Polyester roundslings had their origins in the Scandinavian countries and began making their way to the Western Hemisphere in the mid-seventies. Polyester roundslings stretch at half the rate of nylon rigging straps. Polyester roundslings can be made in either an endless or eye and eye configuration. There is a unique advantage endless polyester roundslings have over eye and eye configuration slings. The endless configuration polyester roundsling is more versatile because the connection and load contact points can be rotated, enhancing sling service life. Another key advantage for polyester roundslings is that many slings can be made simultaneously, while nylon web slings have to be made individually, one at a time.
Due to the manufacturing efficiencies, polyester roundslings will generally be less expensive than nylon rigging straps. Because the body of polyester roundslings is comprised of multiple windings of polyester yarn, the sling body is soft and supple. The supple body prevents the polyester roundsling from locking to the load or binding at the point of choke when polyester round slings are used in a choker hitch. Polyester roundslings are color coded, but never rely upon color to determine roundsling strength. 15% of the male population is color blind and one producer’s red, polyester round sling may look similar to another’s orange polyester round sling.
A prudent safety practice is to always determine sling capacity by obtaining the sling capacity from its capacity or identification tag. The outer sheath which encapsulates the load carrying yarns on Lift-It® polyester round slings is a double wall thickness material. Lift-It polyester round slings can be provided with a contrasting color inner sheath to alert the user that the outer cover has been breached. Remember, when you see inner load carrying yarns, you cannot use the sling. An outer bulked nylon cover can also be provided which is four times more abrasion resistant than normal polyester covers. There are major manufacturers that will tell you that if you see yarn, and it is undamaged that duct tape is the solution to problem, do a temporary repair and you’re good to go. This is simply not what is recommended in the OSHA regulations for polyester round slings, RS-1, the Recommended Standard Specification for Roundslings or ASME in B30.9, the consensus sling safety standards. Uninformed manufacturers will also tell you that the standard issue, polyester sheath used to encapsulate the load carrying yarns in polyester roundslings will protect the load carrying yarns from ALL ultraviolet degradation and this is not true. Darker, dense covers provide better UV degradation protection than thinner, light colored sheaths, but ALL synthetic products are degraded by sources of UV light.
When your nylon lifting slings, polyester round slings and Twin-Path® slings are not in use, store them in a dark, dry, cool location that is free from mechanical and environmental damage. We manufacture polyester round slings from 2650 Lbs. to 90,000 Lbs. rated vertical capacities. Depending upon the capacity, polyester round slings can be made from 18 inches to over 150 feet in length. Remember the sling length for polyester roundslings is always measured from one end or bearing point of the sling to the other.
We recommend that you consider Twin-Path® high performance fiber slings when weight and stretch are considerations. Large capacity, polyester round slings become extremely heavy when they become wet. Twin-Path® high performance fiber slings feature K-Spec® fiber which is a blend of aramid fibers and high molecular polyethylene fibers. Twin-Path® slings are roughly a third of the weight of polyester roundslings and high performance fiber Twin-Path® slings only stretch at 1% when loaded to their work load limit. Polyester roundslings stretch at approximately 3% at work load limit.
Tremendous advances have been made in the last few years in the development of fibers with tremendous strength to weight ratio advantages. Consider the line of Synthetic Rope Slings made by Lift-It Manufacturing as another option. Synthetic rope slings can be fabricated from conventional fibers such as nylon and polyester. More exotic fibers like Vectran® or Dyneema® can also be used. Be sure and inquire about the custom rope slings we provide that are adjustable. Adjustable rope slings take all the fun out of rigging!