Fibre rope and slings

Lifting slings and winch lines

What you need to know when working with HMPE fibre rope lifting slings to AS18264, including: working load limit, rope size, bending radius, end fittings, installation and environment.

Rope selection

Rope selection for lifting slings and winch lines involves the evaluation of a number of factors. For example:

Working Load Limits (WLL)
application (lifting slings or winching)
temperature
type of end fittings required to carry out a job safely.

How to calculate the working load limit according to AS18264

The WLL including factor of safety (FOS) are calculated by taking the relevant minimum breaking strength (MBS) and dividing it by the required FOS:

WLL = MBS ÷ FOS

This factor helps to provide greater safety and extend the service life of ropes.

Safety factors do not account for dynamic forces such as shock loads.

Engineering assistance may be needed to:

determine the service loads
determine risks (such as environment and bend on radius connections)
set the appropriate factor of safety if an engineered "one off lift".

The below High Modulus Polyethylene (HMPE) Fibre Rope WLL chart is an example. These will vary subject to materials used.

HMPE Fibre Rope WLL chart

Installing and tensioning winch lines

Install lines under a minimum of 10% of the designated line pull or working load limit.

If a controlled method for applying back tension is available, install lines with a back tension close to the WLL.

When determining the length of rope to be installed, allow enough rope for a minimum of 8 wraps on the anchorage side of the winch drum. This ensures that the connection point of rope to the drum is not under too much tension.

The wraps may loosen over time. They may need retention to original installation loads to prevent downward wrap slippage.