JPS5861919A - Manufacture of double-ply tube - Google Patents

Abstract

PURPOSE:To enable easy manufacture of a double-ply tube of strong fitting, by filling and passing pressurized cooling water in metallic inner tube, closely winding a heated steel band on the outer peripheral face, and welding its both edges. CONSTITUTION:An inner tube 2 made of stainless steel is set with swivel joints 4, 4'. Cooling water is pressed into at high pressure by tubes 7, 9 to cool the inner tube and maintain circular section by internal pressure. While rotating the inner tube 2 by a motor 5, a band 13 of carbon steel heated by a high- frequency heating device 15 is wound. In this case, an end of the steel band 13 is fixed to the end of the surface of inner tube 2 with a clamp, and joined end 16 of the band steel 13 wound by rotation of the inner tube 2 is welded by the welding gun 11 of a TIG welding machine 10. After winding the steel band 13 to the end and welding, the steel band is cut and rotation of the inner tube 2 and cooling are stopped. A double-ply tube of strong fitting due to themal expansion of the inner tube 2 by steel band 13 and contraction by cooling of outer tube 1' made of steel band.

Description

DETAILED DESCRIPTION OF THE INVENTION The disclosed technology belongs to the technical field of manufacturing a corrosion-resistant double pipe for oil country tubing by winding a strip steel plate in a spiral shape.

Therefore, this invention integrates a cooling corrosion-resistant inner tube made of stainless steel or the like with a circular cross section by wrapping it in a heated state with an outer tube made of carbon steel or the like. This invention relates to a method for manufacturing double tubes in which the inner tube is cooled and rotated, and the outer tube is rotated while the inner tube is cooled. The raw material steel strips are heated and wound in a spiral shape, and the joining edges of the wound spiral steel strips are joined and fixed by welding, etc., and the part that becomes the outer tube by this joining becomes the inner tube. After the outer tube is completed, it expands due to the temperature increase of the natural number of the inner tube + dt4, and in conjunction with the upper 14 pi contraction, the inner and outer parts are self-constricted and a high degree of confinement is obtained. This invention relates to a method for manufacturing a double-walled pipe.

As usual, oil country tubular goods, plant piping, etc. are equipped with pressure and heat resistance capabilities as well as corrosion resistance functions.
In addition, a self-contained corrosive fluid-feeding tube that satisfies the economical conditions of being lightweight and inexpensive is adopted, and is generally used as shown in Figure 1.
A double tube 3 is adopted in which the inner tube 1 has the above-mentioned pressure and heat resistance functions, and the inner tube 2 has corrosion resistance.

However, in the case of the corrosion-resistant double tube, if the gap is bent toward the outer tube during operation, it may cause implosion, so a high degree of alignment is required during manufacturing.

・Therefore, a divine double-pipe manufacturing method has been developed, but the hydraulic pipe expansion method can achieve a sufficiently high degree of fit. arise,
It has the disadvantage of causing so-called stress corrosion cracking, and the disadvantage of the shrink fitting method is that the equipment is large and expensive, and it is difficult to obtain long tubes, so it is difficult to obtain a uniform fit. There was also a problem with accuracy control being performed at the top of the furnace.

The purpose of the present invention is to solve the problems of the double-pipe manufacturing method based on the prior art described above, and improve precision by winding a heated strip steel plate in a spiral shape using a rotating track in the cooling inner tube and joining the joint lines to each other. It is an object of the present invention to provide an excellent method for manufacturing a double-walled tube that can be made uniform, long, and have a high degree of fit through thermal expansion and contraction.

The structure of the present invention in accordance with the above-mentioned object is that a corrosion-resistant inner tube made of stainless steel or the like is cooled and rotated, and a steel band plate made of carbon steel or the like is heated and tightly wound in a spiral shape. The ends of the wound spiral steel strips are joined together by welding or the like to form an outer tube portion, and the formed outer tube portion is cooled by the inner tube to contract and exhibit a tight state, After the outer tube is integrally connected to the inner tube in this way, if the double tube is left unattended, the temperature of the inner tube increases and expands, which, together with the cold contraction of the outer tube, increases the temperature. The gist of this is that it is not a scale that can measure the degree of fit, but rather that compressive residual stress is formed in the inside a to prevent stress side erosion cracks from occurring during operation after choreography.

Next, one embodiment of the present invention will be described below with reference to FIGS. 2 and 6. Note that the same parts as in FIG. 1 will be explained using the same reference numerals.

A stainless steel inner tube 2 with a set diameter, wall thickness, and length is rotatably set on a stand (not shown) via predetermined swivels 1-4, 4', and one end is connected to a motor 5 (rotated by a motor 5). It is designed to be transferable.

One of the swivel joints 4 and 4' has a water supply pipe 7 having a pressure regulating valve 6, and the other pipe is connected to a water pipe (not shown) for feeding tap water cooled to about 10'C under pressure, for example. Pergejoint 4'Ha Contribution A
It is connected to a drain pipe 9 via a valve 8.

In addition, as the welding device 10 (TJC) brings the welding gas/11 close to the inner tube 2, the guide 12 is brought into contact with the inner tube 2, and the inner tube 2 is moved along the seal (not shown) by an appropriate drive device. It is installed so that it can be operated along the axial direction.

On the other hand, reference numeral 13 denotes a steel band plate made of carbon steel and serving as an outer pipe material having a set width and thickness, and a reel 14 is also fed out and passed through a high frequency heating device 15 to be heated to a set temperature.

Note that the heating device 15 and reel 14 are the same as the welding device io.
The inner tube 2 is connected to the inner tube 2 by a rail (not shown), and is movable coaxially with the inner tube 2 via a drive device.

Therefore, the inner pipe 2 is rotated at a set speed by the motor 5, the pressure regulating valve 6 and the flow regulating valve 8 are adjusted, and the inner pipe 2 is filled with cooling tap water under pressure via the swivel joints 4 and 4'. The water is allowed to flow through the inner tube 2 so as to maintain its circular cross-section.

Thus, the reel 14, the heating device 15, and the welding device 10
The steel strip 1 is moved coaxially with the inner tube 2 at a set speed.
3 is fed out from the reel 14 and heated to a set temperature through the heating device 15, the tip is fixed to the end of the inner tube 2 by an appropriate flange device (not shown), and wound around the inner tube 2 in a spiral shape.

In this case, the guide 12 of the bath welding device 10 brings the joint edges 16, 16 of the spirally wound steel strip 15 into close contact with each other, and the welding gun 11 is used to apply TIG welding to the joint ends. 17 are combined.

In this case, as shown in FIG. 6, it may be melt-fitted into the inner tube 2 and connected integrally with the inner tube 2.

In this manner, the outer tube part 1' is formed, but since the inner rib 2 is cooled with tap water as described above, the outer tube part 1'
is cooled and contracted by heat transfer radiation and is tightly connected to the inner tube 2.
However, compressive residual stress is also formed in the inner tube 2.

This method is especially effective when the inner and outer tubes are integrally connected to the bath as shown in Figure 3. In this way, Tatokan 1 is formed.

Finally, when the spiral strip steel plate 13 is integrally assembled to the set position, the steel plate 13 is cut using a cutter as appropriate.

Then, the cold water supply stopped, and the cooling water came from the -inner V2Q? i
After pouring water into the well, remove the double pipe 3 from the swivel joints 4 and 4' and leave it in the atmosphere.

From this point on, the temperature of the inner tube 2 rises naturally, and the temperature of the double tube 3 reaches its natural temperature.Therefore, the inner tube 2 expands with increasing temperature, and together with the aforementioned cooling contraction of the spiral outer tube 1, the degree of fitting becomes higher. grow bigger,
The tightening is strengthened, and a larger compressive residual stress is formed in the inner tube 2.

Therefore, when the product double pipe 3 is used as a unit double pipe and is operated via a joint, implosion and stress corrosion cracking will not occur.

It should be noted that the embodiments of the present invention are of course not limited to the first embodiment described above. Various embodiments can be employed, such as mutual bonding via an industrial adhesive, or in that case, bonding to the inner tube, as well as a double, triple or more spiral structure.

As described above, in the method of manufacturing a corrosion-resistant double pipe, the inner pipe is cooled and rotated, and a steel strip serving as the material for the outer pipe is spirally wound around the inner pipe. By joining and integrating the mutual edges by bath welding, adhesive, etc., the outer tube is tightly joined to the inner tube during the spiral winding process, and it is possible to manufacture long tubes, making it possible to avoid problems during the manufacturing stage. The formed outer tube part is cooled and contracted by the inner tube (cooled) and has a degree of fit, producing a collapsed effect in which compressive residual stress is formed in the inner tube.

In addition, by installing a double pipe after manufacturing, the temperature of the inner pipe is raised and it expands, which, together with the above-mentioned contraction of the outer pipe, increases the degree of fitting, provides a strong bond, and creates a large compressive residual stress. There are excellent effects that can be obtained.

Furthermore, since a constant tension is applied during the spiral winding process to ensure a uniform fit and fastening accuracy, the effect of reducing product accuracy is also reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially cut perspective explanatory view of a double pipe, Fig. 2 is a schematic explanatory view of one embodiment of the present invention, and Fig. 6 is an explanatory cross-sectional view of the fitting part of the spiral strip steel plate bath contact part to the inner pipe. It is.

Claims (1)

[Claims] In a method for manufacturing a double pipe in which an outer pipe is tightly integrated with a corrosion-resistant inner pipe, the inner pipe is cooled and rotated, and a heated strip steel plate is tightly wound in a spiral shape around the rotating inner pipe. The joint edges of the heated steel strips wrapped in a single wrap were joined together to form an outer tube while cooling, and after the outer tube was wrapped, the temperature of the inner tube was increased to cause the inner and outer tubes to tighten. A double tube manufacturing method characterized by: