RU2326287C1 - Facing process of internal surface of metallic tube by polymer shell - Google Patents

Abstract

FIELD: pipeline transportation.

SUBSTANCE: invention is referred to field of pipeline transportation and can be used in a pipe lines construction in the oil-extracting and petrochemical industry, and also in housing and communal services system. Into a metallic tube a polymer shell is injected, the shell ends is affixed to a tube by pinching collars by radial strain of collars. For facing the shell with the external diameter exceeding an inside diameter of a tube is used. Before inputting in a tube the shell is stretched in an axled direction until its external diameter does not become less than inside diameter of a tube, then a shell extension is taken out, therefore its external diameter is elastically restored and the shell tightly fit to an internal surface of a tube.

EFFECT: improvement of quality of tubes facing.

3 dwg

Description

The invention relates to the field of pipeline transport and can be used in the construction of pipelines in the oil and petrochemical industries, as well as in the housing and communal services system.

A known method of lining metal pipes with thermoplastic material (US Pat. RF No. 2100687, F16L 58/10, published in Bull. No. 36 dated 12/27/1997), including the introduction of a blank in the form of a sleeve of thermoplastic material, pressing the blank to the surface pipe overpressure in the cavity of the workpiece and heating the workpiece with the movement of the heating zone. Previously, before being introduced into the pipe, the workpiece is subjected to reversible drawing while heating with decreasing diameter, the workpiece is deformed by cooling to room temperature and the workpiece is pressed to the pipe when it is heated to a temperature not lower than the temperature of the workpiece’s reversible drawing. Simultaneously with the hood, the workpiece is bent in the radial direction along the entire length in one or more places with subsequent fixation of the deflections. In this case, use a workpiece with an outer diameter equal to a small tolerance (1-2 mm) of the smallest diameter of the metal pipe.

The disadvantages of this method include:

- the inability to eliminate the gap between the pipe and the preform of thermoplastic material during cooling after pressing the preform to the pipe at a temperature of reversible drawing due to thermal shrinkage of the thermoplastic material;

- the complexity and complexity of the process;

- the energy intensity of the process due to repeated heating of the workpiece from a thermoplastic material.

The closest in technical essence and the achieved result to the proposed one is a method of protecting a steel pipe from corrosion (US Pat. RF 2217651, F16L 8/02, published in Bul. No. 33 of 11/27/2003), including lining the inner surface of the pipe with a plastic sheath lining the inner surface of the pipe ends with corrosion-resistant steel and attaching the ends of the shell to the pipe with jamming rings by radial deformation of the rings. In this case, the lining of the pipe is carried out by pulling into it a plastic shell with its preliminary drawing through a compression die.

The disadvantage of this method is the possibility of a gap between the polyethylene sheath and the steel pipe due to the large tolerances on the inner diameter of the pipe. To eliminate this gap, it is necessary that the initial outer diameter of the polyethylene sheath be greater than or equal to the inner diameter of the pipe. If the deformation of the shell when dragging it through the compression die is in the elastic zone of its material, then the restoration of the outer diameter of the shell will occur immediately after passing through the die, which will not allow the pipe lining process to occur due to the possibility of breaking the polyethylene shell. If the deformation is in the ductility zone of the sheath material, its outer diameter will not take its initial value, which will lead to the formation of a gap between the polyethylene sheath and the pipe. The presence of such a gap can lead to breaks and collapse of the plastic shell inside the steel pipe during operation.

The objective of the invention is to improve the quality of the lining of a metal pipe with a polymer shell by eliminating the gap between the shell and the pipe.

The problem is solved in that in the method of lining the inner surface of the metal pipe with a polymer shell, comprising introducing a polymer shell into the metal pipe and attaching the ends of the shell to the pipe with pinching rings by radial deformation of the rings, according to the invention, a polymer shell with an outer diameter exceeding the inner diameter of the pipe is used for facing , before entering the pipe, the shell is subjected to longitudinal tension to a value such that the outer diameter of the shell becomes Chez internal diameter of the pipe is introduced into the tube shell in an expanded state, after which the tensile load is removed.

Figure 1 shows a polymer shell in a stretched state before entering into a metal pipe.

Figure 2 shows the polymer shell in a stretched state inside a metal pipe.

Figure 3 shows a metal pipe with an inner lining.

The method is as follows.

The ends of the polymer shell 1 (see FIG. 1) are cut into petals, with the help of which conical mandrels 2 are installed at the ends. The minimum outer diameter of the polymer shell 1 is larger than the maximum inner diameter of the steel pipe, taking into account tolerances of 0.2-1 mm. The polymer shell 1 is stretched in the axial direction within its elastic deformation using conical mandrels 2 mounted on the ends. Stretching is carried out until the outer diameter of the polymer shell becomes equal to or less than the inner diameter of the metal pipe. In the extended state, the polymer shell 1 is freely introduced into the metal pipe 3 (see Fig. 2), which has undergone the operation of cleaning the inner surface. After installing the polymer sheath 1, the axial load is removed, the conical mandrels 2 are dismantled, the ends of the polymer sheath 1 are cut in the metal pipe 3 to a length exceeding the zone of its thermal destruction under the action of the heat of welding formed when the pipes are joined together (see Fig. 3). After removing the axial load, the shell 1 is pressed without a gap to the inner surface of the pipe 3 due to the elastic forces of the polymer material. At the ends of the metal pipe 3, internal pinching rings 4 are installed. By radially deforming the rings, a shell device (not shown) is attached to the ends of the shell to the metal pipe.

The proposed method reduces the complexity of pipe lining, improves the quality of the lining by eliminating the possibility of breakage and collapse of the polymer shell inside the steel pipe during operation due to the absence of a gap between the pipe and the shell, which will increase the trouble-free operation of the pipeline.

Claims (1)

A method of lining the inner surface of a metal pipe with a polymer shell, comprising introducing a polymer shell into the metal pipe and attaching the shell ends to the pipe with pinching rings by radial deformation of the rings, characterized in that a polymer shell with an outer diameter exceeding the inner diameter of the pipe is used for lining before entering the sheath pipe is subjected to longitudinal tension to a value such that the outer diameter of the sheath becomes smaller than the inner diameter of the pipe, introducing t the shell into the pipe in a stretched state, after which the tensile load is removed.

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