JPS60109686A - Corrosion-resistant double pipe joint section structure - 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] Technical Classification/Field> The disclosed technology belongs to the technical field of joint structures between unit pipes of corrosion-resistant double pipes in which corrosion-resistant pipes such as oil country tubular goods are made into double pipes.

<Explanation of the gist> The invention of this application is based on the invention in which a joint formed at the pipe end of a corrosion-resistant double pipe such as a corrosion-resistant double pipe used for oil country tubular goods, etc. This invention relates to a structure of a corrosion-resistant double-pipe joint formed as a welded joint, and in particular, a thickened part is formed at the pipe end of the general part of the corrosion-resistant double-ply pipe, and a thickened part is formed at the pipe end of the thickened part. Then, the corrosion-resistant pipe for the pressure-resistant pipe of the corrosion-resistant double pipe is replaced and integrated by overlay welding with a corrosion-resistant material, and the pipe ends of these corrosion-resistant pipes and pressure-resistant pipes are integrally connected by welding, or joints are used. Corrosion-resistant double layer @ by non-metallurgical joining, where corrosion-resistant materials for use are welded together and connected by screws, etc.
This invention relates to a joint structure.

<Prior art> As is well known, piping is used in all industries,
In particular, it is extremely widely used as a transport pipe.

Pressure resistance and corrosion resistance are important for such transportation pipes, for example, oil country tubular goods such as oil country tubular goods, and to deal with this, the outer pipe is made of carbon steel and the inner pipe is made of stainless steel. Various types of corrosion-resistant double pipes, such as double pipes made by manufacturing and integrating the two by various means, have been adopted.

In general, these corrosion-resistant double pipes have undergone considerable development in terms of pressure resistance, corrosion resistance, and viscosity, and excellent products have been developed.

However, due to various restrictions such as factory production and transportation to the site, this type of corrosion-resistant double pipe can only be manufactured into unit pipes of a specified length at the factory, and therefore, in order to increase the set length, it is necessary to , it is necessary to connect them via so-called joints during on-site installation.

However, unlike ordinary single pipes, corrosion-resistant double pipes have problems such as corrosion-resistant seals in general parts and joints, and various countermeasures have been taken.

For example, threaded joints such as bottle couplings are widely used for installation because they are easy to connect and disconnect on site, but corrosion resistance is extremely important, so corrosion-resistant materials are used in the joints. There are many.

Therefore, based on FIG. 1, the joint structure of the conventional corrosion-resistant double-layered pipe 1 will be briefly explained. for,
For example, they are connected via a screw thread 4 of a coupling 3 made of a corrosion-resistant material for a joint, and in that case, since the joint is made of a corrosion-resistant material for a joint, a corrosion-resistant An increased thickness part 7 is formed with a step part 6 interposed between the general part of the double pipe and the general part of the double pipe.

The bottle 2 is joined to the one-step portion 5 in the following manner.

That is, the corrosion-resistant tube 9 made of stainless steel is integrated with the pressure-resistant tube 8 made of carbon steel, and corrosion is prevented from entering the joint interface between the pressure-resistant tube 8 and the corrosion-resistant tube 9 from the tube end. Therefore, as shown in Figure @2, seal welding 10 is performed on the tube end to deal with this problem.

After that, a predetermined machining process is performed on the tube end to form a groove, and the bottle 2 is integrally joined by welding 11.
Ru.

<Problems with the Prior Art> However, in the joint structure using the above-mentioned joining means, in addition to the heat-affected zone 13 due to seal welding, the bottle 2 is exposed to heat due to tube end welding, as shown in FIG. Since there is a heat-affected zone 14 and an overlapping portion 15 of the heat-affected zones of both regions, there is a drawback that the strength due to the overlap of the heat-affected zones is reduced, and in particular, as shown in FIG. If the welded joint to the general part is located at the one step part, the strength decreases extremely seriously.

To deal with this, there is a joint structure in which the step part 6 is formed at the pipe end of the one-step part 5 and the thickened part 7 is formed at the pipe end, and the bottle 2 is joined by welding. In order to avoid a decrease in strength at the overlapped part of the affected area, the end of the corrosion-resistant double pipe 1 is cut in the circumferential direction as shown in FIG. If the bottle 2 is directly welded to the end of the corrosion-resistant double-pipe tube 1 while leaving it as it is, there is a problem that blowholes 17 and cracks may occur at the end of the corrosion-resistant double-pipe tube 1.

Therefore, in either case, the non-metallurgical joint 1
6 was located near the welded joint, so there was also the problem that it was difficult to conduct non-destructive inspections such as X-rays.

<Object of the Invention> The object of the invention of this application is to solve the problems related to unit pipe joint joints in the joint structure of corrosion-resistant double pipes based on the above-mentioned technical problems, to increase the strength of the joint, In addition, it can reliably maintain pressure resistance, fully guarantee corrosion resistance, facilitate post-inspection, and allow open pipe installation to be carried out according to design principles, which is beneficial to the field of piping application in the corrosive fluid transportation industry. The purpose of the present invention is to provide an excellent corrosion-resistant double pipe joint structure.

<Structure of the invention> In order to solve the above-mentioned problems, the structure of the invention of this application, which is based on the above-mentioned claims in accordance with the above-mentioned object, is to provide a method for manufacturing a corrosion-resistant double-walled pipe in advance by attaching a bottle at the end of the pipe. On the other hand, by forming a thickened part through the general part and the step part, and making the end of the corrosion-resistant pipe shorter in the length direction than that of the pressure-resistant pipe, only the short part is placed at the end of the pipe. The pipe ends of the corrosion-resistant double pipes are then machined to form a bevel, and the pipe ends of each connit pipe are The strength at the end of the corrosion-resistant double pipe can be increased by welding and connecting the unit pipes together, or by welding and joining a corrosion-resistant material for joints to the end face of the end of the corrosion-resistant double pipe. Technical measures that ensure corrosion resistance, facilitate non-destructive testing using corrosion-resistant pipes, etc., and provide a sound welded joint structure with no blowholes or cracks in the welded part. This study included the following.

<Structure of the Invention> Next, embodiments of the invention of this application will be described below based on the drawings from FIG. 5 onwards.

Incidentally, parts having the same features in FIGS. 1 to 4 will be explained using the same reference numerals.

When making the corrosion-resistant double pipe 11 in the embodiment shown in FIGS. A cutout portion 18 is formed by a predetermined mechanical means or the like around the entire circumference of the end portion of the corrosion-resistant tube 9 whose inner lining is tightened and integrated over a predetermined length in the cutting direction.

Then, as shown in FIG. 6, overlay welding 19 of stainless steel or the like is applied to the missing portion 18 to make it an extension of the corrosion-resistant tube 9, and it is integrated with the end of the pressure-resistant tube 8, so that it is integrated with the pressure-resistant tube 8. The end of the corrosion-resistant tube 9 is sealed.

In this case, instead of cutting off the end of the corrosion-resistant tube 9 that has been formed to the same length as the pressure-resistant tube 8, the length of the corrosion-resistant tube 9 is shortened in advance by an appropriate means, and then the tube is removed. Of course, overlay welding 19 may be applied to the end portions.

As shown in FIG. 7, after the overlay welding 19 is performed, a groove is suitably machined on the end surface of the end of the corrosion-resistant double pipe 1', which has been prepared in advance. A welded joint is formed by welding 20 with the inner pin end face of the pin 2 as a corrosion-resistant material for the joint.

In this case, the welded joint thus formed is formed in the thickened portion 7 as shown in FIG. 7, so that it is sufficiently excellent not only in corrosion resistance but also in pressure resistance.

Moreover, since the overlay weld 19 is also formed on the thickened portion 7, its strength is of course high, and therefore, the non-metallurgical joint is not close to the welded connection portion of the bottle 2, but is far away. Therefore, welding defects such as blowholes and cracks do not occur.

Also, it is easy to carry out non-destructive inspection using X-rays later.

Next, in the embodiment shown in FIGS. 8 to 10, the above-mentioned section 5.6
Similarly to the process explained in the figure, an overlay weld 19 is also formed at the end of the corrosion-resistant pipe 9 to the pressure-resistant pipe 8 at the thickened part of the end of the corrosion-resistant double pipe 1 to integrally join the pipe. This is an embodiment in which the attached units are connected by direct welding as shown in FIG. 10 with the joint surfaces of the thickened portions 7.7 facing each other, and the same effect can be achieved in this case as well. .

It goes without saying that the embodiments of the invention of this application are not limited to the above-mentioned embodiments; for example, the invention can be applied to corrosion-resistant double pipes such as bin box joints and flange joints. be.

<Effects of the Invention> According to the present invention, basically, the corrosion-resistant pipe is integrated with the pressure-resistant pipe at the pipe end through overlay welding at the pipe end of the pipe end thickened part of the corrosion-resistant double pipe. By being joined, when forming a welded joint to the pipe end of a corrosion-resistant double pipe,
The thickened portion not only ensures sufficient strength but also has the excellent effect of ensuring corrosion resistance.

The overlay weld can be made sufficiently large for the thickened part, and therefore, the non-metallurgical joint of the corrosion-resistant pipe to the pressure-resistant pipe is far enough away from the welded joint, and as long as the welded joint is free of blowholes, cracks, etc. An excellent effect is achieved in that no welding defects are formed and a sound joint weld is formed.

Further, since there is an increased thickness part, there is an effect that the corrosion resistance of the built-up part due to accumulation in the pressure tube does not deteriorate when overlay welding is performed.

Since there are no non-metallurgical joints in close proximity to the welded joint, non-destructive inspection using X-rays is easy and the inspection can be performed reliably, which is an excellent effect.

Also, when forming welded joints on-site, even if pre-prepared corrosion-resistant double pipes are piled up in the open, the corrosion-resistant pipes are overlaid on the pressure pipes at the ends of the corrosion-resistant double pipes. Since they are welded, an excellent effect is achieved in that corrosion does not invade the interface between the pressure-resistant tube and the corrosion-resistant tube.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the position of a welded joint based on the prior art, Fig. 2 is a partially enlarged sectional view of Fig. The figures are Fig. 3 ■ Partially enlarged sectional view, Fig. 5 and the following are detailed explanatory views of the invention of this application, Fig. 5 is a sectional view of a corrosion-resistant double pipe before welding of one embodiment, and Fig. 6 is a map. A sectional view of overlay welding, Fig. 7 is a sectional view of the structure of the joint, Figs. 8 and 9 are opposing sectional views of units of corrosion-resistant double pipes of other embodiments, and Fig. 10 is a sectional view of the structure of the joint. 11.1″′...Corrosion-resistant double pipe, 7...Thickened part, 9
...Corrosion-resistant pipe, 8...Pressure-resistant pipe, 19...Applicant for overlay welding Kawasaki Heavy Industries, Ltd.

Claims (2)

[Claims] (1) In a joint structure in which a welded joint is formed on the end face of a corrosion-resistant double pipe by non-metallurgical joining, the end of the pressure-resistant pipe is thickened, and the thickened part of the pipe end is thickened. A corrosion-resistant double-walled pipe characterized in that the longitudinal ends of the corrosion-resistant pipe are integrated with the pressure-resistant pipe in advance through overlay welding, and the thickened parts of the pipe ends are welded and connected to each other. Joint structure. (2) In a joint structure in which a welded joint is formed on the end face of a corrosion-resistant double pipe by non-metallurgical joining, the end of the pressure-resistant pipe is thickened, and the thickened part of the pipe end is thickened. The longitudinal end of the corrosion-resistant pipe is integrated with the pressure-resistant pipe in advance through overlay welding, and the corrosion-resistant material for the joint is welded to the thickened part of the pipe end. Corrosion-resistant double pipe joint structure.