THREADED CONNECTION FOR PIPES Russian patent published in 2005 - IPC

FIELD: screw-threaded joints.

SUBSTANCE: threaded connection comprises steel pipe, whose end is provided with male thread and sealing surface without thread, and coupling, whose inner side is provided with female thread and sealing surface without thread. When the inner surface of the pipe is pressed by the pressure P_y, the mean pressure P_m on the ring section of the contact is P_m/P_y ≥3, and the width of the section in axial direction that undergoes the pressure P_s (P_s/P_y ≥1) in the ring contact section is no less than 1 mm. The roughness of the surface R_y of both of the sealing surfaces without the thread is no more than 25 μm. The relationship between the mean pressure P_m of the ring section of the contact and roughness of the sealing surface R_y (μm) without the thread is P_m/P_y ≥ 0.0324(R_y)² + 1.0. The width of the section in axial direction that undergoes pressure P_s that fits a formula P_s/P_y ≥ 1 in the ring contact section is no less than 1 mm.

EFFECT: enhanced reliability.

6 cl, 7 dwg