JPS60220283A - Pipe joint, which resist high pressure and in which galling is not generated - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pipe joint, and particularly to a pipe joint used in the petroleum industry, which can withstand high pressure and does not cause galling.

(Prior Art and Problems) In recent years, there has been a trend for oil well drilling to become deeper and deeper, and as the wells become deeper, large axial forces and internal pressures are applied to oil country tubular goods. Therefore, the casing used for such wells,
The tubing is under a large axial force and requires a structure that prevents internal gas leaks. - When using a gas knife that contains a lot of hydrogen, don't use steel pipe fittings! ]! Specially designed joints are used.

Conventional joint 1 (, r, sole part butt ゎ-I
There are two methods: one method is to suppress leaks through one metal-to-metal touch, and the other is to suppress leaks by metal root touch by rubbing. The sliding seal method has the advantage that the seal +II is not damaged even under axial force action 1. 1) Komei No. 52-11764 discloses a joint in which the sealing surface and the box-side surface have the same taper in the sealing part.

FIG. 1(a) It is a fitting with a tapered thread.
An example of a joint that connects I-I is schematically shown.
It is made larger than the inner diameter of the threaded part, so when tightened,
The outer diameter of the bottle 2 is tightened, and the inner diameter of the box is swollen.When tightening is completed, the two deform in the direction of the arrow as shown in Figure 1 (1), and the forces are balanced. However, in reality, the sliding stop surface 4 at the tip of the bottle 2.!:
When the sealing surface 3 of the opposing box 1 is tightened, the shape of the tip 5 deforms into a concave shape as shown in FIG. Yoshi can't do it. That is,
If the sealing surfaces have the same taper, especially if the thickness-to-diameter ratio is small, the tips of the pins may become uncontacted as shown in Figure 2 (a) and f, causing internal pressure. When loading 1,
Fluid enters the uncontacted area, and under high pressure, the uncontacted area expands, generating high surface pressure at the rear end of the sealing surface, making the sealing performance unstable.

On the other hand, JP-A-58-152994 proposes a joint with a different taper between a bottle and a box. However, in such cases, although the sealing performance is improved, the blood pressure at the boundary of the sealing surface becomes uneven, as shown in Figure 2 (b), and there is generally a high surface pressure at the tip or rear end of the sealing surface. This may be undesirable from the viewpoint of galling resistance, that is, seizure resistance.

(Object of the Invention) The present invention improves the 11-line sealing method such as C, and devises so as to provide a substantially uniform and low 10-line seal on the top surface of the cut. 1 month, negative -1f hour 1 hour' LJ city, the blood pressure that occurs increases due to the self-containment effect, suppresses the 11. glue, and even if the force is 1 cry, the pressure is adjusted HHB
4.1. A joint that reduces low I during bending due to movement and pin springback, and has good galling resistance. IIj
The purpose is to provide

(Structure of the Invention) That is, the gist of the present invention is that in the pipe joint tip seal portion having a sealing surface of -χ·1, one or each of the stopping surfaces has a curvature of 300 to 1000+Il+11. There is a pipe joint that is characterized by being processed into a curved surface that can withstand high pressure and does not cause galling.

The present invention will be explained in detail below.

1. In the first aspect of the present invention, the main point is that one or each of the pair of stopping surfaces of the pipe joint tip nA seal portion is processed into a curved surface. In this case, the curved surface is a spherical or spheroidal shape.

Alternatively, it refers to a curved surface with a fairly large radius of curvature formed by rotation of a curve such as a parabola.The radius of curvature refers to a sealing surface.These curved surfaces to be processed can be approximated to a spheroidal shape. It refers to the radius of curvature that is considered and displayed. It is appropriate that the radius of curvature is in the range of 300 to 1000 W+; if it is less than 1 m, the tip of the seal portion will not come into close contact.

On the other hand, if the thickness exceeds 10 (10 tm), the seal part cannot be made to adhere uniformly, and the result will be the same as in the case of the straight line <-, so the effect of the present invention cannot be exhibited in either case.Also, the curved surface may be provided on one of the sealing surfaces of the bottle or the box, or one of both may be provided, but if curved surfaces are provided on both, the sealing surface during tightening may be Care should be taken to process the shape so that the deformation is shared between the pin sealing surface and the box sealing surface.

1f In this case, one of the sealing surfaces is processed to have a curvature, and the other is made into a normal conical shape. It is a good idea to vary the difference between the inner diameter of the box sealing surface and the inner diameter of the box sealing surface, and make the cross-section margin slightly larger at the leading end of the stopping surface and slightly smaller at the rear end. In this way, it is possible to fit the pin by taking into account the deformation of the pin sealing surface when tightening it, and even if the blood pressure is low, it is possible to apply a uniform force, and it is possible to automatically apply the force at high pressure F. It is expected to have a stress effect and a galling prevention effect. Also, the curvature 'l'
ff f, L The larger the wall thickness-to-diameter ratio of the tube, the better it is to have a larger value. The reason for this is that when the wall thickness v1 diameter ratio of the tube is large, the sealing surface at the tip of the bottle deforms little during tightening.1 Even if the radius of curvature is large, the sealing surfaces stick together uniformly. This is because when the diameter ratio is small, the deformation of the sealing surface at the tip of the inverted one-coat becomes large, so in order to uniformly bring the sealing surfaces into close contact with each other, it is necessary to keep the radius of curvature small.

To further specifically explain these relationships based on the drawings, FIG. 3 shows an example in which the present invention is applied to a joint having a tapered threaded portion. In the figure, 6 is a stop part and 7 is a Luxholter.The stop part 6 in the figure is enlarged to show details. It is.

First, in Fig. 4(a), the sealing surface 4 at the tip of the pin 2 is at an angle θ.
The sealing part 3 of the corresponding box 1 is finished with a radius of curvature R. Next, Figure 4 (,
Figure 4 (1) shows the shape of the sealing part after it is machined into the shape shown in a), the gamma joint 1 is attached, and the final tightening is performed. As shown in FIG. 1, the tip of the pin 2 is deformed in the direction of the arrow, and the sealing surfaces 3 and 4 are brought into close contact with each other with substantially uniform surface pressure.

1. In Fig. 5(a), contrary to the case in Fig. 4, the box l side has a conical sealing surface 3, and the pin 2 side is machined with a radius of curvature R to form a sealing f. Figure 1 shows a joint with surface 4. In this case, too, the final tightening is performed.
As shown in Figure (b), the sealing surfaces 3 and 4 are in close contact with each other, and a uniform surface pressure can be generated.

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples.

(Example) Test material 71φx 29 lb/ft (177,
8 simple φX I O, 36 simple t), API -N -80
Create a steel pipe joint of the type shown in Figure 3 using the material. Dimensions and shape (, [shown in Figure 6, where l = 4.0] m (
Bottle tip ☆; 1 sheet uniform thickness], length l = 7 m, θ
-5°, minimum fitting distance (1 = Q, l tan, maximum change value of fitting distance h = O, G as 5 pieces =
” = from t2/211, the internal pressure of the screw and sealing part was calculated as a contact problem using the finite element method computer program “J-gram”.
In the case of 5-5, the particles were distributed uniformly in the sealing part.

A make-up test was repeated 10 times using this joint, but no galling occurred.

After one more repetition, the internal pressure was 1000, and the axial force was 30 and 9/
, ), and the joints were sound with no leaks at all.

[Brief explanation of drawings]

Figures 1 (a) and (1)) are schematic diagrams showing a pipe joint with a stop surface of the same taper, and Figure 2 (a) is a schematic diagram showing the state of deformation of the tip of the joint shown in Figure 1. Figure, Figure 2 (1))
FIG. 3 is a schematic diagram showing the deformation state of a joint tip having a sealing surface with a different taper, FIG. 3 is a cross-sectional view of a joint having a tapered threaded portion, and FIG. 4(a). (1)) and Fig. 5 (aL (b) are schematic diagrams showing an embodiment of the joint of the present invention and the state of deformation of the tip portion at the time of final tightening. 1 is a diagram showing the dimensions and shape of a joint. 1... Box, 2... Pin, 3... Box sealing surface. 4... Pin sealing surface, 5... Pin tip, 6. ... Sealing portion. 7... Torque shoulder. Patent applicant Representative Patent attorney Tomoyuki Yafuki (and one other person) Fig. 1 (61) 2 (b) 3 /, L Fig. 6 1 /i ' 2 \ 2

Claims (1)

[Claims] A pipe joint end seal having a pair of sealing surfaces, one or each sealing surface being processed into a curved surface with a radius of curvature of 300 to 1000 days.It can withstand high pressure and does not cause galling. pipe fittings.