Shackles are typically used as connection points for lifting equipment in many securing and rigging applications.
The type of shackle you use will depend on the lifting operation—Each has a slightly different design to suit them to various functions. There are three main types of shackles typically used for lifting applications:
- Bow (commonly known as an anchor shackle)
- Screw Pin (commonly known as a grab)
Dee shackles are mostly used for single-point lifting.
Bow Shackles are designed to be used to carry out multi-point lifts.
Screw Pin/Grab Shackle
Screw Pin or Grab Shackles are used when the shackle is required to pass through an opening, like a pipe or over an object. It is designed with a countersunk pin to facilitate this.
- Used where a shackle is removed on a regular basis
- When fitted, the pin must engage with the shackle body and tighten fully
- Screw pins can be moussed in place for long-term applications, or when there’s a risk of the pin backing out due to vibration, etc. Confirm with your supervisor to make sure this is accepted on your worksite.
Bolt Types: Nut, Bolt and Cotter Pins
- The bolt type pin (bolt, nut or cotter) is used when a load is permanent or semi-permanent.
- This requires the rigger to insert a split pin, which captivates the nut on the pin.
- If fitted correctly, the pin will rotate freely within the shackle body.
The round pin is commonly use for tie-down, suspension, towing and straight line lifting only. Don’t use round pins with multiple slings or where side loading may occur.
- A shackle will be sized from the diameter of the bow, not pin.
- A pin of a shackle is usually one size larger than the bow to achieve the strength of the bow. Consider this when you order a shackle for specific jobs, like a lifting lug.
Never replace a shackle’s pin with:
- A bolt
- A differently branded pin
- An incorrect pin size
- Do not exceed included angle of 120° when rigging with shackles and multiple slings.
- Apply reductions in WLL when you use shackles loaded at angles
Round and web sling shackles that are used with synthetic slings look slightly different.
- Wide body shackles have a larger D/d ratio for the sling, and improve the life and efficiency of the sling.
- ROV or remotely operated vehicle shackles are painted bright yellow or white so they are visible in dark waters, the pin is also easier to access with a ROV.
- Web sling shackles are wider and bow out in the middle
- Round sling shackles are narrow and sometimes have tiny valleys in the bow of the shackle so the strands are better supported.
How-To: Your Pre-Use Check
Before you use your shackle, you must inspect the following on all shackles:
- Markings are present, correct and legible including: manufacturer, working load limit (WLL), size, grade/material type
- The correct pin is fitted
- No visible signs of damage to the body or pin like nicks, gouges, deformations, stretch, bends, corrosion, etc.
- No evidence of misuse
In addition to your pre-use check, be sure to avoid swing loading and shock loading, secure sling legs not in use, never leave a load suspended—or walk under it.
How it’s Made
Lifting shackles are manufactured using the drop-forge process.
The drop forge process involves a steel rod hammered with a large ‘drop’ hammer, and a die is fitted to it. This die has the upper impression of a shackle cut into it and this shape imprints on the steel rod. A fixed die has the lower impression of the shackle.
The forged shackle is heated then treated—this ensures a uniform structure and gives the shackle it’s desired uniform thickness.
For more on shackles, check out our blogs below:
- Talking Shackles – Know your D from your Bow with our informative shackle guide
- Learn what means to Never Saddle a Dead Horse
- Discover what it’s like to inspect a shackle with Hercules SLR Inspector Heather Young
- Learn more about synthetic slings, their construction and applications here
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