619 Materials Handling Safety

Safe Lifting Practices

Slings should be selected based upon the characteristics of the load and the environmental conditions surrounding the lift. Be sure to inspect slings prior to each use and that you know how to use it safely.

There are four primary factors to consider when safely lifting a load. They are:

1. the size, weight, and center of gravity of the load;
2. the number of legs and the angle the sling makes with the horizontal line;
3. the rated capacity of the sling; and
4. the history of the care and usage of the sling.

Size, Weight, and Center of Gravity of the Load

The center of gravity of an object is that point at which the entire weight may be considered as concentrated. To make a level lift, the crane hook must be directly above this point. While slight variations are usually permissible, if the crane hook is too far to one side of the center of gravity, dangerous tilting will result causing unequal stresses in the different sling legs. This imbalance must be compensated for at once.

Number of Legs and Angle with the Horizontal

As the angle formed by the sling leg and the horizontal line decreases, the rated capacity of the sling also decreases. In other words, the smaller the angle between the sling leg and the horizontal, the greater the stress on the sling leg and the smaller (lighter) the load the sling can safely support. Larger (heavier) loads can be safely moved if the weight of the load is distributed among more sling legs.

Rated Capacity of the Sling

The rated capacity of a sling varies depending upon the type of sling, the size of the sling, and the type of hitch. Operators must know the capacity of the sling. Charts or tables that contain this information generally are available from sling manufacturers. The values given are for new slings. Older slings must be used with additional caution. Under no circumstances shall a sling's rated capacity be exceeded.

History of Care and Usage

Mishandling and misusing slings are the leading cause of sling-related accidents. Most injuries and accidents, however, can be avoided by becoming familiar with the essentials of proper sling care and use. Be sure to check this history of the sling to be used and that it has passed inspections.

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