Rigging Capacity Quick Check
WLL at angle for shackles / slings / span sets / hoists with safety factor and pass/fail.
Example
You enter
- Hardware sling_5_8_steel
- Configuration vertical
- Load (lb) 1500
- Legs 2
You get
- Base WLL (lb) 6700
- Effective WLL (lb) 6700
- Tension per leg 750 lb
- Safety factor 8.93:1
- Pass / fail PASS
- Derate factor 1
Checked against published worked examples from: OSHA 1926.251 + ASME B30.9 sling capacity tables.
Details, formula, and sources
Formula or tableWLL at angle: leg tension L = W / (n × cos(θ/2)) for basket slings and W / (min(n, 2) × cos(θ/2)) for bridles (a bridle of three or more legs is taken as two carrying the load) at included (apex) angle θ (W/n with legs vertical, diverging as they open toward horizontal); choker derate 0.75. WLL by component class (shackles per ASME B30.26; slings per ASME B30.9; span sets / hoists per manufacturer specs).
Source and editionASME B30.9 (Slings) + ASME B30.26 (Rigging Hardware) + ASME B30.16 (Overhead Underhung and Stationary Hoists) by name and section. Manufacturer hoist data sheets (CM Lodestar, Columbus McKinnon, Chain Master) by name.
Free accessASME B30 series licensed; principles free at most rigging-manufacturer training pages.
What governsEstimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
API field nameshardware, configuration, load_lb, n_legs, base_wll_lb, effective_wll_lb, tension_per_leg_lb, safety_factor, pass, derate_factor
- Choker derate 0.75 (ASME B30.9 typical)ASME B30.9