Shackle / Eye-Bolt WLL and Angular Derate
Working load limit and the angular derate of a shackle (side load) or shoulder eye bolt from the pull angle.
Example
You enter
- Leg load (lb) 3000
- Catalog WLL of the hardware (lb) 7000
- Angle of pull off axis (deg) 45
- Hardware shoulder_eyebolt
You get
- Derate at this angle 0.3
- Derated capacity 2100 lb
Checked against published worked examples from: ASME B30.26 / B18.15 manufacturer data.
Details, formula, and sources
ScopeWorking load limit and the angular derate of a shackle (side load) or shoulder eye bolt from the pull angle, with a pass / fail. The manufacturer's chart governs.
Formula or tablederated_capacity = rated_wll x derate(angle, hardware); pass = derated_capacity >= leg_load. Shackle side-load 0->1.00 / 45->0.70 / 90->0.50; shoulder eye bolt 0->1.00 / 15->0.75 / 30->0.53 / 45->0.30 / 90->0.25 (Crosby chart at 45 and 90 deg; 15 and 30 set at or slightly under the 0-45 straight line). MBS = rated_wll x design_factor (5:1).
Source and editionASME B30.26 (Rigging Hardware) and ASME B18.15 / manufacturer eye-bolt data by name; the eye-bolt curve carries the Crosby chart points (30% at 45 deg, 25% at 90 deg), and the shackle side-load curve is a fixed approximation (100% in line, 70% at 45 deg, 50% at 90 deg).
Free accessASME B30.26 is a published consensus standard. The angular derate follows the manufacturer's chart.
What governsEstimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
API field namesleg_load_lb, rated_wll_lb, angle_deg, hardware, derate, derated_capacity_lb
- Derate curves fixed [angle, factor] breakpoints per hardware typeASME B30.26 manufacturer charts
- Design factor 5:1 on the WLL (reported as MBS)ASME B30.26 / B30.9