Rotary Well Drilling Stem

The uppermost joint of a string of drill pipe. It passes through the rotating mechanism of a rotary well drilling machine and may be rotated and simultaneously moved vertically by means of evenly spaced driving flutes or flats running lengthwise to within a few inches of either end. The upper end usually has a left-hand thread for connection by means of an adapter to the body of a swivel, but may also be connected to the adapter or swivel by means of a coupling. The lower end has a right-hand thread for connection to a short length of drill pipe.