Threaded joint for steel pipes

Patent metadata

Field	Value
Publication number	US-9568125-B2
Application number	US-77490910-A
Country	US
Kind code	B2
Filing date	May 6, 2010
Priority date	Nov 8, 2007
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

A threaded joint for steel pipes comprising a pin ( 1 ) and a box ( 2 ). The pin has a male thread ( 11 ) and a lip ( 12 ) which comprises (i) a sealing surface ( 13 ) and (ii) a nose portion ( 16 ) provided with a shoulder surface. The box has a female thread ( 21 ), a sealing surface ( 23 ) and a shoulder surface. The shoulder surface of the pin comprises two distinct adjacent surfaces, main shoulder ( 14 ) in the inner side and sub shoulder ( 15 ) in the outer side. Correspondingly, the shoulder surface of the box comprises two distinct adjacent surfaces, main shoulder ( 24 ) in the inner side and sub shoulder ( 25 ) in the outer side. The main shoulder surfaces of the pin and box are disposed such as to prevent a radially inward deformation of the lip end, and the sub shoulder surfaces of pin and box are disposed such as to limit a radially outward deformation of the lip end. The main shoulder of the pin has a greater radial dimension than said sub shoulder of the pin, and at least the main shoulder surface of the pin is in axial abutment with at least the corresponding main shoulder surface of the box.

First claim

The invention claimed is:

1. A threaded joint for steel pipes comprising:
a pin and a box,
the pin having a male thread and a lip comprising:
(i) a sealing surface; and
(ii) a nose portion provided with a shoulder surface,

the box having a female thread, a sealing surface and a shoulder surface,
the male thread being interengaged with the female thread,
the sealing surface of the pin being in sealing contact with the corresponding sealing surface of the box, the shoulder surface of the pin being arranged at an end face of the pin, the sealing surface of the pin being located on a pipe end side near the male thread, the nose portion existing between the sealing surface and the shoulder surface, said nose portion not contacting a portion of the box facing said the nose portion of the pin,
wherein the shoulder surface of the pin comprises two distinct adjacent surfaces,
a main shoulder surface on an inner side; and
a sub shoulder surface on an outer side, and

in that the corresponding shoulder surface of the box facing the shoulder surfaces of the pin comprises two distinct adjacent surfaces,
a main shoulder surface on an inner side; and
a sub shoulder surface on an outer side,

said main shoulder surfaces of the pin and box being disposed so as to prevent a radially inward deformation of the lip, said sub shoulder surfaces of the pin and the box being disposed so as to limit a radially outward deformation of the lip, said main shoulder surface of the pin having a greater radial dimension than said sub shoulder surface of the pin, at least said main shoulder surface of the pin being in axial abutment with at least the corresponding main shoulder surface of the box,
wherein at least a part of the nose portion of the pin has an outside peripheral surface which is not in prolongation of the sealing surface of the pin and the sealing surface of the pin, the outside surface of the nose portion of the pin and sub shoulder surface of the pin are not aligned and wherein the sealing surface of the box, the inner surface of the portion of the box facing the outside surface of the nose portion of the pin and the sub shoulder surface of the box are not aligned, and further wherein
the sub shoulder surfaces of the pin and the box do not contact each other in a normal tightened state, where the normal tightened state means that the pin and the box are tightened to reach a proper tightening torque, and
wherein when compared to the normal tightened state, higher compressive load is acting or an excessive tightening torque is applied, the sub shoulder surfaces contact and suppress outward deformation of the lip.

2. A threaded joint according to claim 1 , wherein the main shoulder surface of the pin is a reverse shoulder surface having a negative angle with respect to as plane perpendicular to a joint axis.

3. A threaded joint according to claim 1 , wherein the sub shoulder surface of the pin has a positive angle with respect to a plane perpendicular to a joint axis.

4. A threaded joint according to claim 1 , wherein only the main shoulder surface of the pin is in axial abutment with the corresponding main shoulder surface of the box.

5. A threaded joint according to claim 1 , wherein the sub shoulder surface of the pin is designed to interfere with the sub shoulder surface of the box, the geometrical diametric interference between the sub shoulder surfaces of the pin and box being equal to or less than 1.1 times the geometrical diametric interference between the sealing surfaces of the pin and box.

6. A threaded joint according to claim 5 , wherein the geometrical diametric interference between the sub shoulder surfaces of the pin and box is substantially equal to the geometrical diametric interference between the sealing surfaces of the pin and box.

7. A threaded joint according to claim 2 , wherein the angle of the reverse shoulder with respect to a plane perpendicular to a joint axis is between 5 and 25 degrees.

8. A threaded joint according to claim 1 , wherein the shoulder surfaces of the pin and the box are substantially frusta-conical.

9. A threaded joint according to claim 1 , wherein the main shoulder surface and the sub shoulder surface of the pin can be supported by the corresponding main shoulder surface and the sub shoulder surface of the box when the main shoulder and sub should surfaces receive compressive load.

10. A threaded joint according to claim 1 , wherein the sealing surfaces of the pin and the box are sloping with regard to an axis of the threaded joint at an angle between 5 and 25 degrees.

11. A threaded joint according to claim 1 , wherein the sub shoulder surfaces of the pin and the box are sloping with regard to an axis of the threaded joint at an angle between 5 and 30 degrees.

12. A threaded joint according to claim 1 , wherein the slope of the sub shoulder surfaces is greater than the slope of the sealing surfaces.

13. A threaded joint according to claim 1 , wherein a main part of the nose portion of the pin is in a clearance fit with the facing portion of the box with a minimum clearance fit value of 0.1 mm.

14. A threaded joint according to claim 1 , wherein the slope of the sealing surface of the box, the inner surface of the portion of the box facing the outside surface of the nose portion of the pin, and the sub shoulder surface of the box is monotonic.

15. A threaded joint according to claim 1 , wherein the pin comprises a rounded apex between the sub shoulder surface and the main shoulder surface, with a radius lower than 1.5 mm.

16. A threaded joint according to claim 1 , wherein one of the sealing surface of the pin and of the sealing surface of the box is a frusto-conical surface and the other sealing surface is selected from the group consisting of a torical surface having a radius of curvature larger than 20 mm and a combination of the said torical surface and a frusto-conical surface.

17. A threaded joint according to claim 1 , wherein both sub shoulder surfaces of pin and box are frusto-conical surfaces.

18. A threaded joint according to claim 1 , wherein a thickness of the main shoulder surface of the pin is at least 1.5 times greater than a thickness of the sub shoulder surface of the pin.

19. A threaded joint according to claim 1 , wherein the outside peripheral surface of the nose portion of the pin and the inner surface of the portion of the box facing said the nose portion of the pin have substantially cylindrical shape.

20. A threaded joint according to claim 1 , wherein the outside peripheral surface of the nose portion of the pin and the inner surface of the portion of the box facing said the nose portion of the pin have substantially frusto-conical shape, the taper angle is less than 10 degrees.

21. A threaded joint according to claim 1 , wherein the shoulder surface of at least one member of the pin and box has at least one groove which extends from the space between the nose portion of the pin and the portion of the box opposing the nose portion to the interior space of the threaded joint.

22. A threaded joint according to claim 21 , wherein the groove comprises a first groove portion formed on the sub shoulder surface and a second groove portion formed on the main shoulder surface which directly communicates with the first groove portion at the interface between the sub shoulder surface and the main shoulder surfaces.

23. A threaded joint according to claim 21 , wherein the groove comprises a first groove po

Assignees

• Yamaguchi Suguru
• Nakamura Keiichi
• Sugino Masaaki
• Iwamoto Michihiko
• Briquet Gabriel
• Patureau Claire
• Daly Daly
• Maillon Bertrand
• Beigneux Sylvain
• Nippon Steel & Sumitomo Metal Corp
• Vallourec Oil & Gas France

Inventors

• Yamaguchi Suguru
• Nakamura Keiichi
• Sugino Masaaki
• Iwamoto Michihiko
• Briquet Gabriel
• Patureau Claire
• Daly Daly
• Maillon Bertrand
• Beigneux Sylvain

Classifications

• F16L15/004 Primary

  with axial sealings having at least one plastically deformable sealing surface (with sealing rings F16L15/003) · CPC title

• E21B17/08

  Casing joints · CPC title

• F16L15/06

  characterised by the shape of the screw-thread · CPC title

• E21B17/042

  Threaded · CPC title