Multi-Leg Sling Load per Leg

Per ASME B30.9, a rigid load on 3 or more legs is assumed to hang from only 2, so the conservative tension divides the load over 2 legs and then by sin(angle from horizontal), with an equal-share reference and the 1/sin load factor. The qualified rigger and the sling tag govern.

share_legs = (num_legs >= 3) ? 2 : num_legs; tension_per_leg = (total_load / share_legs) / sin(angle); load_factor = 1/sin(angle); equal-share reference = (total_load / num_legs) / sin(angle).

ASME B30.9 (Slings) by section; classical sling statics, no edition cycle.

The statics are public; the qualified rigger and the sling's tag rating govern.

Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.

Field names used by the API: total_load_lb, num_legs, horizontal_angle_deg, tension_per_leg_lb, equal_share_lb, load_factor, share_legs

• Two-leg rule per ASME B30.9 a rigid load on 3 or more legs is assumed to hang from only 2; the conservative tension divides over 2 legsASME B30.9
• Equal-share reference the equal-share value is reference only; do not use it unless an engineer qualifies a true equal-share liftASME B30.9
• Angle the load factor 1/sin(angle from horizontal) grows fast as the angle flattens (1.155 at 60 deg, 2.0 at 30 deg)first principles