BTH-1 states that there must be two bolts per bolted connection (3-3.2 Bolted Connections). However, crosby sells swivel hoist rings and other lift tools that are only one bolt for the connection. Can anyone explain the difference here?
If you were to put two separate committees to work on the identical issue, you'd come up with two different results. That doesn't mean either is wrong, just that they're based on informed opinions, and those opinions don't always agree, especially on somewhat arbitrary rules. In this case, you're seeing the convergence of the civil/structural world and the mechanical world.
In this case, I don't think the Crosby items fall under BTH, though.
The two-bolt requirement in BTH is just a carryover from standard structural steel requirements (AISC) if I remember correctly.
You've got fabricated structural steel vs forged parts. Crosby may use a higher proof load than the test requirement of BTH, also.