Tubular threaded joint capable of being subjected to diametral expansion

The invention relates to the screw thread;, comprising an external thread (1) is convex lip (5) and is adapted to the opening of the internal thread (2) on the shell, and enable the screw joint is sealed and undergoing passing larger than 10% of stretching with the maximum inner passage section. The expansion, through the matching of; the convex free end surface (9) is inserted in transversely concave shoulder surface of the shell (10), and lip (5) circumferential surface (7) (8) is a gap between the upper shell (6) in circumferential surface. Such screw thread is specially suitable for the casing pipe or a tube of the oil well.