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Pad Eye Design Check

Verify lifting pad eye geometry and stress capacity according to DNV-ST-E273.

Load Parameters

The safe working load in tonnes.
Standard DNV DAF is 2.0 for offshore lifts.

Material & Geometry

Yield stress of the steel (MPa), e.g., 355.
Elastic modulus of the material (MPa), e.g., 210000.
External radius of the pad eye (mm).
Diameter of the shackle pin (mm).
Diameter of the pad eye hole (mm).
Thickness of the main plate (mm).
Thickness of one cheek plate (mm). Set to 0 if none.
Documentation

About the Calculator

This tool verifies pad eye geometry and stress capacity according to DNV-ST-E273 Appendix A (Portable Offshore Units). It evaluates clearance, geometry, bearing pressure (Hertzian contact), and tear-out capacity.

Methodology

$$ P_{design} (RSF) = SWL \cdot DAF $$
1. Geometry Checks
  • Pin/Hole Clearance: A maximum clearance of 6% is typically recommended.
    $$ \text{Clearance} (\%) = \frac{d_{hole} - d_{pin}}{d_{pin}} \cdot 100 \le 6\% $$
  • Radius Check:
    $$ R_{pad} \ge d_{hole} $$
2. Bearing Pressure (Appendix A.3)

The bearing verify checks if the allowable stress $\sigma_e$ is sufficient to resist the contact pressure. Depending on pin fit, one of the following criteria applies:

If $d_{pin} \ge 0.94 \cdot d_{hole}$:

$$ \sigma_e \ge 0.045 \cdot \sqrt{\frac{RSF \cdot E}{d_{hole} \cdot t_{total}}} $$

If $d_{pin} < 0.94 \cdot d_{hole}$:

$$ \sigma_e \ge 0.18 \cdot \sqrt{RSF \cdot \left(\frac{1}{d_{pin}} - \frac{1}{d_{hole}}\right) \cdot \frac{E}{t_{total}}} $$
3. Tear out (Appendix A.4)

Checks the material capacity above the hole.

$$ \sigma_e \ge \frac{2 \cdot RSF}{(2 \cdot R_{pad} - d_{hole}) \cdot t_{total}} $$

References

  1. DNV. (2016). DNV-ST-E273 Portable Offshore Units. Appendix A. Det Norske Veritas.