Padeye

A padeye is a device often found on boats that a line runs through, or provides an attachment point. It is a kind of fairlead and often is bolted or welded to the deck or hull of a boat.

It is also used in oil and gas projects to assist in the purpose of lifting.

Detail

It's made of steel plate with radius at one side. lifting is done with the help of a D-shackle or sling, which fits into the hole of the padeye. There may be one or more circular plates (cheek plates) welded around the hole.

Designing

The following check should be done for the design of padeyes and to keep the stress less than the allowable stresses:

At the hole:

1. Bearing stress

2. Shear stress

3. Tensile stress

4. Hertz Bearing stress

At the base

1. Shear stress

2. Tensile stress

3. Bending stress

4. Combined bending stress and tensile stress

5. Von-Mises stress^[1]

Analysis on a padeye is commonly performed in accordance with the Air Force Stress Analysis Manual^[2] or ASME BTH-1.^[3] The methodology in ASME BTH-1 only allows for axially loaded lugs, whereas the methodology in the Air Force Stress Analysis Manual allows for axial loading, transverse loading, or oblique (combined) loading.^[4]

References

[1] ttp://e-book.lib.sjtu.edu.cn/otc-2007/pdfs/otc19040.pdf

[2] ""Stress Analysis Manual," Air Force Flight Dynamics Laboratory, October 1986" (PDF).

[3] "ASME BTH-1, "Design of Below-the-Hook Lifting Devices," The American Society of Mechanical Engineers, 2014".

[4] "Padeye/Lug Analysis".

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