If you run into carriage bolts that just spin in place when you try to tighten them, they need to be replaced. To remove them ...

As provided by Machinery's Handbook and ASME B18.2.1, bolts are externally threaded fasteners that are prevented from being turned during assembly, but are positioned or released by torqueing a nut.

Bolt Type: Anchor Bolt; Carriage Bolt; Elevator Bolt; Flange Bolt; Hexagon Bolt; Lag Bolt; Machine Bolt; Plow Bolt; Shoulder Bolt; Square Head Bolt; T-Head Bolt; U ...