Connecting oil country tubular goods

Ends of separate tubular members used in oil and gas drilling are connected pin-to-pin by a threaded coupling and made leak tight by an internal pressure seal, wherein the male or field end pin of a first tubular member has an integral geometry designed to mate with the female or mill end pin of a second tubular member. The coupling and tubular members possess a modified buttress thread form having a negative load flank angle and a positive stab flank angle. When assembled, the coupling connects the field end pin of the first tubular member with the mill end pin of the second tubular member, wherein integral geometries of the mated pin ends generate the interference necessary to produce a single, metal-to-metal, leak-tight, internal contact pressure seal. An external ball and cylinder contact seal at each end of the coupling provides additional sealing capacity when used in combination with the internal contact pressure seal.