OIL WELL STEEL PIPE WITH THREADED CONNECTION, METHOD FOR PRODUCING OIL WELL STEEL PIPES CONNECTED BODY USING OIL WELL STEEL PIPE WITH THREADED CONNECTION, AND METHOD FOR PRODUCING OIL WELL STEEL PIPE WITH THREADED CONNECTION

20240200410

18/555581

April 28, 2022

This invention provides an oil well steel pipe with a threaded connection with which excellent galling resistance is obtained without using a compound grease, and which can suppress the occurrence of rust on a pin contact surface and can also keep shouldering torque at a low level. An oil well steel pipe with a threaded connection of the present disclosure includes a pipe main body including a first end portion and a second end portion. The pipe main body includes a pin formed at the first end portion, and a box formed at the second end portion. A light oil is applied to a pin contact surface of the pin. A solid lubricant coating is formed on a box contact surface of the box.

1. An oil well steel pipe with a threaded connection that is fastenable to another oil well steel pipe with a threaded connection, comprising: a pipe main body including a first end portion and a second end portion, wherein: the pipe main body includes: a pin formed at the first end portion, wherein, during fastening, the pin is inserted into a box of the other oil well steel pipe with a threaded connection and is fastened to the box of the other oil well steel pipe with a threaded connection, and a box formed at the second end portion, wherein, during the fastening, a pin of the other oil well steel pipe with a threaded connection is inserted into the box, and the box is fastened to the pin of the other oil well steel pipe with a threaded connection; the pin includes: a pin contact surface which at least includes an external thread part formed on an outer peripheral surface of the first end portion of the pipe main body and which, during the fastening, contacts the box of the other oil well steel pipe with a threaded connection; a light oil is applied to the pin contact surface; and the box includes: a box contact surface which at least includes an internal thread part formed on an inner peripheral surface of the second end portion of the pipe main body and which, during the fastening, contacts the pin contact surface of the pin of the other oil well steel pipe with a threaded connection, and a solid lubricant coating formed on or over the box contact surface.

2. The oil well steel pipe with a threaded connection according to claim 1, wherein: the pin contact surface further includes: a pin sealing surface that is formed further on a front end side than the external thread part on the outer peripheral surface of the first end portion, and a pin shoulder surface provided at a front end of the first end portion; and the box contact surface further includes: a box sealing surface that is formed further on a front end side than the internal thread part on the inner peripheral surface of the first end portion, and a box shoulder surface provided at a front end of the second end portion.

3. The oil well steel pipe with a threaded connection according to claim 1, wherein: the pin further includes: a chemical treatment coating formed on the pin contact surface; and the light oil is applied onto the chemical treatment coating.

4. The oil well steel pipe with a threaded connection according to claim 3, wherein: in a chemical composition of the oil well steel pipe with a threaded connection, a content of Cr is, in mass %, 2.0% or less.

5. The oil well steel pipe with a threaded connection according to claim 1, wherein: the box further includes: a plating coating formed on the box contact surface; and the solid lubricant coating is formed on the plating coating.

6. An oil well steel pipe with a threaded connection, comprising: a pipe main body including a first end portion and a second end portion, wherein: the pipe main body includes: a pin formed at the first end portion, and a box formed at the second end portion; the pin includes: a pin contact surface which at least includes an external thread part formed on an outer peripheral surface of the first end portion of the pipe main body; an anti-rust grease is applied to the pin contact surface; and the box includes: a box contact surface which at least includes an internal thread part formed on an inner peripheral surface of the second end portion of the pipe main body, and a solid lubricant coating formed on or over the box contact surface.

7. The oil well steel pipe with a threaded connection according to claim 6, wherein: the pin contact surface further includes: a pin sealing surface that is formed further on a front end side than the external thread part on the outer peripheral surface of the first end portion, and a pin shoulder surface provided at a front end of the first end portion; and the box contact surface further includes: a box sealing surface that is formed further on a front end side than the internal thread part on the inner peripheral surface of the first end portion, and a box shoulder surface provided at a front end of the second end portion.

8. The oil well steel pipe with a threaded connection according to claim 6, wherein: the pin further includes: a chemical treatment coating formed on the pin contact surface; and the anti-rust grease is applied onto the chemical treatment coating.

9. The oil well steel pipe with a threaded connection according to claim 8, wherein: in a chemical composition of the oil well steel pipe with a threaded connection, a content of Cr is, in mass %, 2.0% or less.

10. The oil well steel pipe with a threaded connection according to claim 6, wherein: the box further includes: a plating coating formed on the box contact surface; and the solid lubricant coating is formed on the plating coating.

11. The oil well steel pipe with a threaded connection according to claim 6, further comprising: a protector that is capped over and fastened to the pin; wherein: the protector includes: a tubular part in which an internal thread is formed on an inner peripheral surface, and a cap part disposed at one end of the tubular part; a distance D1 between a thread ridge of the external thread of the pin and a thread root of the internal thread of the tubular part of the protector is longer than a distance D2 between a thread root of the external thread of the pin and a thread ridge of the internal thread of the tubular part of the protector; and a thickness T1 of the anti-rust grease between the thread ridge of the external thread of the pin and the thread root of the internal thread of the tubular part of the protector is thicker than a thickness T2 of the anti-rust grease between the thread root of the external thread of the pin and the thread ridge of the internal thread of the tubular part of the protector.

12. A method for producing oil well steel pipes connected body in which a plurality of oil well steel pipes with a threaded connection are fastened together, comprising: an oil well steel pipe preparation process of preparing an oil well steel pipe with a threaded connection; wherein: the oil well steel pipe with a threaded connection comprises: a pipe main body including a first end portion and a second end portion; the pipe main body includes: a pin formed at the first end portion, and a box formed at the second end portion; the pin includes: a pin contact surface which at least has an external thread part formed on an outer peripheral surface of the first end portion of the pipe main body; an anti-rust grease is applied to the pin contact surface; and the box includes: a box contact surface which at least includes an internal thread part formed on an inner peripheral surface of the second end portion of the pipe main body, and a solid lubricant coating formed on or over the box contact surface; the method for producing oil well steel pipes connected body further comprising: a process of transporting the oil well steel pipe with a threaded connection to a local yard that is a place for temporarily storing the oil well steel pipe with a threaded connection, a process of temporarily storing the oil well steel pipe with a threaded connection transported to the local yard, at the local yard, a process of, before delivering the oil well steel pipe with a threaded connection that is temporarily stored at the local yard to an oil well drilling site at which the oil well steel pipes connected body is to be formed, removing the anti-rust grease applied to the pin contact surface of the oil well steel pipe with a threaded connection, and applying a light oil to the pin contact surface from which the anti-rust grease is removed, a process of delivering the oil well steel pipe with a threaded connection having the light oil applied to the pin contact surface to the oil well drilling site, and a process of, at the oil well drilling site, fastening the oil well steel pipe with a threaded connection having the light oil applied to the pin contact surface to another oil well steel pipe with a threaded connection to form oil well steel pipes connected body.

13. A method for producing an oil well steel pipe with a threaded connection, comprising: a process of temporarily storing, at a local yard, an oil well steel pipe with a threaded connection delivered to the local yard, wherein: the oil well steel pipe with a threaded connection comprises: a pipe main body including a first end portion and a second end portion; the pipe main body includes: a pin formed at the first end portion, and a box formed at the second end portion; the pin includes: a pin contact surface which at least has an external thread part formed on an outer peripheral surface of the first end portion of the pipe main body; an anti-rust grease is applied to the pin contact surface; and the box includes: a box contact surface which at least has an internal thread part formed on an inner peripheral surface of the second end portion of the pipe main body, and a solid lubricant coating formed on the box contact surface; the method for producing an oil well steel pipe with a threaded connection further comprising: a process of, before delivering the oil well steel pipe with a threaded connection that is temporarily stored at the local yard to an oil well drilling site at which oil well steel pipes connected body is to be formed, removing the anti-rust grease applied to the pin contact surface of the oil well steel pipe with a threaded connection, and applying a light oil to the pin contact surface from which the anti-rust grease is removed.

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edspap.20240200410