OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 21 Rigging

Section 306 Wire rope

In applying the requirements of this section, it is helpful to understand how a wire rope is constructed. As shown in Figure 21.34, wire rope is made of three parts: wires, strands and core.

Figure 21.34 Example of wire rope

Rope lay describes the direction the strands rotate around the core:

  • regular lay rope – the strands rotate in the direction opposite to which the wires rotate. This is to counteract the torque in the rope and prevent unwinding under load;

  • lang lay (non-rotating) – the strands rotate in the same direction as the wires. These ropes are used in special applications where torque would cause the line to twist in one direction, e.g. single line lifts, but are approximately 20 percent weaker than regular lay ropes.

A “lay” is the distance it takes one strand to make a complete revolution around the rope.

Figures 21.35 through 21.39 show examples of various types of wire rope damage.

Figure 21.35 Examples of rope damage due to kinking

Figure 21.36 Examples of birdcaging

Figure 21.37 Examples of wire rope damage

Figure 21.38 Reduction of normal rope diameter

Figure 21.39 Examples of wire rope with broken wires