Patent EA-002107-B1 (EA)
Title: Threaded connection of two metal tubes with grooves in the threading
Inventor: NOEL THIERRY
IPC: F16L15/06
Filed: 1999-09-02
Abstract: 1. A threaded connection of two metal tubes comprising a male element at the end of a first tube and a female element at the end of a second tube, the male element including an external male thread, the female element including an internal female thread, each surface of which is parallel to a corresponding surface of the male thread, the male and female threads being screwed into each other, characterized in that at least one of the male or female threads comprises a groove (61, 62) for reducing contact surfaces between the male and female threads, the groove having two walls and a bottom and produced in the thread (31, 32) and emerging either on the engagement flank (33, 34) or at the thread top (39, 38) or even astride between the engagement flank and the thread top. 2. The threaded connection according to claim 1, characterized in that the groove extends continuously along the thread)s) length. 3. The threaded connection according to claim 1 or 2, characterized in that the groove has V-shaped walls and a rounded bottom. 4. The threaded connection according to one of claims 1 to 3, characterized in that the radius of the bottom is at least 0,2 mm. 5. The threaded connection according to one of claims 1 to 4, characterized in that the groove (21, 22, 51, 61, 62) emerging at the thread top has a width at the end not exceeding 2/3 of the thread. 6. The threaded connection according to one of claims 1 to 4, characterized in that the groove (41, 67) emerging on the engagement flank has a width not exceeding 2/3 of the thread height  7. The threaded connection according to one of claims 1 to 4, characterized in that the groove (56, 68) emerging astride between the engagement flank and the thread top has a width at the end not exceeding 2/3 of lesser of either width or the length thread. 8. The threaded connection according to one of claims 1 to 4, characterized in that the groove (21, 22, 51, 61, 62) emerging at the thread top has a depth not exceeding the tread height. 9. The threaded connection according to one of claims 1 to 4, characterized in that the groove (56, 68) emerging astride between the engagement flank and the thread top has a depth not exceeding 2/3 of the thread width. 10. The threaded connection according to one of claims 1 to 4, characterized in that the groove (56, 68) emerging astride between the engagement flank and the thread top has a depth not exceeding either the thread height or 2/3 of the thread width. 11. The threaded connection according to one of claims 1 to 10, characterized in that the male and female threads are conical with trapeziformed threads disposed along one or a plurality of screw lines. 12. The threaded connection according to claim 11, characterized in that at least one of tops of the male and female threads counteracts radially with one or plurality of conjugating recesses when the screwing is over. 13. The threaded connection according to claim 11, characterized in that the male and female threads are threads with trapezoid projections without axial gap. 14. The threaded connection according to one of claims 1 to 10, characterized in that the male and female threads are cylindrical single or multiple threads or cylinder-conic thread. 15. The threaded connection according to one of claims 1 to 14, characterized in that the width of the male and female threads varies coordinated along the whole length of the thread or each part of it forming wedge-shaped ends. 16. The threaded connection according to one of claims 1 to 10, characterized in that the male and female threads are conical threads with rounded ends according to API 5B specification. 17. The threaded connection according to one of claims 1 to 10, characterized in that the male element comprises at least one male sealing surface (207, 307) and female element comprises at least one female support sealing surface (208, 308), the corresponding male and female surfaces counteract radially when the screwing is over providing at least one sealed contact metal-metal between the male and female elements. 18. The threaded connection according to one of claims 1 to 17, characterized in that each male and female comprises at least one thrust, wherein the thrust(s) (209, 309, 309') of the male element rest upon the corresponding thrust(s) (210, 310, 310') of the female when the screwing is over. 19. The threaded connection according to one of claims 1 to 18, characterized in that the connection is integral. 20. The threaded connection according to one of claims 1 to 18, characterized in that the connection is a sleeve joint.