THREADED CONNECTION FOR STEEL PIPE

摘要

A threaded connection for a steel pipe includes a box which is an opening end of a second pipe and a truncated cone shaped pin which is an end of a first pipe and is inserted into the box, wherein the pin includes a male thread portion which is a tapered thread and a seal portion which includes a tapered surface, the box includes a female thread portion which is a tapered thread and a seal portion which includes a tapered surface, and in a state before make-up between the pin and the box, a minimum diameter of the tapered surface of the pin is smaller than a maximum diameter of the tapered surface of the box.

主权项

1. A threaded connection for a steel pipe, which connects a first pipe and a second pipe, the threaded connection comprising:
a box which is an opening end of the second pipe; and a truncated cone shaped pin which is an end of the first pipe and is inserted into the box, wherein the pin includes a male thread portion which is a tapered thread, and a seal portion which includes a tapered surface, and the box includes a female thread portion which is a tapered thread, and a seal portion which includes a tapered surface, and wherein when the male thread portion and the female thread portion are made-up by screwing, a root of the male thread portion and a crest of the female thread portion come into contact with each other after the seal portion of the pin and the seal portion of the box come into contact with each other, in a process of the make-up, and in a state before the make-up, a minimum diameter of the tapered surface of the pin is smaller than a maximum diameter of the tapered surface of the box.