Rope inspection criteria for drilling operations.

 

All portions of wire rope must be inspected thoroughly for possible deterioration on a regular basis. This starts with a close examination of the rope’s critical points. The critical points of an application are those that subject the rope to greater internal stresses or greater external forces. Rope wear is more likely in the following critical areas, so it pays to closely inspect these areas:

Drums. When the rope spools properly, normal wear occurs at the crossover, kickover and change-of-layer points. Look for scrubbing on the side of the rope; in other words, rope that rubs against the preceding wrap on the drum. Crushing may result on rope’s top and bottom sides. If severe, remove the rope from service. Both the scrubbing and the crushing normally occur twice with each drum revolution.

Inspection of drums is also critical. Check for signs 
of wear that could damage wire rope. All drums should be smooth, not corrugated. Check for minimum number of dead wraps remaining on the drum, the spooling characteristics of rope and the condition of flanges.

Sheaves. It’s very important to check for broken wires in the wire ropes traveling over the sheaves in your system. (See section on broken wires on facing page.)

Grooves tend to wear smaller over time, especially under heavy loading conditions. With a groove gauge, check each sheave for proper sizes as well as smoothness. Grooves that are too small or tight can cause pinching and increased abrasion while grooves that are too wide can cause flattening of the rope — both of which can reduce your rope’s life. Also inspect for corrugation, broken or chipped flanges, cracks in hubs and spokes, signs of rope contact with guards, sheave bearings and shaft, an out-of-round condition, and alignment with other sheaves — all criteria for replacement. 

End attachments. Rope adjacent to end attachments has its movement restricted and is subject to fatigue as rope vibrations are damped. Inspect with an awl to expose broken wires, and if more than one broken wire is found, replace the rope. Be sure to also inspect the fitting itself. 

Other important areas to inspect.

Pick-up points. The sections of a rope that contact sheaves or drums when the initial load is applied. 

Heat exposure. If an electric arc contacts the rope, remove the entire rope from service immediately. Although the problem may not be visible, electric arcs can affect the rope’s properties and the rope needs to be replaced.

Abuse points. Look for “bright” spots where ropes are subjected to abnormal scuffing and scraping.