RU2611218C1 - Method for sealing pre-insulated pipes joint - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method comprises placing the heat-shrinkable sleeve made from sewn translucent plastics, over one of the jacket pipes of the abutting pre-insulated pipes, and applying an adhesive material having a colour different from the colour of the jacket pipe, to the outer surface of the both jacket pipes. After welding the abutting internal working pipes, the sleeve is moved onto the second jacket pipe and heated, providing heat shrinkage and the formation of the adhesive compound, and after heat shrinking and forming the compound "sleeve-jacket pipes", the cavity between the butts of the insulation layers, the working pipes and the sleeve is filled with the foaming composition. Visual inspection of forming the permanent junction of the sleeve and the jacket pipes is performed by means of the sleeve of the sewn translucent plastic.

EFFECT: provision of hydraulic and mechanical protection of insulation in the permanent butt joints of piping systems.

9 cl, 5 dwg

Description

The invention relates to the field of construction and reconstruction of pipeline transport used in the power industry, housing and communal services, the oil and gas industry, and is intended to provide hydraulic and mechanical insulation protection in one-piece butt joints of piping systems, for example, in thermally waterproofed.

A technical solution is known according to the patent US 5869153 (A) - 1999-02-09, IPC B29K 105/02, B29C 61/06, B29K 105/16, B29K 105/32, according to which a hollow cylindrical product containing at least at least one transparent part and one opaque part, while the transparent part is presented in the form of one or more strips and is made by molding or extrusion of a polymeric material having a shape memory.

The known device is non-technological due to the presence of transparent and opaque parts in the structure, the use of two materials (transparent and opaque), which necessitates the use of specialized, expensive equipment in the manufacture of the product and allows you to control only the longitudinal arrangement of the joined elements. In addition, the presence of an opaque part does not allow to visualize, for example, the formation and polymerization of the insulating layer, the transverse placement along the entire length of a different-colored adhesive material / or embedded heating element, does not ensure tightness, does not exclude errors associated with deviation of temperature conditions when the adhesive material / or welding with an embedded heating element (underheating / overheating), there is no possibility of quickly detecting errors for on-site repairs, etc.

Closest to the claimed is a method of connecting two pre-insulated pipes (technical solution EP 0114660 from 01/19/1983, IPC F16L 59/20, B29C 44/12), including the location of two pre-insulated pipes so that the end face of one working pipe is installed end-to-end another working pipe, then welding or other one-piece connection of the adjacent ends of the working pipes, the location of the coupling on the outer surface of the pre-insulated pipes in such a way as to close the gap between their insulation layers and, if available, outer shells, to form an annular cross-sectional space bounded by the uninsulated ends of the inner pipes, the end surfaces of the insulating layers and the inner surface of the coupling, filling said space of the annular cross-section with an insulating material, for example by filling with liquid or mixture liquids introduced into the named space for the formation of foam, filling the space and forming a rigid mass y. According to this technical solution, the hollow sleeve is made of transparent material, which allows visual inspection of the process of filling the coupling space with heat-insulating material, the formation and distribution of the heat-insulating layer, and in case of voids in the heat-insulating layer to repair it.

However, to ensure long-term operation of the pipeline, it is not enough to provide only visual control over the insulation process. It is necessary, before carrying out this process, to first create optimal and high-quality conditions that guarantee the tightness of the connection between the coupling and the pipe-shell and, thus, ensure the reliability and durability of the pipeline system as a whole. Unfortunately, the absence of these conditions leads to negative consequences, such as depressurization of the joint, wetting of the insulation layer, reduction in the life of the unit and pipeline, unnecessary losses and energy costs.

This feature is associated with the presence of a gap between the outer surface of the pipe shells of the connected pre-insulated pipes and the inner surface of the coupling. For the described technical solution, the gap is characterized by unevenness due to the action of gravity on the loose coupling, which is freely supported by the connected ends of the previously insulated pipes, which leads to the absence of a gap at the top of the coupling and its increase in the lower part of the coupling. Thus, the creation of an equally strong and sealed one-piece connection between the coupling and the sheath is difficult.

The next and main disadvantage is the low reliability of sealing the connection, which is carried out on top, at the ends of the coupling, heat-shrinkable tapes. Axial displacements of the pipeline associated with a change in the temperature schedule of the coolant lead to the fact that the soil, in contact with the heat-shrinkable tape, bends its edges over time, which leads to the penetration and wetting of the insulation layer through the above ground water gaps, to increase the thermal conductivity of the insulation , an increase in energy losses associated with heating the coolant, corrosion of the working pipe and reducing the durability of the pipeline system.

The claimed invention relates to one of the stages of installation of a pipeline of previously insulated pipes. A pre-insulated pipe consists of a steel (or polymer) inner working pipe (hereinafter referred to as the working pipe) with centering supports installed on it, an external sheath pipe (hereinafter referred to as the sheath pipe), an operational remote control system (hereinafter referred to as SODK) and an insulation layer, usually made of polyurethane foam. Both ends of the working pipe extend beyond the shell pipe and the insulation layer, i.e. not insulated, which is necessary for future welding (technological indentation), and a coupling is installed above this section after welding the working pipes.

The problem solved by the invention is to increase the reliability of hydraulic and mechanical protection of joints of joints of previously insulated pipes, providing the possibility of visual non-destructive testing of an integral connection “heat-shrinkable sleeve - pipe-shell” at various stages of formation of the connection (sealing, formation and polymerization of the insulation layer).

Improving the reliability of pipelines within weaknesses, such as butt joints, positively affects the technical characteristics of pipelines, increases the life of the pipeline, thereby reducing operating costs for maintenance, repair, maintenance and other maintenance costs.

The problem is solved by using the proposed heat-shrinkable sleeve, completely made of a translucent material with shape memory, with the organization of sealing conditions (heating for heat shrinkage), as well as conditions that allow visual and non-destructive testing of the adhesive connection between the heat-shrinkable sleeve and the sheath pipe due to the light transmission of the material couplings, through which you can see the place of formation of one-piece connection of the clutch and pipe shells of pre-insulated pipes, while for Imaging blegcheniya adhesive bond formed by the adhesive material having a color different from the color of jacket pipe.

In the claimed invention, a coupling is used, which is a hollow cylinder made of translucent plastic, for example polyolefins, with a shape memory effect (heat-shrinkable), long enough to cover the insulated area (joint) with inlets to grip the ends of the connected elements (pipe shells), in this case, the coupling pre-installed on top of the junction on one of the shell pipes after welding the working pipes and cooling the welding places is moved to the working position so that the coupling overlaps with the m shell-shells near their ends. A layer of adhesive material having a color different from the color of the shell pipes, predominantly of a contrasting color or any other color or shade released on the surface of the shell pipe, is preliminarily applied to the pipe tubes. Then the sleeve is heated (create conditions for heat shrinkage) and seated. Adhesive material, receiving energy from heated products (couplings and shell pipes), is activated and evenly distributed between the connected surfaces - on the inner surface of the translucent coupling and the outer surface of the shell pipe, providing an airtight connection after cooling, and the performer of the work - the transmission of the coupling and the difference in the colors of the adhesive material and the material of the sheath pipe creates the conditions for visual non-destructive control of the location, distribution and activation of the adhesive mother Ala at the junctions. In this case, in case of detection by the contractor of defects associated with the activation and distribution of adhesive material, it is possible to correct the defect, i.e. carry out operational repairs.

To protect the ends of the translucent coupling at the joints, including to prevent bending of the edges of the coupling, as well as to reduce the negative effects of friction forces of the soil, the joints of the coupling with the outer surface of the pipe shells can be closed with a heat-shrinkable tape over the overlapping joint of the coupling with the outer surface of the pipe .

Additionally, the translucent sleeve may have at least one process opening for supplying components of an insulating material, air and reaction gases, and its inner surface may be partially or completely coated with an adhesive material. Mostly the coupling has a circular cross section, and its length lies in the range from 0.1 m to 1 m.

The technical result achieved by the invention is to preserve the properties and characteristics of insulation in the places of butt joints for a long period of time and with an increase in the life of the joint and, accordingly, pipeline systems due to the formation of a reliable tight connection "heat-shrinkable sleeve-pipe-sheath" formed shrink sleeve and additionally with an adhesive joint, which is due to the following:

1) while maintaining the ability to visually control the formation of the insulation layer, it is additionally possible to create and visual non-destructive testing of the one-piece adhesive joint “heat-shrinkable sleeve - pipe-sheath”;

2) the level of quality of the coupling-pipe-shell joint increases, due to visualization of the processes of coupling location, placement and activation of adhesive material. Identified defects in the joints are eliminated at the stage of formation of the adhesive joint by conducting immediate repair of defective places;

3) the technological process of sealing is reduced by eliminating the technological operation of crimping the joint;

4) due to the introduction of adhesive material between the heat-shrinkable sleeve and the outer pipe-sheath and their connection with an adhesive seam in combination with compression of the joints of the heat-shrinkable sleeve, the tightness of the joint and its operational reliability increase significantly;

5) due to the heat shrinkage of the coupling, the non-uniform gap arising under the action of gravity between the pipe-sheath and the coupling freely resting on the connected surfaces is compensated.

One of the features of pre-insulated pipelines is that the interconnected elements, which are thermally-insulated pipes and fittings, are manufactured in the factory under all necessary conditions, which makes them highly reliable.

The connection (installation) of the above elements with each other includes the necessary preparatory work, welding of working pipes, sealing, thermal insulation of the joint and is carried out mainly by construction or installation organizations at the facilities.

The complexity of these operations, the need for their implementation in the field, leads to the fact that the joints of a previously insulated pipeline are one of the most vulnerable places to depressurization. The situation is aggravated by the fact that during the operation of pipelines, a change in the temperature regime of the coolant causes significant fluctuations in the pipeline system, leading to axial movements of the pipeline in the soil layer, which leads to an increase in loads, especially in the joints of joints. These factors make it necessary to increase the requirements for ensuring the reliability and quality of the coupling of the coupling with the insulated pipe.

Despite the variety of couplings offered at present, their common feature is that sealing the joints of previously insulated pipes in a polymer shell with the help of such couplings is provided by one or a combination of technological methods: compression of the pipe surface due to the use of a sleeve with heat-shrink properties, connection for account of the adhesive layer in the contact of the coupling - pipe-shell, additional heat-shrinkable tapes from the ends of the coupling. The use of shrink sleeves in black leads to the appearance of initially invisible defects, such as shells and / or gas bubbles, an uneven distribution of adhesive, foreign inclusions at the joints, etc. These defects, being internal stress concentrators, do not go to the surface of the joints, and the absence of visual non-destructive testing significantly complicates their identification, all this limits the capabilities of the performers of these works, and defects can be detected only when process operations, such as crimping, which leads to additional costs.

Even in the case of using a translucent sleeve, for example, as in the closest analogue that allows you to track the formation of the insulation layer, there is no way to control the formation of the main connection between the sleeve and the sheath pipe, since the heat-shrinkable tapes, through which the connection is made, cover the overview of the joints, the most complicate the conditions for the contractor and do not provide visualization.

In another analogue, the coupling has transparent longitudinal stripes alternating with opaque, which also does not allow it to be used to fully visualize the formation of an annular seam, since only a part of the length of the adhesive seam can be seen. The inability to control significantly affects the reliability of the joint sealing of pre-insulated pipes and the operational properties of the entire pipeline.

The proposed method, including the use of a heat-shrinkable sleeve, made entirely of translucent plastic with shape memory, for hydraulic and mechanical protection of joints of joints of previously insulated pipes, in contrast to existing analogues, allows to obtain visual non-destructive testing performed by various known methods, for example, using a magnifier. Control becomes possible due to the combination of heat-shrinkable properties and light transmission in one product (sleeve), as well as through the use of contrasting and / or bright-colored adhesive material, which allows to distinguish the formed seam against the background of the sheath pipe, and will also help visually control the main technological operation " Joint sealing ”, namely, to observe the process of heat shrinkage and the quality of compression of the sleeve pipe sheath, to control the behavior, distribution and activation of the contrast adhesive, add or measure availability. This effect is unattainable when using the technical solution of the closest analogue despite the transparency of the coupling, in which the absence of heat-shrink properties does not allow, firstly, to make an integral adhesive connection “coupling - pipe-shell” without external compression of the coupling and visually control the formation of an integral ring connection.

An additional advantage of using translucent couplings is: prevention of insufficient / or excessive melting of the adhesive material.

The length of the proposed coupling should exceed the length of the insulated section (butt joint), which is caused by the peculiarity of the installation of the device, which is made over the pipe-shell and lap. At the same time, for the proposed coupling, its optimal length for different types of thermally insulated pipelines lies in the range from 0.1 m to 1 m, which allows you to close the joint to a sufficient degree for its reliable sealing and elimination of material overruns.

The materials for the coupling are mainly translucent plastics with a shape memory effect, including mesh (crosslinked) polymers, for example polyethylene, which is largely due to the wide distribution of heat-insulated pipelines with waterproofing in a polyethylene sheath pipe.

In order to increase the physicomechanical or operational properties, the materials from which the coupling is made can be filled, i.e. contain in its recipe known excipients, for example, an antistatic agent, a nucleator, a stabilizer for protection against ultraviolet radiation, etc.

Clutch blanks are made by various known methods, for example, by extrusion, injection molding, molding, and others.

In US Pat. No. 5,869,153 A, known from the prior art, a heat-shrinkable sleeve for sealing has transparent and opaque portions, which partially allows controlling the longitudinal arrangement of abutting elements, but is not intended for ring quality control of the connection of a heat-shrinkable sleeve with elements along the entire length with the formation of a permanent adhesive seam.

In the claimed invention, the heat-shrinkable sleeve is made entirely of translucent material, which, in combination with a contrast adhesive material having a color different from the color of the sheath pipe and the sleeve, allows to obtain a new property - to visualize (control) the sealing process in dynamics with the formation of an adhesive joint, thereby thereby ensure stable quality at one of the initial stages of the coupling-pipe-shell connection and, if necessary, correct possible defects.

A new combination of features characterizing the operation of the method, namely the use of a translucent heat-shrinkable sleeve and the selected color of the adhesive material, allows to achieve the above technical result. The heat-shrinkable sleeve allows not only to form a connection to the sheath pipe due to shrinkage due to heat shrinkage, but also to create conditions for the adhesive joint to be made without additional external devices due to heat shrinkage. Moreover, due to the chosen color of the adhesive material in combination with the property of the coupling material, such as transparency or translucency (for thin-walled couplings), and the absence of interfering visual crimping means, the entire process of the formation of the adhesive joint of the coupling with the pipe-sheath is effectively controlled, which together ensures the achievement of the above technical result. In addition, as in the closest analogue, during the implementation of the method, it is possible to monitor the formation of an insulating (heat-insulating) layer under the sleeve.

The essence of the claimed invention is illustrated by drawings and explanation to them.

FIG. 1 - joint pipe prior to placement of heat-shrinkable sleeve; adhesive tapes are installed over the jacket pipe.

FIG. 2 is an isometric view of the joint of pre-insulated pipes after heat shrinkage of the coupling.

FIG. 3 - connection sleeve-shell with a defect "shell" on the adhesive material, a local cutout, position A.

FIG. 4 - connection sleeve-shell with a defect in adhesive material - uneven seam, local cutout, position A.

FIG. 5 - connection sleeve-shell with defects in the form of accumulation of pores and foreign inclusions, local cutout, position A.

In the drawings, the positions indicated:

1 - inner working tube;

2 - outer pipe-shell;

3 - adhesive material;

4 - heat-shrinkable sleeve, made entirely of translucent material;

5 - insulating (heat-insulating) layer;

6 - tape of adhesive material;

7 - defect of the connection "heat-shrinkable sleeve - pipe-shell" in the form of a "shell";

8 - defect of the connection "heat-shrinkable sleeve - pipe-sheath" in the form of an uneven seam;

9 - defect of the connection “heat-shrinkable sleeve - pipe-shell” in the form of an accumulation of pores and foreign inclusions.

The method is as follows.

Pre-insulated pipes include an inner working tube 1, an outer sheath pipe 2, and an insulating layer 5.

In order to simplify the design images of the butt joint of pre-insulated pipes or fittings, other elements, such as centering supports, conductors of the insulation layer monitoring system (SODK), etc., are not conventionally shown.

During the installation of the pipeline, pre-insulated pipes are connected in series. Before joining the working pipes, a heat-shrinkable sleeve 4 in a protective case made of fully or partially translucent plastic with a shape memory effect is put on one of the joined pre-insulated pipes, having the sleeve 4 with a gap over the pipe shell 2 at some distance from the junction.

The diameter of the heat-shrinkable sleeve 4 before its heat shrinkage may exceed the diameter of the outer tube-shell 2, for example, by 1-50%, preferably by 1-30%. The heat-shrinkable sleeve 4 can be made with a wall thickness of up to 23.5 mm (usually no more than 20 mm), while a transparent material must be selected to enable visualization of the processes occurring under the sleeve. If the wall thickness of the heat-shrinkable sleeve 4 is small, not more than 1-5-10 mm, the sleeve can be made of white (or other color) opaque material.

Technological indentation of the working pipe 1 extends beyond the pipe-shell 2 and the insulating layer 5 mainly from 100 mm to 350 mm. The working pipes 1 are installed end-to-end and welded together to form an airtight integral connection. The pipe shell 2 and the ends of the insulation layer are located at a distance from each other, equal to the sum of the lengths of the technological indents of the joined working pipes 1.

After welding the working pipes 1 and confirming the tightness of the weld, additional work is carried out (cleaning the connected surfaces from dirt, degreasing, connecting the conductors of SODK, etc.).

For the connection "coupling - pipe-shell" by gluing on the prepared surface along the edges of the pipe shell 2 set (wrap around the entire diameter of the pipe shell 2) and fix the adhesive material 3. The adhesive material 3 is made in the form of a tape 6 and differs in color, or brightness, or hue of the color of the pipe-shell 2. The thickness of the adhesive material is in the range from 0.1 to 5 mm, preferably not more than 3 mm.

The preferred color of the pipe shell 2 is black.

Next, remove the protective cover from the coupling 4 and push it into the working position on the joint, while the light transmission of the coupling contributes to its exact location relative to previously fixed adhesive material tapes 3. The heat-shrinkable coupling 4 is positioned so that the coupling is mounted above the mating pipes-shells 2, above the layers adhesive material 3. By the action of heat, for example, a flame of a burner, the ends of the inner surface of the coupling 4 are heated and the adhesive material 3 is melted.

At the same time, the outer surface of the heat-shrinkable sleeve 4 is heated and “seated”. In this case, the heat-shrinkable sleeve 4 as a result of heat shrinkage tightly covers the outer surface of the pipe shells 2. The heat-activated adhesive material 3, made in the form of a tape, covered and compressed due to the heat shrinkage by the edges of the sleeve 4, is evenly distributed over the connected surface of the pipe-shells 2 and heat-shrinkable the coupling 4, forming, after cooling, a tight connection between the coupling 4 and the pipe shell 2. The use of the coupling 4 allows due to the fact that for the manufacture of the coupling taken translucent material mu Visual inspection in a non-destructive way to monitor the sealing process, and in case of defects detected, for example, by simple means, for example using a magnifying glass, repair the integral connection between the coupling 4 and the shell pipes 2.

The joints of the coupling 4 with the outer surface of the pipe shell 2 are closed by a heat-shrinkable tape that overlaps the joint of the coupling 4 with the outer surface of the pipe shell 2 near the end of the coupling 4. As a result, the connection of the coupling 4 with the pipe shell 2 is sealed twice. The first seam is formed by an adhesive material (glue seam), and the second is due to shrinkage of the heat-shrinkable tape, which prevents the coupling from bending along the edges and, as a result, protects the adhesive seam connecting the sleeve to the sheath pipe from mechanical action of external forces.

In FIG. 3, 4, 5 show possible defects of the permanent connection heat-shrinkable sleeve 4 - pipe-shell 2, which are easily detected by visual inspection if the invention is used to seal the joint of pre-insulated pipes using a transparent (translucent) sleeve and adhesive material 3 in the form of a tape having a different color compared to the shell pipe 2.

In FIG. 3 shows a joint defect heat-shrinkable sleeve 4 - pipe-shell 2 in the form of a "shell" 7 on the adhesive material 6.

In FIG. 4 shows the connection "coupling - pipe-shell" with a defect in the form of an uneven seam 8 on the adhesive material 6.

In FIG. 5 shows the connection heat-shrinkable sleeve 4 - pipe-shell 2 with defects in the form of accumulation of pores 9 and foreign inclusions on the adhesive material 6.

Claims (9)

1. A method of sealing the junction of pre-insulated pipes, consisting of an internal working pipe with centering supports installed on it, conductors of the operational-remote control system, an insulating layer and a sheath pipe, including placing the coupling on top of one of the pipe sheaths of the joined pre-insulated pipes, applying on the outer surface of both shell pipes of an adhesive material having a different color compared to the color of the shell pipe, a heat-shrinkable sleeve is used, fully made of translucent cross-linked plastic, after welding the joined internal working pipes, the coupling is moved axially towards the second sheath pipe and placed over the adhesive material of both shell pipes, then the coupling is heated to provide heat shrinkage and formation of an overlap of the coupling with the pipes due to heat shrinkage -shells, while the adhesive material is activated by heating the sleeve with the formation after its cooling of the permanent connection "heat-shrinkable sleeve-pipe-shell", and after it is finished I heat-shrink with the simultaneous formation of the adhesive connection “heat-shrinkable sleeve - pipe-sheath” through the hole in the sleeve fill the foamable composition of the cavity, limited by the uninsulated sections of the connected inner working pipes, the end surfaces of the insulating layers and the inner surface of the sleeve, then seal the hole, while conducting visual inspection for the processes of the formation of a permanent connection of the coupling with the shell pipes, the formation and polymerization of the insulating layer through the couplings of translucent plastic. 2. The method according to p. 1, characterized in that the adhesive material is made in the form of a tape wrapped around an outer pipe-shell. 3. The method according to p. 1, characterized in that the joints of the heat-shrinkable sleeve with the outer surface of the pipe shells are closed with a heat-shrinkable tape overlapping the joint of the heat-shrinkable sleeve with the outer surface of the outer pipe-shell near the end of the heat-shrinkable sleeve, and it is heat-shrink by heating. 4. The method according to p. 1, characterized in that the heat-shrinkable sleeve made of translucent plastic with a wall thickness of 1 ÷ 23.5 mm is made transparent. 5. The method according to p. 1, characterized in that the heat-shrinkable sleeve made of translucent plastic with a wall thickness of 1 ÷ 10 mm is made matte white. 6. The method according to p. 1, characterized in that the thickness of the adhesive material is from 0.1 to 5 mm 7. The method according to p. 1, characterized in that the diameter of the heat-shrinkable sleeve before its heat shrink exceeds the diameter of the outer pipe-shell by no more than 1-50%. 8. The method according to p. 1, characterized in that the diameter of the heat-shrinkable sleeve before its heat shrinkage exceeds the diameter of the outer pipe-shell by no more than 1-30%. 9. The method according to p. 1, characterized in that the wall thickness of the heat-shrinkable sleeve does not exceed 20 mm

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