Box and Pin Joint
Definition - What does Box and Pin Joint mean?
A box and pin joint, also known as tool joint, is a component of drilling pipes that act as a coupling element to make up the drill string. The joint connects with the pipe by welding or with the help of a conical thread. They are located at each end of the drill pipe and the drill pipes are screwed to each other via these joints, making it airtight and easy to assemble and disassemble.
Horizontal directional drilling (HDD) utilizes drill strings for drilling below the earth surface.
Trenchlesspedia explains Box and Pin Joint
The joints of the drill pipe are connected together using tool joints that provide the screw and thread for connection. The seal in the connection is provided by the shoulder to shoulder connection between the box and pin. A hard material is welded onto the surface of the tool joint to prevent abrasion during rotation of the drill string in the borehole. The tool joints are then flash welded onto the pipes.
The cross-sectional area of the box and pin determines the strength of the tool joint, and the size of the tool joint depends on the size of the drill pipe. The tapered shoulder of the box is usually at an angle of 18° and the pin has its shoulder at an angle of 35°. Proper greasing of connections and application of steady torque can extend the life of a tool joint considerably.