Patent Number: 6,167,917

Title: Drill pipe

Abstract: A drill pipe having a length of conduit having a first diameter, a first and a second end portion, where each end portion has a second diameter greater than the first diameter. An enlarged portion is located between and spaced from the first and second end portions, where the enlarged portion comprises a central section which has a third diameter greater than the first diameter. The central section has a substantially smooth external surface, and two end sections, one end section at either end of the central section, which vary in diameter between the first and the third diameter. One of the end sections has a spiral formation thereon.

Inventors: Scott Aitken; William Russell (Kincardineshire, GB)

Assignee: Schoeller Bleckmann Oilfield Equipment Limited

International Classification: E21B 17/00 (20060101); E21B 17/22 (20060101); E21B 17/10 (20060101); E16L 009/02 (); E21B 010/26 ()

Expiration Date: 01/02/2018