Abstract: An inner pipe member for a dual-wall drill pipe assembly having an inner pipe member and an outer pipe member, the outer pipe member having a main bore extending axially therethrough including a first bore and a concentric second bore of smaller diameter than the first bore and axially spaced therefrom by a shoulder, and a circumferential recess in the second bore, the inner pipe member comprising a tubular body portion adapted to be telescopically and concentrically received in the main bore and define an annular fluid passage therewith, a first spacer at one end of the body portion for concentrically spacing the one end of the body portion from the other end of the outer pipe member, and a second spacer at the other end of the body portion, the second spacer including first and second surfaces adapted to be received in sliding fit relation within the first and second bore, respectively, for concentrically positioning the other end of the inner pipe member within the outer pipe member, and a projection exten

Abstract: A drill bit latch assembly for releasably securing an earth drill bit to the bottom end of a drill string comprises a tubular housing adapted to be secured to the bottom end of a tubular drill string, drill bit holder adapted to be secured to a drill bit, and a latch assembly. The drill bit holder is telescopically movably received in one end of the housing and coupled thereto for rotation with the housing. The latch assembly is telescopically received in the other end of the housing. The latch assembly releasably engages the holder and is operative with the housing for maintaining the holder in a predetermined operative position within the housing. The latch assembly is responsive to an unlatching tool lowered down the drill string to unlatch the holder.