Lifting Lug / Padeye Pin-Hole Check
Checks an engineered lifting lug or padeye against all four ASME BTH-1 pin-hole failure modes.
Example
You enter
- Applied load (kip) 20
- Plate thickness t (in) 1
- Hole diameter Dh (in) 1.06
- Pin diameter Dp (in) 1
- Hole-center to edge a (in) 2
- Plate width at hole w (in) 4
- Yield Fy (ksi) 36
- Ultimate Fu (ksi) 58
- Design factor Nd 2
You get
- Bearing (kip) 22.5
- Tearout (kip) 80
- Demand-to-capacity ratio 0.89
Details, formula, and sources
Bearing, net-section tension, and double-plane shear tear-out -- and reports the governing capacity and DCR. The four modes trade off through hole placement; a lug sized for gross tension alone can tear out at the pin.
bearing = 1.25 Fy Dp t / Nd; net tension = Fu (w - Dh) t / Nd; shear tear-out = 0.70 Fu (2 t (a + Dp/2 - Dh/2)) / Nd; governing = min; DCR = load / governing.
The ASME BTH-1 Section 3-3.3 pin-connected-plate (lifting lug / padeye) strength checks, by name.
ASME BTH-1 is available through ASME; the pin-plate strength relations are established design checks. An estimate; the engineer of record governs.
Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
Field names used by the API: applied_load_kip, plate_thick_in, hole_dia_in, pin_dia_in, edge_dist_in, plate_width_in, fy_ksi, fu_ksi, design_factor, bearing_kip, tearout_kip, dcr
- Three checked modes bearing, net-section tension, and double-plane shear tear-out; the minimum governsASME BTH-1 3-3.3
- Design factor Nd 1.67 (Cat A) or 2.0 (Cat B) times the service-class multiplierASME BTH-1 3-1.3