Question: Why doesn’t ASME B30.9 permit wire rope slings to be made from rotation resistant wire rope? Is it because the core direction is different than the strands and not possible to fabricate?

Answer: Rotation resistant wire rope is not to be used in the fabrication of slings because of its design characteristics. Rotation resistant rope breaks from the inside out due to the extreme crossing of the internal strands with the external strands.  This leads to high stresses at the inside of the wire rope and subsequently the internal wires usually will break first. Internal wire breakage is difficult to detect during an inspection since very little external evidence shows up on the rope. Tight bending of the wire rope increases internal stresses and accelerates the wire breakage. The eyes would also deteriorate rapidly and any hitch would promote damage to the internal wires in the body of the sling.