HK1181451B - Multilayer reinforced polymeric pipe and system of pipes - Google Patents

Abstract

The invention relates to the design of a multilayer reinforced polymeric pipe for water. The essence of the invention is that the multilayer reinforced polymeric pipe comprises a polymeric base layer, at least one barrier layer, at least one reinforcing layer, an adhesive layer and a protective layer. The adhesive layer is made from a material which does not adhere to the material of the reinforcing layer and forms channels for the free movement of the fibers of the reinforcing layer. The technical result consists in allowing the axial displacement of the reinforcing fibers inside the pipe structure under the effect of cyclic changes in temperature and mechanical load while maintaining the mesh structure and preventing damage to the polymeric layers of the pipe which surround the reinforcing layer.

Description

Multilayer reinforced polymer pipe and pipe system for transporting water

Technical Field

The present invention relates to the design of multilayer reinforced polymer pipes for water, i.e. hot water, in systems for district heating and hot water supply, and can be used in pipes for transporting liquid and gaseous media to which the pipe material is resistant under operating conditions.

Background

Polymer-reinforced pipes are known, comprising an inner layer and an outer layer of thermoplastic material, and a reinforcing agent of polymeric or mineral material, placed between the layers and made in the form of continuous fibres, which penetrate into the outer surface of the inner layer and into the inner surface of the outer layer (RU, No.2205318, IPC7F16L 9/12).

Such a design provides a considerable increase in the pipe strength, but it is not suitable for hot water transport because there is no barrier against vapor and gas permeation. Furthermore, providing pipe strength requires good adhesion of the reinforcement layer to the polymer.

Multilayer pipes for water and heat supply systems are known, comprising a pipe body preferably consisting of crosslinked polyethylene; at least one layer forming a barrier to the diffusion of water through the multilayer pipe, said barrier layer consisting of a liquid crystal polymer (RU, No.2224160, IPC7F16L 9/12).

Such designs are now widely used in water and heating systems, preferably for hot water supply. However, the lack of reinforcement layers will not provide the required level of continuous strength at increased pressures during operation and results in the need to increase the pipe wall thickness, which in turn causes an increase in pipe mass, as well as a decrease in its flexibility and capacity.

Thus, for example, while the safety factor is 1.53 for a pipe of cross-linked polyethylene for hot water supply at a pressure of 10bar, the safety factor is 1.78 for a reinforced pipe of the same material.

Among all known pipes, the closest in its technical nature to the proposed pipe is the polymer multilayer reinforced pipe "G-PEX-AM" produced under TU2248-025-40270293-2005, the design of which comprises a pipe of crosslinked polyethylene (PEX-a), a barrier layer to prevent oxygen diffusion, a reinforcement layer formed by a synthetic fiber ("Kevlar") network surrounding the barrier layer, an adhesive layer applied on the reinforcement layer, and an outer protective layer made of medium density polyethylene.

In this design, a double-sided adhesion of the reinforcing layer formed by the synthetic fiber mesh to the barrier layer and the outer protective layer is provided in order to stabilize the position of the reinforcing fibers.

The achievement of double-sided adhesion of the reinforcement layer can cause the destruction of the polymer surface immediately adjacent to the reinforcement layer, caused by its axial displacement under the action of cyclic variations in temperature and mechanical load.

Disclosure of Invention

The technical task of the proposed pipe design is to provide the possibility of axial displacement of the reinforcing fibers inside the pipe structure under the action of cyclic changes in temperature and mechanical load, while maintaining the mesh structure and preventing damage to the polymer layer of the pipe surrounding the reinforcing layer.

This technical result is achieved in the proposed multilayer reinforced polymer pipe comprising a base polymer layer, at least one barrier layer, at least one reinforcing layer, an adhesion layer and a protective layer, the adhesion layer being made of a material that does not adhere to the reinforcing layer and that forms channels for the free movement of the reinforcing layer fibres.

In the proposed pipe design, the reinforcement layer fibers are free and reversibly axially displaceable under fluctuations in pipe dimensions under the influence of changes in temperature and mechanical load.

The base polymer layer of the proposed pipe is made of a cross-linked or heat resistant polymer, preferably polyethylene or polybutylene.

The reinforcement layer of the pipe is made of high strength and high modulus polymer fibers, preferably aramid, polyester or polyethylene fibers. The reinforcing layer may be composed of a mesh. It can be made by overlapping several successive layers of the web.

The barrier layer providing resistance to oxygen diffusion and water vapor is made of a polar polymer and a non-polar polymer.

The protective layer of the pipe is made of medium density polyethylene. The thickness of the protective layer is at least 3 mm.

A piping system for transporting water, preferably hot water, in a district heating and water supply network is proposed, consisting of two or more multilayer reinforced polymer pipes of the proposed design.

The proposed design is distinguished by the fact that the barrier layer of the pipe is tightly bonded to a reinforcing layer made of polymer fibres, onto which an adhesion layer made of a material that does not adhere to the reinforcing layer and that forms channels for the fibres of the reinforcing layer to be freely and reversibly axially displaceable under the effect of temperature and mechanical load changes under fluctuations in the dimensions of the pipe is applied.

Drawings

Figure 1 shows a general view of a pipe according to the invention.

Detailed Description

The multilayer polymer reinforced pipe comprises a polymeric substrate layer 1, a barrier layer 2 to prevent oxygen diffusion and water vapor, a reinforcement layer 3, an adhesion layer 4 which adheres the pipe layers other than the reinforcement layer, and a protective layer 5.

The multilayer polymer reinforced pipe operates in the following manner. The piping is usually installed using pipes of the proposed design, under a solution involving rotation at different angles. When the tube bends, the reinforcing fibers and the substrate layer are displaced relative to each other. After installation of the pipeline, the pipeline was tested by increasing pressure when some variation in its dimensions (its diameter and length) occurred. During the dimensional change, the pipe polymer layer is displaced relative to the reinforcement layer due to the different elastic moduli of the reinforcement layer material and the base layer material. After the test is completed, the test bed pressure is relieved and a reverse displacement of the reinforcing fibers relative to the polymer layer occurs. Due to the supply of the heat carrier (hot water), the same opposite displacement of the reinforcing fibres and the polymer layer relative to each other occurs during the transport and the interruption of the supply thereof.

During its installation, testing and operation, the multilayer reinforced polymer pipe according to the invention provides for the free and reversible displacement of the polymer layers and the reinforcing fibers with respect to each other, which ensures a high level and stability of its operating characteristics during its service life.

Claims (14)

1. A multilayer reinforced polymeric pipe comprising a base layer, at least one reinforcing layer made in the form of a mesh, an adhesive layer and a protective layer, characterized in that the adhesive layer is made of a material that does not adhere to the material of the reinforcing layer and forms channels for the reversible movement of the fibres of the reinforcing layer.

2. The multilayer reinforced polymer pipe of claim 1, wherein the substrate layer is made of a crosslinked polymer.

3. The multilayer reinforced polymer pipe according to claim 2, characterized in that the crosslinked polymer is crosslinked polyethylene.

4. The multilayer reinforced polymer pipe of claim 1, wherein the substrate layer is made of a heat resistant polymer.

5. The multilayer reinforced polymer pipe of claim 4, wherein the heat resistant polymer is polybutylene.

6. The multilayer reinforced polymer pipe of claim 1, comprising at least one barrier layer.

7. The multilayer reinforced polymer pipe of claim 1, wherein the reinforcing layer is made of high strength and high modulus polymer fibers.

8. The multilayer reinforced polymer pipe of claim 7, wherein the high strength and high modulus polymer fibers of the reinforcement layer are aramid fibers.

9. The multilayer reinforced polymer pipe of claim 7, wherein the high strength and high modulus polymer fibers of the reinforcement layer are polyester fibers.

10. The multilayer reinforced polymer pipe of claim 7, wherein the high strength and high modulus polymer fibers of the reinforcing layer are polyethylene fibers.

11. The multilayer reinforced polymer pipe of claim 6, wherein the barrier layer is made of a polar polymer and a non-polar polymer.

12. The multilayer reinforced polymer pipe of claim 1, wherein the protective layer is made of medium density polyethylene.

13. The multilayer reinforced polymer pipe of claim 1, wherein the protective layer has a thickness of at least 3 mm.

14. A pipe system for transporting hot water in a district heating and water supply network, consisting of at least two multilayer reinforced polymer pipes according to any of claims 1 to 13.