Drill pipes are steel tubes with threaded ends that are used to connect a drill rig's surface equipment with its drilling equipment, or bottomhole assembly, at the bottom of a well. They are used to transport drilling fluid to drill bits, and to raise, lower and rotate the bottomhole assembly along with the drill bit. Drill pipes must be manufactured to withstand severe internal and external pressure, distortion, bending and vibration. They are reusable and are not considered consumables in the process of exploring for and extracting oil and gas.