Technical Info. & Warnings

Angle Reduction

Angle

Degrees

Factor Angle

Degrees

Factor
90 1 55 0.819
85 0.996 50 0.766
80 0.985 45 0.707
75 0.966 40 0.643
70 0.94 35 0.574
65 0.906 30 0.500
60 0.866

Caution: Sling should fit the hook. On eye and eye type slings, the eyes must be of ample length to easily slip over the crane hook, thus reducing stress on stitching.

Reduction of sling capacity depends on the angle of the sling leg. See charts for loss factor.

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

Mechanical Considerations

  • Determine the weight of the load
  • Select sling having suitable characteristics for the type of load, hitch and environment
  • Sling shall not be loaded in excess of the rated capacity.  Consideration should be given to the angle from the horizontal (load to sling angle) which affects rated capacity.
  • Slings with fittings which are used in a choker hitch shall be sufficient length to assure that the choking action is on the webbing.
  • Slings used in a basket hitch shall have the load balanced to prevent slippage
  • Slings shall not be dragged on the floor or over an abrasive surface.
  • Slings shall not be twisted or tied into knots, or joined by knotting
  • Slings shall not be pulled from under loads when the load is resting on the sling.
  • Slings shall always be protected from being cut by sharp corners, sharp edges, protrusions or abrasive surfaces.
  • Do not drop slings equipped with metal fittings.
  • The opening in fittings shall be the proper shape and size to insure that the fitting will seat properly in the hook or their attachments.

Environmental considerations

Slings should be stored in a cool, dry and dark place; and should not be exposed to ultra violet light (sunlight). Chemically active environments can affect the synthetic web slings in varying degrees ranging from none to total degradation.  The Sling manufacturer should be consulted before slings are used in a chemically active environment.

Acids

  • Nylon is subject to degradation in acids, ranging from none to total degradation.
  • Polyester is resistant to many acids, but is subject to degradation ranging from none to moderate in some acids.
  • Each application shall be evaluated, taking into consideration the following; Type of Acid, Exposure Conditions, Concentration, and Temperature.

Alkalis

  • Polyester is subject to degradation in alkalis, ranging from none to total degradation.
  • Nylon is resistant to many alkalis, but is subject to degradation ranging from none to moderate in some alkalis.
  • Each application shall be evaluated taking into consideration the following: Type of Alkalis, exposure conditions, concentration and temperature.

Nylon and polyester slings shall not be used at a temperature in excess of 194F (90C). However they may be used in temperatures as low as -40F(-40C). For sling applications where temperatures exceed 194F (90C) contact your fling fabricator supplier.

Slings incorporating aluminum fittings shall not be used where fumes, vapors, sprays, mists or liquids of alkalis and/or acids are present.

Environments in which synthetic web slings are continuously exposed to ultra violet light (sunlight) can affect the strength of synthetic webbing varying degrees, ranging from slight to total 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 and geographic location

Suggested procedures to minimize the effects of ultra violet light (sunlight):

1. Store slings in 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 use

Visual indications:

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

Recommended Operating Practices are in accordance with the Web Sling & Tie Down Association

Nylon vs Polyester

Nylon Polyester
Strength 9800 lbs per square inch 9800 lbs per square inch
Ability to Float Sinks Sinks
Stretch @ Break 16 to 20% 10 to 12%
Stretch @ WLL 6 to 10% 3 to 4%
Moisture Absorbency 9% of Weight 1% of weight
Effect of Heat Melts @ 235 Deg. C

Max Work Temp

90 Deg. C

Melts @ 400 Deg. C

Max Work Temp

90 Deg. C

Identification Melts before burning.

Forms bead, celery odor.

Melts before burning.

Forms bead, pungent odor.

Abrasion Resistance Good Good
Working Temperature 82 deg. C / 180 Deg. F 82 Deg. C / 180 Deg. F
Strength Reduction From Water 15% 0%