Whether you transport machinery, use tow chains, or are in the logging industry, it's important to know the working load limits of chain you are using. Chains have a working load limit- or WLL- of approximately one third of their break strengths (the amount of force the chains can withstand before they break).
How to determine a chain's working load limit
The WLL of a chain is determined by both the grade and the diameter. Chain is embossed with both the grade and size so you can determine its WLL using this chart.
Types of chain
Grade 30 Chain
Grade 30 is a multipurpose, economical chain. Also known as Grade 30 Proof Coil Chain, it's used in a variety of industries and jobs, including light construction, barrier chains, and in the marine industry. It is not safe for overhead lifting. Grade 30 chain is embossed using a 3, 30, or 300.
Grade 43 Chain
Also called Grade 43 High Test Chain or Grade 43 Tow Chain, this is common in the towing and logging industries. It is not rated safe for overhead lifting. Grade 43 chain is embossed using a 43 or a G4.
Grade 70 Chain
Grade 70 Transport Chain is also called Grade 70 Truckers Chain as it's common in securing loads for over-the-road hauling. It is not rated safe for overhead lifting. Grade 70 chain is embossed using a 7, 70, or 700.
Grade 80 Chain
Grade 80 Alloy Chain is heat-treated making it safe and rated for overhead lifting. It's also commonly used as a heavy duty tow chain. Grade 80 chain is embossed using an 8, 80, or 800.
Grade 100 Chain
Considered premium quality chain, it offers about a 25% higher work load limit over Grade 80 chain. It is safe for overhead lifting. Grade 100 chains are embossed with a 10 or 100.
Grade 120 Chain
A newer product in the market, Grade 120 chain is up to 50% stronger than Grade 80 chain and 20% stronger than Grade 100 chain. It's also more resistant to abrasion than both Grade 80 and Grade 100 chains. It's safe for overhead lifts.
Learn more about the differences between grades 70, 80 and 100 here: What are the Differences Between Grade 70 Chain, Grade 80 Chain, and Grade 100 Chain?