Wire rope retirement criteria*
Several of the current criteria for the retirement of wire hoist ropes were developed by a U.S. Bureau of Mines committee in 1915. These criteria were based on the two main rope constructions in use then, but today, more constructions are in use and great improvements in steels and production methods have evolved. Bureau work to date has shown that the criteria involving rope diameter lass and outer wire diameter loss are not consistent for any one rope construction, and in fact, vary widely among constructions. Another criterion that needs revision is that ropes should be retired when loss of strength exceeds 10% as determined by nondestructive testing. Electromagnetic NOT is the most common method used today, and while it can measure loss of metallic area and can detect broken wires if there is separation of the ends, it cannot measure lass of strength. The Pittsburgh Research Centre is working on developing the relationship among these parameters. Modernisation of the criteria would improve the safety of a great many people in addition to the U.S. mining industry, because retirement criteria in Canada, the U.S. Army and Navy, and others are largely based on the 1915 criteria.
Author(s): McKewan, W.M.