WO2017045426A1

WO2017045426A1 - Bimetal spiral steel pipe and manufacturing method therefor

Info

Publication number: WO2017045426A1
Application number: PCT/CN2016/082936
Authority: WO
Inventors: 战福军
Original assignee: 南京联众建设工程技术有限公司
Priority date: 2015-09-18
Filing date: 2016-05-22
Publication date: 2017-03-23
Also published as: CN105156771A; CN105156771B

Abstract

A bimetal spiral steel pipe comprising a pipe body (100), the surface of the pipe body (100) extending outwards to form a rib (102) which is spirally arranged around the outer wall of the pipe body. A groove (103) and an auxiliary inner steel band (200) capable of covering the notch of the groove are provided on the rib (102) and the surface of the pipe body (100). A hollow cavity (300) is formed between the groove (103) and the auxiliary inner steel band (200), and is filled with concrete (400). Also disclosed is a manufacturing method for a bimetal spiral steel pipe. By means of the bimetal spiral steel pipe and the manufacturing method therefor, the rib on the outer wall of the pipe body and the pipe body are integrally formed, and can resist the dynamic load fatigue when bearing dynamic load; the corrosion resistance and wear resistance of the steel pipe are enhanced; further, the thickness of the steel pipe main body is reduced, and material costs are reduced.

Description

Bimetallic spiral steel pipe and manufacturing method thereof

Technical field

The invention discloses a steel pipe and a manufacturing method thereof, in particular to a bimetallic spiral steel pipe and a manufacturing method thereof.

Background technique

At present, in the transportation and storage and transportation of fluids, pipelines are generally used for transportation. Commonly used pipes include cement pipes, plastic pipes, ordinary carbon steel pipes, stainless steel pipes and galvanized steel pipes. Among them, the cement pipe is a kind of prefabricated pipe made of cement and steel bar as the material and centrifugal force principle, but it is easy to leak and has poor internal pressure resistance; and the caliber is not large, the general caliber is 3 meters or less; each tube The length is not long, the joints are many, the joint is easy to leak, and the construction is difficult; the foundation must be made first during construction, and the construction cost is high. The plastic pipe is made of plastic resin as raw material, adding stabilizer and other additives, and is extruded in the pipe making machine, which is light in weight, convenient in processing, but has small caliber, poor internal pressure bearing capacity, low mechanical strength and anti-destruction. Poor performance; not resistant to wear, not resistant to high temperatures, easy to age. Ordinary carbon steel pipe is made of carbon steel. The inner wall is not wear-resistant and corrosion-resistant. The caliber cannot be made too much. The wall thickness is greatly increased at large diameters and the cost is high. At present, some provinces in China have clearly banned it. Ordinary carbon steel pipes are used in the water supply project. Stainless steel tubes are too costly. The diameter of galvanized steel pipe can not be too large, and galvanizing is a polluting industry. It has great damage to the environment. Generally, the galvanized layer is thin, generally less than 0.1mm thick, and is not resistant to abrasion and erosion. Existing ordinary bi-metal steel pipe, the outer pipe generally adopts ordinary standard steel pipe, the wall thickness is quite thick, does not save material, the inner pipe and the outer pipe are set, easy to delaminate and fall off, and the caliber can not be too large, can only reach 1.2 meters To 1.5 meters, the inner tube should have sufficient thickness to support its shape, and the wall thickness is often greater than 2mm or even 4mm, which does not save material.

The applicant has long been committed to research in this field, and has a patent for the patent number 201410477708.6, entitled "A spiral steel pipe with a reinforcing ring and its manufacturing method", in which the reinforcing ring and the main steel pipe Can be made separately and then welded. The following defects exist: 1. The pipe body and the reinforcing ring are two separate parts, which are integrally connected by the weld seam. When the reinforcing ring is stressed, the weld is a stress concentration zone with a hidden danger; 2. The winding process In the weld, the weld is in the outer side of the processing deformation zone, the weld is stretched, the deformation is large, and it is easy to crack. 3. If the pipe body is subjected to long-term load, such as subway, vehicle, etc., the weld seam is easily broken due to dynamic load. Cracking; 4, in view of the fact that the pipe structure of this type is a semi-flexible structure, especially for large-diameter pipes, the dependence on the common force effect of pipe and soil (ie, the co-deformation of the pipe body and the surrounding backfill) is large, and should be increased. The stiffness of the tube itself to avoid large deformations.

Therefore, it is urgent to solve the above technical problems.

Summary of the invention

OBJECT OF THE INVENTION: The first object of the present invention is to provide a bimetallic spiral steel pipe having a large diameter, high strength, improved corrosion resistance and wear resistance;

A second object of the present invention is to provide a method of producing the steel pipe.

Technical Solution: The steel pipe according to the present invention comprises a pipe body, and the surface of the pipe body extends outward to form a convex rib spirally disposed along the outer wall of the pipe, the convex rib forms a groove with the pipe body, and is provided with a cover covering the concave An auxiliary inner steel strip of the groove, a hollow cavity formed between the groove and the auxiliary inner steel strip, and the hollow cavity is filled with concrete.

In the present invention, the material of the steel pipe body is carbon steel; the auxiliary inner steel strip can cover the entire inner wall of the pipe, and can also cover part of the inner wall of the pipe; the auxiliary inner steel strip can be selected from special alloy steel, stainless steel, wear-resistant steel, aluminum or Copper, etc., can improve the corrosion resistance of the inner wall of the pipe, and at the same time, the thickness of the main steel can be reduced, and the material cost is reduced.

Of course, a sealing steel strip for sealing the groove notch is also provided between the auxiliary inner steel strip and the groove.

Another steel pipe of the present invention comprises a pipe body, and the surface of the pipe body extends outward to form a rib arranged spirally along the outer wall of the pipe, the pipe body and the rib form a groove, and the groove is provided to block the groove. a sealing steel strip at the notch, a hollow cavity formed between the groove and the sealing steel strip, and the hollow cavity is filled with concrete, and at the same time, an auxiliary inner steel strip is arranged on the inner wall of the pipe below the water level line .

The rib has a cross section of an omega shape, a groove shape, a wave shape, a semicircular shape, a parabolic shape or a trapezoidal shape.

In the steel pipe of the present invention, the pipe body is formed by a main steel strip having at least one row of ribs on one side, a groove corresponding to the other surface, and an auxiliary inner steel strip for covering the groove notch. The auxiliary inner steel strip enhances the delivery force of the main steel strip and avoids deformation of the steel strip during winding.

The manufacturing method of the bimetallic spiral steel pipe of the present invention comprises the following steps:

A. Prepare the main steel strip and the auxiliary inner steel strip;

B. The main steel strip has a first pair of sides and a second pair of sides, and the main steel strip is bent into a steel strip with a rib, the ribs are spaced along the first pair of sides of the main steel strip, and the second The length of the opposite side is uniform and forms a groove with the main steel strip;

C. The auxiliary inner steel strip is attached to the groove of the main steel strip groove to form a composite steel strip, and a hollow cavity is formed between the convex rib and the auxiliary inner steel strip;

D. spirally winding the composite steel strip to form a tubular body with a spiral hollow cavity;

E. Cut the pipe body according to the required length, and weld the gap between the main steel strip and the auxiliary inner steel strip at the slit of the convex rib at both ends of the pipe body;

F. Casting concrete from the incision of the convex rib at one end of the pipe body until the concrete flows out from the slit of the rib at the other end of the pipe body, and the hollow cavity body is filled with concrete, that is, the production is completed.

In step C, the steel strip is firstly attached to the groove of the groove of the main steel strip, and then the auxiliary inner steel strip is attached on the plugged steel strip to form a composite steel strip, and then the steel pipe is completed according to the AF step. Production.

Principle of the invention: The invention simultaneously applies the principle of joint force of soil and soil and the principle of concrete steel pipe, and the joint force of pipe and soil The principle is that after the pipeline is buried, the upper load of the pipeline is not supported by the rigidity of the pipeline, but by the interaction between the pipeline and the surrounding earth and stone, the common force effect of the pipe and the soil is formed, and the vertical downward load is formed. It will be converted into the ring-inward pressure of the pipe wall. The working principle of the concrete steel pipe is to fill the hollow steel pipe with concrete, and the superior pressure bearing capacity of the concrete and the surrounding effect of the steel pipe on the concrete greatly enhance the vertical bearing capacity of the steel pipe. The invention combines ordinary carbon steel, stainless steel and concrete organic materials into one body, and fully exerts their respective characteristics and advantages, and bears different roles in the overall structure.

The formation of a fully closed rib on the outer wall of the spiral steel pipe not only increases the circumferential moment of inertia of the pipe wall, but also greatly reduces the wall thickness of the main steel strip compared to the wall thickness of the general steel pipe, reduces the cost of the material, and can manufacture large diameter and super large diameter. Steel pipe; when the main steel is thin, during the winding process, the delivery force will cause the steel strip to flex and cannot be delivered, so the main steel strip is first formed into a cross-section with a rib structure, and then welded with an auxiliary inner steel strip. The closed shape is formed, the cross-sectional area and the moment of inertia of the steel strip are greatly increased, and the delivery is easy to realize when the coil is rounded, which is convenient for processing; most importantly, the convex rib is directly formed by the tube body, and there is no weld seam between the two. There is no stress concentration zone, no cracking hidden danger; at the same time, the rigidity of the steel pipe is improved, and it is not easy to produce large deformation in the joint force effect of the pipe and soil (that is, the pipe body and the surrounding backfill soil co-deformation), and can be well tolerated by the outside world. Dynamic loads caused by vibration, such as subways, vehicles, etc. At the same time, all or part of the inner wall of the pipe is provided with auxiliary inner steel strip, which can avoid or reduce the corrosion of the main steel pipe by the fluid, the wear and the pollution of the main steel pipe to the fluid, and also the auxiliary inner steel strip is disposed inside the pipe, the main steel The thickness can be reduced again, and the special inner material of the auxiliary inner steel strip greatly improves the anti-corrosion and wear resistance of the steel tube. In addition, by injecting plain concrete or reinforced concrete into the hollow cavity, the radial and circumferential compression resistance of the inner wall of the rib is greatly improved. When buried, the ribs and the concrete inside it can withstand the circumferential pressure under the action of the common force effect of the pipe and soil, further improve the overall strength of the pipe body, thereby further reducing the thickness of the main steel, further Reduce material costs.

Advantageous Effects: Compared with the prior art, the present invention has the following significant advantages: First, the rib of the outer wall of the tube is integrally formed with the tube body, and there is no weld between the two, and can withstand dynamic load when subjected to dynamic load. Fatigue; secondly, the inner wall of the pipe is provided with a special inner steel strip of specific metal material, which can improve the corrosion resistance and wear resistance of the steel pipe, avoid fluid pollution, and can reduce the thickness of the main pipe body and reduce the material cost. At the same time, the inner wall of the pipe can also be provided with a sealing steel strip, which forms a hollow cavity with the rib, and can be filled with concrete in the hollow cavity, and the plugged steel strip can also be used to bear the medium in the pipe to assist the inner steel strip. Pressure to prevent the inner steel strip from deforming into the groove; finally, the pipe can be used for conveying water or special media, such as water supply, drainage or corrosive medium, medium with high purity and high temperature The medium, etc., greatly reduces the manufacturing cost.

DRAWINGS

Figure 1 is a schematic cross-sectional view of a main steel strip of the present invention;

2 is a schematic structural view of a main steel strip having a convex rib on its surface;

Figure 3 is a schematic cross-sectional view of a main steel strip having a rib on its surface;

Figure 4 is a schematic view showing the welding position of the main steel strip and the plugged steel strip of the present invention;

Figure 5 is a schematic view showing the welding position of the main steel strip, the plugged steel strip and the auxiliary inner steel strip of the present invention;

Figure 6 is a partial enlarged view of a portion A in Figure 5;

Figure 7 is a partial enlarged view of B in Figure 5;

Figure 8 is a partial enlarged view of a portion C in Figure 5;

Figure 9 is a schematic view showing the spiral winding process of the composite steel strip of the present invention;

Figure 10 is a perspective view of the spiral steel pipe of the present invention after being rolled;

Figure 11 is a cross-sectional view showing the pipe joint butt welding in the spiral winding process of the steel pipe of the present invention;

Figure 12 is a partial enlarged view of the portion D in Figure 11;

Figure 13 is a schematic view showing the overall structure of a single-section steel pipe of the present invention;

Figure 14 is a schematic cross-sectional structural view of a steel pipe of the present invention;

Figure 15 is a schematic longitudinal sectional view of the present invention;

Figure 16 is a schematic cross-sectional view showing the inner wall of the present invention completely covering the inner steel strip of the auxiliary inner steel strip;

Figure 17 is a schematic cross-sectional view showing a portion of the inner wall portion of the present invention covering the auxiliary inner steel strip.

detailed description

The technical solution of the present invention will be further described below with reference to the accompanying drawings.

The steel pipe of the present invention comprises a pipe body 100, comprising a pipe body 100, the surface of the pipe body 100 extending outwardly to form a rib 102 spirally disposed along the outer wall of the pipe body, the pipe body 100 and the rib 102 forming a groove 103, auxiliary The inner steel strip 200 covers the groove notch position, the hollow cavity 300 is formed between the groove 103 and the auxiliary inner steel strip 200, and the hollow cavity 300 is filled with the concrete 400.

In the invention, the outer wall of the tube has a convex rib structure, which can greatly improve the moment of inertia of the main body of the main body, and the moment of inertia is much higher than that of the general reinforcement method, and the bearing capacity is improved, so that the wall thickness ratio of the main steel strip formed into the tube body is increased. Generally, the wall thickness of the steel pipe is greatly reduced, and the material cost is reduced. At the same time, the thin steel plate can be delivered when the main steel strip is wound, and the winding process is broken. The ribs may have an omega shape, a groove shape, a wavy shape, a semicircular shape, a parabolic shape or a trapezoidal shape.

The invention is a bimetallic spiral steel pipe, wherein the “bimetal” means that the steel pipe main body and the auxiliary inner steel strip are respectively made of two kinds of metal materials. Wherein, the auxiliary inner steel strip can cover the entire inner wall of the pipe or cover part of the inner wall of the pipe. Wherein, the inner wall of the covering part of the tube is the position of the notch covering the groove of the tube body, thereby forming a hollow cavity. The auxiliary inner steel strip is made of a specific metal material including, but not limited to, special alloy steel, stainless steel, wear-resistant steel, aluminum or copper, which can improve the corrosion resistance and wear resistance of the inner wall of the pipe, and avoids fluid pollution. At the same time, the thickness of the main steel can be reduced again, and the material cost is reduced. At the same time, the auxiliary inner steel strip can also enhance the delivery force when the main steel strip is wound, and avoid deformation of the main steel strip during winding. The main body of the steel pipe can be made of ordinary carbon steel with low price, and the cost can also be reduced.

A sealing strip 500 for sealing the groove notch is also provided between the auxiliary inner steel strip and the groove. On the one hand, the plugged steel strip seals the groove formed on the inner wall of the main steel pipe, and on the other hand, can bear the pressure of the medium inside the pipe on the auxiliary inner steel strip, and prevents the auxiliary inner steel strip from being deformed into the groove; Including but not limited to special alloy steel, stainless steel, wear-resistant steel, aluminum or copper and other metal materials.

In the invention, filling the hollow cavity with plain concrete or reinforced concrete can enhance the overall radial and circumferential compression resistance of the pipe body, so that the wall thickness of the main steel strip is thinner than the thickness of the general steel pipe, thereby further reducing The cost of the material.

The steel pipe of the invention is mostly used for conveying special media, such as corrosive medium, medium with high purity and high temperature medium, etc., can be used for water supply pipe or drainage pipe; conveying sand and dust; urban sewage and industry Sewage; chemical fluid; high temperature medium; seawater pipeline; water collection pipe; other pipelines conveying special media. The lower part of the pipe (water or other media parts) is susceptible to corrosion and should be protected to form another steel pipe.

The steel pipe includes a pipe body, and includes a pipe body 100. The surface of the pipe body 100 extends outward to form a rib 102 spirally disposed along the outer wall of the pipe body. The pipe body 100 forms a groove 103 with the rib 102, and is provided with a seal. Blocking the steel strip of the groove slot, forming a hollow cavity between the groove and the plugged steel strip, and filling the hollow cavity with concrete, and at the same time, being disposed on the inner wall of the tube below the water line Auxiliary inner steel strip.

The invention can produce a steel pipe with a large diameter (up to a diameter of 8 meters or more); when it is used as a buried pipe, the force sharing effect of the pipe and the soil is utilized, and the concrete and the concrete inside thereof are mainly subjected to the pressure. When the diameter is too large (D>4m), the buried soil can reach a depth of 10 to 35 meters.

A. Prepare the main steel strip and the auxiliary inner steel strip;

B. The main steel strip 101 has a first pair of sides 107 and a second opposite side 108, and the main steel strip 101 is bent into a steel strip with a rib 102 along the first side of the main steel strip 101. 107 spacing, and the length of the second pair of sides 108, and forming a groove 103 with the main steel strip 101;

Embodiment 1: The inner wall completely covers the tube of the auxiliary inner steel strip

First, adjust the spiral tube forming machine to a suitable forming angle according to the diameter of the spiral welded steel pipe to be produced. Secondly, after the main steel strip 101 is subjected to rust removal and shot peening, it is rolled into a cross-sectional shape of a downward projection (quantity and size set according to actual conditions) having a regular pitch by a forming unit, in the present invention Referring to the "bumps 102", correspondingly, grooves 103 are formed over the ribs 102, and then the weld cuts 104 are machined on both sides of the main steel strip, as shown in Figures 1-3. Next, a number of plugged steel strips 500 are placed over the notch locations of the groove 103 formed by the main steel strip, and the two are welded together to form a closed hollow cavity 300, as shown in FIG. On the upper surface of the main steel strip 101 and the sealing steel strip 500, a plurality of (the number is set according to actual conditions) auxiliary inner steel strips 200 are laid side by side, and the auxiliary inner steel strip 200 is unwound, leveled and trimmed. A strip of a specific metal material having a certain width after the process, a gap of 1-2 mm is left between the adjacent auxiliary inner strips 200, and at the same time, the sides of the auxiliary inner strip 200 are slightly shorter than the main strip 101. length. The gas shielded welding will be used to weld the adjacent auxiliary inner steel strip 200 to the same portion of the main steel strip 101 in the same position, and the both sides of the auxiliary inner steel strip 200 are welded to the main steel strip 101, before welding, in the auxiliary. The steel belt is opened with a small hole to extract the air and moisture in the interlayer, and then the small hole is sealed and smoothed, so that the rust prevention of the inner wall of the interlayer is facilitated, so that the main steel tube and the auxiliary inner steel tube are fitted together, as shown in Fig. 5-8. As shown, a composite steel strip is obtained in this way. The composite steel strip formed as described above is fed to a winding mechanism 700 (1#roll 701, 2#roll 702, 3#roll 703) for spiral winding, as shown in Figs. 9-10. At the same time as the spiral winding, the spiral welds 105 between the pipe joints and the pipe joints are welded by submerged arc welding, as shown in Fig. 11-12. At the same time, the parts to be welded between the pipe joints and the pipe joints are processed. The Y-shaped groove is suitable for different welding methods for different materials. Thus, the coil is formed into a bimetallic spiral welded steel pipe as shown in FIG. After the steel pipe spiral coiling welding reaches the required length, the steel pipe is cut, and the main steel strip 101 between the rib cuts 106 at both ends of the steel pipe is welded to the gap 600 of the auxiliary inner steel strip 200, as shown in FIG. Then, the concrete or reinforced concrete is filled in from the one end of the steel pipe incision 106 until it flows out from the other end of the steel pipe, and the hollow cavity is filled with concrete 400, as shown in FIG. 15; the bimetal of the present invention is finally completed. Spiral steel pipe is produced as shown in Figure 16.

Embodiment 2: The inner wall portion covers the pipe body of the auxiliary inner steel strip

First, adjust the spiral tube forming machine to a suitable forming angle according to the diameter of the spiral welded steel pipe to be produced. Secondly, after the main steel strip 101 is subjected to rust removal and shot peening, it is rolled into a certain pitch gauge through a forming unit. The cross-sectional shape of the downward projection (the number and the size are set according to actual conditions) is referred to as "the rib 102" in the present invention, and correspondingly, the groove 103 is formed above the rib 102, and then in the main steel strip. The welded section 104 is machined on both sides. Next, a number of the blocked steel strips 500 are laid at the notch positions of the grooves 103 of the main steel strip, and the two are welded to form a closed hollow cavity 300, thus obtaining a composite steel strip. The composite steel strip formed as described above is fed to a winding mechanism 700 (1#roll 701, 2#roll 702, 3#roll 703) for spiral winding. At the same time of spiral winding, the spiral welds 105 between the pipe joints and the pipe joints are welded by submerged arc welding, and at the same time, the portion to be welded between the pipe joints and the pipe joints is processed into a Y-shaped groove, which is advantageous. Different materials use different welding methods. The roll is thus formed into a bimetallic spiral welded steel pipe. The auxiliary inner steel strip is then welded to the lower half of the inner wall of the steel pipe, that is, below the water level line. After the steel pipe spiral coil welding reaches the required length, the steel pipe is cut, and the main steel strip 101 between the rib cuts 106 at both ends of the steel pipe is welded to the gap 600 of the auxiliary inner steel strip 200. Then, the concrete or reinforced concrete is filled in from the one end of the steel pipe at the end of the steel pipe to the inside of the steel pipe until the other end of the steel pipe is out of the rib cut 106, the hollow cavity is filled with the concrete 400; finally, the bimetallic spiral steel pipe of the invention is finished, as shown in the figure 17 is shown.

Claims

A bimetallic spiral steel pipe, comprising: a pipe body (100), the surface of the pipe body (100) extending outward to form a rib (102) spirally disposed along an outer wall of the pipe, the rib (102) and The surface of the pipe body (100) forms a groove (103) and is provided with an auxiliary inner steel strip (200) covering the groove of the groove (103), and the groove (103) and the auxiliary inner steel strip (200) A hollow cavity (300) is formed therebetween, and the hollow cavity (300) is filled with concrete (400).
The bimetallic spiral steel pipe according to claim 1, characterized in that the auxiliary inner steel strip (200) covers the entire inner wall of the pipe body (100).
The bimetallic spiral steel pipe according to claim 1, characterized in that a plug for sealing the groove of the groove (103) is further disposed between the auxiliary inner steel strip (200) and the groove (103). Steel strip (500).
A bimetallic spiral steel pipe, comprising: a pipe body (100), the surface of the pipe body (100) extending outward to form a rib (102) spirally disposed along an outer wall of the pipe, the rib (102) and The tube body (100) forms a groove (103) and is provided with a sealing steel strip (500) covering the groove of the groove (103), between the groove (103) and the sealing steel strip (500) A hollow cavity (300) is formed, and the hollow cavity (300) is filled with concrete (400), and at the same time, an auxiliary inner steel strip (200) is disposed on the inner wall of the pipe below the water line.
The bimetallic spiral steel pipe according to claim 1 or 4, wherein the rib (102) has an omega shape, a groove shape, a wave shape, a semicircular shape, a parabolic shape or a trapezoidal shape.
The bimetallic spiral steel pipe according to claim 1 or 4, wherein the auxiliary inner steel strip (200) is made of special alloy steel, stainless steel, wear-resistant steel, aluminum or copper; and the pipe body (100) The material is carbon steel or stainless steel.
The bimetallic spiral steel pipe according to claim 1, wherein the pipe body (100) has a main steel strip (101) having at least one row of ribs (102) on one side and a groove (103) on the other side (101). And the auxiliary inner steel strip (200) for covering the notch of the groove (103) is spirally wound together.
The method of manufacturing a bimetallic spiral steel pipe according to claim 1, comprising the steps of:

A. Preparing the main steel strip (101) and the auxiliary inner steel strip (200);

B. The main steel strip (101) has a first pair of sides (107) and a second pair of sides (108), and the main steel strip (101) is bent into a steel strip with a rib (102), the rib ( 102) spaced along the first pair of sides (107) of the main steel strip (101), and consistent with the length of the second pair of sides (108), and forming a groove (103) with the main steel strip (101);

C. The auxiliary inner steel strip (200) is attached to the groove of the main steel strip groove (103) to form a composite steel strip, and the convex rib (102) and the auxiliary inner steel strip (200) are formed. Hollow cavity (300);

D, the composite steel strip is spirally wound to form a tube body (100) with a spiral hollow cavity;

E. Cut the pipe body (100) according to the required length, and weld the gap between the main steel strip (101) and the auxiliary inner steel strip (200) at the slit of the convex rib (102) at both ends of the pipe body (100) (600) ;

F. pouring concrete (400) from the slit of the rib (102) at one end of the pipe body (100) until the concrete (400) flows out from the slit of the rib (102) at the other end of the pipe body (100), the hollow cavity (300) is filled with concrete, which is finished.
The method for manufacturing a bimetallic spiral steel pipe according to claim 8, wherein in step C, the steel strip (500) is first attached to the notch of the main steel strip groove (103), and then sealed. The auxiliary steel strip (200) is attached to the steel strip (500) to form a composite steel strip, and then the steel tube is completed according to the AF step.