FR2808861A1 - Flexible tube, used for transporting liquids or fluidized solids, comprises flexible thermoplastic polymeric core reinforced with rigid helical structure and surrounded with knitted reinforcing sleeve - Google Patents

Abstract

A flexible tube has a flexible thermoplastic polymeric core reinforced with a rigid helical structure and surrounded with a knitted reinforcing sleeve. The sleeve may be covered with a thermoplastic protective layer. The reinforcing sleeve is made from textile fibers.

Description

The invention relates to a flexible pipe for transporting liquids or powdery products.

Flexible pipe structures are known which are made of a tubular matrix of thermoplastic polymer reinforced by a rigid helical structure embedded in the matrix, along the longitudinal axis of the pipe. The formulation of the matrix is adapted to the fluid transported.

The purpose of the helical structure is to provide the pipe with a certain burst resistance, which is likely to occur during transport of fluids under pressure, as well as resistance to collapse by depression, which could occur during the depression of the pipe, when for example the pipe is connected to the suction of a pump.

The helical structure does not however penalize the flexibility in bending of the pipe, since the latter is able to follow the bending deformations of the matrix. This composite flexible matrix / rigid helical structure is generally obtained by extrusion, in particular by rotating the pipe one turn when its advance is equal to the pitch of the propeller.

In certain applications of these pipes, the bursting strength is not sufficient. It has already been proposed to reinforce the matrix by a gimped or braided external reinforcement, having a high resistance to bursting. This external reinforcement is placed directly at the outlet of the extruder. Unfortunately, such reinforcements can only be envisaged for limited pipe diameters and have the notable drawback of stiffening the pipe in bending.

The problem therefore arises of providing a structure having a high resistance to collapse by depression, a high resistance to bursting, while remaining flexible in bending. According to the invention, a flexible pipe is provided, consisting of a flexible tubular matrix of thermoplastic polymer, in which a rigid helical structure is embedded along its axis. The composite thus obtained is surrounded by a knitted tubular reinforcement.

The flexible matrix can be made of polyvinyl chloride, or alternatively of polyurethane, while the helical structure can be provided from rigid vinyl chloride or any other rigid chemically compatible polymer.

The knitted reinforcement gives the structure great resistance to bursting, and allows the pipe to keep all its flexibility in bending. In addition, the knitting operation accommodates the rotation of the pipe leaving the extruder, and large pipe diameters. Advantageously, this reinforcement will consist of natural or synthetic textile fibers, such as for example polyester fibers.

Advantageously, the knitted reinforcement is covered with an outer protection made of thermoplastic polymer, for example polyvinyl chloride, polyurethane, or other thermoplastics, possibly elastomers, chemically compatible with the matrix and the reinforcement.

This protection is intended to isolate the pipeline from the environment, in particular from mechanical or chemical attack.

Other characteristics and advantages will emerge on reading the description which follows of the single figure, which represents a longitudinal section of the pipe in a particular embodiment.

Referring to the figure, the pipe consists of a tubular matrix 2 with a longitudinal axis 1. This matrix is made of thermoplastic polymer, for example polyvinyl chloride. In this matrix is embedded a helical structure 3 of longitudinal axis 1; this structure is for example made of rigid polyvinyl chloride.

channeling is reinforced from the outside by a knitted sleeve 4 forming reinforcement. This reinforcement 4 adheres to the matrix 2, and gives it great resistance to bursting. This reinforcement 4 is knitted directly on the die 2 at the outlet of the extruder which produces the composite flexible core / rigid helical structure. The knitted reinforcement 4 is here made of natural or synthetic textile fibers, for example polyester fibers.

knitted reinforcement is covered with a protective layer 5 of thermoplastic polymer, for example polyvinyl chloride, polyurethane or any other elastomeric thermoplastic polymer. This protective layer 5 isolates the composite 3,4 from the external environment, both from the point of view of mechanical shock and chemical pollution.

in general, the external coating will be chosen from a material chemically compatible with that of the matrix of the internal core, and at the very least made adhered to the latter by a surface activation operation. In practice, a polyvinyl chloride will be chosen for a polyvinyl chloride matrix core, or a polyurethane for a polyurethane core.

The invention does not intend to limit itself to a particular embodiment which has just been described, but on the contrary intends to encompass any variant with equivalent means, reproduces the essential characteristics described above.

Claims (1)

<U> CLAIMS </U> l.Flexible pipe for transporting pulverulent or liquid materials comprising a core consisting of a tubular matrix (2) of flexible thermoplastic polymer in which is embedded a rigid helical structure (3), surrounded by a knitted tubular reinforcement (4). 2. Pipe according to claim 1, characterized in that the reinforcement is covered with a protective layer (5) of flexible thermoplastic polymer. 3. Pipe according to one of the preceding claims, characterized in that the matrix (2) is made of polyvinyl chloride. 4. Pipe according to one of the preceding claims, characterized in that the matrix (2) is made of polyurethane. 5. Pipe according to one of the preceding claims, characterized in that the helical structure (3) is made of polyvinyl chloride. 6. Pipe according to one of the preceding claims, characterized in that the reinforcement (4) is composed of textile fibers. 7. Pipe according to one of the preceding claims, characterized in that the protective layer (5) is made of polyvinyl chloride. 8. Pipe according to one of the preceding claims, characterized in that the protective layer (5) is made of polyurethane. 9. Pipe according to one of the preceding claims, characterized in that the protective layer (5) is made of elastomeric thermoplastic polymer.