Drill rod structures

Claim 1

A drill pipe having an internally upset enlarged joint section at each end thereof, each of said sections having a threaded portion of tapering diameter and an annular shoulder at each end of said threaded portion, each said shoulder having an axially presented face disposed at an angle of approximately 30* to a plane normal to the axis of the pipe, the threaded surface of one of said sections being on the inside of said pipe and the threaded surface of the other of said sections being on the outside of said pipe, said outside threaded joint section being of substantially less maximum diameter than the outside diameter of the remaining portion of said pipe, said outside diameter of said pipe being constant from end to end thereof, each said upset joint section having an inside wall surface parallel to the outer surface of said pipe and merging into the inside wall surface of the remaining section of said pipe in a curved contour, said inside wall surfaces being axially aligned and having equal diameters which have less than the minimum diameter of each of said threaded portions, said remaining section of said pipe having a constant diameter said inside-threaded joint section having an inside annular seal-receiving groove disposed between the inner of said shoulders and the threaded portion thereof.