Abstract: An improved drill pipe assembly that is formed as a concentric walled pipe having both an axial and an annular space therethrough, and the pipe section includes means for selectively communicating the adjoining annular spaces through the series of respective box end/pin end joints whereby equipment compartmentation, conductor traverse, ballast containment, gas pressurization and weight addition can be effectively utilized in controlled manner. The pipe is assembled by threaded engagement of the pin end joint to each of an outer pipe and an inner pipe, and subsequent threaded joinder of the concentric pipes to a box end joint while also utilizing an intermediate double-threaded sleeve between the inner pipe threads and the box end collar threads.

Abstract: An improved drill pipe assembly wherein each pipe section is formed as a concentric walled pipe having both an axial and an annular space therethrough, and the pipe section includes means for communicating the adjoining annular spaces through the series of respective box end/pin end joints whereby equipment compartmentation, conductor traverse, ballast containment, gas pressurization and weight addition can be effectively utilized in controlled manner.