Using Lifting Accessories

 How to use and de-rate chain slings and wire ropes

One thing I have noticed with lifting guidance is the explanation in the manufacturers brochures always relate to the grade and the link diameter.  This is not how most people refer to the capacity of chain slings and wire ropes in the real world. See a few example below where I will use the rules above using the chain SWL rating.

Examples:

Single Leg:

Single leg chain are, as you would expect, rated on the safe capacity of the single leg chain in a vertical position, therefore the calculation is quite simple, a single leg chain can only be used vertically if used alone, therefore conforms to the stated safe working load.

Two Leg:

Here is where it starts getting interesting. The factors can be seen above in the chart.

For example you have some 6.7 tonne SWL 2 leg chains. This means you have 2 chains rated at 3.35 tonne when used vertically. If they are used over 0 and under 45 degrees, the safe working load is 3.35x1.4=4.69 tonne. If the chains are used between 45 and 60 degrees the rating is reduced to 3.35x1=3.35 tonne.

Three and Four Leg:

This follows the same procedure as the two leg chain, such that you need to find the SWL of the individual leg.

For example, with 6.7 tonne 4 leg chains, the individual chains are rated individually to 1.675 tonne. If they are used over 0 and under 45 degrees, the safe working load is 1.675x2.1=3.5 tonne. If the chains are used between 45 and 60 degrees the rating is reduced to 1.675x1.5=2.5 tonne.