Web slings are an important component for lifting operations. They serve as a connection between the load to be carried and the lifting equipment. Web slings should be of adequate strength to handle heavy industrial loads and it is due to this reason that each webbing sling is marked at a rated capacity which may even be higher than 30,000 pounds. This limit determines the point beyond which the sling doesn’t not function. However, the rated capacity of a web sling depends upon the type of sling in use.
There are several configurations of web slings out of which flat-eye and twisted-eye are the most commonly used in the industry. Both the types of slings are made of either polyester or nylon. A polyester web sling is more suitable for use in conditions where the load may be exposed to acids, as it is tolerant to chemicals, however, they do not provide much stretchability. The nylon slings, on the other hand, are more tolerant to alkalis and offer some degree of stretchability. A flat-eye sling is a strap made of a predetermined width whose ends are folded to make an eye. The eye is on the same plane as the body of the sling. On the contrary, the eye of a twisted eye-sling stands at a 90° angle to the plane of the body of the sling. These differences play out in the rated capacity of the sling, which varies for each type of hitch.
By virtue of its design, a flat-eye sling is more suitable for a vertical hitch and a basket hitch; however, a twisted-eye sling is better equipped to bear the weight of the load for a choker hitch. A vertical hitch is a simple hitch where one eye is hooked to the equipment and the other is attached to a hook on the load. A basket hitch is one which has both the ends of the sling attached to the hook of the equipment, such that the sling is wrapped around the load. Alternatively, in a choker hitch, the sling is first wrapped around the load and one eye of the sling is made to pass through the other eye to create a snug hold around the load. This type of hitch first creates a knot around the load, after which one end of the sling is connected to the equipment. The knot is created more securely if a twisted eye sling is used in such a case. All the remaining features of flat-eye and twisted-eye slings are the same. Their configuration depends upon the length, width and material of the sling.