JP2584495Y2 - Pipe fittings for oil country tubular goods with excellent external pressure resistance - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint for oil country tubular goods having improved external pressure resistance.

[0002]

2. Description of the Related Art With the recent severe environment of oil and gas well development, whether or not an oil well pipe assembled as one well by a pipe joint can be used for a long period of time depends on the performance of the pipe joint (particularly airtightness). ). Therefore, there is a strong demand for improving the performance (airtightness) of special joints provided with metal-to-metal contact sealing surfaces, which have been increasing in recent years.

[0003]

[Problems to be solved by the invention] By the way, the conventional metal
Special joints provided with a sealing surface where metal and metal are in contact have been studied to withstand internal pressure, but little consideration has been given to external pressure. However, actually, not only the internal pressure but also the external pressure acts on the oil country tubular good. Therefore, when an external pressure acts on such a special joint, there is a problem that the sealing portion of the pin is deformed toward the inner peripheral surface side, whereby airtightness cannot be maintained and oil or gas leakage occurs.

The present invention has been made in view of the above-mentioned problems. Even when an external pressure is applied, the sealing portion is not deformed and has excellent external pressure resistance which can maintain airtightness. It is intended to provide a pipe joint for oil country tubular goods.

[0005]

In order to achieve the above object, a pipe joint for oil country tubular good having excellent external pressure resistance according to the present invention is provided with a box having a female thread on the inner peripheral surface at the distal end and the outer peripheral surface on the distal end side. in oil well pipe fitting comprising a pin having a male thread to be screwed into the female screw, after extending the front end side of the male screw of the pin, the upper surface in the thickness direction of the external thread
A recess having a slope of downward slope toward the direction provided, further to form a inclined surface of the required downward slope on its front end side, the inner part from the female screw of the box, at the time of screw tightening,
Along with providing a similar extension forming an oil reservoir with the extension of the pin, and at the back thereof, a convex portion having a downwardly inclined surface in which metals are closely attached to the upper inclined surface of the concave portion, The inclined surface of the downward slope and the inclined surface of the same downward slope where the metals are in close contact with each other are formed, and the gap between the female screw and the external thread screwed to the female screw is set to 0 over the entire length of the screw portion. It is.

[0006]

The pipe joint for oil country tubular goods according to the present invention has two stages (two places) of seal portions for maintaining airtightness, and the metal formed by the thick and thick concave and convex portions having a large thickness. But dense
The attached first seal portion is designed to withstand external pressure. Further, in the present invention, since the gap between the male thread of the pin and the female thread of the box is zero over the entire length of the thread part, even if a strong pulling force or compressive force is applied, the entire thread is formed.
The force is evenly distributed, and the threads are not crushed, so that play between the threads can be prevented.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a joint for an oil country tubular good according to the present invention. FIG. 1 is a cross-sectional view showing a main part of the pipe joint for an oil country tubular good of the present invention, FIG. 2 is a drawing showing a thread shape of FIG. 1, and FIG. It is a figure showing the adhesion state of the 1st seal part formed.

In FIG. 1, reference numeral 1 denotes a box, 2 denotes a pin, and a female screw 1a is provided on the inner peripheral surface of the distal end portion of the box 1, and a male screw 2a is provided on an outer peripheral surface of the distal end side of the pin 2.
The box 1 and the pin 2 are connected by the screwing of the female screw 1a and the male screw 2a. By the way, these boxes 1
As shown in FIG. 2, the thread shape of the screw provided on the pin 2 is, for example, a quadrilateral and one of the flank angles is negative. Therefore, even when a strong pulling force or compressive force acts, the force is evenly distributed to all the threads, so that the threads are not crushed. The female screw 1a and the male screw 2a
Is zero over the entire length of the thread. Therefore, in combination with the above-mentioned thread shape, even if a strong pulling force or compressive force acts, no looseness occurs between the threads.

The pin 2 extends from the male screw 2a on the distal end side to provide a recess 2b in the thickness direction, and further has a required inclined surface 2c with a required downward slope on the distal end side.
Is formed. The upper surface of the concave portion 2b has a downward slope in a direction opposite to the inclined surface 2c.

An extension 1b for forming an oil reservoir 3 together with the extension 2d of the pin 2 at the time of screwing is provided at a portion deeper than the female screw 1a of the box 1,
Further, as shown in FIG.
A convex portion 1c having a similar downward slope in which metals are closely attached to the upper inclined surface of
An inclined surface 1d having the same downward slope where c and the metal are in close contact with each other is formed.

That is, the first sealing portion is formed by the inclined surface of the convex portion 1c of the box 1 and the inclined surface of the concave portion 2b of the pin 2, and the inclined surface 1d of the box 1 and the inclined surface 2 of the pin 2 are formed.
the second seal portion is formed by is c, Contact to the both seal portions
While maintaining airtightness by the close contact of
In particular, the first seal portion is designed to withstand external pressure.

[0012]

[Effects of the Invention] As described above, since the oil well pipe joint of the present invention is configured, even if a strong external pressure is applied, the seal portion of the pin and the thread of the threaded portion are not deformed. In addition, there is no play between the threads. Therefore, the airtightness can be favorably maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a pipe joint for an oil country tubular good of the present invention.

FIG. 2 is a drawing showing the thread form of FIG. 1;

FIG. 3 is a drawing showing a state of close contact of a first seal portion formed by a concave portion provided on a pin and a convex portion provided on a box.

[Explanation of symbols]

 1 Box 1a Female screw 1b Extension 1c Convex 1d Inclined surface 2 Pin 2a Male screw 2b Concave 2c Inclined surface 2d Extension 3 Oil sump

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shoji Yakugawa 1850 Minato, Wakayama-shi, Wakayama Sumitomo Metal Industries, Ltd. Wakayama Works (56) References JP-A-1-288693 (JP, A) -158887 (JP, U) JP 2-33835 (JP, B2) JP 61-501411 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16L 15/00- 15/04

Claims (1)

(57) [Scope of request for utility model registration] And 1. A box having a female thread in the distal end portion peripheral surface, the oil well pipe fitting comprising a pin having a male thread screwed into the female thread on the distal end side outer peripheral surface, the tip than males <br/> threaded pin side after extended, upper surface before its thickness direction
A recess having a slope of downward slope toward the direction of the serial external thread provided, further to form a inclined surface of the required downward slope on its front end side, the inner part from the female screw of the box, at the time of screw tightening, the extension of the pin Along with providing a similar extension forming an oil sump portion, and at the back thereof, a convex portion having a downwardly inclined surface in which metals are in close contact with the upper inclined surface of the concave portion, Inclined surface and metal
Judges is to form the inclined surface of the same downward slope close contact,
A pipe joint for an oil country tubular good having excellent external pressure resistance, wherein a gap between the female screw and a male screw engaged with the female screw is set to zero over the entire length of the screw portion.