| CPC E21B 17/0423 (2013.01) | 20 Claims |
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1. A pipe assembly, comprising:
a first pipe comprising a first external thread and a first annular lip residing between the first external thread and a rim of the first pipe, the first external thread comprising a load flank slanted such that an edge between the load flank and a crest of the first external thread overhangs a root of the first external thread, the first annular lip comprising a first external seal surface and a first internal annular beveled surface, the first external thread comprising a first shoulder residing along the first external thread;
a second pipe comprising a second external thread and a second annular lip residing between the second external thread and a rim of the second pipe, the second annular lip comprising a second external seal surface and a second internal annular beveled surface, the second external thread comprising a second shoulder residing along the second external thread; and
a collar configured to be disposed between and threadedly coupled to the first pipe and the second pipe to form a coupling connection, the collar comprising a first internal thread configured to be threadedly coupled to the first external thread and a second internal thread configured to be threadedly coupled to the second internal thread, the collar comprising a bore residing between the first internal thread and the second internal thread and configured to contact, with the coupling connection formed, the first external seal surface and the second external seal surface to form respective metal-to-metal seals that are energized under fluid pressure at the first and second internal annular beveled surfaces to increase a contact pressure of the respective metal-to-metal seals,
wherein the first and second internal threads of the collar each comprises respective internal shoulders configured to bear against the first and second shoulders of the first and second pipes.
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