Industrial Rope Access Ropes

Dynamic, Semi Static or Static?

Ropes used for industrial access, climbing and fall arrest can be classified as three types:

Dynamic = elongation at break above 40%
Semi Static = elongation at break 35-40%
Static = elongation at break below 35%

As nylon (polyamide) is the most stretchy rope it is used almost exclusively as semi static and dynamic lines. But Nylon in its yarn state will only stretch 16-27% so extra stretch is added by braiding and by special heat treatments to ensure a 40% stretch is achieved.

The stretch is an important safety factor as the G force of a falling object can be roughly calculated by the fall distance divided by the arrest distance. Therefore a person falling 2m being arrested by a nylon rope which stretched 200mm would be subjected to a G force of 10 but if the rope was dyneema with just 2mm stretch the G force would be 1000 and possibly fatal.

Dynamic and Semi Static lines are classed as PPE [personal protective equipment] Category 3, C type inspection. They must be made by a ISO9001 registered company.