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July 26, 2016
Chain Slings can be a nightmare to understand, we aim to make choosing your lifting chains as easy as possible, read this article to simplify all things Chain Sling related.
Chain slings are noted for their durability and they are one of the toughest categories of rigging. Industrial lifting slings that are made up of chain guarantee better performance compared to polyester round slings, nylon web slings, and twin-path slings. Recognised for their adjustability, chain rigging slings exhibit better temperature tolerance and cut resistance. Notably, the chain is manufactured in various grades. The strength of the rigging chain is indicated in terms of the lifting chain’s grade number and larger grade number indicates greater chain strength. Chains numbered as Grade 30 or Grade 40 are often found at hardware stores and they can be used safely for segmenting parking lots, but they are not fit for use in lifting operations.
Trucking and transportation companies typically use Grade 70 transport chains to tie down loads, but such tie-down-chains should never be used as rigging chain slings. Chains with grades 80, 100, and 120 can only be used for lifting purposes in industrial settings. This is mainly due to the fact that the metal used to make these slings demonstrates a strong capability to stretch and elongate. This becomes one of the major considerations when annual inspections are conducted to measure chain slings. These days, most rigging chain manufacturers have started focusing on manufacturing grade 100 lifting chains that are stronger yet lighter than grade 80 rigging chains.
Chain slings come in standard form as well as with custom-made fittings that are designed to suit specific conditions. The manufacture of chain slings is governed by standards that demand proof-testing and certification of all individual components that are used in the fabrication of rigging chains. Commonly, alloy steel is used to manufacture chain slings that are used for overhead lifting applications. Stringent quality control techniques are applied to 8600 series alloy before it is approved for use in overhead lifting operations. Alloy steel chains demonstrate the appropriate strength, mechanical properties, and chemical content that are required to adhere to the government and industry standards. The standards require chain slings to have minimum proof-test and elongation values and require chain slings to bear specifications regrading minimum statistical breaking strengths and working load limits.
It is very important to be able to distinguish alloy steel from other popular grades of welded chain and you can identify alloy chain through its hallmark or identification code that normally comes engraved into chain links. Make sure that you do not use chain slings for overhead lifting unless you verify that it is made out of alloy steel.
Chain slings are used in different forms and are specified in terms of a three character symbol that indicates the types of components that are used in the assembly and the number of legs.
First Character Reflecting The Basic Type of Construction:
S = Single leg sling
D = Double leg sling
T = Triple leg sling
SB = Single basket
DB = Double basket
C = Single leg sling with master link at each end
Q = Quadruple leg sling
Second Character Indicating The Type of Master Link or End Link:
O = Oblong master link
P = Pear shaped master link
Third Character Specifying The Type of Hook:
S = Sling hook
G = Grab hook
F = Foundry hook
Both mechanical coupling links and permanent, welded coupling links can be used in the manufacture of chain slings, but in any case, you need to ensure that the sling comes with an identification tag that provides information on sling-type, reach, size, grade, serial number, and working load limit at specific lift angles. Compared to other slings, chain slings exhibit strong resistance to abrasion and high temperatures, best flexibility, and weakest strength/ weight ratio.