WO2019066670A1

WO2019066670A1 - Steel pipe and method of producing radiation-modified coating

Info

Publication number: WO2019066670A1
Application number: PCT/RU2017/000650
Authority: WO
Inventors: Дмитрий Вячеславович АЛЯВДИН
Original assignee: Закрытое акционерное общество "Уральский завод полимерных технологий "Маяк"
Priority date: 2017-09-26
Filing date: 2017-09-26
Publication date: 2019-04-04

Abstract

The invention relates to the field of mechanical engineering, and specifically to technology for manufacturing steel pipes having a wear-resistant polymer coating used for building and operating oil and gas pipelines, heat supply systems, and water supply systems, including large-diameter pipes. The technical result of the claimed group of inventions is an increase in the impact resistance and the durability of a polymer coating in the process of long-term pipe operation. A method of producing a radiation-modified wear-resistant polymer coating on a steel pipe, including the application of a primer layer on a surface of the steel pipe, the application of an adhesive layer on the primer layer, and the subsequent application onto the adhesive layer of a composite polymer layer in the form of a matrix based on polyolefins and a reinforcing filler-fiber, and the radiation modification of the coating using at least one electron accelerator with a radiation dose of 1-100 Mrad at a ratio of displacement speed to rotation speed of the pipe equal to 0.1-5.0.

Description

STEEL PIPE AND METHOD FOR OBTAINING A RADIATION-MODIFIED COATING

TECHNICAL FIELD

The invention relates to the field of engineering, namely, to the production technology of steel pipes with reinforced polymer coating used for the construction and operation of oil and gas pipelines, heat supply systems and water supply, including large diameter pipes.

BACKGROUND

Production volumes and application areas of fiber-reinforced polymer composites are constantly increasing worldwide. Polymeric materials modified with asbestos, glass, carbon, basalt and other fibers are promising for critical structures.

Reinforcing fibers in combination with a polymer matrix provide composites with an increase in mechanical strength indicators: impact resistance, wear resistance.

Carbon fibers are expensive for mass use in industry and construction, and the production of glass fiber fillers is constrained by the lack of special components (boron oxide, soda, etc.). In this connection, fillers, which are capable of replacing glass fiber and carbon fiber, are of particular importance. These may be basalt fibers, because they, being a type of glass fibers, have practically all the positive properties of glass and carbon fibers, as well as a number of significant advantages: the production of basalt fibers does not require the introduction of special components, the raw materials are generally available and cheap, and its reserves are unlimited. (Quail Kin KE, Reinforcing fibers and fibrous polymer composites. - S-Pb., 2009. - 118).

One of the main tasks in the construction and operation of steel pipelines is to ensure high performance characteristics of polymer anticorrosive coatings on pipes in such parameters as impact strength, wear resistance, penetration resistance, coating resistance to cathodic peeling, increased adhesion, and adhesion stability during long-term pipe operation. To solve this problem, factory protective polymeric coatings are currently being used, which are applied to the external prepared pipe surface. For anticorrosive protection of the outer surface of the pipe, you can use a multilayer polymer coating, which may consist of a primer layer, an adhesive layer and an outer layer made of a polymer composition based on polyolefins and specialized additives. The method of obtaining the specified multilayer coating and a pipe with a multilayer coating is disclosed in EN 2458952 C2, publ. 08/20/2012. Also appeared monolayer polymeric coatings that combine the properties of adhesive and outer polymer layers. The pipe with a similar factory anti-corrosion polymer coating is characterized by a fairly high level of operational mechanical properties of the coating.

However, the described anticorrosion polymer coating of steel pipes does not provide the required modern level of resistance to corrosive media, mechanical damage. There is also a lack of adhesion of the polymer coating material to the base material of the pipe and the stability of the adhesion of the polymer coating during long-term operation of the pipes.

There is a method of applying a multilayer polymer insulation on a steel pipe and steel pipe with multilayer polymer insulation consisting of four layers, disclosed in RU 2413615 C2, publ. 03/10/2011. The proposed polymer-insulated pipe has a multilayer structure to protect the surface from damage, in which the first lower layer consists of epoxy primer, the second middle layer consists of adhesive polymer underlayer, the third upper layer consists of high density polyethylene of HDPE series, and the fourth outer layer consists of silane-modified HDPE (according to ΡΕΧ-b classification) with which it is possible to increase the impact strength and impact strength of the sample.

The disadvantage of this method and the steel pipe with a multilayer coating is the requirement to use complex additional and, therefore, expensive technological operations to apply an additional fourth polymer layer modified with silane HDPE (according to ΡΕΧ-b classification). Also for PEX-b modification, it is necessary to stand for several hours with a silane crosslinkable polyolefin in a water bath at a temperature of about 95 ° C, which limits the performance of the technology as a whole and significantly increases production costs.

In addition, there is a method of applying a multilayer coating and a steel pipe modified with multilayer insulation "TSIM", disclosed in EN 164448 U1, publ. 08.27.2016 (prototype). The steel pipe, modified with multilayer insulation "TSIM" contains the lower, middle and outer polymer layers, while the lower layer of the polymer coating is made of epoxy primer, the middle layer of the polymer coating is made of adhesive adhesive polymer underlayer, and the outer layer is made of a modified composite based on polyolefin, and the outer the layer is made with the possibility of deposition on the middle layer by extrusion of a composite based on polyolefins and subsequent radiation crosslinking under the action of an electron accelerator.

The disadvantages of the coating obtained are the unsatisfactory mechanical strength of the coating, which does not allow the use of coated pipes in rocky and frozen soils without additional protection measures. This complicates the work and entails additional costs in the construction of pipelines.

DISCLOSURE OF INVENTION

The task of the claimed group of inventions is to develop a method for applying a radiation-modified reinforced polymer coating on a steel pipe in order to obtain a steel pipe with high mechanical characteristics.

The technical result of the claimed group of inventions is to increase the impact strength and wear resistance of the coating on the pipe.

This technical result is achieved due to the fact that the method of obtaining a radiation-modified wear-resistant polymer coating on a steel pipe involves applying a primer layer to the surface of a steel pipe, applying an adhesive layer to the primer layer, followed by applying a composite polymer layer to the adhesive layer polyolefins and reinforcing filler - fibers, and radiation modification of the coating using at least one electron accelerator with a dose of th exposure 1-100 Mrad, when the ratio of the speed of movement to the speed of rotation of the pipe is 0.1-5.0.

The method of obtaining radiation-modified polymer coating on a steel pipe involves applying a primer layer to the surface of the steel pipe, followed by applying to the primer layer a composite polymer monolayer in the form of a matrix containing polyolefins and a glue based on polyolefins and a reinforcing filler - fiber, and radiation modification coatings using at least one electron accelerator with a dose of 1-100 Mrad with the ratio of the speed of movement to the speed of rotation of the would be 0.1-5.0.

A steel pipe with a radiation-modified polymer coating containing a coating based on layers obtained in accordance with the above methods, while the coating is radiation-modified using at least one electron accelerator.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clear from the description, not having a restrictive nature and is given with reference to the accompanying drawings, which depict: FIG. 1 is a cross section of a steel pipe with a three-layer coating.

FIG. 2 is a cross section of a steel pipe with a monolayer coating.

FIG. 3 is a plot of tensile strength (MPa) versus radiation dose for beams of 5 and 10 MeV.

FIG. 4 - Process of radiation modification of a coated pipe

1 - steel pipe; 2 - primer layer; 3 - adhesive layer; 4 - polymer layer based on polyolefins; 5 - polymer monolayer; 6 - electron accelerator; 7 - electron beam.

IMPLEMENTATION OF THE INVENTION

In accordance with the first embodiment of the invention (see FIG. 1,) the steel pipe (1) contains a primer layer (2) deposited on the outer surface of the steel pipe (1), an adhesive layer (3) deposited on the primer layer (2), composite polymer layer (4) in the form of a matrix based on polyolefins and reinforcing filler - fibers deposited on the adhesive layer (3). In this case, a steel pipe with a polymer coating containing the layers disclosed above is subjected to radiation modification by an electron beam using at least one electron accelerator.

In accordance with the second variant of the invention (see FIG. 2), the steel pipe (1) contains one primer layer (2) deposited on the outer surface of the steel pipe (1), a composite polymer monolayer (5) deposited on the primer layer (2) in the form of a matrix containing polyolefins and adhesive composition based on polyolefins, and reinforcing filler - fibers. In this case, a steel pipe with a polymer coating containing the layers disclosed above is subjected to radiation modification by an electron beam using at least one electron accelerator.

The matrix of the composite polymer layer based on polyolefins (4) is made in the form of a polymer selected from the group: polyethylene, sevilen, polypropylene, polyvinyl chloride, polystyrene, natural rubber, synthetic rubbers, polysiloxanes, polyamides, polyethylene oxide.

The adhesive layer (3) contains an adhesive composition based on polyolefins selected from the group: based on “Methalen APE-1” polyethylene, based on Sevilen ATI-06; based on sevilen TRISOLEN 190, based on sevilen TRISOLEN 200 / U.

The primer layer (2) contains a material selected from the group: epoxy primer Primer MB, rubber-resin Primer PL-L, rubber primer Primer NK-50, TRANSCOR-GAS primer.

The matrix of the composite polymer monolayer (5) contains two components, while the first component contains a polymer based on polyolefins selected from the group: polyethylene, sevilen, polypropylene, polyvinyl chloride, polystyrene, natural rubber, synthetic rubbers, polysiloxanes, polyamides, polyethylene oxide, and the second component is an adhesive based on polyolefins selected from the group: based on Metilen APE-1 polyethylene, based on sevilen ATI-06; based on sevilen TRISOLEN 190, based on sevilen TRISOLEN 200 / U. The mass ratio of the content of these components in the matrix is 1: 1.

Glass, carbon and basalt fibers are used as reinforcing filler.

A radiation modified coating on a steel pipe is obtained as follows.

In accordance with the first embodiment of the invention, the outer surface of the steel pipe (1) is pre-cleaned. To do this, first produce its degreasing alkaline solution by filing it on the outer surface of the pipe under pressure, after which the steel pipe is subjected to drying and blasting to obtain a rough surface of the outer surface of the pipe that does not exceed R _z = 100 μm.

Then the cleaned surface of the steel pipe (1) is subjected to induction heating to a temperature of at least 200 ° C, followed by applying to the outer surface of the pipe a primer layer (2) in the form of a primer powder based on epoxy composition, for example, primer epoxy Primer MB, thick 90-100 microns by electrostatic spraying. Particles of dry powder deposited on the surface of the steel pipe (1) are held on it mainly due to the forces of electrostatic attraction. Wetting occurs when the powder particles melt at a temperature above 200 ° C. In this case, the epoxy powder on the surface of the pipe melts and polymerizes, forming a soft continuous film.

Then, an adhesive layer (3) is applied to the primer layer (2), which contains an adhesive composition based on polyolefins, for example, on the basis of “Methalen APE-1” polyethylene. The adhesive layer (3) is applied by conventional methods used for coating pipelines, for example, by the method of side melt extrusion of the adhesive composition. To apply the adhesive layer (3), the adhesive composition heated to the state of melt is squeezed into the flat die of the extruder to form a tape with a thickness of 100 to 500 μm, which is wound on the primer layer (2).

Then a composite polymer layer (4) is applied over the adhesive layer (3) in the form of a matrix based on polyolefins and a reinforcing filler - glass, carbon or basalt fibers, by spiral winding of a composite polymer tape heated to the state of melt (extrusion), also extruded through a flat-slit head extruder thickness of 5-50 mm. After that, the obtained multilayer coating is rolled under pressure to the outer surface of the steel pipe (1) with a roller, and then the steel pipe (1) is cooled to a temperature not higher than 60 ° C and radiation modification of the polymer coating of the steel pipe (1) is performed using electronic accelerator technology (see Fig. 4).

In the case of radiation modification, a steel pipe (1), coated with a multilayer coating, is exposed to electron beams with an energy of 0.5-10 MeV and an irradiation dose of 1-100 Mrad using at least one electron accelerator (6) of the type ELV and ILU and similar. In the case of radiation modification, the steel pipe (1) under the electron beam (7) passes with certain speeds of movement and rotation of the pipe, with a ratio of the speed of movement to the speed of rotation of the pipe equal to 0.1-5.0. The speed of movement is determined by the required dose, which is absorbed by the polymer coating, and the rotation ensures the uniformity of the absorbed dose over the entire surface of the polymer coating of the pipe.

The absorbed dose collected by the polymer coating of the pipe is chosen to cover the polymer material from the free molecular state to the partially cross-linked state, which is characterized by the formation of three-dimensional molecular structures with a higher molecular weight. Due to this, there is an increase in impact strength, wear resistance, resistance to penetration of the polymer coating, adhesive strength and stability of the adhesion of the polymer coating of steel pipes.

In accordance with another embodiment of the invention, a primer layer (2) is applied to the cleaned outer surface (cleaning operations similar to those described above) of a steel pipe (1), as described above, followed by applying a composite polymer monolayer (5), similar to applying a composite polymer layer ( 4) as described above. Next, the pipe with a two-layer coating is cooled to a temperature not higher than 60 ° C and radiation modification of the polymer coating of the steel pipe (1) is carried out using the technology of electronic accelerators, as described above.

Studies on the structural changes and properties of irradiated polymers on the example of polyethylene made it possible to distinguish distinct stages through which the polymer passes as the dose increases. At the initial stage of radiation modification, with an absorbed dose of up to 2.0 Mrad, the formation of transverse covalent bonds between individual carbon atoms of linear molecules and the creation of three-dimensional spatial polymers with a higher molecular weight. Acquired at this stage, the properties of the polymer are determined not so much by the newly emerging rigid bonds that form branched molecular systems, as by intermolecular interactions. between these systems, allowing the possibility of their mutual displacements and deformations under external mechanical actions. In such conditions, polyethylene in its properties becomes close to rubber-like materials. With further increase in the absorbed dose, the density of cross-links increases and the structure of polyethylene turns into a single spatial grid. Due to this, the material acquires new useful properties: the modulus of elasticity increases, the tensile strength increases, resistance to chemical and thermal effects occurs. Changes in the tensile strength (MPa) as a function of the radiation dose for polyethylene are marked on the graph (Fig. 3).

The claimed invention, when applying the technology of radiation modification of polymer coatings by an electron beam, allows to improve the strength characteristics of the obtained polymer wear-resistant coating, the results of experiments on a steel pipe with a wear-resistant polymer coating are presented in Table. one.

Table 1

Factors such as electron beam power, electron beam energy, electron beam sweep length, specified absorbed dose, and tube diameter affect the speed of rotation and movement of the tube. The dependence of these parameters in general form can be described by the formula:

216 ^" P / D = 25 '10 ³ ' R ^" H 'Vx, where P is the electron beam power of the accelerator; D is the specified value of the absorbed dose; H is the width of the irradiation zone; Vx - the speed of movement of the pipe; R is the depth of penetration of electrons (for polyethylene R = 2.4 g / cm ² ).

The ratio of the speed of movement of the pipe and the speed of its rotation in general form is described by the formula: ν ^χ = ϊ ^ ^Ν ·

where Vx - the speed of movement of the pipe; D is the diameter of the pipe; H is the beam width of the electron accelerator; N- pipe rotation speed.

Almost the ratio of the speed of movement to the speed of rotation of the pipe falls in the range of 0.1-5.0. Properly selected ratio of the speed of movement to the speed of rotation allows you to achieve a uniform level of absorbed dose of the coating on the entire surface of the pipe

The presence of more than one electron accelerator allows us to speed up the process of radiation modification of the pipe coating, which is important in the industrial production of pipes with radiation-modified insulation.

The fibers of the reinforcing filler perceive mechanical stresses, determining the basic physicomechanical properties of the polymer coating: strength, deformability, rigidity, wear resistance. The matrix (polyethylene, sevilen, polypropylene and their composites), located in the interfibre space, serves to distribute the mechanical stresses between the fibers, also partially perceives these mechanical stresses, and, very importantly, determines the solidity of the material.

The interaction of reinforcing fibers with the matrix should ensure a high realization of the mechanical properties of the fibers in the reinforced material and its solidity. This requires: good wettability of the fibers by the matrix and / or binder; high adhesion between the fiber and the matrix, characterized by shear strength at the interface of the fiber-matrix; high adhesion should be maintained for a long time under the operating conditions of the composite with active external influences, including moisture; preservation or minimal change in the properties of fibers under the influence of the components of the matrix; relaxation of internal stresses in the elementary volume of the fiber-matrix during heat treatment or under the influence of components of the binder and other factors.

Radiation modification results in efficient crosslinking of polyolefin molecules. Also increases the value of adhesion between molecules of polyolefins with reinforcing filler. Due to this, the physicomechanical properties of the polymer coating increase synergistically: strength, deformability, rigidity, wear resistance. Wear resistance (intensity of mass wear of the polymer composite) was determined by testing according to generally accepted methods (GOST 11629-75) on a CETR friction machine (USA). The finger-disk scheme was used (the sample was a column with a diameter of 10 mm, a height of 20 mm, a counterbody was a steel shaft made of steel 45 with a hardness of 45-50 HRC and a roughness of Ra = 0.06-0.07 µm, load 150 N, sliding speed - 200 rpm). Test time - 3 hours.

To determine the mass wear, the samples were treated with ethyl alcohol and weighed on an analytical balance before and after friction. After treatment with ethyl alcohol, the samples were left for a day in order to evaporate the alcohol.

The content of the reinforcing filler in the prepared composition has a significant impact on the process of its homogenization in a single-screw mixer in the process of factory extrusion and the imposition of the surface layer of polymer insulation of steel pipe. With a volumetric filling of more than 30%, the highly viscous mixture moves in the dosing zone not in a laminar, but in the so-called piston mode, and the polymer component melt forms a lubricating layer, as it were, at the boundary with the surface of the cylinder and screw screw channel. This limits the technological capabilities of the extrusion of a polymer coating when creating an insulating coating for a steel pipe. Therefore, filling with reinforcing fibers is possible in fractions of not more than 30%.

Thus, the invention allows to increase the impact strength and wear resistance of the polymer coating in the process of long-term operation of pipes.

The invention has been disclosed above with reference to a specific embodiment. Other embodiments of the invention that do not change its essence as disclosed in the present description may be obvious to those skilled in the art. Accordingly, the invention should be considered limited in scope only by the following claims.

Claims

CLAIM

1. A method of obtaining a radiation-modified wear-resistant polymer coating on a steel pipe, comprising applying a primer layer to the surface of a steel pipe, applying an adhesive layer to the primer layer, followed by applying a composite polymer layer in the form of a matrix based on polyolefins and a reinforcing filler - fiber on the adhesive layer and radiation modification of the coating using at least one electron accelerator with a dose of 1-100 Mrad, with a ratio of the speed of movement to scab rotation equal pipe 0.1-5.0.

2. A method of producing a radiation-modified polymer coating on a steel pipe, comprising applying a primer layer to the surface of the steel pipe, followed by applying to the primer layer a composite polymer monolayer in the form of a matrix containing polyolefins and an adhesive based on polyolefins, and a reinforcing filler - fibers, and radiation modification of the coating using at least one electron accelerator with an irradiation dose of 1-100 Mrad with a ratio of the speed of movement to the speed of rotation t Rubs equal to 0.1-5.0.

3. A steel pipe with a radiation-modified polymer coating containing a coating based on layers obtained according to any one of claim 1 to 2, wherein the coating is radiation-modified using at least one electron accelerator.