JPH02160186A - Production of clad pipe - Google Patents

Abstract

PURPOSE:To obtain the clad pipe having an excellent adhesion property by concentrically combining a pipe material consisting of a base metal and a pipe material consisting of a cladding metal via an air adsorbing alloy interposed in a part in the pipe axis direction between the pipe materials and bringing the pipe materials into tight contact with each other at cold, then sealing the ends of the two pipes and elongating the pipe materials. CONSTITUTION:A shallow annular groove 10 is provided on the inner peripheral surface at both ends of the outside pipe 1 consisting of the base metal, such as carbon steel or low- alloy steel, and the tape-shaped air adsorbing alloy 2 is fitted therein. The air adsorbing alloy is an alloy to adsorb gas, such as air, by heating, for which alloys, such as Zr-V-Fe, are used. The size of the alloy 2 is determined according to the contact area of the outside pipe and the inside pipe. The inside pipe 3 which is of the same length as the length of the outside pipe 1 and consists of the cladding metal, such as stainless steel and Ni-based alloy, is concentrically inserted into the outside pipe and after both the pipes are bright into tight contact with each other by cold working, both the pipe ends are seal-welded to form a weld zone 4. This pipes are heated and are elongated by a mandrel mill and plug mill, etc., to form the clad pipe. A high vacuum is developed between the outside pipe and the inside pipe in the heating stage by which the complete boundary joining is attained. The high-quality clad pipe is produced with the high efficiency in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing seamless clad steel pipes by hot stretching and rolling.

[Conventional technology]

Recently, seamless steel pipes used in harsh conditions such as high-temperature and highly corrosive environments, such as oil country tubular goods in deep wells, have been developed by using stainless steel or Ni-based alloy steel in outer pipes made of carbon steel or low-alloy steel base material. Seamless clad pipes lined with a laminate of corrosion-resistant materials have come to be widely used as an economically advantageous material in terms of quality. Conventionally, such seamless clad pipes have been manufactured industrially by the following method.

First, an outer tube made of a base material and an inner tube made of a laminated material are concentrically assembled, and then the outer tube and the inner tube are brought into close contact with each other in the cold. As a means for bringing the outer tube and the inner tube into close contact with each other in the cold, cold drawing and expanding the diameter of the inner tube using water pressure (Japanese Patent Application Laid-open No. 59-1
63088) and expanding the diameter of the inner tube using a tube expansion jig (Japanese Patent Application Laid-Open No. 61-63315). When the outer tube and the inner tube are brought into close contact with each other, seal welding is performed between the outer tube and the inner tube at both tube ends. The double element tube thus obtained is heated to a predetermined temperature and hot-stretched and rolled using a mandrel mill, a plug mill, etc. to form a clad tube.

[Problem to be solved by the invention]

In such a rad tube, it is important to completely remove air from between the outer tube and the inner tube during the assembly stage of the double element tube. If air remains between the outer tube and the inner tube constituting the double element tube, sufficient interfacial bonding will not be achieved during hot stretching and rolling, and separation will occur at that portion. In order to prevent this separation, the outer tube and inner tube are coldly brought into close contact with each other before end sealing. It is difficult to remove air, and when mass producing clad pipes on an industrial scale, there is a risk of separation due to air pockets. Some attempts have been made to use a vacuum pump to bleed air between the outer tube and the inner tube without bringing them into close contact, but this is time-consuming and not industrially practical.

The present invention was made in view of this situation,
The purpose is to provide a method for manufacturing a clad pipe that can easily and completely prevent interfacial peeling due to residual air.

(Means for Solving the Problems) The manufacturing method of the present invention is such that a tube material made of a base material and a tube material made of a laminated material are made in the same manner with an air adsorption alloy interposed in a part of the tube axis direction between the two tube materials. After combining them into a core, the two tube materials are brought into close contact with each other in the cold, and after sealing between the two tube materials at both tube ends, the resulting double tube is hot-stretched and rolled.

[For production]

Even if the two tube materials are brought into close contact with each other in the cold, they are microscopically connected in the tube axis direction. Therefore, if an air adsorption alloy is interposed in a part of the pipe in the axial direction during this period, the air remaining in this period will be adsorbed by the air adsorption alloy during the heating stage prior to hot stretching and rolling, and after hot stretching and rolling. Both tube materials are completely interfacially bonded except for the air adsorption alloy part.

〔Example〕

The present invention will be described below with reference to Examples.

In the manufacturing method of the present invention, first, as shown in FIG. 1(a), an outer tube 1 made of a base material such as carbon steel or low alloy steel.
A shallow annular groove lO is provided on the inner circumferential surface of both ends of the tube, into which a tape-shaped air adsorption alloy 2 is fitted in an annular shape.

Air adsorption alloy 2 is an alloy that adsorbs gases such as air by heating, specifically 70% Zr-24, 6% V
-5.4% Fe (required heating temperature 450°C or more, required heating time 10 minutes or more), etc.

The size of the air adsorption alloy 2 is determined so that the air remaining between the outer tube 1 and the inner tube 3 can be completely adsorbed after they are brought into close contact with each other.
It is determined as appropriate depending on the contact area between the inner tube 3 and the inner tube 3.

Specifically, 5 per 1M of contact area between the outer tube 1 and the inner tube 3
g to 50 g is preferable, because if it is less than 5 g, the expected high vacuum cannot be obtained. If the amount is large, there is no problem unless it is an extreme amount, and 50
Make it less than g.

The shape of the air-adsorbing alloy 2 is preferably tape-like, mainly from the viewpoint of workability, and it is also easy to interpose the air-adsorbing alloy in an annular groove as shown in FIG.

It is preferable to select both ends of the pipe as the intervening part of the air adsorption alloy 2, as that part will be cut off later. However, if the pipe length is long, it should also be inserted appropriately in the middle part in the pipe axis direction. If the pipe length is short, it may be provided at only one end of the pipe.

When the outer tube 1 is manufactured in this way, next, as shown in FIG.
As shown in b), an inner tube 3 of the same length as the outer tube 1 and made of a composite material such as stainless steel or N1-based alloy is inserted concentrically into the inner surface of the outer tube 1, and cooled in this state. After the outer circumferential surface of the inner tube 3 is brought into close contact with the inner circumferential surface of the outer tube 1 by machining, seal welding is performed between the outer tube 1 and the inner tube 3 over the entire circumference at both tube ends. 4 indicates a welded portion.

In order to bring the outer circumferential surface of the inner tube 3 into close contact with the inner circumferential surface of the outer tube 1, the diameter of the inner tube is expanded by water pressure as shown in JP-A-59-163088, or JP-A-61-63315. Adopt inner tube diameter expansion using a tube expansion jig as shown in the publication. Further, instead of these, cold drawing or the like may be employed.

When the double element tube is obtained as described above, it is finally heated and stretched and rolled using a mandrel mill, a plug mill, etc. to form a clad tube.

In a double-layered tube, the outer tube 1 and the inner tube 3 are sealed by the welded part 4 at both ends of the tube, and are microscopically connected in the entire tube axis direction. Impurity gas such as air remaining between the outer tube 1 and the inner tube is adsorbed by the air adsorption alloy 2, creating a high vacuum between them. It has been confirmed through research by the inventors that the degree of vacuum obtained here reaches 10-'Torr or more, and compared to the degree of vacuum (10-'' to 10-'Torr) obtained with a vacuum pump. Therefore, at the stage of elongation and rolling, the outer tube 1 and the inner tube 3 are completely interfacially bonded except for the air adsorption alloy 2.

The manufactured clad pipe is appropriately shaped with a stretch reducer or sipe, and then the air adsorption alloy 2 portion is cut off to produce a product.

The results of actually manufacturing a clad pipe using the above-described method of the present invention will be described below.

The outer tube has an outer diameter of 2105 m, a wall thickness of 445 m, and a length of 50 m.
00- carbon steel is used, and the outer diameter is the inner tube! S L+ 3316L stainless steel with a thickness of 16 mm, a wall thickness of 12 mm, and a length of 5000 mm was used. The air adsorption alloy contains 70% Z r −
24,6%V -5,4%Fe (SAESGET
TER3/USA INC, 5L707), 0.5
It was in the form of a tape with an aw* thickness and a width of 30 m, and was interposed between the outer tube and the inner tube at both tube ends. The outer tube and the inner tube were brought into close contact with each other using a tube expansion jig disclosed in Japanese Patent Application Laid-Open No. 61-63315. The dimensions of the double pipe are outer diameter 210m, wall thickness 56cm,
The length is 5000cm.

After heating the 20 double tubes to 1,250°C (furnace time: 4 hours, soaking time: 15 minutes), the outer diameter was 219 m, the wall thickness was 21.5 mm, and the length was 80 mm using a Mannesmann plug mill.
When the tubes were drawn and rolled to 0.00 mm to form clad tubes, it was confirmed that there was no peeling at all in any of the clad tubes except where the air-adsorbing alloy was interposed. In addition, the above 2
Outer diameter 219mm, wall thickness 15.0mm, length 110cm from heavy steel pipe
Similar results were obtained when 20 00■ clad pipes were manufactured. Incidentally, when interpolated cladding pipes were manufactured without using an air-adsorbing alloy, peeling of approximately 20m x 40m was observed at the ends of two cladding pipes with a wall thickness of 21.5cm.

In the embodiments described above, the base material is used for the outer tube and the laminated material is used for the inner tube, but in the method of the present invention, it is also possible to use the laminated material for the outer tube and the base material for the inner tube.

〔Effect of the invention〕

The method of the present invention can completely remove the air that remains between the pipes when they are brought into close contact with each other in the cold, by simply using an air-adsorbing alloy. Moreover, this air removal is performed using the heating that accompanies stretching and rolling.

Therefore, the method of the present invention can produce a clad steel pipe with excellent adhesion with high efficiency, and has a great industrial effect of improving the quality of the clad steel pipe without substantially increasing the cost thereof. It is something.

[Brief explanation of the drawing]

FIG. 1(a) Φ) is a sectional view showing a typical procedure of the method of the present invention. In the figure, l, 3: tube material, 2: air adsorption alloy.

Claims (1)

[Claims] 1. A tube material consisting of a base material and a tube material consisting of a laminate material are assembled concentrically with an air adsorption alloy interposed in a part of the tube axis direction between the two tube materials, and then both tube materials are assembled in a cold state. A method for manufacturing a clad pipe, which comprises bringing the double pipe materials into close contact with each other and sealing the space between the two pipe materials at both pipe ends, and then hot-stretching and rolling the obtained double pipe material.