Airtight economical screwed joint

The utility model relates to an airtight economical screwed joint belongs to oily casing thread connection technology field. The joint comprises female joint and male joint two parts, and processing has internal thread, cylinder hole, moment of torsion circular bead in the female joint, and processing has external screw thread, transition inclined plane, planar end surface, inner wall inclined plane in the male joint. The screw thread of male joint and female joint is standard API screw thread, but the pitch diameter than API screw thread 0.2 big~0.4mm to the moment of torsion circular bead has been designed. The utility model discloses internal thread and the radial interference fit of external screw thread undertake connect function, and the moment of torsion circular bead is showing andhas improved the sealing performance and the anti -torque capacity that connect, can satisfy natural gas well's exploitation requirement, have that the in -process measurement is simple, interchangeability reaches advantages