WEB SLING & TIE DOWN ASSOCIATION’S RECOMMENDED STANDARD SPECIFICATION FOR SYNTHETIC WEB SLINGS
The purpose of this section is to provide guidelines of webbing sling preparation, inspection, and use.
1. Web slings in contact with edges, corners, protrusions or abrasive surfaces SHALL ALWAYS be protected with materials of sufficient strength and construction to prevent sling damage.
2. Web slings should be protected from abrasive surfaces.
3. Determine the weight of the load. Web slings shall not be loaded in excess of the rated capacity. Consideration shall be given to the sling angle, which affects rated capacity.
4. Select web slings having suitable characteristics for the type of load, hitch, and environment.
5. Web slings that are used in a choker hitch shall be of sufficient length to ensure that the choke point should always be on the sling body – not on the sling eye, fitting, base of the eye or fitting, load bearing splice or tag.
6. Web slings used in a basket hitch shall have the load balanced to prevent slippage and maintain control of the load.
7. The openings in fittings shall be the proper shape and size to ensure that the fittings will seat properly on the web sling, crane hook or other attachments.
8. Web slings should not be dragged on the floor or over an abrasive surface.
9. Web slings shall not be twisted, shortened, lengthened, tied into knots or joined by knotting. Web slings shall be shortened, lengthened or adjusted only by methods approved by the manufacturer.
10. Web slings should not be pulled from under loads when the load is resting on the web sling. Loads resting on web slings could damage the sling.
11. Web slings shall not be used for pulling against stuck, snagged or restrained objects if loading conditions are unknown.
12. If a sling is used for non-lifting applications under known loading circumstances and within the rated sling capacity, it may be returned to lifting service.
13. Marking Slings for Dedicated Applications – Slings that are used for pulling against stuck, snagged or restrained objects in loading conditions that are unknown shall not be used for ANY lifting application. These Dedicated Application slings shall be marked “Not For Lifting”.
14. Do not drop web slings equipped with metal fittings.
15. Web slings that appear to be damaged shall not be used unless inspected and accepted as usable per Section 4.4 Sling Inspection of Web Sling & Tie Down Association’s Recommended Standard Specification for Synthetic Web Slings.
16. Web slings shall be hitched in a manner providing control of the load.
17. Personnel shall not stand under, on or next to suspended loads or rigging that is under tension.
18. All portions of the human body shall be kept from being placed between the web sling and the load and from between the web sling and handling or lifting device.
19. Personnel shall not ride web slings or loads suspended by web slings. Web slings shall not be used as bridles on suspended personnel platforms.
20. Shock loading shall be avoided.
21. Excessive twisting of the legs (branches) shall be avoided.
22. Load applied to a hook shall be centered in the bowl of the hook to prevent point loading.
23. During use, personnel shall be alert for possible snagging.
24. The web sling legs (branches) shall contain or support the load from the sides above the center of gravity when using a basket hitch.
25. Tags and labels should be kept away from the load, hook and point of choke.
26. Web slings should not be constricted or bunched between the ears of a clevis, shackle or in a hook. When a web sling is used with a shackle, it is recommended that it be used (rigged) in the bow of the shackle. When this is not possible, protect the sling eyes or connection points from damage.
27. Place blocks under load prior to setting down the load to allow removal of the web sling, if applicable.
28. For multiple-leg slings used with nonsymmetrical loads, an analysis by a qualified person should be performed to prevent overloading of any leg.
29. Do not wash web slings as a loss of strength is possible due to mechanical/chemical damage.
Environmental factors such as an exposure to sunlight, dirt or gritty-type matter and cyclical
changes in temperature and humidity can result in an accelerated deterioration of web slings. The
rate of this deterioration will vary with the level of exposure to these conditions and with the
thickness of the sling material. For example, single ply slings will generally degrade more rapidly
with this exposure than multiple ply slings. All web sling slings that are exposed to these
conditions should be highly scrutinized during their inspection.
1. Web slings, when not in use, should be stored in a cool, dry and dark place to prevent loss of strength from exposure to sources of ultraviolet light. Web slings shall not be stored in chemically active areas and/or in areas where mechanical and/or environmental damage could occur.
2. Chemically active environments can affect the strength of web slings in varying degrees ranging from little to total degradation. The web sling manufacturer, or a qualified person, should be consulted before web slings are used in a chemically active environment. In addition, water absorption can decrease the strength of nylon web slings by as much as 10-15%. Sling strength returns when the sling dries completely.
3. Each chemical application shall be evaluated, taking into consideration the following:
A. Type of acid or alkalis
B. Exposure conditions, i.e., liquid, vapor, mist
E. Duration of exposure
• Nylon is subject to degradation in acids, ranging from little to total degradation.
• Polyester is resistant to many acids, but is subject to degradation, ranging from little to moderate in some acids.
• Polyester is subject to degradation in alkalis, ranging from little to total degradation.
• Nylon is resistant to many alkalis, but is subject to degradation, ranging from little to
moderate in some alkalis.
6. Nylon and polyester slings shall not be used in contact with objects or used at temperatures in excess of 194°F (90°C) or at temperatures below minus 40°F (minus 40°C).
7. Web slings incorporating aluminum fittings shall not be used where fumes, vapors, sprays, mists or liquids of alkalis and/or acids are present, unless material compatibility is verified.
8. Environments in which synthetic web slings are continuously exposed to sources of ultraviolet light can affect the strength of synthetic web slings in varying degrees, ranging from slight to total degradation.
WARNING Slings used in environments where they are subject to continuous exposure to sunlight or ultraviolet light shall be proof tested to twice the rated capacity semi-annually or more frequently depending on severity of exposure. Web slings that are used outdoors regularly should generally be permanently removed from service within a period of 2 to 4 years.
CAUTION: Degradation can take place without visible indications.
A. Factors which affect the degree of strength loss are:
1. Length of time of continuous exposure.
2. Web sling construction and design.
3. Other environmental factors such as weather conditions and geographic location.
B. Suggested procedures to minimize the effects of sunlight or ultraviolet light:
1. When not in use, store web slings in a cool, dry and dark location free of mechanical and environmental damage.
C. Some visual indications of environmental degradation are:
1. Fading of webbing color.
2. Uneven or disoriented surface yarn of the webbing.
3. Shortening of the sling length.
4. Reduction in elasticity and strength of the sling material due to an exposure to sunlight, often evident by an accelerated abrasive damage to the surface yarn of the sling.
5. Breakage or damage to yarn fibers, often evident by fuzzy appearance of the web.
6. Stiffening of the web, which can become particularly evident when web slings are exposed to outdoor conditions without being used or cyclically tensioned.
three stage procedure is recommended to help ensure that slings are inspected with appropriate frequency.
1. Initial Inspection – Prior to use, all new, altered, modified or repaired web slings shall be inspected by a designated person to verify compliance with the applicable provisions of Web Sling & Tie Down Association’s Recommended Standard Specification for Synthetic Web Slings.
2. Frequent Inspection – In normal service conditions, a visual inspection for damage shall be performed by the user or other designated person each day or shift before the sling is used. In severe service conditions, a visual inspection for damage shall be performed by the user or other designated person before each use. Manufacturer’s recommendations must be followed if a higher rate of inspection frequency, such as before each use, is prescribed. Written records are not required for frequent inspections.
3. Periodic Inspection – A complete inspection for damage shall be performed by a designated person. This inspection should be done by someone other than the individual(s) who most commonly perform the frequent inspection.
A. Periodic Inspection Frequency – Periodic inspection intervals shall not exceed one year. The frequency of periodic inspections should be based on:
1. Frequency of sling use.
2. Severity of service conditions.
3. Nature of lifts being made.
4. Experience gained on the service life of slings used in similar circumstances.
B. Time Interval Guidelines – The guidelines for time intervals are as follows:
1. Normal Service – Yearly
2. Severe Service – Monthly to quarterly
3. Special Service – As recommended by a qualified person
C. Written Records – A written record that the most recent inspection was performed shall be maintained documenting that the event occurred. It is not required that the condition of individual slings be recorded during the periodic inspection. If documentation of the individual slings is maintained, it should be based upon a unique sling serial number, color coding, electronic tracking (RFID) or other means. If individual tracking is not maintained, the inspection process should provide some means of identifying which slings have been inspected at the periodic level of inspection.
4. Removal Criteria – A web sling shall be removed from service if any of the following forms of damage are visible:
A. If web sling identification tag is missing or not readable.
B. Holes, tears, cuts, snags or embedded materials.
C. Broken or worn stitches in the load bearing splice.
D. Knots in any part of the sling webbing.
E. Acid or alkali burns.
F. Melting, charring, or weld spatter of any part of the web sling.
G. Excessive abrasive wear or crushed webbing.
H. Signs of ultraviolet light (UV) degradation.
I. Distortion, excessive pitting, corrosion or other damage to fitting(s).
J. If provided, exposed red core yarn. However, if damage is present and red yarns are not exposed DO NOT USE the sling.
K. Any conditions which cause doubt as to the strength of the web sling.
1. There shall be no repairs of sling webbing or stitching.