What is the maximum included angle that two slings can be connected to a shackle?

The maximum included angle for two slings connected to a shackle is specified as 120 degrees. This angle is important because it helps to maintain the effective load distribution and to prevent undue stress on the slings and other lifting equipment. When the angle exceeds this limit, the load can become unevenly distributed, leading to increased forces on the slings, which may cause premature wear or even failure.

When two slings are used with a shackle at larger angles, the tension in each sling increases significantly beyond the weight of the load being lifted. Maintaining an angle up to a maximum of 120 degrees ensures that each sling can effectively support the load without exceeding their safe working load limits. This practice is derived from safety standards and rigging guidelines that emphasize stability and safety during lifting operations.