Definition - What does Drill Pipe mean?
Drill Pipe is a thin-walled, hollow, steel and aluminum alloy piping which is used in horizontal drilling and on drilling rigs to facilitate the drilling of a borehole. It comes in a series of sizes, weights and strengths but it is generally 27 to 32 feet long and the longest length ranging around 45 feet. It is hollow inside and thus it allows the drilling fluids to be pumped through it. It is a portion of an overall drill string, which is composed of a both bottom hole assembly and drill pipes that are tubular portions close to the bit.
Petropedia explains Drill Pipe
Drill Pipes are designed for transferring the drilling torque for the combined lengths which often outstrip 1 mile below into the Earth's crust. These are the tempered tubes which are expensive and the owners spend huge efforts to reuse the pipes even after drilling the wells. These pipes connect the surface equipment of the rig with the bottom hole assembly and drill bits to help them pump the drilling fluids and lower, rotate or raise the bottom hole assembly and the drill bits. The bottom hole assembly is made up of thick-walled heavy weight drill collars and Drill Pipes of small internal and large diameters which give stiffness to the drilling assembly and weight to the drill bits.