KEVOS® MAKEOS · Fabrication
Lap Joint Overlap (Brazed, Soldered or Bonded)
How much overlap does this brazed, soldered or bonded lap joint need?
Overlap length for a lap or sleeve joint so the joint’s shear capacity matches or exceeds the strength of the thinner member, and the capacity at a chosen overlap.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Thickness of the thinner member | mm | Thickness of the thinner part (for tubes, the wall). |
| Joint width (or circumference for tubes) | mm | Width of the joint, or circumference for a sleeve joint. |
| Strength of the member | MPa | Strength of the member (yield or tensile, matching your design basis). |
| Shear strength of the joint material | MPa | Shear strength of the braze alloy, solder or adhesive from its data sheet (reduce for temperature and ageing). |
| Joint strength ÷ member strength wanted | How much stronger than the member the joint should be. | |
| Overlap used | mm | Overlap length you plan to use. |
| Applied load (0 = not set) | N | Service load on the joint, if known. |
Method and formulas
- Member capacity = w t σ; joint capacity = w L τ.
- Required overlap L = factor × t σ ÷ τ.
- Brazed joints commonly use 3 to 6 × t overlap; longer overlaps add little because stress concentrates at the ends.
- Example: 1.5 mm sheet at 210 MPa with a 70 MPa braze needs 5.625 mm (3.75 × t).
Limitations
- Uniform shear assumed; real lap joints peak at the ends, especially bonded joints.
- Joint clearance, fill and fillet quality strongly affect strength.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Design brazed tube and sheet joints
- Choose overlap for bonded joints
- Check an existing overlap
Who it is for
- Fabrication supervisors
- Manufacturing engineers
- Estimators
What you get
- Overlap needed
- Overlap in member thicknesses
- Joint and member capacity at the chosen overlap
Interpreting the result
- For adhesives, a longer overlap gives diminishing returns; increase width instead.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1423–1430. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
Open the Lap Joint Overlap (Brazed, Soldered or Bonded) calculator
