US Patent 7438329 Methods and connections for coupled pipe

A threaded and coupled connector with tapered threads having equivalent heights (same height on pin and box threads), negative load flanks, biased tapered thread forms with a torque shoulder formed by pin noses that abut at a central point within a coupling constructed from standard coupling stock. The connection design meets the internal/external pressure performance requirements of industry standards with capabilities equal to or exceeding those of “premium” connections, with a coupling constructed from thin walled coupling stock.