Balanced thread form, tubulars employing the same, and methods relating thereto

Patent metadata

Field	Value
Publication number	US-10041307-B2
Application number	US-201514602947-A
Country	US
Kind code	B2
Filing date	Jan 22, 2015
Priority date	Jan 22, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A tubular member has a longitudinal axis, a first end, and a second end. The tubular member includes a pin connector including an external shoulder, an internal shoulder axially spaced from the external shoulder, and a plurality of threads in a region between the external shoulder and the internal shoulder that taper relative to the longitudinal axis at 1.0 to 1.5 inches per foot. The threads include an axial density measured in a number of threads per inch (TPI), and when the pin connector is threadably engaged with a box connector, each of the threads contacts a corresponding box thread on the box connector along a projected radial distance HC. In addition, the threads are configured such that the product of 2(√{square root over (3)})(HC)(TPI) is greater than or equal to 0.95 and less than or equal to 1.05.

First claim

What is claimed is:

1. A tubular member having a longitudinal axis, a first end, a second end opposite the first end, and comprising:
a first threaded box connector disposed at the first end;
a first threaded pin connector disposed at the second end, wherein the first pin connector includes:
a pin external shoulder configured to engage a box external shoulder on a second threaded box connector of another tubular member when the pin connector is threadably engaged with the second box connector;
a pin internal shoulder axially spaced from the pin external shoulder, wherein the pin internal shoulder is configured to engage with a box internal shoulder on the second box connector when the pin connector is threadably engaged with the second box connector; and
a plurality of threads in a region between the pin external shoulder and the pin internal shoulder that taper relative to the longitudinal axis at 1.0 to 1.5 inches per foot, wherein each of the plurality of threads includes:
a crest;
a root disposed radially inward from the crest;
a stab flank extending between the crest and the root; and
a load flank extending between the crest and the root, wherein the stab flank is more proximate the pin internal shoulder than the load flank;
wherein the plurality of threads has an axial density measured in a number of threads per inch (TPI);
wherein when the pin connector is threadably engaged with the second box connector, each of the plurality threads on the threaded pin connector contacts a corresponding box thread on the second box connector along a projected radial distance H C measured in inches along the load flank; and
wherein the plurality of threads are configured such that the product of 2(√{square root over (3)})(H C )(TPI) is greater than or equal to 0.95 and less than or equal to 1.05.

2. The tubular member of claim 1 , wherein each of the threads further includes:
a first radius extending between the crest and the stab flank and having a first radius of curvature; and
a second radius extending between the crest and the load flank and having a second radius of curvature;
wherein the first radius of curvature is larger than the second radius of curvature.

3. The tubular member of claim 2 , wherein the first radius of curvature is at least four times larger than the second radius of curvature.

4. The tubular member claim 3 , wherein the first radius of curvature is 0.065 in, and wherein the second radius of curvature is 0.015 in.

5. The tubular member of claim 1 , wherein the stab flank on each of the threads is oriented at a first angle α relative to a radius of the longitudinal axis, and wherein the load flank of each of the threads is oriented at a second angle β relative to the radius, wherein α is equal β.

6. The tubular member of claim 1 , wherein the stab flank on each of the threads is oriented at a first angle α relative to a radius of the longitudinal axis, and wherein the load flank of each of the threads is oriented at a second angle β relative to the radius, wherein α is larger than β.

7. The tubular member of claim 6 , wherein α is equal to 45° and β is equal to 30°.

8. The tubular member of claim 7 , wherein the root of each of the threads has an elliptical curvature when viewed in cross-section along the longitudinal axis.

9. The threaded pin connector of claim 1 , wherein the plurality of threads taper relative to the longitudinal axis at 1.2 to 1.3 inches per foot.

10. A method for manufacturing a tubular member including a longitudinal axis, a first end, and a second end opposite the first end, the method comprising:
(a) forming a threaded pin connector on the first end of the tubular member, wherein the threaded pin connector includes a pin external shoulder and a pin internal shoulder axially spaced from the pin external shoulder;
(b) forming a threaded box connector on the second end of the tubular member, wherein the threaded box connector includes a box external shoulder and a box internal shoulder axially spaced from the box external shoulder; and
(c) forming a plurality of pin threads along the pin member in a region between the pin external shoulder and the pin internal shoulder and a plurality of box threads along the box member in a region between the box external shoulder and the box internal shoulder, wherein the pin threads and the box threads each taper relative to the longitudinal axis at 1.0 to 1.5 inches per foot, and wherein the plurality of the pin threads and the plurality of box threads have an axial density measured in a number of threads per inch (TPI), and wherein each of the plurality of pin threads and each of the plurality of box threads includes:
a crest;
a root;
a stab flank extending between the crest and the root; and
a load flank extending between the crest and the root, wherein the stab flank on each pin thread is more proximate the pin internal shoulder than the load flank on the pin thread, and wherein the stab flank on each box thread is more proximate the box external shoulder than load flank on the box thread;
wherein when the pin member is threadably engaged with a box member on another tubular member, each of the plurality of pin threads contacts a corresponding box thread along a projected radial distance H C along the load flank;
wherein when the box member is threadably engaged with a pin member on a another tubular member, each of the plurality of box threads contacts a corresponding pin thread along the projected radial distance H C measured in inches along the load flank; and
wherein the plurality of pin threads and box threads are configured such that the product of 2(√{square root over (3)})(H C )(TPI) for the pin threads and the box threads is greater than or equal to 0.95 and less than or equal to 1.05.

11. The method of claim 10 , further comprising:
(d) forming a first radius having a first radius of curvature between the crest and the stab flank of each of the plurality of pin threads and each of the plurality of box threads; and
(e) forming a second radius having a second radius of curvature between the crest and the load flank of each of the plurality of pin threads and each of the plurality of box threads, wherein the first radius of curvature is larger than the second radius of curvature.

12. The method of claim 10 , wherein (c) further comprises:
(c1) forming the stab flank of each of the plurality of pin threads and each of the plurality of box threads at an angle α relative to a radius of the longitudinal axis; and
(c2) forming the load flank of each of the plurality of pin threads and each of the plurality of box threads at an angle β relative to the radius, wherein the angle α is larger than the angle β.

13. The method of claim 10 , wherein (c) further comprises:
(c1) forming the stab flank of each of the plurality of pin threads and each of the plurality of box threads at an angle α relative to a radius of the longitudinal axis; and
(c2) forming the load flank of each of the plurality of pin threads and each of the plurality of box threads at an angle β relative to the radius, wherein the angle α is equal to the angle β.

14. The method of claim 10 , further comprising:
(d) forming an elliptical curvature for the root of each of the plurality of pin threads and for the root of each of the plurality of box threads.

15. The method of claim 10 , wherein (c) comprises forming the plurality of pin threads and the plurality of box threads to have a TPI of 3.5 and an H C of 0.0830 in.

16. The method of claim 10 , wherein (c) comprises forming the plurality of pin threads and th

Assignees

• Nat Oilwell Varco Lp

Inventors

• Muradov Andrei
• Jellison Michael Joseph

Classifications

• E21B17/042 Primary

  Threaded · CPC title

• F16L15/001

  with conical threads · CPC title