THREADED JOINT OF CASING PIPES Russian patent published in 2017 - IPC E21B17/42 F16L15/00 E21B17/08 

FIELD: oil and gas industry.

SUBSTANCE: union includes male and female elements, at the ends of which on the outer and inner surfaces respectively, there are trapezoidal threads with taper 1:16 and radial sealing and stop end surfaces contacting therebetween, made at angle of 9-11° to normal line of thread axial line. The inclination angle of embedded face of the thread profile is 14-16° to the normal line of the thread axial line, angle of inclination of bearing face ranges from -4° to -6°, vertices and cavities of thread profile are parallel to axial line of the thread. Radial sealing surfaces on male and female elements are made in form of concave and convex spherical surfaces, respectively. The radius of sealing surface sphere of the male element is greater than radius of sealing surface sphere of the female element. The radial sealing surfaces and stop end surfaces on male and female elements are separated by a section of cylindrical surfaces, the transition from which to stop end surfaces on male and female elements is made in the form of a surface consisting of two spherical surfaces of different radii.

EFFECT: hundred percent connection resistance against compression and tension load, gas-tightness under said loads, resistance to high torque and improvement of screw characteristics.

4 dwg, 1 tbl