A sling is an assembly designed to connect a load to be lifted or turned to a lifting device such as the hook on a crane. A wire rope sling is a safe tool when properly selected to meet the requirements of the lift, and when used in a safe, workmanlike manner. However, as is the case with any machine, a sling requires care and must be inspected to determine if its condition is such that a lift can be safely made.
The end point in a wire rope sling’s useful service life is prior to the failure of the sling. It must be removed from service when normal wear or accidental damage weakens the sling to the degree that an adequate factor of safety no longer exists.
The term “Breaking Strength” is never used with reference to slings. Slings have a “Rated Capacity” that is determined by the manufacturer. A sling should never be used to lift a load that is greater than the published “Rated Capacity” for the particular sling and for the type of hitch being used. The design factor used in the calculation of a sling’s Rated Capacity compensates for normal dynamic loading and builds useful life into the sling.
Selection of a sling to lift a load is based on selecting a sling with a Rated Capacity at least equal to the weight of the load. The sling must also be proper to allow the user to select a hitch that will conform to the shape of the load and keep it under control during the lift, The use of multiple leg slings is not recommended when the angle between any leg and the vertical is greater than 450• In any case when lifting headroom is restricted and a larger leg angle is necessary, care must be exercised in selecting a sling with a proper Rated Capacity at the leg angle which will be used. A visual inspection of the sling must be conducted before each lift to make sure the sling is in new or near new condition. A manufacturer’s Rated Capacity applies only to an undamaged sling.
Slings used in selected industries are presently covered by specific codes seffing standards for the removal of a sling from service. However, many industries are presently without standards. Safety is the prime consideration on all jobs and the user must inspect a sling before each lift, and must remove the sling from service upon observation of any of the following conditions:
- Ten randomly-distributed broken wires in one rope lay, or five broken wires in one strand of one rope lay.
- Kinking, crushing, birdcaging, or any other damage resulting in distortion of the wire rope structure.
- Evidence of heat damage.
- Cracked, deformed, or worn end attachments.
- Hooks that have been opened more that 15% of the normal throat opening measured at the narrowest point.
- Hooks that are twisted more than 10 degrees from the plane of an unbent hook.
- Corrosion of the rope or end attachments.
Our responsibility is limited to the sling as purchased new; and the responsibility for safe operation, maintenance and use rest with the purchaser.Whenever a sling is being rigged, tensioned or used to lift a load, a potentially hazardous condition exists and extreme caution should be used by riggers and personnel in the area. In all cases, safe rigging practices must be employed.