Definition - What does Break Out mean?
Break out is the process of unscrewing drill string components which are coupled by various thread forms, or connections, including tool joints and other threaded connections. The break out process serves to perform the disconnecting of joints to allow for the removal of joints and other components from the drill string.
Trenchlesspedia explains Break Out
The drill string is composed of drill pipe, drill collars, the bottom hole assembly and the various tools to make the drill bit turn. The process of removing components from the drill string, such as when removing a steerable pilot to replace it with a reamer or drill bit, you break out the pilot.
Hazards associated with the break out process include being struck by drill pipe or other components as well as coming into contact with drilling fluid.