RU115247U1 - PRODUCTION LINE FOR APPLICATION OF ANTI-CORROSION COATING TO LARGE-SIZED STEEL PIPE - Google Patents

Abstract

1. A production line for automatically applying anti-corrosion coating to a large-sized steel pipe, containing a feed mechanism that allows the steel pipe to rotate and move horizontally along the axis of the steel pipe, a degreasing and drying machine that removes grease and water on the surface of the steel pipe, an automatic shot blasting machine that removes rust and oxide coatings on the surface of the steel pipe and a preheating chamber that heats up the steel pipe, while the automatic shot blasting machine is positioned between the degreasing and drying machine and the preheating chamber , characterized in that after the preheating chamber there is an installation for spray painting and hardening, and this installation consists of a spray painting chamber, a film-paint hardening chamber and a cooling chamber located at consequently in line; ! there is a spray painting machine in the spray painting booth, which sprays paint with anti-corrosion coating on the surface of the steel pipe, and a hot air circulation system is located in the curing chamber of the paint film. ! 2. The production line of claim 1, wherein the pipe feeding mechanism includes a plurality of groups of wheels spaced apart from each other and at the same height, each group of wheels consists of two wheels arranged in parallel and rotatable in the same direction, and the distance between two adjacent groups

Description

2420-179500EN / 010

PRODUCTION LINE FOR APPLICATION OF ANTI-CORROSION COATING TO LARGE-SIZED STEEL PIPE

Description

The technical field to which the utility model relates.

This utility model relates to a method for anticorrosion treatment of a steel pipe and a production line for implementing the method, in particular, to a variation of a method for automatically applying an anticorrosion coating to a large steel pipe and a production line for implementing the method.

Description of the Related Art

Oversized steel pipes usually have a diameter of 0.5-2.4 m, a length of 12-90 m and are made of steel. Due to the rapid development of the national economy of China, more and more large-sized steel pipes in recent years have been used in harbors and docks, shipbuilding and urban planning. In order to effectively combat corrosion of large steel pipes in order to extend the life of large steel pipes and guarantee the safe operation of the infrastructure, the surface of large steel pipes should be treated with protective coatings. The most commonly used anti-corrosion treatment is to apply anti-corrosion paint to the surface of a steel pipe. At present, in China and abroad there are three main methods of applying anticorrosion paint to the surface of a large-sized steel pipe, that is, manual painting, deposition of an epoxy coating (NEP (FBE)), and applying polyethylene in three layers (NPTS (3LPT)) .

In this case, the method of manual painting is mainly painting a large steel pipe with bitumen paint, that is, firstly, manual or mechanized shot blasting of the steel pipe is carried out, and secondly, paint is applied to the surface of the steel pipe by coating with rollers manually or by painting spray. With the above manual painting, the steel pipe can be treated with anti-corrosion paint, but this method has several of the following disadvantages, listed below.

(1) Since the solvent content in bitumen paint is relatively large, a lot of organic solvent will volatilize during the drying process of the coating, which will lead not only to environmental pollution, but also to worsening production conditions, this can increase the labor intensity of people and cause problems related to human health.

(2) In this case, a large-sized steel pipe cannot be rolled at the place of work during manual painting, and in addition, the viscosity of the selected paint cannot be very high, and the organic solvent content in the paint can usually reach 15% or more, and this will lead to paint film after painting, which results in the phenomenon of uneven coating, thinner on top and thicker on the bottom, which significantly reduces the overall anti-corrosion performance of the coating on the steel pipe.

(3) Hand-painting of a large-sized steel pipe is usually applied in conditions of ventilated rooms or in the open air, and due to the restrictions imposed by the production environment and weather conditions, the time of the painting operation should depend on the weather. Therefore, it is impossible to guarantee the quality, progress of the operation and the effectiveness of the operation of painting a large-sized steel pipe; in this case, the hardening of the coating after application of the paint is completed under natural conditions, the hardening time should be long, and the occupied work area should be large.

At the same time, epoxy coating is automatically fused to a mechanical assembly line. When a large steel pipe is helically rolled forward in a drive unit after removing the rust on the steel pipe by a shot peening machine, the steel pipe will be heated to a certain temperature due to medium frequency induction, and the epoxy powder will quickly be applied as a paint to the surface of the steel pipe by electrostatic spraying. The epoxy powder melts, becoming a paint film immediately after contact with a steel pipe having a high temperature, and is bonded to the surface of the steel pipe. In conclusion, the coating quickly hardens due to rapid cooling with water.

Compared to manual painting, the deposition of epoxy coatings obviously increases the degree of automation, and the environment and weather will not affect the application and hardening of the coating, as a result of which the labor costs of people are reduced, and the efficiency is relatively high. However, this method is rarely used abroad as part of an autonomous coating system, mainly because the temperature changes so significantly during the coating process, and the steel pipe and coatings have such different expansion coefficients that the coating on the steel pipe has a high internal (mechanical) voltage, as a result of which this coating will be very susceptible to damage under the influence of external force, and after damage to the coating it is very difficult to patch it at the construction site means of the same method.

At the same time, the application of polyethylene in three layers is used when applying an anti-corrosion coating for a buried steel pipe. The length of the steel pipe processed in this way is only about 10 meters, and this method is not applicable for a longer steel pipe. Therefore, the application of polyethylene in three layers cannot be applied when applying an anti-corrosion coating in the case of a large-sized steel pipe, and this application of polyethylene in three layers can rarely be observed in harbors and docks, shipbuilding and urban planning. Currently, several production lines for large steel pipes are described in documents such as Chinese publications CN1673604A, CN1672809A and CN1122772C. In these documents, a primer applied as a winding in the form of a tape or polyethylene is described as a coating material.

Utility Model Summary

The first objective of this utility model is to develop a method for automatically applying an anti-corrosion coating to a large steel pipe, involving the use of high solids paint, high painting efficiency and reduced environmental pollution at the same time, while the coating has the proper ability to resist impact.

The second objective of this utility model is to develop a production line for automatically applying an anti-corrosion coating to a large steel pipe, and this line involves the use of paint with a high solids content, high painting efficiency and reduced environmental pollution at the same time, while the coating has the proper ability to resist shock.

To solve the first problem, a method for automatically applying an anti-corrosion coating to a large steel pipe provides:

step 1, in which the steel pipe is placed on the pipe feeding mechanism, the pipe feeding mechanism is started, and the steel pipe is first passed through a degreasing and drying machine designed to remove grease and water located on the surface of the steel pipe;

step 2, in which, after removing grease and water, a steel pipe is introduced into an automatic shot blasting machine to remove the rust coating and oxide coating located on the surface of the steel pipe and to make the surface of the steel pipe meet the requirements for cleanliness and roughness before painting spray;

step 3, in which the steel pipe is introduced into the preheating chamber, in which the steel pipe is heated to the first temperature, which is in the range between the pour point of the selected paint reduced by 40 ° C and the pour point of the selected paint reduced by 20 ° C;

step 4, in which, after heating, the steel pipe is introduced into the spray booth and the spray booth spray-paints a second temperature onto the surface of the steel pipe, the second temperature being in the range between the pour point of the selected paint, reduced by 40 ° C , and the pour point of the selected paint, reduced by 20 ° C;

step 5, in which a coated steel pipe is introduced into the film-paint freeze chamber, and the hot air circulation system located in the film-paint freeze chamber supplies hot air to heat the steel pipe to the pour point of the selected paint;

step 6, in which a steel pipe is introduced into the cooling chamber to effect rapid cooling;

step 7, in which if a plurality of coating layers is to be applied to the cooled steel pipe, the steel pipe is introduced into the next spray and curing unit, which consists of a spray painting chamber, a film-paint curing chamber, and a cooling chamber, repeating step 4 sequentially, step 5 and step 6 until all coating layers are ready.

In the method according to this utility model, both the value of the first temperature in the preheating chamber, which is the heating temperature of the steel pipe, and the value of the second temperature that the spray paint has, correspond to the pour point of the selected paint. Therefore, the steel pipe and coating can be heated synchronously, and this can accelerate the curing of the film-paint and can significantly reduce the curing time of the coating.

In order to also reduce environmental pollution caused by volatilization of the solvent present in the paint and to reduce the number of (gas) bubbles in the paint film, the solvent content in the paint should be less than 10%.

In a preferred embodiment, the hot air circulates in the freezing chamber of the film-paint. This will reduce costs, add safety to operation and improve the freezing conditions of the coating.

Preferably, the spray paint machine may be a high pressure airless spray paint machine, and the time taken from the moment the ink enters the high pressure airless paint machine until the paint is sprayed out is limited to 3 minutes. Under the conditions of a high pressure airless spray paint machine, it is possible to easily control the paint spray temperature, the time during which the paint and the curing catalyst are mixed together, and the time between heating the paint and spraying the paint.

To solve the second problem, a production line has been proposed for the automatic application of an anti-corrosion coating on a large steel pipe, containing a feed mechanism that ensures rotation of the steel pipe and its horizontal movement along the axis of the steel pipe, a degreasing and drying machine that removes grease and water on the surface steel pipe, an automatic shot blasting machine that removes the rust coating and the oxide coating located on the surface of the steel pipe, and the pre-heating chamber that heats the steel pipe, while the automatic shot-blasting cleaning machine is located between the degreasing and drying machine and the pre-heating chamber, and the production line is characterized in that

after the pre-heating chamber, there is a spray painting and pouring apparatus, this installation consisting of a spray painting chamber, a film-paint freezing chamber and a cooling chamber arranged in series in a line

at the same time, a spray painting machine is located in the spray booth, which sprays a paint with an anti-corrosion coating on the surface of the steel pipe, and a hot air circulation system is located in the freezing chamber of the film-paint.

In this utility model, the spray and curing unit performs all operations - coating in the form of paint, curing and cooling - in a mechanically automated mode, in contrast to the traditional method of manual painting, curing and cooling in natural conditions. This installation also increases the efficiency of painting, in particular, the curing time of the film-paint is significantly reduced, and in this utility model it takes only 20 minutes, while in the usual way it takes 24 hours. Efficiency is increased by more than 10 times. In addition, it is possible to avoid the negative impact of natural conditions on the hardening and cooling of the film-paint, and you can also increase the ability to resist impact. In this case, it is also possible to avoid environmental pollution and harm to the operator due to volatilization of the solvent.

In a preferred embodiment, the pipe feed mechanism includes a plurality of groups of wheels located at a distance from each other and at the same height, each group of wheels consists of two wheels arranged in parallel and rotatable in the same direction, and the distance between two adjacent groups of wheels should be large so that the steel pipe, when it is transported, covers at least two groups of wheels at the same time. Of course, the pipe feed mechanism may be another one known in the art.

In a preferred embodiment, the installation for spray painting and solidification has only two groups of wheels, which are located, respectively, in front of the spray painting chamber and after the cooling chamber. Therefore, in the process of applying paint to the steel pipe, hardening the coating and cooling the coating, the portion of the steel pipe to be coated will not come into contact with the wheel, and then the paint film will not be damaged due to adhesion of the coating and the feeding mechanism.

Preferably, on either side of the bottom of the steel pipe in the preheating chamber are two nozzles inclined to the steel pipe, and these nozzles communicate with a source of hot air. The heating rate according to this method is high, and the necessary equipment and a source of hot air are easy to find.

In a preferred embodiment, the spray paint machine is a high pressure airless spray paint machine that is associated with an automatic paint heating mechanism. The automatic paint heating mechanism may be located at the inlet of the high pressure airless spray paint machine, and may also be located in the middle of the high pressure airless paint spraying machine, that is, between the pump of the high pressure airless paint spraying machine and the paint spraying channel . By using the characteristics of a high pressure airless spray paint machine, the paint can be applied as an aerosol after heating. As a result, the solvent content in the paint can be significantly reduced by achieving rapid curing of the paint film.

In a preferred embodiment, several spray painting and curing units can be arranged according to the number of coating layers, and when three coating layers are provided on the surface of the steel pipe, accordingly, there are three spray painting and curing units arranged in series. This is specifically provided for the painting process, which usually requires a primer, an intermediate coat of paint and a surface coat of paint at these three stages of painting.

Compared with the known technical solutions, in this proposed utility model, a method for automatically applying an anti-corrosion coating to a large steel pipe and a production line for implementing the method provide continuous and automatic processing of a steel pipe in one production line, for example, dehydration and cleaning, surface treatment, heating, painting and other procedures. This utility model combines the methods of heating a steel pipe and painting with airless spray under high pressure, which make the processing of large-sized steel pipes continuous and automatic.

Thus, in comparison with traditional manual painting, it is possible to significantly reduce the labor intensity of people and to increase production efficiency (it is possible to increase by more than 10 times). And the solvent content in the paint can be reduced to less than 10% from the traditional range from 40% to 60%, the volatilization of the organic solvent can be reduced by 4-6 times, as a result of which it is possible to reduce environmental pollution by reducing the amount of volatile organic solvent, and reduce energy consumption, and it is also possible to minimize the negative impacts on the quality of the coating caused by the production environment.

And compared with the method of depositing a coating containing oxide powder, the ability to resist impact is significantly improved, which allows stably satisfying or exceeding the requirements (50 kg · cm) of the national standard of China.

Therefore, in this utility model, working time is much reduced, production costs are reduced, and the quality of the anticorrosion coating and the anticorrosive ability of a large-sized steel pipe can be guaranteed. During field tests, an unexpected technical result will be achieved. It is useful for popularizing and applying to an existing bulky steel pipe.

Brief Description of the Drawings

Figure 1 presents the sequence diagram of the operations of the production line in accordance with a possible embodiment of this utility model.

Figure 2 presents a section along the line aa shown in figure 1.

Figure 3 presents a section along the line bb shown in figure 1.

Figure 4 presents a section along the line CC shown in figure 1.

Detailed Description of a Preferred Embodiment

In order to guarantee a better understanding of the innovative and production content of the presented utility model, we refer to the following detailed description of the utility model and the accompanying drawings.

Figure 1 - figure 4 illustrate an embodiment of this utility model.

As shown in FIG. 1, in this embodiment, the production line for automatically applying an anti-corrosion coating to a large steel pipe comprises a steel pipe supply mechanism 1, a degreasing and drying machine 2, an automatic shot blasting machine 3, a pre-heating chamber 4 and an installation for spray painting and solidification, which consists of a spray painting chamber 5, a film-freezing chamber 6, and a cooling chamber 7. In this embodiment, three layers of coating need to be applied to the steel pipe 8, so the three spray and curing units are respectively arranged in series in a line, that is, in this order: the first unit for spray painting and curing, the second unit for spray painting and hardening and the third installation for spray painting and hardening.

In this case, the steel pipe supply mechanism 1 contains several groups of wheels located at a distance from each other and at the same height, each wheel group consisting of two wheels located in parallel and rotatably in the same direction, and the line coinciding with the axis of each wheel in each group of wheels, inclined relative to the horizontal, to carry out the spiral rolling of the steel pipe 8 forward along these wheels. In addition, the distance between two adjacent groups of wheels should be large so that the steel pipe 8, when it is transported, covers at least two groups of wheels at the same time. Installation spray painting and solidification has two groups of wheels, which are respectively located in front of the camera 5 spray painting and after the cooling chamber 7.

Installation 2 for degreasing and drying uses a diesel burner for a gas boiler or other existing equipment is used. The automatic shot blasting machine 3 uses conventional equipment. In the preheating chamber 4, on either side of the bottom of the steel pipe 8, there are two nozzles inclined to the steel pipe 8, as shown in FIG. And these nozzles communicate with a source of hot air, and they spray hot air at an angle on both sides from the bottom of the pipe 8 to heat the steel pipe 8.

In each spray painting chamber 5, a high pressure airless spray paint machine 9 is located, and the nozzle of the high pressure airless paint spraying machine 9 is located at the top of the steel pipe 8, tilted to the steel pipe 8, as shown in FIG. 3. The paint inlet of this high pressure airless paint spraying machine 9 is connected to the output of an automatic paint heating mechanism, which is a conventional automatic paint heating mechanism. In each chamber 6 hardening film-paint is a hot air circulation system in which conventional technology is used. In this embodiment, natural air flow is used for cooling in the cooling chamber 7, and if necessary, air conditioning can be used.

In this embodiment, three layers of coating should be applied to the steel pipe 8, that is, when painting with a primer, an epoxy resin is used as a paint, the solvent content of this paint being about 8%, and its pour point is 90 ± 10 ° C. When applying an intermediate layer of paint, an epoxy resin is used as a paint, with a solvent content of about 6% of the paint and a pour point of 90 ± 10 ° C. When applying the surface layer of paint, an epoxy resin is used as a paint, the solvent content of this paint being about 1% and the pour point of 90 ± 10 ° C.

In the conditions of a production line for automatically applying an anticorrosive coating to a large steel pipe, a method for automatically applying an anticorrosive coating to a large steel pipe includes the following steps.

Stage 1: place a steel pipe 8 with a diameter of 1.8 m and a length of 60 m for coating on the pipe feed mechanism 1 by means of a hoist, start the pipe feed mechanism 1, and two wheels in each group of wheels rotate in the same direction, making a spiral rolling a steel pipe forward between groups of wheels; when the steel pipe 8 first passes through the machine 2 for degreasing and drying, the flame caused by the diesel burner reaches the surface of the steel pipe 8, removing grease and water located on the surface of the steel pipe 8.

Stage 2: after removing grease and water, the steel pipe 8 is introduced into the automatic shot blasting machine 3 to remove the rust coating and oxide coating located on the surface of the steel pipe 8 and to make the surface of the steel pipe 8 meet the requirements for cleanliness and roughness before spray painting.

Stage 3: the steel pipe 8 is introduced into the preheating chamber 4, as shown in FIG. 2, and two nozzles spray hot air onto the steel pipe 8 from both sides at the bottom of the steel pipe 8, heating the steel pipe 8 to a first temperature, which is 50- 70 ° C, and then the steel pipe 8 is transported to the spray booth 5.

Stage 4: the automatic heating mechanism heats the paint to a second temperature, which is 50-70 ° C, and transport the paint to the machine 9 for painting by high-pressure airless spraying, mix the paint with the curing catalyst, and spray the mixture in the form of an aerosol on top of the steel pipe 8 on the surface of the steel pipe 8, as shown in Fig.3. The time taken from the moment the ink enters the paint machine for painting by high pressure airless spraying until the ink is sprayed out is adjusted to 3 minutes.

Step 5: a steel pipe with a primer coating is introduced into the film-paint freezing chamber 6, and the hot air circulation system located in the film-paint freezing chamber 6 supplies hot air, as shown in FIG. 4. This hot air heats the steel pipe 8 with a primer coating on both sides of the steel pipe 8, and this heating occurs to a temperature of 90 ± 10 ° C, that is, the film-paint obtained by painting with a primer quickly solidifies, and the hot air circulation system can to ensure the removal of volatile solvent from the operation of the primer.

Stage 6: enter the steel pipe 8 into the cooling chamber 7, where the natural air flow blows the steel pipe 8 on both sides of the steel pipe 8, quickly cooling the steel pipe 8.

Since the two groups of wheels are respectively located in front of the spray paint chamber 5 and after the cooling chamber 7, in the process from applying the primer to hardening of the coating and cooling of the coating, the portion of the coated steel pipe 8 will not come into contact with the wheel, and then the paint film will not will be damaged due to adhesion of the coating and feed mechanism.

Step 7: inject the steel pipe 8 with a cooled primer coating into a second spray painting and curing unit and a third spray painting and curing unit, sequentially repeating step 4, step 5 and step 6. In this second installation for spray painting and curing, after heating the paint of the intermediate layer to 50-70 ° C by means of a mechanical heating machine in the spray painting chamber 5, the paint of the intermediate layer is introduced into the machine 9 for painting by airless spray under high pressure, and the temperature measures the pour-paint film of 90 ± 10 ° C.

In the third installation for spray painting and solidification, the temperature of the paint of the surface layer, which is introduced into the machine 9 for painting by airless spraying under high pressure, is 50-70 ° C and the temperature of the freezing chamber of the film-paint is 90 ± 10 ° C.

After that, the process of painting a large steel pipe 8 ends.

In this embodiment, the pipe portion that is not described is the same as with prior art.

Under the conditions of the aforementioned production line, when three coating layers are applied to the large steel pipe 8, the time for applying each coating layer from painting to finish cooling after solidification is only 20 minutes. Therefore, it takes only 1 hour to complete the application of three coating layers. Operation time is significantly reduced, and production efficiency is increased; in addition, due to the automatic implementation of the entire procedure as a whole, the quality of painting for coating is improved.

Claims (6)

1. A production line for automatically applying a corrosion-resistant coating to a large-sized steel pipe, comprising a feed mechanism that rotates the steel pipe and moves it horizontally along the axis of the steel pipe, a degreasing and drying machine that removes grease and water located on the surface of the steel pipe, an automatic shot blasting machine that removes rust and oxide coatings on the surface of the steel pipe and chambers pre-heating, which heats the steel pipe, while the automatic shot-blasting cleaning machine is located between the machine for degreasing and drying and the pre-heating chamber, characterized in that after the pre-heating chamber is a spray painting and pouring machine, and this installation consists of a spray painting chamber , curing film-paint and cooling chambers arranged in series in line; at the same time, in the spray booth there is a spray booth that sprays paint with an anti-corrosion coating on the surface of the steel pipe, and a hot air circulation system is located in the freezing chamber of the film-paint. 2. The production line according to claim 1, in which the pipe feed mechanism includes many groups of wheels located at a distance from each other and at the same height, each group of wheels consists of two wheels located in parallel and rotatable in in the same direction, and the distance between two adjacent groups of wheels should be large so that the steel pipe, when it is transported, covers at least two groups of wheels at the same time. 3. The production line according to claim 2, in which the installation for spray painting and solidification has only two groups of wheels, which are located respectively in front of the spray painting chamber and after the cooling chamber. 4. The production line according to claim 1, in which on either side of the bottom of the steel pipe in the preheating chamber are two nozzles inclined to the steel pipe, and these nozzles communicate with a source of hot air. 5. The production line according to claim 1, in which the machine for spray painting is a machine for painting by airless spray under high pressure, which is associated with a mechanism for automatic heating of the paint. 6. The production line according to claims 1-5, in which three installations for spray painting and hardening, respectively, are arranged sequentially in a line.