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 Find the Working Load Limit
The chain grade and diameter determines the working load limit of the chain. 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, people use this product 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. Never use this chain for overhead lifting. This chain includes designs embossed using a 43 or a G4.
Grade 70 Chain
Grade 70 Transport Chain, also called "Grade 70 Truckers Chain," works in securing loads for over-the-road hauling.Never use this chain for any overhead lifting. This chain include designs embossed using a 7, 70, or 700.
Grade 80 Chain
Grade 80 Alloy Chain works for overhead lifting due to its heat-treated design. People commonly use this type of chain as a heavy duty tow chain. Grade 80 chain include designs 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 includes designs 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?