Selection criteria and design of a chain used for Lifting Application

Lifting chain is designed for use with hoists, cranes, winches, and other material handling equipment. It is also used in rigging slings and for lashing. There are two standard grades for lifting chain: grade 80 lifting chain and grade 100 lifting chain. Grade 80 lifting chain is made from alloyed steel and is specifically designed for overhead lifting applications. This grade of lifting chain has a good strength-to-weight ratio and excellent durability. Grade 100 lifting chain is also made of alloyed steel, but is hardened and tempered for superior durability and fatigue resistance. Most Grade 100 lifting chain is made of Herc-Alloy 800, a heat-treated alloy with very high strength. Although many types of chain fittings are available, Grade 80 fittings should not be used with Grade 100 chain. Selecting lifting chain requires an analysis of performance specifications. Lifting chain size is measured in inches (in.) or millimeters (mm). Common sizes include 7/32 in. (5.5 mm), 9/32 in. (7.0 mm), 5/16 (8.0 mm), 3/8 (10.0 mm), 1/2 in. (13.0 mm), 5/8 in. (16.00 mm), 3/4 in. (20.0 mm), 7/8 in. (26 mm), and 1 1/4 in. (32.0 mm). Nominal dimensions include inside length and inside width. Other important considerations for choosing lifting chain are the approximate number of links per foot (ft.) and the approximate weight (lbs.) per 100 ft. When working with lifting chain, working load limit and rated capacity vary with the angle of use and the number of lifting chain used in a sling. For example, a single 5.5 mm lifting chain may be rated for 2100 lbs. at 90 degrees. A double 5.5 mm lifting chain may be rated for 60, 45, or 30 degree use with working loads of 3600, 3000, and 2100 lbs. respectively. Lifting chain should meet requirements from organizations such as the U.S. Occupational Safety and Health Administration (OSHA), the American Society for Testing Materials (ASTM), and the International Standards Organization (ISO). Working load limits for Grade 80 and Grade 100 lifting chain are based on a 4 to 1 design factor from ISO. By testing all these parameters of chain we can easily select the required dimension of chain link for lifting purpose.