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Nylon Slings

 

 
Nylon Slings - Technical & Usage Information


Nylon Web slings are constructed of nylon synthetic webbing material and offer several attractive features which promote their popularity among rigging products. They are often selected when expensive, highly polished, fragile or delicate loads must be lifted. The softness of the web will not mar, deface or scratch loads, while its flexibility assures a firm, secure grip around the item being lifted. The light weight of the material, combined with superb flexibility allow the slings to be quickly and safely handled by riggers. Web slings have the ability to elongate, absorbing and minimizing the effects of heavy shock loads. Nylon slings may stretch 6-8% at rated capacity. Long life cycles may be experienced since synthetic web is unaffected by moisture, mildew, rot and certain chemicals. Nylon web slings are manufactured from heavy duty material that has been surface "treated" to improve abrasion resistance, seal out moisture, and prevent grit from penetrating the web and causing internal wear. Slings can be fabricated from single or multiple plies, may include accessories such as edge guard, wear pads, sleeves, hardware and are available in several configurations:

Recommended Operating Practices
Mechanical Considerations

SYNTHETIC WEB SLINGS SHALL ALWAYS BE PROTECTED FROM BEING CUT BY CORNERS, EDGES, PROTRUSIONS OR ABRASIVE SURFACES.

Determine weight of the load. Synthetic web slings shall not be loaded in excess of their rated capacity. Consideration shall be given to the angle from the horizontal (load to synthetic web sling angle) which affects rated capacities.

Synthetic web slings with fittings that are used in a choker hitch shall be of sufficient length to ensure that the choking action is on the synthetic web slings and never on the fitting.

Synthetic web slings used in a basket hitch shall have the load balanced to prevent slippage.

Synthetic web slings should not be dragged on the floor or over an abrasive surface.

Synthetic web slings shall not be twisted or tied into knots, or joined by knotting.

Synthetic web slings shall not be pulled from under loads when the load is resting on the sling.

Synthetic web slings shall be used with lifting devices that are compatible with synthetic web slings.

Do not drop synthetic web slings equipped with metal fittings.

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

Synthetic web slings that are cut shall be removed from service.

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

Environmental Considerations

Synthetic web slings should be stored in a cool, dry and dark place when not in use to prevent loss of strength through exposure to ultra-violet light.

Synthetic web slings shall not be stored in chemically active areas.

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

Nylon and polyester slings shall not be used at temperatures in excess of 180OF (90OC), or at temperatures below minus 40 degrees F (-40OC). For sling applications where temperatures exceed 194 degrees F (90OC), contact your synthetic web sling supplier.

Nylon and polyester slings 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.

Ultra-Violet Light

Environments in which synthetic web slings are continuously exposed to ultra-violet light can affect the strength of synthetic webbing in varying degrees, ranging from slight to total degradation. The degradation is also cumulative.

Factors which can determine the degree of strength loss are:

  1. Length of time of continuous exposure.
  2. Sling construction and design.
  3. Other environmental factors such as weather conditions, altitude and geographic location.

Suggested procedures to minimize the effects of ultra-violet light:

  1. Store slings in a cool, dry and dark place when not being used for prolonged periods of time.
  2. Inspect slings weekly or more often depending on frequency of slings use.

Visual indications of ultra-violet degradation are:

  1. Bleaching out of sling color.
  2. Increased stiffness of sling material.
  3. Surface abrasion in areas not normally in contact with the load.

Environmental Considerations

Nylon and polyester are seriously degraded at temperature above 180o F.

Prolonged exposure to ultraviolet light adversely affects nylon and polyester. Slings become bleached and stiff when exposed to sunlight or arc welding.

Many chemicals have an adverse effect on nylon and polyester. See chemical chart this page.

Chemical Environment Data

General guide only. For specific temperature, concentration and time factors, please consult Super Slings prior to purchasing or use.

Inspection Criteria

Inspection Criteria for Synthetic Web Slings
Refer to illustrations do damaged webbing

Remove from service if any of the following are visible:

  • Capacity tag is missing or illegible
  • Red core warning yarns are visible
  • Sling shows signs of melting, charring or chemical damage
  • End fittings are excessively pitted, corroded, distorted, cracked or broken
  • Cuts on the face or edge of webbing
  • Holes, tears, snags or crushed web
  • Signs of excessive abrasive wear
  • Broken or worn threads in the stitch patterns
  • Any other visible damage which causes doubt as to its strength

Red Core - warn of dangerous sling damage. All Super Slings Web Slings shown in this section of the catalogue have this warning feature. When red yarns are visible, the sling should be removed from service immediately. The red core yarns become exposed when the sling surface is cut or worn through the woven face yarns.

Examples of Web Sling Abuse

Most of the damage shown here would cause immediate catastrophic failure of the sling. Not all of the damage you will see will be this obvious or extreme, but still requires removal from use.

Elasticity - The stretch characteristics of web slings depends on the type of yarn and the web finish. Approximate stretch at RATED SLING CAPACITY is:

Nylon

Treated - 10%
Untreated - 6%

Polyester

Treated - 7%
Untreated - 3%

General Usage Guide

Physical Factors Effecting Strength

Your care in the use and handling of slings will prolong sling life significantly. The following physical factors should be considered when using any of the three basic types of slings in this catalog:

Cutting — The number one cause of web sling damage/failure, usually caused by load edge movement against sling.

Temperature — Nylon & polyester are seriously degraded at temperatures above 180°F.

Improper Loading — Shock loading, unbalanced loading, over loading and inadequate consideration for the effect of angle factors can adversely affect strength.

Punctures & Abrasions — These can seriously degrade sling strength.

Foreign Matter — Material such as metal chips, weld spatter, heavy grit, etc. can damage a web sling both internally and externally.

Ultraviolet Light — Nylon & polyester web slings are adversely affected by prolonged exposure to UV light, i.e. sunlight or arc welding. Slings appear bleached and stiff.

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.

Effect of Angle on a Slings

Rated Capacity

When slings are used at an angle (i.e. two slings or one sling in a basket attached to only one crane hook), sling capacity is reduced. How much it is reduced depends on the degree of the angle. You can determine whether a sling will be rated high enough if you know the angle between the sling leg and the vertical. Once you know this angle, multiply the sling’s rating by the appropriate factor in the table. This will give you the sling’s reduced rating.

Sling capacity decreases as the angle from vertical increases.

A sling capable of lifting 1,000 lbs. in a 90° vertical basket hitch, can only lift:
866 lbs. at a 60° angle, 707 lbs. at a 45° angle and 500 lbs. at a 30° angle.