A threaded steel pipe and a preparation method thereof

Abstract

The present invention discloses a threaded steel pipe and a preparation method thereof. The threaded steel pipe is spirally wound from a corrugated steel strip with flanges on both sides in a flanged bite manner. A liquid rapid-setting anti-corrosion coating is filled in the bite groove formed by the upper flange and the lower flange, and the liquid rapid-setting anti-corrosion coating overflows the groove opening; a fiber rope is provided in the liquid rapid-setting anti-corrosion coating; anti-corrosion coatings are provided on the inner and outer walls of the threaded steel pipe; during processing, a continuous fiber rope with a liquid rapid-setting anti-corrosion coating is brought into the groove of the flange and is tractioned along with the rolling of the pipe body; after the bite is rolled, the liquid rapid-setting anti-corrosion coating fills the entire bite groove and overflows, and the anti-corrosion coatings on the inner and outer walls and the liquid rapid-setting anti-corrosion coating in and overflowing from the bite groove are melted and solidified into one body. The present invention solves the problems of anti-corrosion and sealing at the bite of the threaded steel pipe at the same time, and the anti-corrosion and sealing structure of the threaded steel pipe body has continuity and no dead angle for anti-corrosion.

Description

[0001] This application claims the priority of the invention application with the application number 2021112252766 and the invention title of "A threaded steel pipe and its preparation method" filed on October 21, 2021, the entire content of which is incorporated herein by reference. Technical Field

[0002] The present invention relates to a threaded steel pipe and its preparation method. Background Art

[0003] Threaded steel pipes are often used as drainage pipes, which are generally made by helically winding galvanized corrugated steel strips with a locked joint. However, the anti-corrosion problem of the locked joint structure has always been difficult to solve: 1. Due to the very high rolling pressure at the locked joint, the galvanized layer peels off and delaminates seriously; 2. The ends of the side of the raw material steel strip are sheared and have no galvanized layer; 3. After the threaded steel pipe is wound, when applying a plastic anti-corrosion coating to the entire pipe body, it is difficult to implement anti-corrosion inside the locked joint, and the plastic anti-corrosion coating may crack at the locked joint seam after being used for a period of time, and water will enter the locked joint. Thus, in actual engineering applications, the locked joint of the threaded steel pipe often rusts. In addition, the locked joint of the threaded steel pipe is not completely sealed, and water leakage is very common in actual use. The anti-corrosion and sealing of threaded steel pipes are technical problems to be solved urgently. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a threaded steel pipe with excellent anti-corrosion and sealing performance, and the second object of the present invention is to provide a preparation method for the threaded steel pipe.

[0005] Technical Solution: The threaded steel pipe described in the present invention is helically wound by corrugated steel strips with flanges on both sides in a flange-locked manner, and a liquid quick-setting anti-corrosion coating is filled in the locking groove formed by the upper flange and the lower flange, and the liquid quick-setting anti-corrosion coating overflows the groove opening.

[0006] This technical solution solves the anti-corrosion problem at the locked joint of the threaded steel pipe by filling a liquid quick-setting anti-corrosion coating in the locking groove, and at the same time realizes the full sealing at the locked joint of the threaded steel pipe. The overflow of the liquid quick-setting anti-corrosion coating from the groove opening can ensure the effectiveness of anti-corrosion and sealing at the locking position. This threaded steel pipe can not only be used as a drainage pipe without internal pressure, but also be used for drainage pipes with internal pressure and maintain good water leakage prevention performance.

[0007] Furthermore, anti-corrosion coatings are provided on the inner and outer walls of the threaded steel pipe, and the anti-corrosion coatings on the inner and outer walls are integrated with the liquid quick-setting anti-corrosion coating, so that the anti-corrosion and sealing structure of the threaded steel pipe body has continuity and ensures no dead angle in anti-corrosion.

[0008] Furthermore, the liquid quick-setting anticorrosive coating and the inner and outer wall anticorrosive coatings are made of epoxy resin materials, which can solidify quickly and can be hot-melted. The water contains silt and sand, and the galvanized layer is not wear-resistant. The epoxy resin materials have excellent wear resistance, which can solve the problems of corrosion prevention and silt and sand wear at the same time. Moreover, the surface of the coating formed by the epoxy resin materials is relatively smooth, resulting in a small flow resistance of the pipeline.

[0009] Furthermore, a fiber rope is provided in the liquid quick-setting anticorrosive coating, and the fiber rope is saturated or wrapped with the liquid quick-setting anticorrosive coating.

[0010] Furthermore, the material of the fiber rope is high molecular fiber or glass fiber.

[0011] Furthermore, the fiber rope is in a flat strip or film structure, so that it is easy to adhere to the inner wall of the bite hem.

[0012] The present invention also protects a preparation method of a threaded steel pipe. When the threaded steel pipe is rolled, a continuous fiber rope with a liquid quick-setting anticorrosive coating is brought into the groove of the hem and is tractioned along with the rolling of the pipe body; after the bite is rolled and pressed, the liquid quick-setting anticorrosive coating fills the entire bite groove and overflows. This preparation method can be conveniently applied to the existing threaded steel pipe production line.

[0013] Furthermore, the fiber rope is supplied by a fiber rope roll and is released by a roller wire feeding mechanism, and is immersed in a coating tank filled with the liquid quick-setting anticorrosive coating during the process. In this way, it can well ensure the continuous supply of the fiber rope with the liquid quick-setting anticorrosive coating, meet the continuous production of the threaded steel pipe, and improve the production efficiency.

[0014] Furthermore, the inner and outer walls of the threaded steel pipe are sprayed with anticorrosive coatings, and the inner and outer wall anticorrosive coatings and the liquid quick-setting anticorrosive coating in and overflowing from the bite groove are hot-melted and solidified into one body. As mentioned above, this can make the anticorrosive and sealing structure of the threaded steel pipe body continuous and ensure no dead angle in anticorrosion.

[0015] Furthermore, the inner and outer wall anticorrosive coatings are sprayed by electrostatic spraying, and a coil induction heating device is used to heat the threaded steel pipe circumferentially during hot melting. The thickness of electrostatic spraying is controllable. Taking epoxy resin as an example, the general thickness is not less than 300μm, which is several times the thickness of the galvanized layer, and the wear resistance is greatly improved. The coil induction heating device has a fast heating speed. The application of electrostatic spraying and the coil induction heating device can meet the anticorrosive processing of the threaded steel pipe on the threaded steel pipe production line, greatly improving the production efficiency.

[0016] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: The present invention can solve the anti-corrosion and sealing problems at the bite of the threaded steel pipe at the same time. After the inner and outer wall anti-corrosion coatings and the liquid quick-setting anti-corrosion coating in the bite groove and the overflowing one are melted and solidified into one body, the anti-corrosion and sealing structure of the threaded steel pipe body can also have continuity, ensuring no dead angle in anti-corrosion. Description of the Drawings

[0017] Figure 1 is a schematic structural view of the bite of the threaded steel pipe;

[0018] Figure 2 is a schematic rolling view of the threaded steel pipe;

[0019] Figure 3 is a schematic view of the fiber rope paying-off. Specific Embodiments

[0020] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments.

[0021] As Figures 1 to 3 shown, a threaded steel pipe is spirally rolled by a corrugated steel strip 6 with flanges on both sides in a flange-biting manner. The bite groove formed by the upper flange 1 and the lower flange 2 is filled with a liquid quick-setting anti-corrosion coating 3, and the liquid quick-setting anti-corrosion coating 3 overflows the groove opening. A fiber rope 10 is provided in the liquid quick-setting anti-corrosion coating 3. An inner wall anti-corrosion coating 5 is provided on the inner wall of the threaded steel pipe, and an outer wall anti-corrosion coating 4 is provided on the outer wall. The inner and outer wall anti-corrosion coatings are integrated with the liquid quick-setting anti-corrosion coating 3 in the bite groove and the overflowing one. In this embodiment, the liquid quick-setting anti-corrosion coating 3 and the inner and outer wall anti-corrosion coatings are made of epoxy resin. The fiber rope 10 is made of fiberglass, and the fiber rope 10 is a flat strip-shaped fiber rope.

[0022] See Figure 2 , a preparation method of a threaded steel pipe. First, the steel strip is subjected to surface cleaning treatment (such as degreasing and rust removal), then the surface of the steel strip is roughened (such as knurling and sandblasting), and then the steel strip is rolled into a continuous corrugated steel strip 6 with pre-flanges on both sides by a corrugated roll 7, and then sent to a special device for spiral rolling and bite connection. Before the corrugated steel strip 6 enters the bite, two continuous fiber ropes 10 soaked with the liquid quick-setting anti-corrosion coating are sent to the bottom of the grooves of the pre-flanges on both sides of the bite, and enter the bite together with the pre-flanges on both sides of the bite. After the bite is rolled and pressed, the space of the flange groove is compressed, and the coating fills the entire bite groove and overflows, realizing the anti-corrosion and sealing at the bite. The fiber rope 10 is tractioned along with the bite of the pipe body and is synchronized with the rolling speed of the pipe body. See Figure 3 , the fiber rope 10 is supplied by a fiber rope reel 9 and released by a roller pay-off mechanism. During the process, it is immersed in a coating tank 8 filled with the liquid quick-setting anti-corrosion coating, and then the fiber rope 10 soaked with the coating is pulled out of the coating tank 8 and sent to the flange groove.

[0023] Powdery epoxy resin coating is sprayed on the inner and outer walls of the threaded steel pipe through an electrostatic spray gun, and the pipe body is heated by a coil induction heating device surrounding the threaded steel pipe, so that the anticorrosive coatings on the inner and outer walls are melted and solidified into one body with the coating overflowing inside and at the seams of the seamed structure. It should be particularly noted that electrostatic spraying needs to be carried out after the threaded steel pipe is rolled and formed and cut, because sparks will be generated when the pipe body is cut. If the pipe body cutting and electrostatic spraying are carried out simultaneously, powder explosion may be caused.

Claims

1. A preparation method of threaded steel pipe, characterized in that: The threaded steel pipe is formed by spirally winding a corrugated steel strip (6) with flanges on both sides in a flanged bite manner. A liquid quick-setting anti-corrosion coating (3) is filled in the bite groove formed by the upper flange (1) and the lower flange (2), and the liquid quick-setting anti-corrosion coating (3) overflows from the groove opening; a fiber rope (10) is provided in the liquid quick-setting anti-corrosion coating (3). The preparation method of the threaded steel pipe includes: when the threaded steel pipe is wound, a continuous fiber rope (10) with a liquid quick-setting anti-corrosion coating is brought into the grooves of the upper and lower flanges and is tractioned along with the winding of the pipe body; after the bite is rolled, the liquid quick-setting anti-corrosion coating fills the entire bite groove and overflows.

2. The preparation method according to claim 1, characterized in that: Anti-corrosion coatings are provided on the inner and outer walls of the threaded steel pipe, and the inner and outer wall anti-corrosion coatings are integrated with the liquid quick-setting anti-corrosion coating (3).

3. The preparation method according to claim 2, characterized in that: The liquid quick-setting anti-corrosion coating (3) and the inner and outer wall anti-corrosion coatings adopt epoxy resin materials.

4. The preparation method according to claim 1, wherein: The material of the fiber rope (10) is high molecular fiber or glass fiber.

5. The preparation method according to claim 1, characterized in that: The fiber rope (10) has a flat strip-shaped or film-shaped structure.

6. The preparation method according to claim 1, wherein: The fiber rope (10) is supplied by a fiber rope reel (9) and is released by a roller wire-releasing mechanism, and is immersed in a paint tank (8) filled with a liquid quick-setting anti-corrosion coating during the process.

7. The preparation method according to claim 1, characterized in that: Anti-corrosion coatings are sprayed on the inner and outer walls of the threaded steel pipe, and the inner and outer wall anti-corrosion coatings and the liquid quick-setting anti-corrosion coating in the bite groove and the overflowing one are melted and solidified into one body.

8. The preparation method according to claim 7, characterized in that: The inner and outer wall anti-corrosion coatings are sprayed by electrostatic spraying, and a coil induction heating device is used to heat the threaded steel pipe circumferentially during hot melting.

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