We turned one our most popular posts, “What are the Differences Between Grade 70 Chain, Grade 80 Chain, Grade 100 Chain, and Grade 120 Chain?”, into a simple chart for quick and easy chain grade comparison.
Typical Chain Uses
General purpose economical chain. Used in a variety of industries and jobs including light construction, agricultural applications, and the marine industry.
Typically used for container securement, logging, farming, towing, marine applications, and as general purpose utility chain.
Made from a higher strength, heat-treated carbon steel that has a load rating approximately 20 percent higher than Grade 43. The gold chromate finish makes it easy for DOT officials to recognize. Typically used by truckers, loggers, and highway crews for load securement and towing.
A high strength, heat treated alloy chain that can be used as a sling component for overhead lifting as well as heavy duty tow chain. The most economical choice that is suitable for overhead lifting.
A high strength, heat treated alloy chain. Primarily used as a sling component for overhead lifting. Has approximately 25 percent higher strength than Grade 80. Popular in construction, manufacturing, and rigging applications.
An ultra-premium high strength chain designed specifically for the rigorous requirements of overhead lifting applications. The links have a unique square shape and it has approximately 50 percent higher strength compared to Grade 80. There are currently no official standards for Grade 120 chain in the U.S. or Europe, however, it does meet or exceed the standards of Grade 100 chain.
Safety Standards for Chain
Organizations like ASTM (American Society of Testing & Materials), ASME (American Society of Mechanical Engineers), and OSHA (Occupational Safety & Health Administration) have released safety standards and regulations for various materials and grades of a chain.
Essentially, it’s a formal way of recognizing and documenting that not all chain is created equally and therefore, it should not all be used for the same applications.
ASTM Chain Specification
What does A413, A391, and A973 all mean? Those are simply how the ASTM categorizes and references their specification standards. Each specification outlines the different manufacturing and testing requirements as well as the appropriate performance standards, grades, and applications.
Determining Chain Grades
Chain grades are a standard method for showing the ultimate breaking strength (tensile strength) of a chain. Grades help determine what sort of applications are appropriate for a given chain.
Chain grades are determined by calculating newtons per square millimeter, using the formula “N/mm2”.
Where “mm” is the area of the two cross-sections of a single chain link, and “N” is newtons. A newton is approximately 0.224805 lbs.
So, to determine a chain grade, manufacturers must find the ultimate breaking strength. Then, divide that number by .224805 to determine ultimate breaking strength in newtons. Next, take that number and divide by the total area of two cross-sections of a single link. That number is the chain grade.
You could reverse this formula to determine ultimate breaking strength if all you know if the chain grade.
Note: chain grades advertised by manufacturers are one-tenth of the actual mathematical grades. So grade 80 is really 800, and grade 120 is 1,200.
Determining Chain Working Load Limits
Working load limit (WLL) of a chain is another designated safety measure. WLL is a weight significantly less than the weight that would cause a chain to fail (tensile strength).
WLL = MBL / SF. Where MBL is minimum breaking load and SF is the safety factor.
A safety factor is the ratio between allowable stress and actual stress. In other words, it’s the ratio between the chain strength and the expected maximum stress.
In lifting and rigging applications, factors such as gravity and the additional force caused by angles must be considered.