Patent EA-003267-B1 (EA)
Title: Threaded joint for tubes
Inventor: NOEL THIERRY
IPC: F16L15/00
Filed: 2000-10-17
Abstract: 1. A threaded joint for tubes, comprising a male element (1) arranged at the end of a first tube (3) and a female element (2) arranged at the end of a second tube (4), central sealing means (9) formed by a male bearing surface (10) and a female bearing surface (11), resting on each other when the joint is assembled, the male element is (1) provided with an external taper thread (7) and the female element is provided with an internal taper thread (8) corresponding to the male element thread (7), screwing stop (12, 13, 21) is further provided for interrupting screwing of the male element (1) into the female element (2) at a predetermined assembled position of the joint, characterized in that the male thread (7) comprises only one male thread zone and the female thread comprises the female thread zone, the male bearing surface and the female bearing surface of the central sealing means are arranged in the central zone of the male thread zone in case of the male bearing surface (10) and the female thread zone in case of the female bearing surface (11) in which respective male thread and female thread are interrupted. 2. The threaded joint according to claim 1, characterized in that the male thread zone and the female thread zone comprise simultaneously complete, imperfect, vanishing or incomplete threading. 3. The threaded joint according to claim 1 or 2, characterized in that the central sealing means is located in the zone spaced from the center point of the male thread zone or the female thread zone at a distance equal to 1/4 of the length of the threaded zone, on each side of the center point. 4. The threaded joint according to one of claims 1 to 3, characterized in that the screwing stop which permits interrupting screwing the male element into the female element at a predetermined assembled position of the joint is means directly linked to the threads (12, 13). 5. The threaded joint according to one of claims 1 to 3, characterized in that the screwing stop which permits interrupting screwing the male element into the female element at a predetermined assembled position of the joint is independent of the thread (12, 13). 6. The threaded joint according to claim 5, characterized in that the screwing stop independent from the thread is made as an abutment. 7. The threaded joint according to one of claims 1 to 6, characterized in that at least one of the bearing surfaces, the male bearing surface or the female bearing surface is formed by a conical surface, the conicity of which have similar direction with the thread conicity and an angle of which relative to the threaded joint axis exceeds preferably the angle of the thread cone relative to that angle. 8. The threaded joint according to claim 7, characterized in that the angle formed by the conical bearing surface with the threaded joint axis exceeds the cone thread angle relative to that axis by the value at least equal to 20 degree . 9. The threaded joint according to one of claims 1 to 8, characterized in that maximum dimensions of the male bearing surface and the female bearing surface of the central sealing means is determined by a space between the generatrices (G1-G2), defining the limits of the thread dimensions. 10. The threaded joint according to one of claims 1 to 9, characterized in that of the male bearing surface and the female bearing surface of the central sealing means are designed in the form of two conical surfaces, the conicity of which exceeds preferably the thread conicity. 11. The threaded joint according to one of claims 1 to 10, characterized in that further comprises another sealing means. 12. The threaded joint according to one of claims 1 to 11, characterized in that a part of the generatrices (G1-G2) defining the limits of the thread dimensions and arranged from one side of the central sealing means in case of one thread, male or female, is slightly displaced radially relative to the tube axis from the part of the similar generatrix arranged on the other side of the central sealing means. 13. The threaded joint according to claim 11 or 12, characterized in that the second sealing means is formed by the male bearing surface disposed beside the free end of the male element and the female element disposed on the corresponding part of the female element, wherein in the process of the assembling of the thread joint the male and the female surfaces rest on each other. 14. The threaded joint according to claim 11 or 13, characterized in that the interference of the male surface and the female surface of the central sealing means exceeds the interference between the male thread and the female thread. 15. A threaded assembly of two tubes forming a straight connector, characterized in that produced using a threaded joint according to one of claims 1 to 14, a male element arranged at the end of a first tube and a female element arranged at the end of a second tube. 16. The assembly according to claim 15, characterized in that the female element is made on a pre-expanded end of a tube, wherein the male element is made on the end of a pipe which can be optionally thickened, forming a collar fitting. 17. A threaded assembly of two tubes (49, 50) of spigot joint type (51), characterized in that two threaded joints are coupled according to one of claims 1 to 16, each end of a tube (49, 50) is provided with a male element (53, 54) and each end of a spigot (51) is provided with a female element (55, 56), the male element of each tube is screwed into each of the female element of the spigot end. 18. The assembly according to claim 17, characterized in that the free end of each male element (49, 50) when the joint is assembled rests on the part of the spigot (51) made in the form of a central shoulder (52) forming two thrusts (61, 62). 19. The assembly according to claim 17, characterized in that two free ends (71, 72) of male elements (66, 68), rest on each other forming a common thrust (70, 89) when the joint is assembled. 20. The assembly according to claim 19, characterized in that each male element (66, 68) and each female element (67, 69) are provided with cuts (77, 78, 90, 91) forming shoulders permitting precise positioning of the common thrust (70, 89).