There are many different types of chains on the market and to find out what chain is best for your particular towing, lifting, rigging, or everyday application, it’s important to get a general idea of what is meant by the term chain grades. Chain grades are numerical levels that segment types of chains by their overall strength. There are six key chain grades ranging from chain grade 30 to chain grade 120. The higher the number, the stronger the chain. Furthermore, high-grade chains are typically harder, more resistant to abrasion, and contain a much higher strength-to-weight ratio compared to low-grade options. Selecting the right chain grade for your rigging application or chain slings is imperative as low-grade chains are subject to bending and breaking under extreme force. This can spell disaster and be extremely dangerous and even fatal in certain rigging scenarios. Knowing the grade of chain is imperative for the application due to the fact only ALLOY chain is approved for overhead lifting. Also, chain slings must be tagged with Working Load Limit (WLL), grade, length, name or logo of manufacturer and diameter. Serial number for traceability is also important.
How do you calculate chain grade?
A chain’s grade number (30, 43, 70, etc.) refers to its maximum tensile force in Newtons divided by a link’s cross-sectional area in millimeters. Or to put it more simply, a chain’s grade is its maximum stress in Newtons per millimeter squared. The mathematical equation would look like this:
Chain Grade = Newtons / millimeters2
By using this equation, we acknowledge that grade 30 chain can endure 300 Newtons per millimeter squared before bending or breaking. While this chain is perfect for your backyard swingset, it would be far too fragile and have much too low of a working weight limit for heavy-duty, towing, or overhead lifting applications.
What are the different grades of chain?
There are six common grades of chain: grade 30 chain, grade 43 chain, grade 70 chain, grade 80 chain, grade 100 chain, and grade 120 chain. For the purposes of this blog, we’ll only dive into the differences between welded graded chain (weldless chain is not strong enough to be used in rigging applications). There are also Grade 50 and Grade 63 stainless steel that are approved for lifting, but no need to muddy the waters. Also, an older Grade 63 that has a higher heat tolerance than standard G80.
Chain Grade 30
Chain grade 30 is an economical and handy general-purpose chain with practical agricultural, industrial, marine, and household applications. It is perfect for swingsets, chain guard rails, light-duty tie-downs, or other everyday needs. Composed of carbon steel, this chain is much too fragile to be used in heavy-duty applications like towing or overhead lifting. Depending on the width of the link, grade 30 chain carries a working load limit of 1,300 to 6,900 pounds.
Chain Grade 43
Chain grade 43 is, of course, stronger and more durable than chain grade 30 and can be used in more demanding applications like towing, construction, or trucking. However, it is also carbon steel and thus still not strong enough for overhead lifting needs. Depending on the width of the link, grade 43 chain carries a working load limit of 2,600 to 13,000 pounds.
Chain Grade 50
Relatively uncommon as compared to other chains on this list, type 316 stainless steel chain grade 50 is the only stainless steel chain rated for overhead lifting applications and approved by OSHA when properly tagged. Depending on the width of the link, grade 50 carries a working load limit of 660 to 11,000 pounds.
Chain Grade 63
Chain grade 63 is an excellent choice for food processing applications or settings in which chemicals are used. Grade 63 boasts excellent resistance to heat, rust, chemicals, and saltwater and, if properly tagged, can be used in some overhead lifting applications. Depending on the width of the chain, grade 63 carries a working load limit of 2,800 to 9,000 pounds.
Chain Grade 70
Often coated in yellow chromate for an instantly recognizable bright gold appearance, chain grade 70 is the strongest carbon steel chain on the market as far as common chain grades go. It is used most commonly in trucking applications like tying down heavy loads or towing. Although remarkably strong, chain grade 70 (often called “transport chain”) is still carbon steel and thus not suitable for overhead lifting. Depending on the width of the link, grade 70 chain carries a working load limit of 3,150 to 15,800 pounds.
Chain Grade 80
Unlike previously mentioned carbon steel chains, chain grade 80 is a steel alloy chain that is suitable and OSHA-approved for overhead lifting. It is an excellent option for heavy-duty towing or rigging as well. Usually, black in color, chain grade 80 is often referred to as “alloy chain”. Depending on the width of the link, grade 80 chain carries a working load limit of 3,500 to 18,100 pounds.
Chain Grade 100
Chain grade 100 is about 25 percent stronger than chain grade 80 and the strongest chain available by most chain suppliers. Like grade 80, grade 100 is alloy steel and can be used in virtually any industrial application including, but not limited to, overhead lifting. Depending on the width of the link, grade 100 chain carries a working load limit of 4,300 to 22,600 pounds.
Chain Grade 120
Relatively new to the market, and still fairly rare among common suppliers, chain grade 120 is the strongest chain in the industry–about 50 percent stronger than grade 80 and about 20 percent stronger than grade 100. Chain grade 120 is perhaps the most easily distinguishable of the chain grades, not only because of its distinctive blue color but because the links are rectangular rather than round ovals. Chain grade 120 is suitable for the most demanding of rigging applications and carries a working load limit of between 5,200 to 27,500 pounds depending on the width of the link. Laclede Chain Manufacturing currently makes a traditional rounded link G120 and it will coat it green for visibility.
OSHA and ASTM Standards for Chain Grades
Regardless of the chain grade you select, in the interest of safety, OSHA and ASTM echo that overhead lifting should only be administered with properly tagged alloy chain slings. Per their regulations, only high-grade alloy chains are permissible for heavy-duty chain sling assemblies. It is also key to adhere to all ASME B30.9 specifications regarding proper components including hooks, coupling links, and other rigging hardware. ASME outlines several approved sling configurations including quadruple-leg bridle slings, single-leg slings, single-basket slings, multiple-leg bridle slings, and single-leg choker hitches. Selecting the proper chain and rigging configuration to get the job done efficiently and safely can be challenging, especially in the instances of overhead lifting applications. For this reason, it is always best to consult with the services of a chain rigging supplier familiar and well-versed in current OSHA and ASTM guidelines and stipulations before putting your team and your equipment at risk. If you have questions about chain grades, chain slings, or rigging options, contact the chain slings experts at John Sakach Co.