GUIDELINES
FOR
MARINE
LIFTING
&
LOWERING
OPERATIONS
0027/ND Rev 11
Page 43 of 84
12.4.2
The bearing surface of cast padears in contact with the sling shall preferably be elliptical (rather than
circular) in cross-sections orthogonal to the local sling axis, see Figure 12-1. This is to allow for the
flattening/ovalisation
of the sling cross-section
which occurs when the sling is bent and under
tension which allows more of the wire strands
to work. It is not possible to generalise on
dimensions
for this purpose, as each sling
would deform by a different amount, depending
on the load that it is required to take. The sling
arrangement
should therefore be closely
examined at an early stage in order to
determine the amount of deformation which will
need to be allowed for in the padear design.
Figure 12-1 Indicative shaping of padear bearing surface
12.5
PADEYES
12.5.1
The outside radius of the padeye main plate shall be no less than the diameter of the pin hole.
12.5.2
Pin-holes should be bored / reamed, and should be designed to suit the shackle proposed.
The pin
hole diameter shall be 2 mm or 3% larger than the diameter of the shackle pin, whichever is the
greater, up to a maximum of 6 mm.
12.5.3
When determining the pin-hole diameter, the tolerance on the pin diameter should also be considered
to ensure that the pin will enter the pin hole on the lift point.
12.5.4
The pad eye thickness at the hole shall not be less than 75% the inside width of the shackle.
12.5.5
The total thicknesses of cheek plates on one side of the main plate should not exceed 100% of the
main plate thickness. The cheek plates should be symmetric either side of the main plate.
12.5.6
Non-load bearing spacer plates may be used to centralise shackle pins, by effectively increasing the
padeye thickness. The diameter of the internal hole in such spacer plates shall be greater
than the pin
hole diameter. Spacer plates, if used, shall provide a 20-30 mm clearance to the inside width of the
shackle (i.e. 10 to 15 mm each side).
12.5.7
Cheek plate welds shall be proportioned and designed with due regard
to possible uneven bearing
across the padeye/cheek plate thickness due to combined nominal (3%) and actual lateral loads.
12.5.8
It is permissible to use the nominal shackle pin diameter and hole diameter in the strength calculations
for the lift point provided the tolerance on the hole diameter is acceptable to GL Noble Denton.
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