Is the minimum breaking strength of a rope the same as its safe working load?
Quoted breaking strength of rope is usually the optimum strength achieved under laboratory conditions, in accordance with prescribed test procedures, on new rope, pulling at a slow, steady rate in a straight line. Real life applications normally involve many different types of forces and factors which will cause the rope to fail at much reduced loads. Accordingly, the safe working load of any rope is much lower than its nominal strength. The following article reprinted with permission from Cordage News, a publication of the Cordage Institute provides a good overview of factors to consider when determining the safe working load of the rope. TOTAL POTENTIAL LOAD (TPL) is the weight to be lifted, towed, restrained, suspended, or secured, not just in a static condition, but in a dynamic condition. Examples: the jerking of a weight being lifted, the heaving of a vessel, the slalom of a water skier, the falling of a body, the swaying of scaffolding, the tethering of a balloon, the wind press
