Why is it difficult to Size a shackle for G4 Hi Test Chain

[Mantus Anchors]

guys this what I found, if someone has an explanation I would love to hear it...
Greg

Ramble | MantusAnchors

[Adelie]

That link's explanation pretty much sums it up.

I have long wondered why the difference in the factor is safety for HT. My best guess is that a bigger difference in SWL was needed to justify the cost difference and that this was rationalized by increased inspection of the links after proof testing, 100% instead of 5% are checked for elongation or other types of failure. I don't know how this works with higher grades. I suspect the reason for the difference is lost in history though the folks at Acco might know.

[Mantus Anchors]

There is more interesting facts, manufacturers of shackles can randomly decide what safety factor they use when designating WLL? For overhead lifting shackles they have to comply with Specs that call for WLL 1/5 of the UTS. But all you have to do is say "not for lifting" and you can make up you safety factor....

For example check out this shackle:

A Wichard standard pin bow shackle is the ultimate choice for safety
Drop forged in 316L stainless steel for superior strength
The Self Locking Pin is designed for safety
Small indentations in the shackle engage the head of the pin
Head of shackle pin locks into one of the notches
Avoids accidental release due to vibrations
Final tightening then creates the tension that locks the pin in place
Even the most violent vibrations will not loosen the pin
Specifications:

Pin Diameter: 5/8" (16 mm)
Working Load: 3200 kg
Breaking Load: 10,000 kg
A = 70 mm
B = 32 mm

Here they use safety factor of 3????? and most people think the WLL is hi bc the shackle is supper duper....

[motion30]

Hey Greg
Thanks for tip on wichard shackles
This was timely as I was searching for a good shackle for my 5/16 ht chain. Found the wichard 1246. With a WL of 4576lb and a breaking load of 13200lb. That ought to hold my months 105

[Mantus Anchors]

More rant on shackles and working load
Which Shackle, so you know the working load limit, are you done? -

[motion30]

I read your article and I am happier NOT buying a shackle made in china