Load securing Grade 70 chains are stamped, as are the hooks. Import hooks sometimes have a working load rating, but I would NOT recommend ever expecting half of that. Usually they just stamp the SIZE on 'em.
A chain for overhead lifting will have a certification tag with it's load rating in several configurations (i.e. straight, basket, etc) for which it has been designed, proof-tested, and certified for load.
DOT chain requirements don't require a certification tag, but if you have a chain WITH one, the enforcement officer will USUALLY be sharp enough to spot it, and know what it means. It's better to use transport chain, because transport is hard on an expensive piece of hoist rigging.
Grade 70 'proof' chain is NOT for overhead lifting. The use of 70,000psi steel is for abrasion resistance, both on exterior of the links, and INSIDE the link's bends, but it is more brittle than lifting chain, so it won't ever get a tag.
The term 'proof', means it was applied to it's working load plus some margin (IIRC, it's about 300% for transport, and 1000% for hoisting. In manufacturing, they actually feed the chain through a pair of hoist capstans, down to a physical load, and back up, and in doing so, the continuous feed applies the test working load to find any weaknesses. Pretty cool. Works like a weight hanging in a grandfather clock.
They do the same type of rating and proof testing of shackles, hooks, and eyes...
But there's nothing at all they can do about poor focus... there's just no way.
But hey, if you pin up a Hooters calendar at the end of the hallway, they'll get a little exercise...
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