RU132857U1 - POLYMER PIPE - Google Patents

Abstract

1. A polymer pipe, characterized in that it has at least one inner shell, and the inner shell is made of PERT of the second type, crosslinked with a crosslinking agent. The polymer pipe according to claim 1, characterized in that the inner shell is made of PERT of the second type, crosslinked with a crosslinking agent and having a tear resistance by the reinforcing element at a temperature of 125 ° C of at least 25 N / mm. The polymer pipe according to claim 1, characterized in that the crosslinking agent is peroxide. The polymer pipe according to claim 1, characterized in that the crosslinking agent is a combination of peroxide and ionizing radiation. The polymer pipe according to claim 1, characterized in that it is equipped with a reinforcing system covering the inner shell. The polymer pipe according to claim 5, characterized in that it contains at least one fixing layer. A polymer pipe according to claim 6, characterized in that at least one fixing layer is a protective layer. The polymer pipe according to claim 5, characterized in that the reinforcing system is made of high strength threads. The polymer pipe of claim 8, characterized in that the threads have a specific breaking load of at least 0.5 N / tex. 10. The polymer pipe of claim 8, characterized in that the threads are made of synthetic fiber, mainly from aramid fiber or carbon fiber or fiberglass. The polymer pipe of claim 8, characterized in that the threads of the reinforcing system are combined into groups forming ribbons. The polymer pipe according to claim 11, characterized in that the tape is made of filaments of synthetic fiber, mainly of aramid fiber

Description

The invention relates to polymer pipes, preferably for heating and water supply systems, in particular for transporting media with temperatures up to 125 ° C.

To date, metal and steel pipes, for example, copper or steel, with their inherent disadvantages, such as high cost, corrosion susceptibility, lack of flexibility, making piping construction difficult, are used for heating and water supply systems with a worker.

However, in the last 25-30 years, polymer pipes, which are not subject to corrosion and have chemical resistance, have been widely used.

In particular, polyethylene is used for the manufacture of polymer pipes. However, its use has temperature limitations. This drawback is overcome by cross-linking of polyethylene, which leads to the expansion of the temperature range to 95 ° C, and the strength characteristics of pipes, including operating pressure up to 1 MPa.

But the manufacture of pipes from cross-linked polyethylene leads to the fact that the technological process of manufacturing the pipe is supplemented by a stitching operation.

As an alternative to cross-linked polyethylene, PERT can be used as the material from which the polymer pipe is made. The properties of PERT pipes are described in ISO 22391-2. The main characteristic of PERT is its long-term strength at a temperature of 110 ° C, which for PERT of the first tin is more than 1 MPa after exposure to the indicated pressure for more than 10,000 hours (based on 10,000 hours). For PERT, the second type is more than 2 MPa based on 10,000 hours. Such high strength characteristics at a temperature of 110 ° C were achieved by overcoming the tendency of the material to brittle fracture due to the structure obtained by the synthesis of the copolymer.

Polymer pipes are known containing at least one inner shell for transporting a medium made of PERT, in particular, a copolymer of ethylene with alpha-olefins, (see http://meto.ru/analiz/publ_4.htm). Such pipes have strength characteristics at the level of cross-linked polyethylene and operate at a temperature of 70-95 ° C. However, this pipe cannot be used to transport a medium with a working temperature exceeding 95-100 ° C. The limitations are due to the fact that with an increase in the operating temperature of the transported medium above the specified value, the material of the inner shell turns into a melt with a loss of strength up to the adhesion of the walls of the shell. Adhesion of the walls of the shell leads to irreversible consequences, consisting in the loss of the transporting ability of the pipeline and the impossibility of its further use. As a result of this, a complete replacement of the pipeline is required in the entire area where an emergency temperature rise occurred. In addition, such emergencies are extremely dangerous for people, especially in places with a high population density.

Given the structure of the material of the inner shell, the closest analogue to the proposed utility model is a pipe containing an inner shell for transporting a medium of molecularly cross-linked polyethylene of the RERT type, known under the trade name "ThermoTech PERT" (see http://www.teppol.ru/ articles / detail.php? ID = 10187).

The specified pipe has all the advantages of PERT, but has limitations on the operating temperature of the transported medium.

The use of molecularly cross-linked PERT as the material of the inner shell of the polymer pipe does not provide the required level of strength properties, since it has no transverse chemical bonds between the molecules and turns into a liquid in the melting temperature range 130-135 ° С.

At the same time, the operating temperature of the transported medium, which, according to safety conditions, should be 20-25 ° C lower than the melting temperature, cannot exceed 110-115 ° C.

The objective of the utility model is to create a polymer pipe having an operating temperature of up to 125 ° C.

The technical result consists in expanding the arsenal of technical means and expanding the range of pipe operating characteristics, in particular, operating temperature and pressure.

This result is achieved due to the fact that in a polymer pipe having at least one inner shell, the inner shell is made of PERT of the second type, crosslinked with a crosslinking agent.

It is possible to make the inner shell of PERT of the second type, crosslinked with a crosslinking agent, and having a tear resistance of the reinforcing element at a temperature of 125 ° C of at least 25 N / mm.

In one embodiment of the utility model, peroxide may be used as a crosslinking agent.

In another embodiment, the crosslinking agent is peroxide and ionizing radiation.

The polymer pipe may be provided with a reinforcing system covering the inner shell.

Additionally, the polymer pipe may contain at least one fixing layer.

It is possible to use at least one fixing layer as a protective layer.

The reinforcing system can be made of high-strength yarns having a specific breaking load of at least 0.5 N / tex, made mainly of aramid fiber or carbon fiber or fiberglass.

It is possible to combine the threads of the reinforcing system into groups forming ribbons.

The tapes can be made of yarn of aramid fiber or carbon fiber or fiberglass or from various combinations of these fibers.

The reinforcing system can be formed by threads wound at an angle to each other and to the axis of the pipe or tapes wound in a similar manner.

In another case, the reinforcing system may be formed by interwoven threads arranged at an angle to each other and to the axis of the pipe.

In some cases, the reinforcing system of the polymer pipe is supplied either with individual threads located along the axis of the pipe, or similarly arranged tapes.

It is possible to perform a reinforcing system by applying at least one pair of layers of reinforcing threads or one pair of layers of reinforcing tapes.

The polymer pipe may be provided with an oxygen-protective layer made of a material having barrier properties with respect to oxygen and selected from the group comprising a copolymer of ethylene with vinyl alcohol, polyamide, aluminum.

When using the pipe under conditions that require maintaining the temperature of the coolant, it can be equipped with a heat-insulating layer made of a cellular polymer, preferably polyurethane foam or polyisocyanurate foam.

One of the protective layers (shells) is the outer shell of the pipe and can be made of polyethylene or ethylene copolymers.

The heat-insulating layer and the outer shell can be made corrugated.

Preferably, the polymer pipe can be used in heat supply networks with an operating temperature of up to 125 ° C at a pressure of up to 1 MPa.

PERT, as a thermoplastic material, has a distinct drawback - a complete loss of mechanical properties at a temperature of 135 ° C, since at this temperature the material melts and turns into a liquid.

It is theoretically possible to overcome the melting process by crosslinking polymers, as was done with other types of polyethylene. However, since crosslinking introduces major changes in the polymer structure, it is not possible to predict that a crosslinked PERT will retain a high level of mechanical properties at temperatures above 110 -5 ° C.

It was experimentally established that in the manufacture of the inner shell of PERT of the second type crosslinked with a crosslinking agent, it is possible to transport a medium with a working temperature of up to 125 ° C without sticking the walls of the inner shell.

The use of PERT of the second type is due to the fact that it has a greater long-term strength compared to PERT of the first type, which provides the required strength characteristics of the pipe,

Examples of the second type of PERT are materials such as Hostalen 4731B, Dowlex 2388 and other ethylene copolymers.

Advantageously, the inner shell of the polymer pipe can be made of a PERT of the second type, crosslinked with a crosslinking agent, and having a tear resistance of the reinforcing element at a temperature of 125 ° C. of at least 25 N / mm.

The indicator “Resistance of polymer to tear by a reinforcing element at 125 ° C” is determined according to STO 73011750-009-2012 and allows you to calculate the pressure in the inner pipe, which pushes the material of the inner pipe through the reinforcing system. The essence of the method is to measure the force required to tear a sample with a wire modeling a reinforcing element. During the test, the force necessary for tearing the sample into two parts is measured. The force required for tearing is applied using a tensile testing machine operating at a constant traverse speed, ensuring destruction of the sample. To calculate the tear resistance, the average achieved force is used, in accordance with ISO 6133: 1998 method A.

The tear resistance of the reinforcing element, measured at a temperature of 125 ° C, allows us to evaluate the performance of the pipe at a temperature of the transported medium to 125 ° C.

It has been experimentally established that with a tear resistance index of 25 N / mm and higher at 125 ° C, the pipe can be operated when transporting a medium with a temperature of up to 125 ° C at a pressure of up to 1 MPa.

Peroxides can be used as a crosslinking agent. The use of peroxides in practice as crosslinking agents is characterized by two main features:

- peroxides must decompose into free radicals capable of detaching hydrogen atoms from the polyolefin macromolecule, thereby leading to the formation of macroradicals, due to which all subsequent necessary reactions occur;

- the processes occur in the polymer melt, i.e., the temperature is high (130-300 ° C), and the reaction time is short (several minutes).

Examples of such peroxides are Di-t-butylperoxide or 2,5 dimethyl-2,5di (t-butyl-peroxy) hexyne-3. As crosslinking agents, ionizing radiation can be used.

The use of these cross-linking agents provides stable cross-links between PERT molecules, which increases the extrusion temperature of the material of the inner shell and provides an increase in the operating temperature of the medium transported through the shell.

The operation of a PERT pipe of the second type, crosslinked with a crosslinking agent, at a pressure of 1 MPa, requires the manufacture of a pipe wall of large thickness, which leads to a decrease in the flexibility of the pipe and a significant increase in its weight. The reinforcing system makes it possible to achieve a pipe strength sufficient for transporting the medium at an operating pressure of up to 1 MPa and an operating temperature of up to 125 ° C, with a significant reduction in wall thickness, providing the flexibility of the pipe necessary for winding onto a drum.

It is possible to include at least one fixing layer in the pipe structure. The fixing layer ensures constant positioning of the threads or tapes of the reinforcing system during the manufacturing process and in the operation of the pipe. Clear positioning of the thread provides increased pipe strength by eliminating defective areas in the reinforcing system, and, ultimately, allows transporting a medium with higher parameters (temperature and pressure).

The fixing layer may be located between the inner shell and the reinforcing system. In this case, it acts as a tread that protects the inner shell heated by the transported medium from the cutting action of the reinforcing system, which allows transporting the medium with a higher temperature and pressure.

If the fixing layer is located on top of the reinforcing system, then it serves to protect the system from external influences, in particular, in the pipe manufacturing process.

The presence of these layers increases the strength characteristics of the polymer pipe and the operating temperature of the transported medium.

For a uniform distribution of reinforcing threads over the surface of the pipe, and, consequently, a uniform distribution of the load during operation of the pipe, the reinforcing system is made in the form of a structure wound in the opposite direction, that is, “clockwise” and “counterclockwise”, at an angle to a friend and to the axis of the pipe of threads or tapes, or in the form of a structure of interwoven threads or tapes. The reinforcing system may also further comprise a longitudinal thread or tape, including woven into a weave of threads or tapes located at an angle to the axis of the pipe. The pressure that the reinforcing system withstands is determined by the strength of the threads and their number. The number of threads is selected from the condition that the reinforcing system must withstand a destructive pressure at least equal to the operating pressure multiplied by the safety factor. To ensure the required strength characteristics, the reinforcing system can be made either in the form of a pair of layers of reinforcing threads or tapes located at an angle to each other and to the axis of the pipe with the opposite direction of winding, or by applying several consecutive pairs of layers of threads and / or tapes. The implementation of the reinforcing system as described above increases the strength of the pipe as a whole, allowing you to transport the medium with higher pressure and temperature, including temperatures up to 125 ° C.

The implementation of the reinforcing system of high-strength synthetic yarns having a specific breaking load of at least 0.5 N / tex, mainly of aramid fiber or carbon fiber or fiberglass, allows the medium to be transported with high temperature and pressure.

The threads of the reinforcing system into groups, combined into groups, form ribbons. The tapes can be made of synthetic yarns, mainly of aramid fiber, or carbon fiber or fiberglass, or from various combinations of these fibers. Tapes contribute to a more even load distribution on the threads, which further increases the range of pipe performance, including operating pressure and temperature.

In some cases, the reinforcing system of the polymer pipe is supplied either with individual threads located along the axis of the pipe, or similarly arranged tapes. Threads or tapes arranged in this way increase the longitudinal strength of the pipe.

The presence of a barrier oxygen protective layer made, for example, of a copolymer of ethylene with vinyl alcohol, polyamide or aluminum, which protects against diffusion of atmospheric oxygen and saturation of the coolant, provides a decrease in the rate of aging of the polymer pipe, leading to a decrease in the strength characteristics of polymer materials, especially at high temperatures. Thus, the presence of an oxygen-protective layer provides the strength parameters of the pipe sufficient for transporting a medium with a temperature of up to 125 ° C and a pressure of up to 1 MPa for a long time of operation. The thickness of this layer is mainly 0.1-0.35 mm

The presence of a heat-insulating layer, preferably made of polyurethane foam or polyisocyanurate foam, minimizes changes in the temperature of the transported medium and dampens external mechanical stresses on the pipe, which leads to an increase in the strength of the pipe as a whole and makes it possible to operate the pipe at high temperatures of the transported medium.

The heat-insulating layer is protected from external influences by an outer shell made, for example, of polyethylene or ethylene copolymers. The outer shell protects the pipe from environmental influences and mechanical damage, which increases the strength of the pipe and is necessary to ensure safe operation of the pipe at elevated temperatures of the transported medium.

The implementation of the insulating layer and / or the outer shell corrugated provides the flexibility of the pipe, contributes to the stable positioning of the pipe in the trench, which also contributes to the operation of the pipe at elevated temperatures of the transported medium without its destruction.

The polymer pipe is preferably used in heat supply networks with an operating temperature of up to 125 ° C at a pressure of up to 1 MPa.

Figure 1 shows a longitudinal section of one of the variants of the pipe according to the proposed utility model.

The polymer pipe contains an inner shell 1 provided with a reinforcing system 2, an oxygen-protective layer 3, a first and second fixing layer 4, a heat-insulating layer 5 and an outer protective shell 6. The heat-insulating layer 5 and the outer protective shell 6 are shown corrugated.

The pipe production process is as follows:

Using a pultruder or extruder, a polymer composition in the form of a powder or a melt of granules, including a second type PERT, for example, Hostalen 4731B or Dowlex 2388, and a crosslinking agent, are pressed into the annular gap between the mouthpiece and the mandrel, heated to a temperature above the melting temperature of the composition. As a result, when moving along the annular gap, an inner shell 1 of crosslinked polymer is formed, which then passes through a cooling bath, where it is calibrated and cooled below the melting temperature.

Further, in accordance with the standard technology for manufacturing a multilayer pipe, the following layers are successively applied to the inner shell: an oxygen-protective layer 3, one fixing layer 4, over which reinforcing threads or tapes 2 are laid, and a second fixing layer 4. Then, a thermal insulation layer 5 is formed and outer protective shell 6.

A multilayer polymer pipe passes through a cooling vacuum bath, where it acquires the final geometric dimensions, and is wound on a drum.

The implementation of the utility model can be demonstrated by the following example.

Example 1

A pipe made of a PERT type 2 ethylene copolymer, namely HOS-TALEN 4731 V, which has a tear resistance of a reinforcing element at a temperature of 125 ° C of at least 25 N / mm, crosslinked with a cross-linking agent, is equipped with aramid yarn reinforcing system 2, located between fixing layers 4 of ethylene-propylene copolymer, and made in the form of two layers of threads superimposed on one another, twisted at an angle to each other and to the pipe axis with threads interwoven along them along the pipe axis, an oxygen-protective layer 3 made of nozzles measure of ethylene with vinyl alcohol, polyurethane foam insulation layer 5, and the outer shell 6 of polyethylene. Layers 5 and 6 are corrugated. The pipe is characterized by a long-term strength index of 2.0 MPa when exposed to a medium with a temperature of 110 ° C for at least 1000 hours and the absence of sticking of the pipe walls at temperatures up to 170 C. The pipe can be used to transport a medium with a temperature of up to 125 ° C in case of an emergency temperature increase - up to 170 ° C.

This utility model can be used in networks of cold and hot water supply and heat supply, however, its most appropriate use in the circuits of heating networks operating in the range up to 125 ° C at a pressure of up to 1 MPa. It is possible to use a polymer pipe for transporting other media to which the pipe is chemically resistant.

Claims (29)

1. A polymer pipe, characterized in that it has at least one inner shell, and the inner shell is made of PERT of the second type, crosslinked with a crosslinking agent. 2. The polymer pipe according to claim 1, characterized in that the inner shell is made of PERT of the second type, crosslinked with a crosslinking agent and having a tear resistance of the reinforcing element at a temperature of 125 ° C of at least 25 N / mm 3. The polymer pipe according to claim 1, characterized in that the crosslinking agent is peroxide. 4. The polymer pipe according to claim 1, characterized in that the crosslinking agent is a combination of peroxide and ionizing radiation. 5. The polymer pipe according to claim 1, characterized in that it is equipped with a reinforcing system covering the inner shell. 6. The polymer pipe according to claim 5, characterized in that it contains at least one fixing layer. 7. The polymer pipe according to claim 6, characterized in that at least one fixing layer is a protective layer. 8. The polymer pipe according to claim 5, characterized in that the reinforcing system is made of high strength threads. 9. The polymer pipe of claim 8, characterized in that the threads have a specific breaking load of at least 0.5 N / tex. 10. The polymer pipe of claim 8, characterized in that the threads are made of synthetic fiber, mainly from aramid fiber or from carbon fiber or fiberglass. 11. The polymer pipe of claim 8, characterized in that the threads of the reinforcing system are combined into groups forming the tape. 12. The polymer pipe according to claim 11, characterized in that the tape is made of threads of synthetic fiber, mainly of aramid fiber, or carbon fiber or fiberglass or from various combinations of these fibers. 13. The polymer pipe of claim 8, characterized in that the reinforcing system is formed by threads wound at an angle to each other and the axis of the pipe. 14. The polymer pipe according to claim 11, characterized in that the reinforcing system is formed by ribbons wound at an angle to each other and to the axis of the pipe. 15. The polymer pipe of claim 8, characterized in that the reinforcing system is formed by interwoven threads located at an angle to each other and to the axis of the pipe. 16. The polymer pipe according to claim 11, characterized in that the reinforcing system is formed by interwoven tapes located at an angle to each other and to the axis of the pipe. 17. The polymer pipe according to item 13 or 15, characterized in that the reinforcing system of the polymer pipe is equipped with threads located along the axis of the pipe. 18. The polymer pipe according to 14 or 16, characterized in that the reinforcing system of the polymer pipe is provided with tapes located along the axis of the pipe. 19. The polymer pipe according to claim 5, characterized in that the reinforcing system is made by superimposing at least one pair of layers of reinforcing threads. 20. The polymer pipe according to claim 5, characterized in that the reinforcing system is made by superimposing at least one pair of layers of reinforcing tapes. 21. The polymer pipe according to claim 1, characterized in that it is provided with an oxygen-protective layer made of a material having barrier properties with respect to oxygen, and selected from the group of a copolymer of ethylene with vinyl alcohol, polyamide, aluminum. 22. The polymer pipe according to claim 1, characterized in that it is provided with a heat-insulating layer. 23. The polymer pipe according to item 22, wherein the heat-insulating layer is made of a cellular polymer, preferably polyurethane foam or polyisocyanurate foam. 24. The polymer pipe according to claim 7, characterized in that one of the protective layers is the outer shell of the pipe. 25. The polymer pipe according to paragraph 24, characterized in that the outer shell is made of polyethylene or ethylene copolymers. 26. The polymer pipe according to item 22, characterized in that the heat-insulating layer is made corrugated. 27. The polymer pipe according to claim 1, characterized in that it contains an outer protective sheath. 28. The polymer pipe according to paragraph 24 or 27, characterized in that the outer shell is corrugated. 29. The polymer pipe according to claim 1, characterized in that it is preferably used in heat supply networks with a working temperature of up to 125 ° C at a pressure of up to 1 MPa.

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