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When it comes to rigging, weld-on permanent lifting points (known as pad eyes) are often used to connect loads or machinery to rigging hardware and slings. Crosby shackles are commonly used to connect the sling to the pad eye. Here are some important things to consider:
Please note that the following recommendations only apply to Crosby shackles and should not be used as guidelines for pad eye design, which involves many other factors.
The pad eye should be designed so that the eye width is 50% to 80% minimum of the width of the exposed shackle pin between the ears of the shackle bow.
Load distribution should be spread across at least half of the exposed length of the shackle pin if the pad eye width is 50% or less than the spread between the shackle ears. Spacers can be used to keep the load centered on the shackle pin.
During pad eye design, the appropriate size and style of shackle to be connected must be determined in advance, and the pad eye hole should be drilled to a proper size diameter to allow for easy pin insertion and provide adequate clearance for the shackle to perform properly without interference.
The pad eye should not have any sharp edges in contact with the shackle pin.
Ensure the shackle is a screw pin or bolt, nut, and cotter design.
If a screw pin shackle is used, make sure the pin is tight and never backed off before use. Additionally, make sure that the shackle pin cannot unscrew or vibrate loose during use.
If a bolt, nut, and cotter pin shackle is used, make sure the cotter pin is in place at all times.
The shackle's working load limit must never be exceeded. If the shackle is subjected to a side load, then the working load limit must be reduced according to the manufacturer's recommendations.
The shackle must be able to align itself with the sling leg or direction of loading without interference.
If the shackle bow has a diameter larger than 3 inches and the pad eye width is smaller than the shackle pin diameter, then the shackle's working load limit must be reduced by 15% due to potential side loading.
ASME B30.26 requires a visual inspection to be performed by the user or designated person each day before the shackle is used. Refer to ASME B30.26 and the manufacturer's inspection guidelines for more information.
For additional information or assistance, contact Crosby Technical Support at 1-800-220-8509.
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