What Grade of Chain Is Acceptable for Overhead Lifting
Lifting a freely suspended load over the ground puts the people standing underneath in a truly vulnerable place. The threat of bodily harm or death is enough to make anyone’s skin crawl. For decades, industries that use chains for overhead lifting struggled to know if the chains were actually secure enough for the task. But in recent years, the ASTM (American Society of Testing & Materials), ASME (American Society of Mechanical Engineers), and OSHA (Occupational Safety & Health Administration) have published safety standards telling employers what grade of chain is acceptable for overhead lifting.
How To Determine Chain Grades
To determine chain grades, manufacturers must first uncover the breaking strength of the chain, or the amount of force required to make the chain unfasten. Then they must divide that number by 0.224805 pounds, or one Newton.
Finally, they take that number and divide it again by the total area of two cross-sections of a single link. One-tenth of that number is what manufacturers list when they sell the chain, meaning grade 70 is really grade 700.
Grade 70 Chain
Grade 70 chain is primarily used by truckers as a tie-down on over-the-road trailers. It’s heat-treated in carbon steel and has a recognizable golden chromate finish.
It should not be used for overhead lifting. It is a trucker’s chain, built for fastening and placing, but definitely not for carrying loads in high places. It also has applications in oil rigs, logging, and towing.
Grade 80 Chain
With its high strength-to-weight ratio and heat-treated steel, grade 80 chain is safe for overhead lifting and rigging slings. It can also be used for recovery, safety, and towing chains. In recent years, grade 80 chains have become more popular in the flatbed trucking industry.
Grade 100 Chain
The grade 100 chain, considered among chain manufacturers to be a premium product, was designed for its overhead lifting capabilities. In many ways, it is a vast improvement on grade 80, which has a workload at only a fraction of what grade 100 can accomplish.
Grade 120 Chain
With the strongest tensile strength in the industry, grade 120 chains can absolutely handle overhead lifting. Its square link design increases the contact between the bearing surfaces and links, which overall reduces the chain’s pressure.
Standards Set by NACM (National Association of Chain Manufacturers)
No matter which chain you use, you must make sure to follow all the standards set out by NACM, which include:
- Never suspending loads over people, regardless of what grade of chain is acceptable for overhead lifting.
- Conducting periodical inspections of the chain’s health.
- Avoiding excessive temperatures or exposure to chemically active environments.
- Removing all chains from services if at any spot the link is less than its minimum listed value.
In summation, if you need to finish an overhead lifting job, it’s best to ignore the grade 70 chain. It simply doesn’t have the breaking strength to manage jobs that put peoples’ heads and lives at risk. For the jobs that require that level of safety, it’s best to go with chains graded 80 through 120, with 120 as the gold standard.