Integral spiral heavy weight drill pipe is to extend the central upset of heavy weight drill pipe and to cut spiral grooves on heavy weight drill pipe. Spiral grooves let mud circulate freely around the HWDP to equalize pressure and prevent a seal from forming.
Spiral HWDPs are widely used because of their maintenance features. The special grooves decrease the volume of the contact between the well side and the pipe; it leads to the decrease of the "tack" of the pipe and to turning of the drill pipe string.