Patent EA-004409-B1 (EA)
Title: Pipe integral threaded joint
Inventor: DELLA PINA GUISEPPE
IPC: F16L15/04
Filed: 2001-07-16
Abstract: 1. Pipe integral threaded joint comprising a male element (1) provided on its external surface with two radially spaced, truncated cone-shaped threaded portions (6, 7) with tooth of trapezoidal profile, said two portions (6, 7) being divided by a first annular shoulder (5') lying on a plane orthogonal to the pipe axis and a female element (2) provided on its internal surface with two radially spaced, truncated cone-shaped threaded portions (8, 9), said two portions being divided by a second annular shoulder (5'') lying on a plane orthogonal to the pipe axis, the two threaded portions (6, 7, 8, 9) having the same conicity value and being adapted to screw mutually and reversibly one inside the other in order to produce a contact between said two annular shoulders (5', 5'') in an assembled position, each of said male (1) and female (2) elements being provided with two sealing surfaces (12', 13', 12'', 13'') the first annular shoulder (5') and the second annular shoulder (5'') have the shape of an annulus, lying on a plane for its entirety without presenting any elevation from the plane, and in that the sealing surfaces (12', 13', 12'', 13'') are respectively placed at each axial end of the threaded portions (6, 7, 8, 9) of each male (1) and female element (2) characterized in that a first one of said respective two sealing surfaces (12', 13', 12'', 13'') has a conical shape and a second one has a spherical shape and in that the surfaces of the first and second annular shoulders (5', 5'') are equal or greater to 25% of the area of the section of the pipe walls and in that at least one of said male (1) and female (2) elements comprises along its entire surface a circumference cavity (14, 15) between one of said two threading parts and the corresponding annular shoulder (5', 5''), the at least one cavity (14, 15) being adapted to receive the expansion of the lubricating grease of the joint. 2. Joint according to claim 1, characterized in that both the male (1) and female (2) elements comprise along their entire surface the circumference cavity (14, 15), placed between one of the two threaded portions and the corresponding annular shoulder (5', 5''). 3. Joint according to claim 2, characterized in that the dimension (D') of the external diameter (3) of said female element (2) at the joint is larger than the dimension (D'') of the external diameter (4) of the same female element (2) of a value equal to or smaller than 3%. 4. Joint according to claim 3, characterized in that said corresponding two threaded portions (6, 7, 8, 9) of said male (1) and female (2) elements each have the same conicity value, comprised between 6.25 and 12.5%. 5. Joint according to claim 4, characterized in that said corresponding conical sealing surfaces (13', 12'') of said male (1) and female (2) elements have a conicity value comprised between 12.5% and 25%. 6. Joint according to claim 5, characterized in that the profile of the threading tooth has a loading flank (10) with a negative (alpha) angle and an stabbing flank (11) with a positive (beta) angle. 7. Joint according to claim 6, characterized in that said negative (alpha) angle has a value comprised between 0 and -10 degree and said positive (beta) angle has a value comprised between 10 and 30 degree . 8. Joint according to claim 7, characterized in that said corresponding two threaded portions (6, 7, 8, 9) of each of the male (1) and female (2) elements is provided with a perfect thread for its entire length. 9. Joint according to claim 7, characterized in that at least one of said two threaded portions (6, 7, 8, 9) of at least one of the male (1) or female (2) elements is provided with a first end (6', 7') with an imperfect thread. 10. Joint according to claim 9, characterized in that the corresponding threaded portion of the other of said at least one of male (1) and female (2) elements is also provided with a second area (8', 9') having an imperfect thread placed at the axially opposite end with respect to said first end.