You must also exercise caution when working near overhead lines that have long spans, as they tend to swing laterally because of the wind, and accidental contact could occur.
The safe working loads of hoisting equipment apply only to freely suspended loads on plumb hoist lines. If the hoist line is not plumb at all times when handling loads, then additional side loads will endanger the stability of the equipment. In circumstances such as this, structural failures can result without any warning (fig. 1-18).
Never use kinked or damaged slings or hoist wire ropes. To provide maximum operating efficiency and safety, you should give all slings and fittings thorough periodic inspections as well as daily inspections for signs of wear and abrasion, broken wires, worn or cracked fittings, loose seizing and splices, kinking, crushing, flattening, and corrosion. Special care should be taken in inspecting the areas around thimbles and fittings.
Figure 1-18.- Incorrect lifting procedures.
When using choker hitches, do not force the eye down towards the load once tension is applied. Wire rope damage is the invariable result (fig. 1-19).
Whenever two or more wire rope eyes must be placed over a hook, install a shackle on the hook with the shackle pin resting in the hook and hook the wire rope eyes to the shackle. This will prevent the spread of the sling legs from opening up the hook and also prevent the eyes from damaging each other when under load (fig. 1-20).
The following procedures and precautions should be observed whenever loads are to be handled:
Rig all loads to prevent the dislodgement of any Load and secure materials and equipment being part Suspended loads should be securely slung and hoisted to prevent any movement that could create a Keep the load under control at all times. Where necessary by the rotation, use one or more guide wire ropes or tag lines to prevent the rotation or uncontrolled motion (fig. 1-21).
Land all loads safely and block them properly before unhooking and unslinging them (fig. 1-22).
Never wrap the hoist wire rope around the load Attach the load to the hook by slings or other rigging devices that are adequate for the load being lifted.
Bring the load line over the center of gravity of load before starting the lift.
properly balanced before they are set in motion. hazard in transit.
Figure 1-19.- Proper position of choker hitches for lifting.
Figure 1-20.- Shackle use with two or more wire ropes. Keep hands away from pinch points as the slack is being taken up.
Wear gloves when handling wire rope. Make sure that all personnel stand clear while loads are being lifted and lowered or while the slings are being drawn from beneath the load The hooks may catch under the load and suddenly fly free.
Before making a lift, check to see that the sling is properly attached to the load Never, under any circumstances, ride on a load that is being lifted.
Figure 1-21.- Using tag lines to control load.
Figure 1-22.- Before loads are unhooked, they must be properly blocked. Never allow the load to be carried over the heads of any personnel.
Never make temporary repairs to a sling. Procedures for proper repairs to a damaged sling should be established and followed Remove or secure all loose pieces of material from the load before it is moved.
Make sure that the load is free before lifting and that all sling legs are taking the load.