Expandable threaded connection
View Patent ↗Tubular connections and methods of designing tubular connections having selected root/crest clearance when the box member and pin member are made-up. When the tubular connection is radially expanded, a thread seal is formed over at least part of the tubular connection.
1. An expandable tubular connection comprising:
a pin member having a pin thread, wherein the pin thread comprises a pin thread crest, a pin load flank and a pin stab flank, and a pin thread root;
a box member having a box thread, wherein the box thread comprises a box thread crest, a box load flank and a box stab flank, and a box thread root,
wherein the pin thread and the box thread are wedge threads, such that upon selected make-up of the pin member with the box member:
a selected gap exists between the pin thread crest and the box thread root and the pin thread root and the box thread crest; and
the load and stab flanks of the pin and box threads are in interference;
wherein upon plastic radial expansion of the selectively made-up tubular connection by a selected percentage, the selected gap becomes a selected interference; and
wherein the selected interference results in a thread seal over substantially all of the expanded tubular connection.
2. The expandable tubular connection of claim 1 , wherein the selected gap is from about 0.001 inches to about 0.010 inches.
3. The expandable tubular connection of claim 2 , wherein the selected gap is from about 0.001 inches to about 0.004 inches.
4. The expandable tubular connection of claim 1 , wherein the wedge threads have a generally dovetailed shape.
5. The expandable tubular connection of claim 1 , wherein the wedge threads have an open thread form.
6. The expandable tubular connection of claim 1 , wherein a helical groove is formed on an outer surface of the box member substantially in lead with the box thread root.
7. The expandable tubular connection of claim 1 , wherein a helical groove is formed on an inner surface of the pin member substantially in lead with the pin thread root.
8. The expandable tubular connection of claim 1 , wherein a thread root groove is formed in one of the pin member and the box member.
9. The expandable tubular connection of claim 1 , wherein the resulting thread seal is the only seal mechanism between the pin member and the box member.
10. The expandable tubular connection of claim 1 , wherein prior to plastic radial expansion, the selected gap occurs across an entire length of the pin and box threads.
11. A method of designing a tubular having a connection with a pin member and a box member, the method comprising:
determining an amount of radial expansion and a method for radially expanding the tubular; and
selecting a gap size between a box thread crest and a pin thread root based on the amount of radial expansion and the method for radially expanding the tubular, wherein the gap exists upon selected make-up of the box member with the pin member,
wherein a root/crest thread seal is formed between the box member and pin member after a radial expansion thereof.
12. A method of expanding a connection with a pin member and a box member, the method comprising:
making-up the pin member with the box member such that a selected gap exists between a box thread crest and a pin thread root; and
expanding the connection such that there is a desired interference between the box thread crest and the pin thread root forming a thread seal over a portion of the connection.
13. A method of expanding a connection with a pin member and a box member, the method comprising:
making-up the pin member with the box member such that a selected gap exists between a box thread root and a pin thread crest; and
expanding the connection such that there is a desired interference between the box thread root and the pin thread crest forming a thread seal over a portion of the connection.