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Round Slings
 
Round Slings - Technical & Usage Information

Polyester Roundslings

A polyester roundsling, also referred to as a tubular sling, is composed of a continuous load bearing core(s) made from synthetic polyester yarns, not woven, fully enclosed in a protective cover(s), with or without fitting(s) or coupling component(s) used for general lifting purposes.

Safety is the paramount consideration involved in the use of any polyester roundsling. The proper polyester roundsling must be chosen for the job. Riggers must know the proper hitch to use, where and how to attach polyester roundslings to the load. Therefore, riggers shall acquire the knowledge, not only of the different type hitches, but the way loads can be expected to react when the lift is made.

Polyester Roundsling Identification

EACH POLYESTER ROUNDSLING SHALL BE DURABLYMARKED OR LABELED SHOWING:

A. Name or trademark or manufacturer

B. Manufacturer’s code or stock number

C. Rated capacities for the three basic hitches (vertical, choker, vertical basket).

D. Polyester core - if cover(s) is of a different fiber type, both fiber types shall be identified.

E. Length (reach) - bearing point to bearing point.

F. Sling identification should be maintained by the user so as to be legible during the life of the sling.

RECOMMENDED OPERATING PRACTICES

Mechanical Considerations

Polyester roundslings shall always be protected from being cut by corners, edges and protrusions.

Determine the weight of the load. Polyester roundslings shall not be loaded in excess of their rated capacity. Consideration shall be given to the angle from the horizontal (roundsling to load angle) which affected rated calamities.

Select a proper polyester roundsling having suitable characteristics for the type of load, hitch and environment.

Polyester roundslings with fittings that are used in a choker hitch shall be of sufficient length to assure that the choking action is on the polyester roundsling and never on the fitting.

Polyester roundslings used in a basket hitch shall have the load balanced to prevent slippage.

Polyester roundslings shall not be twisted or tied into knots, or joined by knotting.

Polyester roundslings should not be pulled from under loads when the load is resting on the sling.

Polyester roundslings shall be used with lifting devices that are compatible with roundslings.

Do not drop polyester roundslings equipped with metal fittings.

The opening in fittings shall be the proper shape and size to ensure that the fitting will seat properly on the polyester roundsling, crane hook or other attachments.

Polyester roundslings protective covers that are cut, exposing the load bearing yarn, shall be removed from service.

Consideration shall be given to the fitting’s radius in that it shall be compatible to that of the crane hook on which it is to be used.

Consideration shall be given to the distribution of load weight on a multi-legged lift.

Environmental Considerations

When not in use, polyester roundslings should be stored in a cool, dry and dark place to prevent loss of strength from exposure to ultra-violet rays.

Chemically active environments can affect the strength of polyester roundslings in varying degrees ranging from little to total degradation. The polyester roundsling manufacturer, or qualified person, should be consulted before roundslings are used in a chemically active environment.

Acid

1. Polyester is resistant to some acids, but is subject to degradation, ranging from little to moderate in some acids.

2. Each application shall be evaluated, taking into consideration the following:

a. type of acid

b. exposure conditions

Alkalis

1. Polyester is subject to degradation in alkalis, ranging from little to total degradation.

2. Each application shall be evaluated, taking into consideration the following:

a. type of alkali

b. exposure conditions

Polyester roundslings shall not be used at temperatures in excess of 194 degrees F (90OC), or at temperatures below minus 40 degrees F (-40OC).

Polyester roundslings incorporating aluminum fittings shall not be used where fumes, vapors, sprays, mists or liquids of alkalis and/or acids are present, unless the compatibility of these materials is verified by the manufacturer or a qualified person.

POLYESTER ROUNDSLING HITCHES

 Loads vary in physical dimension, shape and weight. Where and how to attach the roundsling is important to a rigger.

Hitch: Choker - A method of rigging in which the polyester roundsling is passed around the load, then through itself, then attached to the lifting device.

Hitch: Double Wrapped Choker - A method of rigging in which the polyester roundsling is passed around the load twice, then through itself, then attached to the lifting device.

Hitch: Basket - A method of rigging in which the polyester roundsling is passed around the load and both ends are attached to the lifting device.

WARNING! Rated capacities are affected by the Angle of Lift (roundsling to load angle) when multiple polyester
roundslings are used in multi-legged or basket hitches. To determine the actual polyester roundsling capacity at a given angle of lift, multiply the original polyester roundsling rating by the appropriate loss factor.

Hitch: Vertical - A method of rigging in which the load is attached to one end of the polyester roundsling and the other end of the polyester roundsling is attached to the lifting device.

Multi-Leg Polyester Roundsling Bridle - A method of rigging in which the load is attached to two or more legs of a bridle assembly. The assembly can consist of 2, 3, 4 or more legs.

WARNING! Rated capacities for Multi-Leg Bridle assemblies are based on an assumed set of ideal conditions as follows:

1. The load is evenly distributed on all legs.

2. All legs are the same length.

3. All legs are used at the same horizontal angle.
If the conditions of the lift vary from those above, the
rated capacity must be recalculated.

BASIC RULES OF HITCHING

Rated Capacity: Be sure the polyester roundsling you intend to use is strong enough for the job (refer to identification tag on the polyester roundsling).

WARNING! Rated capacities are affected by the Angle of Lift (roundsling to load angle) when used in multi-legged polyester roundslings or basket hitches. To determine the actual polyester roundsling capacity at a given Angle of Lift, multiply the original polyester roundsling rating by the appropriate loss factor.

 Control and Balance: Use a hitch that will keep the load under control at all times and be sure the lifting device is directly over the center of gravity (CG).

Prevent Damage: ROUNDSLINGS SHALL ALWAYS BE PROTECTED FROM BEING CUT OR DAMAGED BY CORNERS, EDGES OR PROTRUSIONS.

Lifting Load: Lift load carefully, accelerating smoothly. Avoid shock loading.

Conditions of Polyester Roundslings: Inspect roundslings and their parts carefully before each lift and at regular intervals.

Regulations: Polyester roundslings shall be used in accordance with the federal, state, provincial, local and industry regulations applicable to the lift.

Use of Lifting Lugs / Eye Bolts: Lifting lugs/eye bolts shall be used in accordance with the lug/eye bolt manufacturer’s recommendations. Many loads are equipped with lifting lugs for each attachment of the polyester roundsling. Make sure pull is transmitted to them straight along the axis of the shank unless prescribed otherwise by the manufacturer. However, if “hoist rings” are utilized, the pull does not have to be along the axis.

PROPER HITCHING METHODS

Single Leg Hitches - Single leg hitches such as the single leg vertical and the single choker hitch may not provide optimum control over the load. In these hitches only one polyester roundsling supports the load.

In a single choker hitch, there is always a part of the polyester roundsling at the choke point not in contact with the bundle being lifted.

Double Wrap Choker Hitch - The double wrap hitch or the double wrap choker hitch provides full contact with the load.

WARNING! No single polyester roundsling hitch shall ever be used to lift and transport a lift load that is not balanced.

Basket Hitches - Basket hitches, whether single or double, may be used successfully in a variety of applications. However, they have inherent limitations.

WARNING! Angles of less than 60 degrees can cause polyester roundslings to slip under the load, creating an imbalanced condition.

Turning Hitch - When turning a load, use a choker hitch. If the turning hitch is made up wrong, the turning action of the load will loosen the hitch, causing it to slip.

WARNING! A polyester roundsling shall not be used in basket hitch for turning a load.

Straight Bearing Surface

Curved Bearing Surface

Effective Inside Width Equals
100% of the Actual Inside Width

Effective Inside Width Equals
75% of the Actual Inside Width

 

Basket Hitches: Rated capacities are affected by angle of lift (sling to load) measured from the horizontal when used with multi-legged slings or choker/basket hitches. To determine the actual sling capacity at a given angle of lift, multiply the original sling rating by the appropriate loss factor determined from the table to the right.

Choker Hitches: For web slings used in a choker hitch, rated capacities in tables are for an angle of choke of 120° or greater for the angle formed in the web sling body as it passes through the choking eye. See table below.