Chains for Overhead Lifting (Part 1)

THE MEANING OF WELDED LINK CHAIN GRADE NUMBERS

The chain grade numbers which manufacturers commonly use are actually one tenth of the actual grade classes. Therefore, our grade 80 is 800, grade 70 is 700, and so on. The markings applied to the chain product are sometimes abbreviated (8 or 80 for 800, etc.).

Grade 30 (300) (Proof Coil). A general purpose chain of standard commercial quality. Made from low carbon steel, this chain is frequently used for fabricating tow chains, logging chains and, when appropriate, tie down or binding chains. Hallmarked every foot or so with manufacturer's symbol and grade marking: 3, 30, or 300 (or DIN ‘L’). NOT rated for overhead lifting. Until recently, was commonly used in many stage rigging systems for Trim Chains on Battens.

BBB Anchor Chain. A compact (short) link chain of standard commercial quality, this is essentially a sub-class of Grade 30. Made from low carbon steel, this chain is used primarily for boat windlasses when hot galvanized. Hallmarked every foot or so with grade marking: 3B (or DIN ‘L’). NOT rated for overhead lifting.

Grade 40 (400) (High Test). Strength levels are the same as Grade 43 but the dimensions of the chain links are smaller using ISO standards. Primarily used for boat windlasses, this grade has become a standard for that industry. The Grade 40 designation was exclusively used by ACCO Chain until 2005 to designate their High Test grade chain. They now use "43" in keeping with the rest of the industry. The chain is hallmarked "G4". NOT rated for overhead lifting.

Grade 43 (430) (High Test). This is a higher strength chain used for years in the trucking industry for tie downs that meet DOT specifications. Made from a high-carbon steel, its strength surpasses proof coil working load limits, size for size, by a factor of 2 to 1. Hallmarked every foot or so with manufacturer's symbol and grade marking: 4, 40, 43, or 430 (or DIN ‘M’). NOT rated for overhead lifting.

Grade 70 (700) (Transport). As its name implies, Transport Chain is used primarily to tie down loads on over-the-road equipment. The yellow chromate (gold) plating makes it easily recognizable even from a distance. Made from heat-treated carbon-steel it has about 25% more strength than high test chains. Hallmarked every foot or so with manufacturer's symbol and grade marking: 7, 70, or 700 (or DIN ‘T’). NOT rated for overhead lifting.

Side Notes:

  • High Tensile chain is anything much above 500 MPa Ultimate Breaking Strength. This is true HT and is not the same as ‘high test’. The galvanized versions from the principle manufacturers are G7 or G70, which has an approximately a tensile strength of 700 MPa, although the galvanizing process can reduce the strength slightly (the manufacturer should adjust the CAP accordingly, e.g. down by 10%). Commonly labeled as 'transport' chain in the US.
  • More on 'high test' and ‘high tensile’
    As above, high test does not mean the same thing as high tensile. The similarity in the abbreviations for the two terms creates much confusion, particularly in the United States where manufacturers and resellers exacerbate matters. American outlets referring to 'HT' chain are typically misusing the engineering abbreviation for High Tensile, and this is incorrect. Moreover, because the chain is 'high tested', it is sold with a Rated Lifting Capacity (CAP / WLL / SWL) which is calculated from a lower ratio to the Ultimate Breaking Strength (instead of the international standard of 4:1).

    This is misleading yet it does not change the ultimate strength of the steel! A particular size of American ‘high test’ chain may look to be stronger than the same sized non-American G40 because the CAP is calculated differently, but in-fact, they are next to identical. The proof certificate using a different system of numbers does not change the physical properties of the steel.

    Just to confuse matters further, G40 / G43 / ‘high test’ is now also being explicitly described by some American sources as ‘high tensile’. Whether a 400-430 MPa grade steel can be properly categorized as HT is a matter for engineers and academics to debate. Regardless, it is the numbers which matter – just try not to get misled!

Grade 80 (800) (Alloy). The first chain specifically designed for safety and approved by OSHA and other agencies for overhead lifting. Its alloy, heat-treated steel makes it ideal for making lifting slings and heavy duty tow chains. Hallmarked every foot or so with manufacturer's symbol and grade marking: 8, 80, or 800. Suitable for overhead lifting.

Grade 10 (100) (Alloy). This new innovation in alloy chain metallurgy provides about 25% higher working load limits over Grade 80 chain with some limitations reported in lower ambient temperatures. Hallmarked every foot or so with manufacturer's symbol and grade marking: 10 or 100. Suitable for overhead lifting.

Bottom Line: Don't use swing set chain, dog chain, or any other chain that is not rated for overhead lifting to support loads overhead. There are chain products that are specifically engineered for this application, and selecting the correct product is vital to the overall safety of your rigging.

Next Week: The saga continues - What the heck is Grade, UBS, WLL, SWL, MGW, Tare, CAP, DF, SF, EN, DIN, LOLER, NACM, Proof, Payload, Shock Load, and all that pesky math?

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Comment by Michael Powers on January 22, 2012 at 9:09pm

I cannot find the specific ANSI code # however, from the JR.Clancy Website.
"...define lifting as 'lengthening or shortening the chain itself by mechanical means, i.e. a chain hoist'. Dead hanging includes raising or lowering an object attached to a length of chain, as long as this isn't accomplished "by the mechanical lengthening or shortening of the chain itself". "When used with in the appropriate workload limits, proof coil chain may be used for dead hanging."

Further from JR Clancy website:
OSHA May 1983, "proof coil chain may be used in chain slings if used within the manufacturers recommendations."

In addition, Grade 80 chain is unacceptable and unusable as a trim chain in any application. Why? Grade 80 chain links have such a large wire diameter that any appropriate load rated connection, such as Crosby Loc-a-loy links, missing links, or load rated forged shackles, cannot be used in intermediate links, only in the free end. This means grade 80 chain is OK for suspending, but not for adjusting trim height.

Combine this with the fact that that 1/4" proof coil chain has a higher WLL than 1/4" GAC, 3/16" Proof coil greater than 3/16" GAC, in fact, properly used, more than twice the WLL of the cable. Properly used, the chain is wrapped around the pipe batten and connected to the cable eye. This means that each section of the chain is supporting only 1/2 the load. So, even in the single path, straight link configuration spec'd by many architects for dead hang situations, the chain is still stronger than the cable it connects to. !/4" Cable is rated at 875# WLL, 3/16" at 575#. The chains are rated at 1250# and 750#, higher than the cable. Destructive testing by D2 Flying Effects, Clancy, ETC et. al. show the wire rope always fails before the chain.

For what it's worth, the following companies, who employ licensed engineers, all agree that grade 30 proof coil chain is acceptable and suitable for trim chains and other dead hang theatrical rigging conditions.
J.R. Clancy, Sapsis Rigging Inc. (SRI), SECOA, H&H Specialties, THERN, Mutual Hardware, Norcostco.......I'm sure there are other companies that also approve of grade 30 proof coil chain as appr

Comment by Erich Friend on January 11, 2012 at 8:54am

Although "ANSI, et al" (any chance you could cite a specific standard?) may refer to chain run over a cog wheel (i.e. a chain motor drive) as the only circumstance as being the 'official' definition of 'overhead lifting', there are many other documents that speak differently. Rarely is anything suspended in the entertainment industry without it potentially being 'overhead'. You can call a cow a duck, but it's still a cow.

The 2010 NACM Welded Steel Chain Specifications specifically state in section 2.1: "Grade 30 Proof Coil Chain - General purpose, carbon steel chain. Used in a wide variety of applications. Not to be used in overhead lifting." (Bold emphasis is theirs.) Only Grade 80 and above are permissible for overhead lifting by NACM standards. The standard further defines 'overhead lifting' in section 3.4: "That process of lifting that would elevate a freely suspended load to such a position that dropping the load would present a possibility of bodily injury or property damage."

The Columbus McKinnon (CM) "Lifting, Pulling & Binding Products Manual" states "Grades 63, 80, and 100 are alloy chains and due to their strength/toughness properties are the only chains recommended for overhead lifting by NACM, OSHA Standard 1910.184, ASTM Standard A391 and ANSI/ASME Standard B30.9." and Table 1 in that document only shows "Recommended for overhead lifting by NACM, ASME, and OSHA." for Grade 80 and Grande 100 chains - it only acknowledges that Grade 63 chain "May be used in rigging and lifting applications."

The ESG 'Trim Chains' article cited also has numerous references to standards that say the same thing.

The German publication "Berufsgenossenschaftliche" Informations Guide (BGI or "Safety for Productions and Events - Loads Suspended above Persons" 2007-03-13) describes Grade 8 (80) chain as being more suitable for Live Event rigging. In that document it describes the chains being used for 'freely suspended' objects and where the chain is constrained by being bent over an edge or wrapped around an object.

And in a more general case, commercial riggers worldwide consider all lifting to be 'overhead' and make their equipment selections according to internationally recognized standards (DIN, TUV, BS, etc.) for safety.

Bottom Line: Don't use under-rated or under qualified equipment for overhead lifting or rigging. It doesn't matter if it is part of a chain-motor hoist, or not - it is still OVERHEAD. If you won't let your children sleep under it, then don't do it.

Comment by Michael Powers on January 10, 2012 at 9:04pm

One thing that is not mentioned here is that according to ANSI et al, overhead lifting with a chain refers to the chain actually being reeved over a cog wheel or drum. i.e., use as a trim chain is not overhead lifting. That is why all the major manufacturers, JR Clancy, SECOA, H&H spec the use of 1/4" G30 proof coil chain for use in trim chains. Two white papers on the JR Clancy web site go into detail.

http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf

http://www.jrclancy.com/Downloads/ChainforTheatricalUse1.pdf

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