Shackle Markings, Materials and Appropriate Standards

Shackle Markings, Materials and Appropriate Standards

shackle markingsS. H. from Georgia writes:

I am unfamiliar with the standards governing shackles and have a question regarding the stamped WLL on your shackles. Our company is using shackles with different ratings on them.  For example, we use a ½” shackle stamped a 2T WLL and a ½” shackle stamped with a 3T WLL.  I understand that there was a change in the standard several years ago and wonder if you could recommend which load rating is the correct one and what should be done with the shackles with incorrect stamping.  Also, neither shackle is stamped or marked as High Strength “HS” as required by the standard RR-C-271D and Amendment 1.  Any information that you can provide would be appreciated.

Peter Cooke, our Training Manager, answers this question on shackle markings:

Both of the WLL stamps on your two types of shackles may be correct.  Shackles fall under ASME B30.26 rigging hardware.  Shackle working load limits differ based on materials used to construct the shackle.  The industry has three types of materials for shackles: Carbon, Super Carbon and Alloy.  This means that you can have three shackles of all the same size (diameter) and have three very different working load limits.  ASME B30.26 requires the working load limit be stamped on all shackles.  A rigger must look for the WLL stamped on the shackle.

This is why you must never base your working load limit by diameter. If the WLL is no longer legible, the shackle should be discarded.

shackle markingsThe classification of a shackle as “High Strength” is based upon the classification of the shackle pin as HS. The HS stamp will be on the pin or bolt, not on the shackle.  All CMCO shackles – carbon, super carbon or alloy – have HS pins. So, you do not need to worry about mixing up pins between carbon, super carbon and alloy when using CMCO products.

See also Shackle Marking Reference File

Peter Cooke

Peter Cooke is a former Training Manager for Columbus McKinnon Corporation, having specialized in Rigging & Load Securement.

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11 Replies to “Shackle Markings, Materials and Appropriate Standards”

  1. I think I’ve found a knock off CM shackle and I need help to identify it. Please email me

  2. Hi Nick,
    To answer your question, our Super Strong Shackles are rated in short tons, so our 30 ton shackle equates to 60,000 lbs.
    Thanks for checking,

  3. Are you Super Strong shackles (or any other shackles) rated in metric tons (2200 lbs) or short tons (2000 lbs)? For example, part number M677G–with a 30 Ton rating, does that translate to 60,000 or 66,000 lbs?

  4. Good day Peter,

    Thanks for your question. For load handling activities we reference ASME B30.26. If the required markings per ASME B30.26 are not present, they would not comply for load handling activities. There is no OSHA law that governs shackles. Hope this helps!


  5. Why is it that some clevises sold at farm supply stores do not have WLL stamped on the clevises??? Specifically, it is a SpeeCo clevis manufactured in India.

    I thought it was required??

  6. Hi Paul,
    Thank you very much for your comment. Your question comes up often. The standards only cover marking required by the manufacturer of the product.
    To better meet the needs of our end users Columbus McKinnon will soon be supplying shackles with a raised pad just for serialization. In the meantime a dot type engraver is the safest method.

  7. Hi Peter, our company operates a rigging department where we manufacture wire rope slings and sell the associated rigging equiment. We are located in Trinidad.

    I have a question regarding the stamping of shackles; either new or after we re-certify them. If we sell new shackles either alone or as part of a sling set, we are required to stamp a unique serial number on them (usually our job number) that ties them back to a certificate of conformance or in some cases a pull test certificate.

    I was wandering if there are any guidelines covered in any of the rigging standards that govern this ? Presently we use manual metal stamps (the ones you strike with a hammer) to stamp around the yolk of the shackle.

    Any comment on this subject would be appreciated.

    Thank you

    Operations Manager
    Process Components Limited

  8. Thank you for providing the link to “Shackle Marking Reference File.” This is exactly what I was looking for.
    (I was afraid that the M with a circle around it somehow meant “Metric.”)

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