Drill pipe slips have a taper of 4”/foot on diameter and other suitable dimensions to permit operation in standard master bushings.
The right size drill pipe slips must always be used for the size drill pipe being handled. Slips that are smaller than the drill pipe will damage the pipe and the corners of slips as well as risk dropping a string of drill pipe entirely. It is paramount that the right size is chosen and used to avoid catastrophic damage to the drill string. Slips that are too large will not contact the pipe all the way around. This risks dropping the pipe and destroys the center part of the gripping surface.
New or “like new” inserts carry a concentrated load and deeply penetrate the pipe. Re-sharpened inserts carry no load. Inserts which carry a concentrated load are forced into slip bodies resulting in permanent damage to slips.