Threaded connection for steel pipe

Patent metadata

Field	Value
Publication number	US-2022010894-A1
Application number	US-201917294474-A
Country	US
Kind code	A1
Filing date	Dec 20, 2019
Priority date	Dec 25, 2018
Publication date	Jan 13, 2022
Grant date	—

Abstract

A threaded connection for steel pipe is provided in which galling does not easily occur on any of the inner and outer threads. A threaded connection for steel pipe 1 includes a pin 10 and a box 20. The pin 10 includes: a nose 12; a tapered inner male thread 14; a tapered outer male thread 17; a pin inner sealing surface 13; a pin intermediate shoulder surface 18; and a pin intermediate sealing surface 16. The box 20 includes: a tapered inner female thread 24; a tapered outer female thread 27; a box inner sealing surface 23; a box intermediate shoulder surface 28; and a box intermediate sealing surface 26. Each of the inner male thread 14, outer male thread 17, inner female thread 24 and outer female thread 27 includes a perfect thread portion 141, 171, 241, 271. Each perfect thread portion includes an inner end located relatively close to the tip of the pin 10 and an outer end located relatively close to the end of the pin 10 opposite to its tip. The threaded connection for steel pipe 1 satisfies the following Expressions (1) and (2):x1+L1<X2  (1), andu1+L2<U2  (2).

First claim

1 . A threaded connection for steel pipe, comprising:
a tubular pin; and a tubular box, the pin being screwed into the box such that the pin and the box are made up, the pin including: a tapered inner male thread provided on an outer periphery of the pin and located relatively close to a tip of the pin; a tapered outer male thread provided on the outer periphery of the pin and located relatively close to an end of the pin opposite to the tip; and a pin intermediate shoulder surface located between the inner male thread and the outer male thread, the box including: a tapered inner female thread provided on an inner periphery of the box to correspond to the inner male thread; a tapered outer female thread provided on the inner periphery of the box to correspond to the outer male thread; and a box intermediate shoulder surface facing the pin intermediate shoulder surface, the box intermediate shoulder surface being in contact with the pin intermediate shoulder surface when the pin and the box are made up, wherein each of the inner male thread, the outer male thread, the inner female thread and the outer female thread includes a perfect thread portion, and each of the perfect thread portions includes an inner end located relatively close to the tip of the pin and an outer end located relatively close to the end of the pin opposite to the tip, the pin and the box, when made up, have a longitudinal cross section containing an axis of the steel pipe, and an orthogonal coordinate system introduced in the longitudinal cross section has an x-axis represented by the axis of the steel pipe, a y-axis represented by a radius of the steel pipe, and an origin (0,0) represented by an intersection of a plane containing the pin intermediate shoulder surface and the box intermediate shoulder surface, on one hand, and the axis of the steel pipe, on the other hand, and the threaded connection satisfies the following expressions, Expressions (1) and (2):
x 1 +L 1 <X 2   (1), and

u 1 +L 2 <U 2   (2),

where, in Expressions (1) and (2),

L
1

=

(

β
pi

-

β
bi

)

α
pi

,

⁢

L
2

=

(

β
po

-

β
bo

)

α
po

,

⁢

α
pi

=

y
2

-

y
1

x
2

-

x
1

,

⁢

α
po

=

v
2

-

v
1

u
2

-

u
1

,

⁢

β
pi

=

-

x
1

⁢

y
2

+

x
2

⁢

y
1

x
2

-

x
1

,

⁢

β
po

=

-

u
1

⁢

v
2

+

u
2

⁢

v
1

u
2

-

u
1

,

⁢

β
bi

=

-

X
1

⁢

Y

Assignees

• Nippon Steel Corp
• Vallourec Oil & Gas France

Inventors

• Inose Keita
• Nakano Hikari
• Sugino Masaaki

Classifications

• E21B17/0423

  with plural threaded sections, e.g. with two-step threads · CPC title

• F16L15/002 Primary

  with more than one threaded section · CPC title

• F16L15/04 Primary

  with additional sealings · CPC title