Pick your best shot

Pick your best shot

Make every pick safer and more productive by using good lifting and rigging practices

There is a good reason for the saying that a building is going “up.” Whether it’s by brute manual force or the finesse of a boom crane, much of it must somehow be strapped, fastened or connected to a lifting tool of some type to be put in place.

The Crane Inspection & Certification Bureau, with offices located in Orlando, Florida and Houston, Texas (www.cicb.com), offers extensive training and certification for crane operators, riggers, supervisors and trainers in all aspects of lifting.

Here, one of its trainers, Larry Kime, offers some best rigging practices that can help crews get the most from every lift and do it as safely as possible.

“The purpose of proper rigging practices is to provide a safe and controlled means of performing a lift and to prevent property damage and injury,” says Kime. Good rigging practices include the following:
Always rig the load to be lifted so its center of gravity is directly under the hook
Always keep the load’s center of gravity below the lifting points
Center the load in the bowl of the load hook

Figuring the center of the load can be tricky. “The center of gravity is the point where the object would be perfectly balanced on a fulcrum. With a symmetrical object that is uniform in shape, the center of gravity is located at the object’s geometric center. With imbalanced or irregular shaped objects, different length slings may be needed to place the object’s center of gravity directly under the hook,” says Kime.

“An unbalanced load will create a greater force on the rigging than the actual weight of the load itself. The center of gravity of a load can be determined from drawings, other documentation, markings on the load or by calculation,” says Kime.

Using attachments
Whether you are using a vertical hitch, choker hitch or basket hitch, the goal is to safely secure and control the load.

“The person responsible for selecting the rigging hardware and slings must know the capabilities and limitations of the attachments that are used,” says Kime. “For example, shoulder eye bolts should never be used on vertical sling angles more than 45 degrees because their capacity is greatly reduced on non-vertical lifts,” he says.

Kime offers other attachment tips:
All rigging hooks, rings, shackles, sockets and other sling attachments should develop the full rated capacity of the sling
All rigging attachments shall be inspected before each use for any signs of defects or wear
When using a choke hitch, make sure the sling is long enough so the choker fitting chokes on the webbing or rope, never on another fitting. The socket shall also be positioned so it does not cut into the sling

Lifting and moving safely
Getting a load off the ground and into the air is a particularly important time in the pick. Kime shares some good lifting ideas:
Make sure all rigging hooks are turned out before hoisting. In case a slack condition occurs, the load hooks will not become dislodged.
If the object has sharp or abrasive edges, use a pad or softeners to protect the sling.
After the slings are in place, slowly raise the hook until there is no slack in the sling and then stop. Ensure that the sling is sitting in the bowl of the hook.
Make a final inspection of the sling at this time. Check contact points for signs of excessive stress.
Use a double sling when hoisting two or more objects more than 12' in length.
Avoid shock loading, which can damage the sling. On a wire rope, for example, it causes bird-caging, which is a sign of sling damage, and means the sling must be taken out of service.
Set the load down before making any rigging adjustments.
OSHA states that a sling shall not be pulled from beneath a load when the load is resting on the sling. “Pulling it from under the load while it is resting on it could damage the sling,” says Kime.
Never drag slings on the floor.
Never shorten a sling with knots, twisting, bolts or other unacceptable means. “Slings should only be shortened or adjusted by methods approved by the manufacturer,” says Kime.
No one should ever get between the sling and the load or between the sling and the crane or hoist hook while the object is being lifted. Riggers and other ground personnel should be in a position for the best view of the load as possible, without being in potential pinch points.
Keep clear of suspended loads and loads about to be lifted.
Never allow anyone to ride the sling or the load.
Communication is an important part of the lift – not only with the crane operator, but with co-workers, too. The person responsible for the lift, operator, rigger and other ground personnel must be familiar with standard hand signals for controlling the crane.
The person responsible for the lift shall notify all co-workers and other personnel in the area affected by the lift.

Storing rigging equipment
“When not in use, slings should be properly stored in a cool, dry place. Do not store slings in areas where they could be exposed to moisture, extreme temperatures, corrosion, mechanical damage or kinking,” says Kime.

Per OSHA regulations, all rigging equipment that is not in use shall be removed from the immediate work area so it does not present a hazard to employees.

Published in the January/February 2008 issue of Contractor Tools and Supplies magazine.