RU2251044C1 - Pipe with inner plastic shell - Google Patents

Abstract

FIELD: rigid pipes.

SUBSTANCE: pipe has bushings concentrically mounted at the pipe ends. The bushings are made of a metal, the concentration of carbon in which exceeds the carbon concentration in the metal of the pipe. The bushing surface, which is in a contact with the inner plastic shell, is provided with threaded bores.

EFFECT: enhanced reliability.

1 cl, 1 dwg

Description

The invention relates to the manufacture of coated pipes and can be used to protect pipelines from corrosion in various industries: oil and gas, housing and communal services, coal, etc.

Known pipe with an inner plastic shell containing concentrically located at the ends of the pipe and fastened with it and between them perforated tread and protective sleeves with annular gaps filled with fusible material (USSR author's certificate No. 1572141, class F 16 L 9/02, publ. 11/15/94).

The disadvantage of this design is that the manufacturing process of protective sleeves is very time-consuming and more than 50% of the metal goes into shavings. In addition, the tread bushings quickly fail due to contact corrosion, since the transported fluid enters through the perforation holes into the contact zone of the tread bushings with the metal of the protective bushings and pipes and galvanic vapor is formed, causing electrochemical corrosion.

Known pipe with an inner plastic shell containing concentrically located at the ends of the pipe and fastened with it prefabricated protective sleeve made and installed with a gap and fastened to each other rings, and the end edges of the inner rings are offset relative to the outer rings, and the edges of the outer rings are bent into the pipe under an angle of 30-40 ° to the axis of the pipe (RF patent No. 2027939, class F 16 L 9/02, publ. 01.27.95).

The disadvantages of this pipe design are the high energy, labor and material costs in the manufacture of protective sleeves and when they are installed at the ends of the pipe. In addition, this pipe design does not provide reliable protection of the joint against corrosion.

Closest to the proposed invention in technical essence is a pipe with an inner plastic sheath, including concentrically located at the ends of the pipe and fastened with her sleeves made of metal with a carbon content not exceeding the carbon content in the metal of the pipe, and on the surface of the sleeves a tread coating is applied material, for example, based on zinc or aluminum (RF patent No. 2171945, class F 16 L 9/02, publ. 2001.08.10 - prototype).

The use of metal sleeves with a carbon content not exceeding the carbon content in the pipe metal helps to protect the pipe joint from corrosion, since the lower the carbon content in the metal of the sleeves, the higher their corrosion resistance.

However, the pipe connection is weakened, as low-strength steels and alloys have to be used as sleeve metal. In addition, the configuration of the grooves of the sleeve does not ensure the tightness of the contact of the plastic shell and the sleeve, which may entail the penetration of the transported medium under the plastic shell to the body of the metal pipe. All this reduces the reliability of the connection of pipes with the inner plastic shell.

The objective of the invention is to increase the reliability of the connection of the pipes with the inner plastic shell.

The problem is solved in that the pipe with an inner plastic sheath, including bushings concentrically located at the ends of the pipe and fastened with it, according to the invention, contains bushings made of metal with a carbon content exceeding the carbon content in the pipe metal and having on the surface in contact with inner plastic sheath, grooves with threads on the surface of grooves.

A pipe with an inner plastic sheath may have an outer plastic sheath on the outer surface.

The features of the invention are:

1. pipe;

2. the inner plastic shell;

3. concentrically located at the ends of the pipe and sleeves bonded to it;

4. bushings made of metal with a carbon content exceeding the carbon content in the pipe metal;

5. the same, having on the surface of the sleeve in contact with the inner plastic shell, grooves with threads on the surface of the grooves;

6. on the outer surface, the presence of an outer plastic shell.

Signs 1-3 are similar to the prototype, signs 4, 5 are essential distinguishing features of the invention, sign 6 is a particular feature of the invention.

In FIG. The proposed design of the pipe with an inner plastic sheath is shown.

The inner plastic shell 2, the sleeve 3, made of a metal with a carbon content exceeding the carbon content in the metal of the pipe 1, and having on the surface of the sleeve 3 in contact with the inner plastic shell 2, the grooves 4 with a thread 5 are located and bonded to each other in a pipe 1 on the surface of the grooves 4.

The pipe is collected in the following sequence. An inner plastic shell 2 is introduced into the pipe 1. Inside the ends of the pipe 1, the ends of the plastic shell 2 are removed to a length at which the material of the plastic shell 2 would not be destroyed by the heat of welding. Install a sleeve 3 made of metal with a carbon content exceeding the carbon content in the metal of the pipe 1, and having on the surface of the sleeve 3 in contact with the inner plastic shell 2, grooves 4 with thread 5 on the surface of the grooves 4. The sleeve 3 is expanded (increase in diameter ), as a result of which the sleeve 3 is fixed to the inner surface of the pipe 1 while jamming the end of the plastic shell 2 between the inner end of the sleeve 3 with grooves 4 and the thread 5 on the surface of the grooves 4 and the inner surface of AEC pipe 1.

In a similar way prepare the second end of the pipe 1.

Pipes 1 with a plastic shell 2 and a sleeve 3 are connected by welding, where the ends of the sleeves 3 of the pipes 1 form a single weld.

Due to the use of a sleeve made of metal with a carbon content exceeding the carbon content in the pipe metal, it becomes possible to use a sleeve of metal of greater strength than the pipe body. For example, a sleeve of steel 20 is used with a pipe of steel 10. Due to the grooves and threads on the surface of the grooves, it is possible to increase the contact area of the plastic shell, for example of polyethylene, and the sleeve, for example, of steel 20, and increase the penetration depth of the sleeve in the plastic shell, which predetermines increased tightness of the connection. All this in general leads to an increase in the reliability of the connection of pipes with the inner plastic shell.

The number of grooves can be at least 1.

As the thread can be used any thread, in particular, formed due to the passage of the surface of the groove through passage cutter.

To increase the corrosion resistance of the sleeve can be coated with protective coatings, for example galvanic.

On the outer surface of the pipe with the inner plastic shell, it is possible to apply the outer plastic shell, for example, of polyethylene, polypropylene, polyvinyl chloride, etc. by melt deposition, compression with a plastic stocking, polymer powder melting, etc.

The application of the proposed technical solution will improve the reliability of the connection of pipes with the inner plastic shell.

Claims (2)

1. A pipe with an inner plastic shell, including sleeves concentrically located at the ends of the pipe and fastened with it, characterized in that the sleeves are made of metal with a carbon content exceeding the carbon content in the pipe metal and have on the surface in contact with the inner plastic shell, grooves and threads on the surface of the grooves. 2. The pipe with an inner plastic shell according to claim 1, characterized in that on the outer surface has an outer plastic shell.