Patent EA-001729-B1 (EA)
Title: Threaded assembly of metal tubes designed to contain a corrosive fluid
Inventor: DUTILLUEL PIERRE
IPC: E21B17/00
Filed: 1999-03-19
Abstract: 1. An integral threaded or assembly of two metal tubes (10, 210), comprising a male element (1) provided externally in the open end of the first tube (10) and a female element (200) provided internally in the open end of the second tube (210), wherein: said male element (1) comprises a threaded male portion (13) and said male element has an unthreaded portion, wherein said unthreaded portion of said male element is arranged from the open end of the male element (1), said female element (200) comprises a threaded female portion (223) and said female element has an unthreaded portion, wherein said unthreaded portion of said female element is arranged from the side opposite to the open end of the female element (200), the male threaded portion (13) of the male element is screwed into the threaded portion of the female element and the unthreaded portion of the male element (1) cooperates with the unthreaded portion of the female element, the unthreaded portion of the male element (1) comprises a ring-shaped transverse support surface (15) from the side of the open end of this male element, said support surface made on the portion of the tube thickness, prolonging for the outer peripheral nozzle surface with a decreased outer diameter and terminating by a radial annular surface (17) or the so called annular surface of the inner portion of the first tube which joins the tube internal peripheral surface of the first tube (10), the unthreaded portion of the female element (200) comprises a ring-shaped transverse support surface (225) from the side opposite to the open end of said female element, said support surface forms a protrusion completing the support surface (15) of the male element (1) prolonged for the inner peripheral surface of a reinforcing zone (226) and the internal peripheral surface of a nest (221) for a sealing ring, and terminating with a radial annular surface (217) or the so called annular surface of the inner portion of the second tube which joins the tube internal peripheral surface of the second tube (210), the support surface (15) of the male element (1) is placed enabling a thrust with the support surface (225) of the female element (200), the annular surfaces of the inner end (17, 217) of two tubes (10, 210) are disposed at a certain distance from each other and opposite each other, the sealing ring (40) made of a synthetic material is set, directly or indirectly, between the annular surfaces of the inner end (17, 217) of two tubes (10, 210) and subjected to compression axially between these surfaces, directly or indirectly, characterized in that: a) the assembly comprises sealing metal ring-shaped surface on each of the unthreaded portion of the male and female elements arranged between threaded part (13) and support surface, wherein the sealing metal male surface (14) of the male element (1) is set on the female metal sealing surface (224) of the female element (200) with a positive diametric counteraction, b) a small clearance is provided between the nozzle outer peripheral surface (16) of the male element and the reinforcement inner peripheral surface (226) opposite the female element (200). 2. The threaded coupling assembly of two metal tubes (10, 10'), comprising a male elements (1, 1') provided externally in the open end of each of two tubes (10, 10') and the female elements (2, 2') provided internally on each end of the coupling, wherein the female elements (2, 2') are disposed on the coupling (20) by opposite sides to each other, wherein: each male element (1, 1') comprises the male threaded portion (13, 13') and the unthreaded male portion , wherein said unthreaded male portion and disposed from the side of open end of each male element, each female element (2, 2') comprises the female threaded portion (23, 23') and the unthreaded female portion and disposed from the side opposite the open end of the female element, the male threaded portion (13, 13') of each male element (1, 1') is screwed into the female threaded portion (23, 23') of a corresponding female element (2, 2'), and the unthreaded portion of each male element cooperates with the unthreaded portion of a corresponding female element, the unthreaded portion of the male elements (1, 1') comprises a ring-shaped transverse support surface (15, 15') from the side of the open end of this male element, said support surface made on the portion of the tube thickness, prolonging for the outer peripheral nozzle surface with a decreased outer diameter and terminating by a radial annular surface (17, 17') or the so called annular surface of the inner portion of the tube which joins the tube internal peripheral surface of the tube (10, 10'), ring-shaped surfaces of the inner end (17, 17') are positioned at a small distance from each other and opposite each other, the unthreaded portion of each female element (2, 2') of the threaded coupling (20) comprises a ring-shaped transverse support surface (25, 25') from the side opposite to the open end of said female element, said support surface forms a protrusion completing the support surface (15, 15') of corresponding male element (1, 1') prolonged for the inner peripheral surface of a reinforcing zone (26, 26') and the surface of a nest (22, 21) for a sealing ring, common with the nest surface (22' 21) of the other female element of the threaded coupling (20), the support surface (15, 15') of each male element (1, 1') is placed enabling a thrust with the support surface (25, 25') of corresponding female element, the sealing ring (40) made of a synthetic material is set, directly or indirectly, between the annular surfaces of the inner end (17, 17') of two tubes (10, 10') and subjected to compression axially between said surfaces, directly or indirectly, characterized in that: a) the assembly comprises sealing metal ring-shaped surface on each of the unthreaded portion of male elements (1, 1') and female elements (2, 2') arranged between threaded part (13) and support surface, wherein the sealing metal male surface (14, 14') of each male element (1, 1') is set on the female metal sealing surface (24, 24') of corresponding female element (2, 2') with a positive diametric counteraction, b) a small clearance is provided between the nozzle outer peripheral surface (16, 16') of each male element (1, 1') and the reinforcement inner peripheral surface (26, 26') disposed opposite corresponding female element (2, 2'). 3. The threaded assembly as claimed in claims 1 or 2, characterized in that the annular surfaces of the inner end (17, 17', 217) of tubes have substantially identical external and internal diameters. 4. The threaded assembly as claimed in claims 1 to 3, characterized in that the support surface (15) of the male element is a strongly open concave conic surface, and the support surface (25, 225) of the female surface (2, 200) is also a conic but convex surface with an angle at the apex, corresponding to the angle at the apex of the support surface (15) of the male element (1). 5. The threaded assembly as claimed in claims 1 to 4, characterized in that the diameter of the interior peripheral surface of the reinforcing zone (26, 226) disposed on the female element (2, 200) decreases as moving from the support surface (25, 225). 6. The threaded assembly as claimed in claim 5, characterized in that the angle between the support surface (25, 225) of the female element (2, 200) and the reinforcing support (26, 226) of said element is an acute or an obtuse angle. 7. The threaded assembly as claimed in claims 1 to 6, characterized in that the sealing metal surfaces, the male (14) and the female (24, 224) are conical surfaces with a substantially half angle at the apex, the diameter of said surfaces decreases as approaching the open end of the male element (1). 8. The threaded assembly as claimed in claims 1 to 7, characterized in that the external peripheral surface (43) of the annular sealing ring (40) is disposed at least on one cross section of the nest peripheral surface (21, 221) made on the female element (2, 200). 9. The threaded assembly as claimed in claims 1 to 8, characterized in that the annular sealing ring (40) comprises means for mechanical blocking (44, 44') preventing from radial displacement towards the axis, susceptible the release of said ring from its nest (21, 221). 10. The threaded assembly as claimed in claims 1 to 9, characterized in that the annular surfaces of tube ends in the assembly, being in contact with annular sealing ring (40) are slightly conic convex surfaces receiving said sealing ring (40) via a wedge and preventing its displacement radially towards the axis. 11. The threaded assembly as claimed in claims 1 to 9, characterized in that at least one tube of the assembly is provided with internal coating on the inner peripheral surface and on its annular surface of the inner end (17, 17', 217) providing continuity of the coating between said two surfaces. 12. The threaded assembly as claimed in claim 11, characterized in that the coating used for the inner peripheral surface of the tube and annular surfaces of its inner end is a layer (11, 11') applied or sprayed a synthetic coating. 13. The threaded assembly as claimed in claim 11, characterized in that the coating of the internal peripheral surface one or two tubes to be assembled is formed by an inner backup tube (51) connected with the corresponding tube (10) of the assembly, thus providing the continuity of the coating on the annular surface of the inner end (17) of the tube by an annular flange (60, 79), one of surfaces of which is fixed on the annular surface of said inner end (17) of the tube (10) and on the surface of the end of the inner end of the backup tube (51) and the opposite surface of which (62, 72)is disposed on the sealing ring (40), the nozzle of the male element is a composite nozzle, formed by a metal part (16, 16') and the annular flange (60, 70). 14. The threaded assembly as claimed in