The design of lifting lugs is critical to ensure the safe lifting and handling of heavy equipment, tanks, or structural components. Lifting lugs are subjected to significant stresses during hoisting operations, and the integrity of their weld connections is paramount. This Excel sheet simplifies the design of welds for lifting lugs, ensuring compliance with standard engineering practices and safety requirements.
What Is a Lifting Lug?
A lifting lug (also called a lifting eye or padeye) is a steel plate welded or bolted to a structure or piece of equipment to provide a attachment point for rigging during lifting operations. They are used extensively in the construction, petrochemical, offshore, and manufacturing industries. A properly designed lifting lug must resist the full dynamic load imposed by the lift, including any dynamic amplification factor (DAF) or sling angle effects.
Forces Acting on a Lifting Lug Weld
The weld connecting a lifting lug to its parent structure experiences a combination of direct tension or shear, depending on the sling angle, plus a bending moment if the load line does not pass through the weld group's centroid. As the sling angle from vertical increases, the horizontal force component grows, increasing both the bending moment on the lug plate and the shear demand on the weld. The dynamic amplification factor is applied to the static load before these forces are resolved.
What This Excel Sheet Calculates
- Resolved vertical and horizontal weld forces based on sling angle
- Weld throat stress under combined tension, shear, and bending
- Required weld size for the governing load case
- Lug plate bending and bearing stress at the pin hole
- Dynamic amplification factor (DAF) applied to the lift load
- Combined stress check against allowable weld capacity
Design Inputs Required
- Lifting load (static weight) and dynamic amplification factor
- Sling angle from vertical
- Lug plate thickness, material grade, and pin-hole diameter
- Weld size and electrode classification
- Weld length and configuration around the lug perimeter
- Parent material thickness and grade
Applicable Design Codes
Weld allowable stresses are based on the AISC-ASD 9th Edition Manual of Steel Construction, applied together with standard rigging and lifting practice for dynamic amplification factors.
Who Should Use This Tool
This tool is intended for engineers designing lifting attachments for equipment, tanks, and modules, as well as riggers and fabricators verifying padeye welds before a lift.
Download the Free Lifting Lug Weld Design Sheet
This free Excel sheet resolves the sling angle into vertical and horizontal weld forces and checks the combined tension, shear, and bending stress on the lifting lug weld against allowable limits. It removes the need to manually resolve forces and recompute weld stress every time the lift weight, sling angle, or lug geometry changes, giving a fast way to confirm that a lug weld is adequate before it is used on site.
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