JPH03124383A - Production of clad pipe - Google Patents

Abstract

PURPOSE:To remove the air from the spacing between a pipe material consisting of a base metal and a pipe material consisting of a cladding metal and to securely join the pipe materials by communicating a capsule contg. an air-absorbing alloy between the two pipe materials and hot elongating the pipe materials at the time of combining these two pipe materials to the same center and bringing the pipe materials into tight contact with each other, then sealing the two pipe materials at the pipe end parts. CONSTITUTION:The inside pipe 2 which has the same length as the length of the outside pipe 1 consisting of the base metal, such as carbon steel or low-allot steel and consists of the cladding metal, such as stainless steel, N2-based alloy is inserted into the outside pipe 1. These pipe materials are then cold worked to bright the inner peripheral surface of the outside pipe 1 and the outer peripheral surface of the inside pipe 2 are brought into tight contact with each other. The outside pipe 1 and the inside pipe 2 are then seal-welded over the entire circumference at both ends. The capsule 4 is airtightly connected so as to cross the outside pipe 1 and the inside pipe 2 at the pipe end faces. The capsule 4 is a cylindrical container opened at one end and the air-absorbing alloy 5 is housed therein. This pipe materials are then heated and are elongated to form the clad pipe. The air or the like remaining between the two pipes 1 and 2 in the stage of heating is adsorbed by the air absorbing ally 5, by which a high vacuum is developed and the two pipes 1, 2 are securely boundary-joined.

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 unsuitable for industrial use.

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 to solve the problem]

In order to achieve the above-mentioned object, the present applicant has developed a technology that, when manufacturing a double-layered tube that combines a tube material made of a base material and a tube material made of a laminated material, air is adsorbed between the two tube materials in the axial direction of the tube. We have previously filed an application for a method of manufacturing a cladding tube in which an alloy is interposed (Japanese Patent Application No. 3172'28/1983). According to this method, the two tube materials are microscopically connected in the tube axis direction even after cold joining, so by sealing the air adsorption alloy between them,
Air remaining between the tube materials is adsorbed by the air adsorption alloy during heating 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 portion. However, the part in which the air-adsorbing alloy is sealed becomes a joint defective part, and even if this part is located at the end of the tube, a slight decrease in yield due to the presence of the air-adsorbing alloy cannot be avoided.

The manufacturing method of the present invention prevents the above-mentioned decrease in yield due to the presence of air-adsorbing alloys as well as interfacial peeling due to residual air. After the two pipe materials are brought into close contact with each other in the cold, when sealing between the two pipe materials at both pipe ends, the capsule containing the air-absorbing alloy is inserted into the pipe with the capsule in communication between the two pipe materials. It is characterized in that the double-layered tube is bound by protruding from the end face, and then the double-layered tube is hot-stretched and rolled.

[For production]

The air adsorption alloy is not interposed between the two tubes, but the capsule containing the air adsorption alloy is in communication between the two tubes.

Therefore, during the heating stage prior to hot rolling, the air remaining between the two tube materials is adsorbed by the air adsorption alloy in the capsule and removed from between the two tube materials.

As a result, after hot rolling, both tube materials are completely interfacially bonded over their entire length, and no yield loss occurs due to the presence of the air-adsorbing alloy.

〔Example〕

Examples of the manufacturing method of the present invention will be described below with reference to FIGS. 1 and 2.

In this manufacturing method, first, the outer tube 1 is made of a base material such as carbon steel or low alloy steel, and the same length as the outer tube 1 is made of stainless steel, N
Insert the inner tube 2 made of a laminate material such as J-based alloy. Next, this is subjected to cold working to bring the inner circumferential surface of the outer tube 1 and the outer circumferential surface of the inner tube 2 into close contact with each other.

Examples of cold working that bring the inner circumferential surface of the outer tube 1 and the outer circumferential surface of the inner tube 2 into close contact include expanding the diameter of the inner tube by water pressure as shown in Japanese Patent Application Laid-Open No. 59-163088, or An example of this is expanding the diameter of the inner tube using a tube expanding jig as shown in Japanese Patent Publication No. 61-63315. Further, instead of these, cold drawing or the like may be employed.

When the cold working is completed, as shown in FIGS. 1 and 2, the outer tube 1 and the inner tube 2 are welded to seal the entire circumference at both end surfaces. 3 represents the welded portion. A groove for welding is previously formed on the inner peripheral edge of the outer tube 1.

During the seal welding, the capsule 4 is airtightly connected to the portion of the tube end surface spanning the outer tube 1 and the inner tube 2 using the welding. The capsule 4 connected to the tube end face is a cylindrical container with one end open, and the open side communicates with the microscopic gap formed between the outer tube 1 and the inner tube 2.

An air adsorption alloy 5 is housed within the capsule 4.

The capsule 4 may be attached to both ends of the tube, or only to one end of the tube. Moreover, a plurality of capsules 4 can be attached in the circumferential direction. The material of the capsule 4 is not particularly limited, but carbon steel similar to that of the outer tube 1 is sufficient.

The air adsorption alloy 5 housed in the capsule 4 is an alloy that adsorbs gas such as air by heating, and specifically, for example, 70% Z r-24, 6% V-5, 4% Fe.
(SAES C[!TT[!R3/USA INC, 5t707)]. This commercially available alloy is in the form of a lump and requires a heating temperature of 450°C or more and a heating time of 10 minutes or more.

In FIGS. 1 and 2, a plurality of these bulk air-adsorbing alloys 5 are housed in a capsule 4. In FIGS.

The size of the air adsorption alloy 5 is determined so that the air remaining between the outer tube 1 and the inner tube 2 can be completely adsorbed after the outer tube 1 and the inner tube 2 are brought into close contact with each other.
It is determined as appropriate depending on the contact area between the inner tube 2 and the inner tube 2. Specifically, the contact area 1 between the outer tube 1 and the inner tube 2 is approximately 5 g to 5 g.
0g is preferred. If it is less than 5 g, the expected high vacuum cannot be obtained, and if it exceeds 50 g, economic efficiency will deteriorate.

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 the above-mentioned double element tube, the outer tube 1 and the inner tube 2 are sealed by welded portions 3 at both tube ends, and microscopically communicate with each other in the entire tube axial direction. Further, the capsule 4 communicates with a microscopic gap between the outer tube 1 and the inner tube 2. Therefore,
During the heating stage, impurity gas such as air remaining between the outer tube 1 and the inner tube 2 is adsorbed by the air adsorption alloy 5 in the capsule 4, creating a high vacuum between the outer tube 1 and the inner tube 2. . It has been confirmed through research by the present inventors that the degree of vacuum obtained here reaches 10-'Torr or more, and the degree of vacuum obtained by a vacuum pump (I P"~10-"Torr) It is significantly higher than that. Therefore, after stretching and rolling, the outer tube 1
and the inner tube 2 are firmly interfacially bonded, and this bonding state can be obtained over the entire length of the tube.

The manufactured clad tube is appropriately shaped using a stretch reducer or sizer, and then a small portion of the tube end including the capsule 4 is cut off to produce a product.

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

The outer tube has an outer diameter of 210mm, a wall thickness of 44m, and a length of 5000m.
The inner tube was made of 5US316L stainless steel with an outer diameter of 116 mm, a wall thickness of 12 mm, and a length of 5000 seconds. One capsule was attached to each end of the tube, and its dimensions were 11 mm in inner diameter and 50 mm in length. Air adsorption alloy is 70% Zr-24, 6% V-5.4% F
e(SAES GETT[!R3/USA ING.

St 707), and had a disc shape with an outer diameter of 10 and a thickness of 3 mm, and 10 g was accommodated in each capsule. The outer tube and the inner tube were brought into close contact with each other using a tube expansion jig having a flexible sealed hollow body filled with fluid, as disclosed in Japanese Patent Application Laid-Open No. 6163315. The dimensions of the double tube after close contact are 210 m in outer diameter.
m, wall thickness 56 mm, and length 5000 mm.

Then, after heating the 20 double-layer tubes to 1250°C, they were stretched and rolled using a Mannesmann plug mill to an outer diameter of 219 mm, a wall thickness of 21.5 mm, and a length of 8000 m to form clad tubes. It was also confirmed that there was no peeling over the entire length of the tube. Furthermore, similar results were obtained when 20 clad tubes having an outer diameter of 219 mm, a wall thickness of 15.0 mm, and a length of 11,000 mm were manufactured from the above-mentioned double-layer tube. Incidentally, when similar cladding tubes were manufactured without using an air-adsorbing alloy, peeling of approximately 20mm x 40mm was observed at the ends of two cladding tubes with a tube wall thickness of 21.5m. In addition, when an air adsorption alloy is interposed between the pipe materials, an excess of about 250 mm must be cut off.

In addition, in the above embodiment, 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. .

[Effects of the Invention] The method of the present invention can completely remove air remaining between the pipes when they are brought into close contact with each other in the cold, by the simple means of using an air adsorption alloy. Moreover, since the air-adsorbing alloy is not interposed between the tube materials, no joint failure occurs due to the presence of the air-adsorbing alloy. Therefore, the tube members are firmly joined over the entire length. Furthermore, air removal by the air adsorption alloy can be performed using heating associated with elongation and rolling. Therefore, the method of the present invention can produce a clad steel pipe with excellent adhesion in a highly efficient and economical manner, and can improve the quality of the clad steel pipe without substantially increasing its cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a tube end illustrating the tube end sealing step in the manufacturing method of the present invention, and FIG. 2 is a front view thereof. In the figure, l: outer tube, 2: inner tube, 4: capsule, 5: air adsorption alloy. 1

Claims (1)

[Claims] (1) After concentrically assembling the base material and the laminate material and bringing them into close contact with each other in the cold, when sealing between the two pipe materials at both pipe ends, air is removed. A cladding characterized in that a capsule containing an absorbing alloy is protruded from the end face of the tube in a state in which both tube materials are communicated with each other to form a double-layered tube, and then the double-layered tube is hot-stretched and rolled. Method of manufacturing tubes.