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DAWSON GROUP LTD. >> Information >> Introduction,Care & Use of Lifting Chain Slings

Introduction,Care & Use of Lifting Chain Slings

Grade 80 chain slings, G100 Chain slings
More information, please kindly check : Chain slings or contact us : info@dawson-group.com
• Introduction to Chain Slings
• Care & Use of Chain Slings

Alloy chain slings are often selected when operating under high temperatures or rugged conditions that would abrade or destroy other types of slings. They are flexible, durable and long lasting, ductile, easy to inspect, collapsible for convenient storage, and will adhere securely to the contours of a load. Although chain will show little or no stretch at rated capacity, it does have the ability to elongate up to 20% prior to failure. This elongation serves as a visual warning sign prompting users to remove the sling from service before injury or damage is sustained from a broken chain sling. Perhaps the most advantageous feature of a chain sling is its ability to be repaired. Nearly any damaged component discovered during an inspection can be repaired and restored to useful condition. During the repair process, slings will be refurbished, proof tested and recertified, offering an economical alternative to new chain sling replacements.

Chain slings used for overhead lifting applications must be manufactured from alloy steel. Alloy chain, commonly 8600 series alloy, is subjected to quality control techniques surpassing those applied to lower grades of chain and is designed, approved and specifically recommended for overhead lifting. Alloy steel chains possess the strength, chemical content and mechanical properties necessary to meet government and industry standards. These specifications prescribe minimum elongation values, minimum proof test values, recommended working load limits and minimum statistical breaking strengths. Alloy chain can be distinguished from other popular grades of welded chain through its hallmark, or identification code, which is embossed into chain links approximately every 12" to 18". Grade 80 (or System 8) is the most frequently used alloy chain and carries a hallmark similar to Campbell Chain Company's "CA8" or "C8". A new, maximum strength Grade 100 (or System 10) alloy is manufactured by Campbell Chain with a "C10" hallmark for easy identification. Do not use any chain sling for overhead lifting before verifying that it is constructed of alloy steel. Different "Types" of chain slings can be fabricated and are usually designated by a three character symbol, based upon the number of legs and types of components used in the assembly:

First Character (Basic Type of Construction):
S = Single leg sling
SB = Single basket
D = Double leg sling
DB = Double basket
T = Triple leg sling
SE = Single endless basket
Q = Quadruple leg sling
DE = Double endless basket
C = Single leg sling with master link at each end

Second Character (Type of Master Link or End Link):

O = Oblong master link (recommended for all assemblies)
P = Pear shaped master link (upon request only)

Third Character (Type of Hook):
S = Sling hook
G = Grab hook
F = Foundry hook Chain slings
Chain slings can be manufactured using permanent, welded coupling links, or if preferred, mechanical coupling links for quicker "in the field" assemblies. Either way, the sling must have an attached identification tag providing the grade, size, reach, type of sling, working load limit at a specific angle of lift, and serial number. Relative to other types of slings, chain slings have the poorest strength/weight ratio, best abrasion and cut resistance, average elongation and shock resistance, best flexibility, and best resistance to high temperatures.

Although chain slings are designed for rugged, lasting service, precautions should be observed to extend the product's useful life. Certain hazards are inherent in the operation of chain slings and users must exercise intelligence, care and common sense to ensure a safe working environment.
Never exceed the working load limit of a chain sling.
All fittings and attachments must have a working load limit (WLL) equal to or greater than that of the chain; if not, the assembly must be rated at the WLL of the weakest component.
Do not rest or drop load on chain.
Eliminate all twists, knots or kinks before lifting.
Do not point load hooks - load should be seated properly within throat opening and centered in bowl of the hook.
Balance the load to avoid undue stress on one leg of multi-leg slings.
Never bounce, jerk or shockload a sling when lifting or lowering items. Remove slack by slowly applying the load to the chain.
Use pads around sharp corners.
Never force or hammer hooks or chain into position.
Never anneal alloy chain slings.
Do not use in acid solutions. Consult manufacturer for recommendations.
If possible, avoid extreme temperatures (under 20 degrees F or over 350 degrees F).
Temporary and permanent reductions to working load limits occur when chain slings are used at high temperatures.

Chain SlingsReturn slings to manufacturer to ensure proper repair procedures are followed.
Clean chain slings regularly since dirt and grit can cause wear at link bearing points.
Protect chain from corrosion.
Store chain slings in a clean, dry area, preferably by hanging on racks or A-frames; slings stored on floors are subject to abuse.
Institute a continuous inspection program to maximize life expectancy.
Sling angles have a direct and oftentimes dramatic affect on the working load limit of a sling. This angle, which is measured between a horizontal line and the sling leg or body, may apply to a single leg sling in an angled vertical or basket hitch, or to a multi-legged bridle sling. Anytime pull is exerted at an angle on a leg, the tension or stress on each leg is increased. To illustrate, each sling leg in a vertical basket hitch absorbs 500 lbs. of stress from a 1,000 lb. load. The same load, when lifted in a 60 degree basket hitch, exerts 577 lbs. of tension on each leg.

It is critical therefore, that working load limits be reduced to account for sling angles. Angles less than 45 degrees are not recommended and those below 30 degrees should be avoided whenever possible. Use the formula and chart shown below to calculate the reduction in working load limits caused by various sling angles.

Actual Sling Working Load Limit = Factor x Working Load Limit
Chain slings working load limits

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