"Boy! Is that load heavy! Look at the beads of sweat on that hook!"
Crane hooks used to be designed so that opening side was parallel to the back and if overloaded you could easily tell by the sprung hook.
Today it is common to use overrated hooks on cranes but on high strength chains the spring open rule holds.
The two signs that a chain has been overloaded and should be scraped (or used for decorative purposes) are
1) the hook sprung so that the front of the opening is no longer parallel to the back of the opening,
2) the chain links have been stretched straight (no longer have slightly rounded sides) and/or are tight to pivot the links.
These are chains that have been loaded to very near breaking and should be scraped.
The last thing to look for in old chain is wear.
Chains wear at the contact surfaces and can become very thin.
Any noticable wear is usually a sign to replace the chain.
Crane hooks used to be designed so that opening side was parallel to the back and if overloaded you could easily tell by the sprung hook. Today it is common to use overrated hooks on cranes but on high strength chains the spring open rule holds.
The two signs that a chain has been overloaded and should be scraped (or used for decorative purposes) are 1) the hook sprung so that the front of the opening is no longer parallel to the back of the opening, 2) the chain links have been stretched straight (no longer have slightly rounded sides) and/or are tight to pivot the links. These are chains that have been loaded to very near breaking and should be scraped.
The last thing to look for in old chain is wear. Chains wear at the contact surfaces and can become very thin. Any noticable wear is usually a sign to replace the chain.
Moving Loads, Rigging and Safety