Tool joint

Tool joint is a heavy coupling device welded onto the ends of drill pipe. Tool joints have coarse tapered threads to withstand the strain of making and breaking connections and to provide a seal. They also have seating shoulders designed to suspend the weight of the drillstring when the slips are set. On the lower end the pin connection is stabbed into the box of the previous joint. Hardfacing is often applied in a band on the outside of the tool joint to resist abrasion.