CN108825886B - One-step forming process of internal and external double-corrosion-resistant plastic-coated composite pipe - Google Patents
One-step forming process of internal and external double-corrosion-resistant plastic-coated composite pipe Download PDFInfo
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- CN108825886B CN108825886B CN201810735297.4A CN201810735297A CN108825886B CN 108825886 B CN108825886 B CN 108825886B CN 201810735297 A CN201810735297 A CN 201810735297A CN 108825886 B CN108825886 B CN 108825886B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/02—Rigid pipes of metal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
- C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
- C09D123/04—Homopolymers or copolymers of ethene
- C09D123/06—Polyethene
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
- C09D5/03—Powdery paints
- C09D5/033—Powdery paints characterised by the additives
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
- F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
- F16L58/04—Coatings characterised by the materials used
- F16L58/10—Coatings characterised by the materials used by rubber or plastics
- F16L58/1009—Coatings characterised by the materials used by rubber or plastics the coating being placed inside the pipe
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
- F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
- F16L58/04—Coatings characterised by the materials used
- F16L58/10—Coatings characterised by the materials used by rubber or plastics
- F16L58/1054—Coatings characterised by the materials used by rubber or plastics the coating being placed outside the pipe
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2202/00—Metallic substrate
- B05D2202/10—Metallic substrate based on Fe
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2254/00—Tubes
- B05D2254/04—Applying the material on the interior of the tube
- B05D2254/06—Applying the material on the interior and exterior of the tube
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2504/00—Epoxy polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D2507/00—Polyolefins
- B05D2507/01—Polyethylene
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Laminated Bodies (AREA)
Abstract
The invention discloses a one-step forming process of an internal and external double-anticorrosion plastic-coated composite pipe, belonging to the technical field of double-anticorrosion plastic-coated composite pipes. The one-step molding process of the plastic-coated composite pipe comprises the following steps: the preheating temperature is increased to 350-400 ℃ by adjusting the formula of the polyethylene coating powder coating, and the coating is finished before the surface temperature of the steel pipe is reduced to 260 ℃; and when the temperature of the steel pipe is reduced to 220-260 ℃, coating an epoxy powder coating on the outer surface, and curing to obtain the inner and outer double-anticorrosion plastic-coated composite pipe. The invention realizes the one-step molding of the double-anticorrosion plastic-coated composite pipe with the flange connection, the polyethylene lining and the epoxy powder coating, and the epoxy powder coating is a heavy-anticorrosion coating, thereby not only solving the defect of long construction period for painting the outer surface of the pipeline, but also solving the defect that painting is limited by seasons, humidity and temperature.
Description
Technical Field
The invention relates to the technical field of plastic-coated composite pipes, in particular to a one-step forming process of an internal and external double-corrosion-resistant plastic-coated composite pipe.
Background
The double-corrosion-resistant pipeline and the pipe fitting are widely applied to the fields of water treatment such as electric power, chemical engineering, seawater desalination, sewage treatment, pharmacy, ports, civil use and the like. At present, the anticorrosion pipes and pipe fittings used at home and abroad are mainly plastic-coated composite pipes internally coated with polyethylene (PE coating) or epoxy resin powder (EP coating), and the outer surface of the steel pipe adopts the treatment forms of primer, intermediate paint and finish paint.
The thickness of the coating EP of the plastic-coated steel pipe is generally 0.3 mm-0.5 mm, the thickness of the coating PE is about 1mm-3mm, and the thickness of the coating PE is larger. The working temperature of the coating EP of the plastic-coated steel pipe is-20-120 ℃, and the coating PE is suitable for the working environment of-20-60 ℃. The coating materials EP and PE of the plastic steel pipe have good corrosion resistance and weather resistance. The conveying fluid (medium) of the plastic-coated composite pipe is only contacted with the coating and is completely and effectively isolated from the metal body, so that the plastic-coated composite pipe has good corrosion resistance, cathode stripping resistance and excellent acid, alkali and salt corrosion resistance; under the condition of severe use environment (such as acid salt alkalinity or desert environment), the pipeline can be normally used, and the service life of the pipeline can be effectively prolonged. The plastic-coated composite steel pipe has smooth inner wall, small friction coefficient, fast flow speed, no accumulated scale and small fluid resistance.
The dry film thickness of paint (anti-corrosion paint) on the outer surface of the plastic-coated steel pipe is required to be 270-300 micrometers, and for northern China and coastal areas, the paint film thickness is required to be constructed for a long time (about 10 days) to reach the technical requirement due to the influence of regions and environments (low temperature and high air humidity), so that the construction period and the site are greatly influenced, the delivery period of each batch of products is prolonged by about 10 days, the products cannot be stacked before pipeline painting is dried, and the site occupation area is large.
The situation is improved by lining the PE coating and overcoating the EP. The proportion of the existing PE plastic dipping powder is generally (wt%): 80% of PE resin, 8% of polypropylene, 3% of EVA, 3% of polybutylene, 3% of cellulose acetate and 3% of terpene resin. In addition, in order to improve other properties of the coating film, some additives such as antistatic agents and the like are often added. The polyethylene resin has three states at different temperatures, namely a glass state, a high elastic state and a viscous state. In a lower temperature environment, the high polymer is in a rigid solid state, has little deformation under the action of external force, is similar to glass, and is called as a glass state. If the environmental temperature is raised to a certain temperature, the shape of the material is obviously changed under the action of external force, the form change is relatively stable in a certain temperature interval, and the state is called a high-elasticity state. If the temperature continues to rise, the deformation quantity gradually increases along with the rise of the temperature until the viscous fluid is formed, the shape of the viscous fluid cannot be recovered, and the viscous fluid state is obtained.
The temperature must be higher than the viscous state temperature Tm when coating and film forming. Therefore, when the existing PE plastic dipping powder is coated to form a film, the workpiece preheating temperature and the film forming time are both proper, the workpiece preheating temperature is generally 300-350 ℃ (the plastic coating is ensured not to foam and the leveling speed is high), and the film forming (plasticizing) temperature is 180-220 ℃; after plasticizing, the temperature is reduced to below 220 ℃, the temperature condition can be used for continuously coating the anti-corrosion paint, but the temperature condition can not reach the temperature requirement for coating the EP coating (220-.
Disclosure of Invention
Aiming at the defect that the prior art can not form a PE inner lining and coat an EP coating on a steel pipe at one time, the invention aims to provide a one-time forming process of an inner and outer double-anticorrosion plastic-coated composite pipe.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the inner and outer double-anticorrosion plastic-coated composite pipe comprises a steel pipe base pipe, a steel pipe liner Polyethylene (PE) coating and an epoxy resin (EP) coating coated on the outer surface of the steel pipe; the thickness of the polyethylene coating is 1-3mm, and the thickness of the epoxy powder coating is 0.3-0.5 mm.
The bonding strength between the base pipe of the steel pipe and the lining is more than 4MPa, and the adhesive force of the outer coating is 1.
Two ends of the plastic-coated composite pipe are respectively connected with a flange and are used for connecting different plastic-coated composite pipes;
the side (back) of the flange connected with the plastic-coated composite pipe is coated with an epoxy resin (EP) coating, and the connecting surface (flange front) of the flange and the flange among different pipelines is coated with a polyethylene coating.
The material of the steel tube base tube can be 20-grade steel or Q235B and the like.
The one-step forming process of the inner and outer double-corrosion-resistant plastic-coated composite pipe comprises the following steps:
(1) preparing a steel pipe base pipe;
(2) coating polyethylene on the inner surface of the steel pipe;
preparing a polyethylene coating, preheating the steel pipe in a heating furnace to 350-400 ℃, discharging, coating the polyethylene coating, and finishing the coating before the surface temperature of the steel pipe is reduced to 260 ℃;
(3) after the temperature of the steel pipe is reduced to be within 260 ℃, polishing the outer surface of the steel pipe, and after the residual polyethylene coating paint on the outer surface of the workpiece is cleaned, ensuring that the temperature of the surface of the workpiece is still between 220 ℃ and 260 ℃;
(4) rolling and coating an epoxy resin coating on the outer surface of the steel pipe;
and coating an epoxy powder coating on the outer surface of the workpiece under the condition that the surface temperature of the workpiece is higher than 220 ℃, and curing to obtain the inner and outer double-anticorrosion plastic-coated composite pipe.
In the step (2), the polyethylene coating paint comprises the following components in parts by weight:
in the polyethylene coating paint, the weight ratio of polypropylene to EVA is (0.8-1): 1.
in the polyethylene coating paint, the polypropylene is preferably 5.0-6.0 parts by weight, and the EVA is preferably 5.5-6.5 parts by weight.
In the polyethylene coating paint, an auxiliary agent such as an antistatic agent and the like can be added according to the requirement.
The design principle and the beneficial effects of the invention are as follows:
1. the structural design of the double-corrosion-resistant pipeline has accurate time and process requirements on the lining rolling process in the pipeline, the temperature of the pipeline discharged from a heating furnace is required to be higher than 350 ℃, the temperature of the pipeline cannot be reduced to below 260 ℃ before the lining rolling construction is finished, otherwise, the pipeline is treated as waste! Then hoisting the outer lining epoxy roller lining workbench, carrying out outer roller lining epoxy coating work before the temperature of the pipeline is reduced to 220 ℃, before the outer coating construction is finished, the temperature of the pipeline is still not lower than 220 ℃, hoisting the pipeline with the inner and outer double coating construction finished to a curing track device, entering a low-temperature furnace for curing and forming, and after the pipeline is discharged from the furnace, hanging and cooling the pipeline to the normal temperature.
2. The coating preheating temperature of the conventional PE coating formula is 300-350 ℃, and the invention adjusts the PE coating formula to ensure that the polypropylene accounts for 5.0-6.5 wt% and the EVA accounts for 5.0-7.0 wt%, so that the coating preheating temperature is increased by 50 ℃ (increased to 350-400 ℃) compared with the conventional temperature, and the plasticizing temperature is above 260 ℃, thereby enabling the roll coating of the EP coating on the outer surface to be possible when the temperature of the inner surface of the pipeline is reduced to below 260 ℃ and above 220 ℃, namely realizing the one-step molding of the PE coating and the EP coating in the steel pipe.
Drawings
FIG. 1 is a schematic view of a one-step formed composite tube structure with internal and external dual corrosion-resistant coatings.
FIG. 2 is a view of the connection between the inner and outer double corrosion-resistant plastic-coated composite pipes through flanges.
FIG. 3 is a plastic layer of the inner and outer surfaces of the steel plastic pipe; wherein: (a) an outer surface; (b) an inner surface.
Wherein: 1-coating a plastic composite pipe; 101-a steel pipe base pipe; 102-polyethylene coating; 103-epoxy resin coating; 2-flange.
Detailed Description
For a further understanding of the present invention, the following description is given in conjunction with the examples which are set forth to illustrate, but are not to be construed to limit the present invention, features and advantages.
The structure of the internally and externally double-corrosion-resistant plastic-coated composite pipe formed in one step is shown in figure 1. The plastic coated composite pipe 1 comprises a steel pipe base pipe 101, a steel pipe lining Polyethylene (PE) coating 102 and an epoxy resin (EP) coating 103 coated on the outer surface of the steel pipe.
As shown in fig. 2, two ends of the plastic-coated composite pipe are respectively connected with a flange 2 for connecting different plastic-coated composite pipes; one side (back side) of the flange connected with the plastic-coated composite pipe is coated with an epoxy resin (EP) coating 103, and the connecting surface (flange front side) of the flange and the flange among different pipelines is coated with a polyethylene coating 102.
The thickness of the polyethylene coating is preferably 1-3mm, and the thickness of the epoxy resin coating is 0.3-0.5 mm.
The material of the steel tube base tube can be 20-grade steel or Q235B and the like.
Example 1:
the process for preparing the inner and outer double-corrosion-resistant plastic-coated composite pipe by one-step molding in the embodiment is as follows:
(1) preparing 20 steel or Q235B steel pipe, and connecting the steel pipe with a flange;
(2) coating polyethylene coatings on the inner surface of the steel pipe and the front surface of the flange:
preparing a polyethylene coating paint, wherein the paint comprises the following components in parts by weight: 80 parts of PE resin, 6 parts of polypropylene, 6 parts of EVA, 3 parts of polybutene, 3 parts of cellulose acetate and 3 parts of terpene resin.
The roll coating process comprises the following steps: heating the steel pipe in a heating furnace to 380 ℃, discharging, and finishing coating before the surface temperature of the steel pipe is reduced to 260 ℃, wherein the coating under the temperature condition can ensure that the plastic-coated powder does not blister (the plasticizing temperature of a polyethylene coating is more than 260 ℃);
(3) after the temperature of the steel pipe is reduced to be within 260 ℃, polishing the outer surface of the steel pipe, and after the residual polyethylene coating paint on the outer surface of the workpiece is cleaned, ensuring that the temperature of the surface of the workpiece is still between 220 ℃ and 260 ℃;
(4) rolling and coating epoxy resin coatings on the outer surface of the steel pipe and the back surface of the flange;
and coating an epoxy resin coating on the outer surface of the workpiece under the condition that the surface temperature of the workpiece is higher than 220 ℃, and curing to obtain the inner and outer double-anticorrosion plastic-coated composite pipe.
The detection results are as follows:
1. the plastic-coated composite pipe obtained in the embodiment has a Polyethylene (PE) lining coating of 2.5mm and an epoxy resin coating of 0.40mm coated on the outer surface.
2. Appearance and surface quality: reference standard: GB/T28897-2012 steel-plastic composite pipe; and (3) testing results: the inner and outer plastic layers of the steel-plastic pipe are smooth, and the steel-plastic pipe has no bubbles, cracks, peeling, scratches and depressions and has uniform color (figure 3).
3. The bonding strength of the inner lining plastic and the outer lining plastic is as follows:
reference standard: GB/T28897-2012 steel-plastic composite pipe;
test results for the outer plastic liner: the coating layer is obviously not stripped, and the grade is judged to be 1.
Test results for the lining plastic: the average inner diameter of the base pipe is 158mm, the length is 20mm, and the bonding strength is 4.43MPa (the bonding strength between the base pipe and the lining is not lower than 1.5MPa according to the standard requirement).
4. And (3) inner lining plastic layer adhesion:
testing equipment: a push-pull machine;
reference standard: GB/T28897-2012 steel-plastic composite pipe;
the testing process comprises the following steps: taking a 100mm long pipe section, cutting two cracks with the width of 10mm on the inner surface plastic coating layer along the pipe shaft direction by using a cutter to the surface of the base pipe, uncovering one end without damaging the plastic coating layer, clamping the plastic coating layer by using a clamp of a dynamometer, gradually peeling off by turning 180 degrees with force, observing the force when peeling off occurs, and determining that the force is qualified if the force is more than 30N.
And (3) testing results: the average adhesion was 101.9N.
4. Cold and hot shock cycle test:
testing equipment: a constant temperature and humidity chamber, a high and low temperature test chamber and a microcomputer control electronic universal material testing machine;
reference standard: GB/T28897-2012 steel-plastic composite pipe;
the testing process comprises the following steps: and soaking the test piece in hot water at 95 ℃ for 30min, taking out the test piece, cooling the test piece for 10min at normal temperature, soaking the test piece in cold water at 5 ℃ for 30min, taking out the test piece, standing the test piece for 10min at normal temperature, wherein the cycle is more than one cycle, and 3 cycles are carried out in total, and then carrying out an adhesion (outer layer) test or a bonding strength (inner layer) test on the test piece.
The test requirements are as follows: outer layer: the plastic layer is not allowed to deform and crack, and the adhesive force of the coating is 1 to 3 grades; inner layer: the plastic layer is not allowed to deform and crack, and the bonding strength is not lower than 1.5MPa.
And (3) testing results: after the outer layer test, the test sample has no crack, and no macroscopic layering phenomenon exists between the steel and the outer plastic layer; the coating layer is obviously not stripped, and the grade is judged to be 1. After the inner layer test, the test sample has no crack, and no macroscopic layering phenomenon exists between the steel layer and the inner plastic layer; 40717N maximum load, and 4.10MPa bonding strength.
5. Impact test of plastic coating layer:
testing equipment: a drop impact tester;
reference standard: GB/T28897-2012 steel-plastic composite pipe;
and (3) testing conditions are as follows: the weight of the hammer is 6.3Kg, and the falling height is 1000 mm.
And (3) testing results: after the test, the coating has no peeling and breaking phenomena.
6. Bending test:
reference standard: GB/T28897-2012 steel-plastic composite pipe;
and (3) testing conditions are as follows: the sample is bent to 90 degrees by a pipe bender, and the sample is cut at the bending deformation position and observed, so that the inner plastic layer and the outer plastic layer can not be separated from the base material.
And (3) testing results: after the test, the outer plastic layer and the steel pipe have no cracks and no delamination; the liner was not separated from the steel pipe substrate.
Comparative example 1:
the process for preparing the internal and external double-corrosion-resistant plastic-coated composite pipe comprises the following steps:
(1) preparing 20 steel or Q235B steel pipe, and connecting the steel pipe with a flange;
(2) coating polyethylene coatings on the inner surface of the steel pipe and the front surface of the flange:
preparing a polyethylene coating paint, wherein the paint comprises the following components in parts by weight: 80 parts of PE resin, 8 parts of polypropylene, 3 parts of EVA, 3 parts of polybutene, 3 parts of cellulose acetate and 3 parts of terpene resin.
The roll coating process comprises the following steps: heating the steel pipe in a heating furnace to 320 ℃, discharging the steel pipe out of the furnace, and then rolling and coating a polyethylene coating on the surface of the steel pipe, wherein the plasticizing temperature is about 180-; after plasticizing, the surface temperature of the pipeline is reduced to below 220 ℃, and an EP coating can not be coated. If the steel pipe is heated again to the rolling temperature of the epoxy coating (220 ℃ or higher), the already applied polyethylene coating is damaged. The coating under the temperature condition can ensure that the plastic-coated powder does not bubble (the plasticizing temperature of the polyethylene coating is more than 260 ℃).
Comparative example 2:
the difference from comparative example 1 is that:
in the roll coating process, the steel pipe is heated to 360 ℃ in a heating furnace and then discharged, and then a polyethylene coating is roll coated on the surface of the steel pipe. When the heating temperature is too high, the powder foams when the polyethylene coating is coated, and the coating fails.
Claims (7)
1. A one-step forming process of an internal and external double-anticorrosion plastic-coated composite pipe is characterized by comprising the following steps of: the plastic-coated composite pipe comprises a steel pipe, a steel pipe lining polyethylene coating and an epoxy powder coating coated on the outer surface of the steel pipe; the thickness of the polyethylene coating is 1-3mm, and the thickness of the epoxy resin coating is 0.3-0.5 mm; the one-step molding process of the plastic-coated composite pipe comprises the following steps:
(1) preparing a steel pipe;
(2) preparing a polyethylene coating on the inner surface of the steel pipe;
preparing a polyethylene powder coating, preheating the steel pipe to 350-400 ℃ in a heating furnace, discharging, then coating the polyethylene powder coating, and finishing the coating before the surface temperature of the steel pipe is reduced to 260 ℃;
(3) after the temperature of the steel pipe is reduced to be within 260 ℃, polishing the outer surface of the steel pipe, and after the residual polyethylene powder coating which is stained on the outer surface of the workpiece is cleaned, ensuring that the surface temperature of the workpiece is still between 220 and 260 ℃;
(4) spraying an epoxy powder coating on the outer surface of the steel pipe;
coating an epoxy powder coating on the outer surface of the workpiece under the condition that the surface temperature of the workpiece is higher than 220 ℃, and curing to obtain the inner and outer double-anticorrosion plastic-coated composite pipe;
in the step (2), the polyethylene powder coating comprises the following components in parts by weight:
75-85 parts of PE resin;
5.0-6.5 parts of polypropylene;
5.0-7.0 parts of EVA;
2-5 parts of polybutylene;
2-5 parts of cellulose acetate;
2-5 parts of terpene resin.
2. The one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 1, characterized in that: the bonding strength between the steel pipe and the polyethylene coating is more than 4MPa, and the adhesive force of the epoxy powder coating is grade 1.
3. The one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 1, characterized in that: the two ends of the plastic-coated composite pipe are respectively connected with a flange and are used for connecting different plastic-coated composite pipes.
4. The one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 3, characterized in that: the surface of the flange connected with the plastic-coated composite pipe is coated with an epoxy powder coating, and the connecting surface of the flange and the flange between different plastic-coated composite pipes is coated with a polyethylene coating.
5. The one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 1, characterized in that: the material of the steel pipe is 20-grade steel or Q235B.
6. The one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 1, characterized in that: in the polyethylene powder coating, the weight ratio of polypropylene to EVA is (0.8-1): 1.
7. the one-step molding process of the internal and external double-corrosion-resistant plastic-coated composite pipe according to claim 1, characterized in that: in the polyethylene powder coating, 5.0 to 6.0 parts by weight of polypropylene and 5.5 to 6.5 parts by weight of EVA are used.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108692134A (en) * | 2018-07-06 | 2018-10-23 | 何敏 | Double corrosion-proof plastic-coated multiple tubes and its one-shot forming technique inside and outside one kind |
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| CN113956698A (en) * | 2021-09-18 | 2022-01-21 | 安徽华辉塑业科技股份有限公司 | Pipeline anticorrosion powder coating |
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| JP2002327867A (en) * | 2001-02-28 | 2002-11-15 | Nkk Corp | Internal surface resin lining steel pipe and manufacturing method |
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| CN108692134A (en) * | 2018-07-06 | 2018-10-23 | 何敏 | Double corrosion-proof plastic-coated multiple tubes and its one-shot forming technique inside and outside one kind |
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