Kelly Bushing (KB)
Definition - What does Kelly Bushing (KB) mean?
Kelly Bushing, also known as Drive Bushing, is a drilling device that is used to connect a Kelly with a rotary table. This tool is used to fit inside the head where the Kelly fits. The Kelly driver is used to rotate the Kelly. This tool also works along with other drilling tools. Another name for Kelly Bushing is Kelly drive bushing.
Petropedia explains Kelly Bushing (KB)
Drilling equipment such as a Kelly Bushing is used to connect a Kelly and a rotary table. A Kelly is a long steel bar, which has a square or hexagon shape with a hole in the middle to allow fluid flow. A rotary table on the other hand is a drill floor with spinning sections that are used to transmit power and rotary motion through the drive bushing to the drill string.
The Drive Bushing or Kelly bushing has a diameter profile located on the inside that is of exact size as that of the Kelly head. It is then used to join with the rotary table, which then transmits the rotary motion from the rotary table to the Kelly or Drive Bushing. A Drive Bushing thus, acts as an adapter that connects the Kelly with the rotary table to allow the power and motion to flow through it.