Method for increase of pipes leak-tightness

FIELD: technological processes.

SUBSTANCE: invention is related to the field of pipes manufacturing. In method for increase of leak-tight properties of pipes (vessels), made of composite materials, including winding of continuous thread, number of helical passes with positive winding angles is not equal to number of helical passes with negative winding angles.

EFFECT: higher leak-tightness of pipes due to reduction of breaking stresses in the first layer.

 

The invention relates to the production of products made of composite materials, in particular the production of GRP pipes by winding continuous filaments.

In the traditionally used methods of winding fiberglass yarns tightness is provided by the first layer in contact with the transported medium. For the perception of the internal pressure of the winding is carried out by the district layers at angles close +54 -54°, symmetrically, creating orthotropic design, precluding the occurrence of torque stresses in the pipe wall. The number of bundles of roving is such that it ensures the continuity of each circuit layer. Optionally, axial loads can be laid axial layers at angles close to 0.

The disadvantage of these methods is the fact that in violation of the integrity of the first layer in contact with the transported medium, the formation of cracks and leakage of the tube (vessel) in General. Depressurization is characterized by vpotevanie fluid dripping or local leakage, the pipe or vessel unusable.

Thus, the known method of manufacturing pipe (patent RU №2323827, 13.03.2006), comprising a continuous winding of a material with naturalchica on the op is avcu and moving pipe it through the camera polymerization.

In order to improve durability and reliability of pipes some of the ways include reinforcement.

Known multilayer pipe and method of its manufacture (patent RU №2293897, 10.10.2005). The tube has a lining layer, sealing layer, the longitudinal layer of reinforcement and transverse reinforcement layer located sequentially on the wall thickness of the pipe. Layers of reinforcement are made of continuous fibers embedded in a block of polymeric binder. Lining layer, the sealing layer and the longitudinal reinforcement layer is made as a separate pipe workpiece, while on its outer surface has a roughness with an average height of the bumps is not less than 2.5 microns. When this sealing layer and lining layer is made in the form of separate strips along the pipe axis, and the longitudinal edges of the strips of each layer are interconnected overlapping. Cross-layer pipe is located on the outer surface of the pipe workpiece, between the rough outer surface of the pipe blank and transverse reinforcement layer is a layer of adhesive, the angle of the fibers in the transverse reinforcement layer ranges from ±89,9° to ±45°. The thickness ratio of the longitudinal layer of reinforcement and transverse reinforcement layer is from 1:5 to 5:1. In the specified method of manufacturing a multilayer pipe lining, sealing and longitudinal with the OI armature is formed by pultrusion, when this fiber longitudinal reinforcement, sealing strip and lining layers served with separate drives, pass through an impregnating bath with a solution of a binder, and then together they pulled through the heated die plate of pultruder using haul-off, resulting cured sealed tube continuous length with a predominantly longitudinal reinforcement, which is then cut into segments of desired length, after which the pultruded pipe-procurement is organized roughness, then the pipe blank is installed in the winding device consisting of a drive of the longitudinal fibers of the valve and actuator, and is wound transverse reinforcement layers, impregnated with a polymeric binder with impregnating bath, and the mandrel is mentioned pultruded pipe-blank.

A known method of manufacturing a high-strength composite cylinder (patent RU №2100200, 1994.12.13), characterized in that the cylindrical mandrel is wound inner layers of the balloon, hold their polymerization and curing, set in blow molding machine, formed by a cylindrical shell, then the inner polymer shell out in a cylindrical shell, which is the form, and then produce the winding outer part of the composite layers on Oteri the military inner composite layers placed within them an inner polymer sheath. Composite layers wound with a high tension.

The closest set of features to the present invention is a method of manufacturing a composite pipe (RU # 2150629, 19.10.1998), including the installation of a mandrel polyolefin (polyethylene) of a tubular preform, the application of a layer Sevillana, wound fiberglass material, subsequent heat treatment with the polymerization and cooling, and removing the finished pipe, with the tubular workpiece taken with the internal diameter less than the diameter of the mandrel with an interference fit, install it first or calibrated for size, the larger the diameter of the mandrel, and with the gap set on it, then pull up backlash-free coupling with the frame.

The disadvantages of this method include low adhesion layer Sevilen to fiberglass. The coefficient of linear thermal expansion of polyolefins two orders of magnitude higher than that of fiberglass. Therefore, when the positive temperature inner polyolefin layer, expands and exerts pressure on the outer layer of fiberglass. At low temperatures the inner layer is reduced in diameter, resulting in separation of the outer layer and, as a consequence, the stratification pipe construction. These circumstances lead to reduced operating life and reliability of pipes.

The aim invented the I is to increase the hermetic properties of tubes (blood vessels) and reliability of the products by reducing destructive stress in the first layer.

This goal is achieved through asymmetrical winding of circumferential layers, i.e. the inequality in the number of spiral passages with positive and negative angles of winding. Thus, the design of the pipe wall during loading by internal pressure generated torque voltage, preventing the occurrence of cracks in the first layer and premature seal failure of the pipe. Depressurization of the pipe occurs due to the destruction of the structural integrity on the border between phases: reinforcing material - binder, due to the action of stresses normal to the reinforcing filaments and tangential stresses. Stresses arise as a result of internal pressure, axial and other possible mechanical loads. Depressurization begins in violation of the integrity of the first layer in contact with the transported medium. Due to the inequality of the number of layers wound with positive and negative angles in the wall of the pipe occur torque voltage. The ratio of the layers are selected so that the torque voltage reduced normal and shear stresses in the first layer of the pipe which is in contact with the transported medium. Thus, improved hermetic properties of the pipe (vessel). The proposed method also reduces the complexity of the manufacturing process of the Tr which would reduce production costs, since it reduces the number of spiral passages and reduces the weight of the pipe.

The implementation of the invention

The production tubing for wells produced by the winding method with the following parameters:

- inner diameter 2 1/2 inches,

each layer consists of 90 bundles of roving 735 tex., simultaneously wound on the winding mandrel,

- resin - epoxy,

- hardener - aromatic amines.

The conventional scheme of winding:

13 cross (spiral) layers at an angle 54,75°,

5 longitudinal (axial) layers at an angle of 6°.

Operating parameters for pipe working pressure is 10 MPa, the pressure test and 15 MPa, the pressure of depressurization - 32-35 MPa.

The way to improve the hermetic properties of the tubes (vessels), made of composite materials comprising winding a continuous filament, characterized in that the number of spiral passages with positive winding angles not equal to the number of spiral passages negative angle of winding.



 

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