Lang's Lay Rope Question

[kander]

The main lift line is a Lang's Lay IWRC rotationally resistant rope on a single fall. The original design had the lifted item restrained from rotation, however the client wishes to remove these restaints. Even though the rope is classed as a 'rotationally resistant' rope, how much un-twisting am I to expect from a Lang's Lay rope when put under tension per unit length? There is no swivel to be used in the setup.

 

[dik]

Catch the link...

http://www.usace.army.mil/publications/eng-manuals/em1110-2-3200/c-2.pdf

 

[pauljohn]

I thought that this type of rope is restrained from twisting because it will eventually unravel if allowed to twist in use. My advice would be to contact the manufacturer.

 

[Compositepro]

Rotation is affected by many factors in the manufacturing process besides the type of construction. Use history of the rope will also be a factor. It would be best to consult with the specific rope manufacturer before selecting the rope.

How critical is rotation? You will never be able to guarantee no rotation of something that is hanging from one rope. The less rotationally stiff the rope is the more rotation will be caused by other factors like wind. But the less stiff it is the easier it will be to prevent rotation by some other restraint.

 

[unclesyd]

Here is some good information on rotation resistant wire rope mainly for land based applications. There are some additional constructions used in the marine exploration industry.

http://www.unirope.com/wireropes/wr_techinfo_0.shtml