EP3600694B1 - Method for coating a pipe and coating system - Google Patents

Description

TECHNICAL AREA

The present invention relates to a method for coating a tube with an inner lining, in particular an inner plating.

TECHNICAL BACKGROUND

There is an increasing demand for corrosion-resistant, media-carrying conduits, which serve, for example, as water, gas or oil pipeline pipes.

In particular, the demand for corrosion-resistant pipes is growing in the oil and gas producing industry, since in the future the fluids to be pumped will have higher water proportions and higher concentrations of hydrogen sulfide (H ₂ S) and carbon dioxide (CO ₂ ). Such increasingly corrosive products often have to be transported over long distances in remote areas and under increased pressure.

Suitable pipes for such media are steel pipes with an inner coating, an inner lining or an inner plating, which offer cost advantages compared to pipes made of corrosion-resistant steels.

Clad steel pipes in particular, which are provided with an inner cladding made of corrosion-resistant steel, have been used successfully for the transport of moist and corrosive petroleum and natural gas products. For example, corrosion-resistant steel grades such as 316L, Alloy 825, Alloy 625 or duplex steel grades, which have high strength and good corrosion resistance, serve as the support material (cladding).

There are two basic processes for producing internally clad pipes:
On the one hand, so-called metallurgically clad pipes are known, which are made from a roll or explosive clad primary material (plates, sheets), from which a pipe is then produced by deformation (rolling, edging) and welding. The steel material and the corrosion-resistant support material are firmly metallurgically connected to each other by a diffusion bridge.

On the other hand, there are mechanically clad pipes in which a corrosion-resistant inner pipe is drawn into an outer steel pipe and is mechanically molded in using a hydroforming process. The inner tube and the outer tube are expanded together using water pressure. When the water pressure is reduced, the elastic recovery rate of the Outer tube puts the inner tube into a residual compressive stress state - the inner tube is immersed in the outer tube.

In a continuation of this classic expansion process, the so-called "rolled lined" methods have been developed. Starting from the flat sheet (two sheets) or from the tube (outer tube and inner tube), mechanical compression is created by moving the sheets during the forming process or when rolling the inner tube into the outer tube. In all cases there is a firm mechanical connection between the inner and outer pipe, but there is no firm metallurgical connection via a diffusion bridge. However, this process is considerably less expensive than the production of metallurgically clad pipes.

There are also internally coated pipes with organic corrosion protection (see e.g. DE 2 348 751 A ). Such inner coatings can, for example, be liquid epoxy layers or also multilayer melt coatings in which epoxy resin mixtures are applied in powder form to the inner surface of the heated pipe. Although such organic coatings are relatively corrosion-resistant, their service life is limited in the case of abrasive media that flow through such pipes.

For oil and gas pipelines, the pipe sections are prefabricated and completely coated on the outside at the factory. A three-layer polyolefin (polyethylene or polypropylene) coating (cf. ISO 21809-1) is customary as the coating. To do this, however, the outer surface of the tube must be heated to temperatures between 150 ° C and 250 ° C, because only at these temperatures does the powdered epoxy components melt, mix with each other, react with one another in the desired manner and then react to a so-called gel - Solidify time and finally harden and thus form the basis for the further layer build-up.

From the EP 1 045 750 B1 it is known to cool the tubes from the inside after coating in order to improve the curing of the outer coating, in particular in the area of the weld seam.

In this coating process, the tubes are passed through ring-shaped induction coils that heat a complete tube section. Organic interior coatings usually do not withstand such temperatures. Clad pipes and in particular mechanically clad pipes are also only suitable for such preparatory heat treatment to a limited extent because the different thermal expansion coefficients of the outer pipes (carbon-manganese steel material) and the inner pipes (corrosion-resistant steel quality) impair the connection between the pipes or even completely loosen them can be. These are the proven methods for the thermally assisted application of resistant outer coatings for such pipes not usable and less resistant outer coating systems may have to be used.

WO 2014/056107 A1 discloses a method and an apparatus for externally coating pipes. It also addresses the problem that existing coatings should not be damaged during coating. For the solution, an application of uncrosslinked polymers is suggested since these have a lower melting point and should only be crosslinked after application. First, a coating is applied, then the coating is heated and then cooled. The possibility of cooling by water application in the inside of the tube is also mentioned.

JP S57 201571 also discloses an apparatus and method for externally coating a pipe, in which the cooling by water injection takes place both on the outside and on the inside. The water cooling takes place away from the local heating of the coating. In addition, it is pointed out that the cooling efficiency is increased by an uncoated inside.

US 3,411,933 A describes a device and method in which an outer coating is applied almost over the entire length and the entire inner length is locally cooled. The cooling is time-controlled after the application and fusion of the outer coating.

The object is to provide an outer coating process in which the disadvantages mentioned above are at least partially eliminated. Another task can be seen in realizing a corresponding coating system for carrying out such a method.

SUMMARY

• Bereitstellen eines Rohrs in einer Beschichtungsanlage,
• lokales Erwärmen eines zu beschichtenden Außenflächenbereichs des Rohrs mit einer Heizvorrichtung,
• lokales Kühlen der Innenbeschichtung mit einer Kühlvorrichtung im Bereich des erwärmten Außenflächenbereichs, so dass dort in einer Übergangszone zwischen Rohr und Auskleidung eine erste Grenztemperatur nicht überschritten wird und im zu beschichtenden Außenflächenbereich eine zweite Grenztemperatur nicht unterschritten wird, und
• Beschichten des erwärmten Außenflächenbereichs mit einer Beschichtungsvorrichtung.

According to a first aspect, the present invention provides a method for the outer coating of a tube with an inner coating, in particular an inner plating, which comprises:

• Providing a pipe in a coating system,
• locally heating an outer surface area of the tube to be coated with a heating device,
• local cooling of the inner coating with a cooling device in the area of the heated outer surface area, so that a first limit temperature is not exceeded there in a transition zone between pipe and lining and a second limit temperature is not fallen below in the outer surface area to be coated, and
• Coating the heated outer surface area with a coating device.

• eine Heizvorrichtung,
• eine Kühlvorrichtung,
• eine Beschichtungsvorrichtung,
• einen Temperatursensor und
• eine Steuerung.

A second aspect of the present invention relates to a coating system for carrying out the method according to the invention, which comprises:

• a heater,
• a cooling device,
• a coating device,
• a temperature sensor and
• a controller.

Further aspects and features result from the dependent claims, the attached drawing and the following description of embodiments.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Beschichtungsanlage,

Fig. 2

die in Fig. 1 dargestellte Beschichtungsanlage in einer anderen Ansicht,

Fig. 3

eine vergrößerte Schnittdarstellung eines zu beschichtenden Rohrs (Detail A aus Fig. 2) mit einer schematischen Darstellung eines Temperaturverlaufs über den Rohrwandquerschnitt und

Fig. 4

eine schematische Darstellung eines erfindungsgemäßen Verfahrens zur Rohrbeschichtung.

Embodiments will now be described by way of example with reference to the accompanying drawings. It shows:

Fig. 1

1 shows a schematic representation of a coating system according to the invention,

Fig. 2

in the Fig. 1 coating system shown in a different view,

Fig. 3

an enlarged sectional view of a pipe to be coated (detail A from Fig. 2 ) with a schematic representation of a temperature profile over the pipe wall cross section and

Fig. 4

is a schematic representation of a method for tube coating according to the invention.

DESCRIPTION OF EMBODIMENTS

Before a detailed description of the embodiment or of the method with reference to the figures, general explanations of the embodiments follow.

In one embodiment of the method according to the invention in accordance with the first aspect of the invention, the following method steps are first carried out in succession and simultaneously in the run-in process: First, a tube is provided in a coating system. An outer surface area of the tube to be coated is locally heated with a heating device. In the same or immediately adjacent area, the inner lining is cooled locally with a cooling device. Heating and cooling are coordinated so that a first limit temperature is not exceeded in a transition zone between the pipe and the lining. The limit temperature is selected so that below this temperature neither the inner lining itself suffers nor the connection between the inner lining (inner tube) and the pipe material (outer tube). This is particularly important for metallic inner linings that have been applied to the inner wall of the pipe using a plating process.

At the same time, local heating and local cooling are coordinated with one another in such a way that a second limit temperature is not fallen below in the (heated) outer surface area to be coated. This limit temperature represents an essential process variable for the coating itself. It is particularly important in the case of powder coatings which are melted onto the pipe surface, since this temperature is responsible for the required melting and curing process.

With correspondingly set parameters (first limit temperature and second limit temperature), the heated outer surface area is coated with a coating device.

The term "inner lining" primarily includes metallic linings, i.e. claddings, made of corrosion-resistant steel qualities such as duplex steels, super duplex steels and alloys such as 316L, Alloy 625, Alloy 825 and copper nickel 9010 (according to relevant material standards and pipe Oil and gas norms / standards: e.g. API 5LD, Saudi Aramco, etc.). In connection with the present application, however, the term “inner lining” should not be restricted to such linings, but also also to such linings or Coatings include, which are either applied in layers in the lining process, melted or applied in liquid form. These include, for example, liquid epoxy paints, anti-rust paints or other organic coatings, but also so-called three-layer polyolefin coatings with a fusion-bonded epoxy (FBE) primer.

For metal linings or metal claddings, the first limit temperature is between 40 ° C and 80 ° C. This temperature can also be lower for organic coatings or paints.

The second temperature limit that must be reached in order to be able to provide a high-quality outer coating (for example an FBE primer) is 150 ° C to 250 ° C. For other coating materials, however, this temperature can also be above or below.

There are methods in which the heat conduction is supported by setting a relative feed movement between the tube on the one hand and the heating device, cooling device and / or coating device on the other hand. First of all, the pipe to be coated is guided past these devices with a feed movement. This feed movement can be a spiral movement, for example, in which a rotational movement around the pipe axis is combined with a feed movement in the direction of the pipe axis. The feed movement can, however, also be carried out in stages, so that a coating strip is applied during a 360 ° rotation of the tube and then the entire tube is continued by a certain amount, which corresponds to the width of a coating strip.

The feed movements can be carried out solely by moving the tube, which is guided past the heating device, the cooling device and the coating device by means of a suitable conveying device. In other versions, however, partial movements can also be carried out by the above-mentioned devices themselves. For example, the rotational movement of the tube can be adjusted via a suitable rotating mechanism, while the corresponding translatory movement is carried out via movable unit carriers on the outside of the tube or inside the tube. Movable supports or rails can be provided for this.

There are methods in which the cooling takes place via a cooling fluid applied to the inner lining with the cooling device and the cooling fluid flow and / or a cooling fluid temperature are adjusted in the process. In this way, the required heat dissipation can be set precisely. Suitable cooling fluids are suitable gases or liquids, in particular water, which can be provided in the desired amount and in the desired temperature.

The use of gases or gas mixtures has the advantage that they can be used without additional drainage or collecting devices. In particular, an air flow is used for cooling minimal effort required and available without additional gas supply. Only the systems for building up pressure and possibly for tempering the cooling air are required.

Water cooling may be more efficient, since a higher cooling effect can be achieved with a water flow and the cooling water can easily be discharged through the pipe and returned to a cycle, so that the water consumption can also be kept comparatively low here.

There are methods in which the surface temperature of the tube is detected with one or more temperature sensors in an effective range of the heating device, the cooling device and / or the coating device. One or more surface temperature values can then be used in a controller to adjust the feed movement, the cooling fluid flow and the cooling fluid temperature such that the first and / or the second limit temperature are maintained in a desired range. In this context, the term "control" is broad and encompasses not only controls in the narrower sense, but also control processes or regulations in which the desired reference variables are set in feedback.

• Oberflächentemperatur des Rohrs im Wirkbereich der Heizvorrichtung, der Kühlvorrichtung und der Beschichtungseinrichtung. Dabei können sowohl Temperaturen an der Außenwand als auch an der Innenwand des Rohrs erfasst, verarbeitet und/oder eingestellt werden.
• Mehrachsige relative Vorschubbewegung des Rohrs (rotatorisch und/oder translatorisch),
• Abstandsregelung der Heizvorrichtung, Beschichtungseinrichtung und/oder der Kühlvorrichtung;
• Steuern eines Beschichtungsmassestroms.

The control system is designed and set up in such a way that it detects, sets and, if necessary, changes any or any combination of the following parameters:

• Surface temperature of the pipe in the effective area of the heating device, the cooling device and the coating device. Temperatures on the outer wall as well as on the inner wall of the tube can be recorded, processed and / or set.
• Multi-axis relative feed movement of the pipe (rotary and / or translatory),
• Distance control of the heating device, coating device and / or the cooling device;
• Controlling a coating mass flow.

There are designs in which the cooling device is arranged on a carrier running inside the tube to be coated. This allows the cooling device to be positioned relative to the coating device and heating device in a simple manner. The cooling device can also be arranged to be movable and / or adjustable on this carrier, so that a relative movement of the cooling device to the tube can also be realized via the movability.

There are designs in which an adjustment device is provided on the cooling device, via which the position and / or an orientation of the cooling device can be adjusted. This further improves the setting options of the cooling device and thus an improvement in the cooling parameters.

There are designs in which the heating device has an induction device, a gas burner device and / or a radiant heat source. An induction device generates eddy currents in the ferritic material of the tube, the energy of which is partly converted into heat by the specific electrical resistance and leads to the heating of the tube. Such a heat source generates the desired heat in a geometrically narrow manner in the range of the magnetic flux precisely specified by induction coils. In this way, a precisely localized supply of heat can take place. The shape of the heat-affected zone (for example round, square, oval) and / or its number and distribution can also be precisely determined using an induction heating device.

In addition or alternatively, more or less conventional gas burner devices or other flow or radiant heat sources (hot air, infrared radiators) can also be provided in order to carry out the desired supply of heat or to preheat the material. Radiant heat sources can have radiation surfaces heated electrically or with fossil fuels.

Versions in which the temperature sensor (s) are designed as laser pyrometers allow quick and contactless temperature determination. They can be attached and adjusted at almost any location in order to monitor the temperature at different locations (for example in the area of the heating device, in the area of the cooling device or in the coating area). In this way, temperature profiles can also be determined in critical areas (for example between the heating device and the coating device on the outside of the pipe or between the heating device and the cooling device on the inside of the pipe), in order to ensure that the relevant limit temperatures on the outside are observed precisely of the pipe and in the transition area in the transition zone between pipe and lining. In alternative versions, suitable contact temperature sensors can also be used.

There are versions in which the coating system is equipped with a pipe conveyor device for carrying out at least one component of the relative feed movement, in particular a rotational movement. The rotational movement can be carried out, for example, by means of a suitable large-tube turning mechanism with which the rotational movement, which is largely decisive for the coating, can be set to control the coating application. Such a rotating mechanism receiving the pipe can in turn be made movable in order to carry out the additional longitudinal movement, so that a spiral feed movement (continuous feed) is realized. In other versions, this longitudinal feed along the tube axis can also take place in stages, that is to say piece by piece with a coating in several rings.

In other embodiments, the coating system is provided with one or more adjustable device carrier (s) for receiving the heating device, the cooling device, the coating device and / or the temperature sensor for carrying out at least one component of the relative feed movement, in particular a translation movement. In such an embodiment, the device (s) then moves translationally along the outer or inner surface of the tube (continuously and / or in stages) and thus takes over the execution of a component of the relative feed movement. With such a design, apart from the rotational movement, the tube can be held stationary during the coating process. This makes it easier, for example, to implement a cooling water circuit in conjunction with internal cooling, for which much more compact water collection and circulation devices can then be implemented.

Coming back to the 1 and 2 these show an embodiment of a coating system 1 according to the invention, which serves for the outer coating of a tube 2 with an inner coating 3, which is designed here as an inner plating. The pipe 2 is made of an oil and / or gas-compliant steel material (so-called X grades such as X65) and typically has a wall thickness of 12.7 mm to 60 mm and is typically used as a pipeline in the oil and gas production industry. The inner plating is made of an austenitic stainless steel, a duplex steel or a nickel-based alloy with a wall thickness of 2mm to 6mm.

The coating system 1 comprises a rotating and conveying system 4, which comprises rotating rollers 5 for rotating the tube, and longitudinal conveying elements 6. The rotating rollers 5 serve to rotate the tube 2 in the circumferential direction about an axis of rotation 7, and the longitudinal conveying elements 6 serve to Perform translation movement along the axis of rotation 7.

In another embodiment, not shown, the turning and conveying system 4 can also be designed as a rotating mechanism arranged on a rail guide, in which the rotating rollers 5 set the tube in rotation and the entire rotating mechanism can be moved along the axis of rotation 7.

For coating the tube 2, a coating device 8 is provided, which uniformly applies a coating material to the outside of the tube 2 along a helical line or a ring line. The helix is generated by the two components 9a and 9b in a relative feed movement. Component 9a designates a rotational component and component 9b a translational component of this relative feed movement of tube 2 to coating device 8.

The coating material is applied in powder form and melts on the heated pipe outer surface 2a. A heating device 10, which is used to heat the outer tube surface 2a Inductor is formed and the tube outer surface or tube 2 is heated so far that the desired temperature of 190 ° C in the area of the coating device 8 (second limit temperature T _G2 ) is reached and is not fallen below, so that the desired melting process occurs.

Furthermore, a cooling device 11 (see Fig. 2 ) is provided, which is arranged on a support 12 projecting into the interior of the tube 2, which sprays cooling water onto the inner surface of the inner coating, so that in a transition zone 14 (cf. Fig. 3 ) a certain limit temperature (first limit temperature T _G1 ) of 35 ° C is not exceeded.

A temperature sensor 15, which is designed as an infrared pyrometer and detects the surface temperature of the tube in the area of the heating device 10, is used for temperature detection. The carrier 12 is optionally coupled adjustable in the direction of the arrow 16 to a support 17 which comprises an adjustment mechanism which adjusts the carrier 12 in the vertical direction 16.

Additionally or alternatively, the cooling device 11 is arranged to be pivotable in the direction 18 (also adjustment of the cooling device) about the axis of rotation 7, so that the coolant flow K (cf. Fig. 3 ) is adjustable along the circumferential direction between the heating device and the coating device (see Fig. 2 ). In this way, the local cooling effect can be optimally adjusted.

Optionally, further temperature sensors are provided between the heating device 10 and the coating device 8 for detecting temperatures of the outer surface and / or corresponding sensors for detecting the inner surface temperature (the inner coating 3).

• Rotations- und/oder Translationskomponente 9a, 9b der relativen Vorschubbewegung über die Dreh- und Förderanlage 4,
• die Heizleistung der Heizvorrichtung 10,
• die Austragsmenge des Beschichtungsmaterials, bzw. Beschichtungsstroms B aus der Beschichtungsvorrichtung 8 (vgl. auch B in Fig. 3),
• die Fluidmenge und/oder die Fluidtemperatur des aus der Kühlvorrichtung 11 ausgebrachten Fluidstroms (K, vgl. Fig. 3) sowie
• die Verstellung der Kühlvorrichtung in Richtung 18.

To control the coating system 1, a controller 19 is provided, which is connected via signal and control lines 20 to the rotating and conveying system 4, the adjusting device of the support 17, the heating device 10, the coating device 8, the temperature sensor 15 and (not shown) the cooling device 11 is coupled. The controller 19 sets (regulating or controlling) one or more of the following parameters:

• Rotation and / or translation component 9a, 9b of the relative feed movement via the turning and conveying system 4,
• the heating power of the heating device 10,
• the discharge amount of the coating material or coating stream B from the coating device 8 (cf. also B in Fig. 3 ),
• the fluid quantity and / or the fluid temperature of the fluid stream (K, cf. Fig. 3 ) such as
• the adjustment of the cooling device in direction 18.

The controller 19 controls these parameters such that the second limit temperature T _G2 required for coating is reached on the outer surface of the tube 2 and the first limit temperature T _G1 in the transition zone 14 between the inner wall of the tube 2 and the inner cladding or Inner coating 3 is not exceeded. A temperature range of 60 ° C to 80 ° C applies to the first limit temperature T _G1 in the case of metallic inner cladding and a temperature range of 150 ° C to 250 ° C for the second limit temperature T _G1 on the outer tube surface 2a.

Fig. 3 shows the detail A from the Fig. 2 together with a temperature wall thickness diagram that shows an exemplary temperature profile over a pipe cross-section. In the area of the tube outer surface 2a of the tube 2, the heating effect H achieves a temperature of T _S0 , which is above the second limit temperature T _G2 and can be set such that the coating material (for example powder) applied in the coating stream B has a melt 22 on it Coating surface 2a of the tube 2 forms. The relative feed movement shown here is essentially formed by the rotation component 9a. On the opposite side, the coolant flow K strikes the inner surface 3a of the inner coating 3, specifically in a range between the local heat flow H (heated area) and the coating flow B. The adjustability in this area is indicated by the arrow 18.

The coolant flow K causes the temperature in the direction of the inner tube wall 3a to decrease so much that the temperature in the transition zone 14, which is formed around the interface 23 between the inner tube side and the lining, is reduced below the limit temperature T _G1 , so that at the interface itself the interface temperature T _SG prevails. It is assumed here that the thermal conductivity in the tube 2 is higher than that in the lining or inner coating 3.

Different limit temperatures T _G1 may also be required for different inner coatings 3 or inner claddings or inner linings 3, which may be selectable and adjustable via the controller 19. The same applies to the second limit temperature T _G2 , which can be different for different coating materials.

The second limit temperature T _G2 on the outer surface of the tube is primarily determined by the heating effect H, while the first limit temperature T _{G1 can be set} primarily by the cooling effect K.

• S1 Bereitstellen eines Rohres in einer Beschichtungsanlage,
• S2 lokales Erwärmen eines zu beschichtenden Außenflächenbereichs des Rohres mit einer Heizvorrichtung,
• S3 lokales Kühlen der Innenbeschichtung mit einer Kühlvorrichtung im Bereich des erwärmten Außenflächenbereichs, so dass dort in einer Überganszone zwischen Rohr und Auskleidung eine erste Grenztemperatur (T_G1) nicht überschritten wird und im zu beschichtenden Außenflächenbereich eine zweite Grenztemperatur (T_G2) nicht unterschritten wird,
• S4 Beschichten des erwärmten Außenflächenbereichs mit einer Beschichtungsvorrichtung,

und optional (ersetzend bzw. ergänzend) die Schritte:

• S5 Einstellen einer relativen Vorschubbewegung zwischen Rohr einerseits und Heizvorrichtung, Kühlvorrichtung und/oder Beschichtungsvorrichtung andererseits,
• S6 Ausbringen eines Kühlfluids mit der Kühlvorrichtung auf die Innenauskleidung,
• S7 Einstellen eines Kühlfluidstroms und/oder einer Kühlfluidtemperatur,
• S8 Erfassen einer Oberflächentemperatur des Rohres mit einem Temperatursensor in einem Wirkbereich der Heizvorrichtung, der Kühlvorrichtung und/oder der Beschichtungseinrichtung,
• S9 Verwenden einer Steuerung zum Einstellen einer der Größen: Vorschubbewegung, Kühlfluidstrom, Kühlfluidtemperatur unter Berücksichtigung wenigstens eines erfassten Oberflächentemperaturwertes, der ersten Grenztemperatur und/oder der zweiten Grenztemperatur.

Fig. 4 schematically shows a method according to the invention for externally coating the tube 2, which comprises the following steps:

• S1 provision of a pipe in a coating system,
• S2 local heating of an outer surface area of the tube to be coated with a heating device,
• S3 local cooling of the inner coating with a cooling device in the area of the heated outer surface area, so that a first limit temperature (T _G1 ) is not exceeded in a transition zone between the pipe and lining and a second limit temperature (T _G2 ) is not fallen below in the outer surface area to be coated,
• S4 coating the heated outer surface area with a coating device,

and optionally (replacing or supplementing) the steps:

• S5 setting a relative feed movement between the tube on the one hand and the heating device, cooling device and / or coating device on the other hand,
• S6 applying a cooling fluid with the cooling device to the inner lining,
• S7 setting a cooling fluid flow and / or a cooling fluid temperature,
• S8 detecting a surface temperature of the pipe with a temperature sensor in an effective range of the heating device, the cooling device and / or the coating device,
• S9 using a controller for setting one of the variables: feed movement, cooling fluid flow, cooling fluid temperature taking into account at least one detected surface temperature value, the first limit temperature and / or the second limit temperature.

Other alternatives and variants of the present invention will be apparent to those skilled in the art within the scope of the claims.

REFERENCE SIGN LIST

1

Coating system

2nd

pipe

2a

Pipe outer surface

3rd

Inner coating (inner plating)

3a

Inner pipe wall

4th

Turning and conveyor system

5

Rotating roller

6

Longitudinal conveyor element

7

Axis of rotation

8th

Coating device

9a

Rotational component

9b

Translation component

10th

Heater

11

Cooler

12

carrier

14

Transition zone

15

Temperature sensor

16

Adjustment direction

17th

Support

18th

Cooling device adjustment

19th

control

20th

Signal and control line

22

Coating melt

23

Interface

T _G1

first limit temperature

T _G2

second limit temperature

T _S0

Pipe outer surface temperature

T _SG

Interface temperature

T _S1

Inner tube temperature

H

Heating effect

B

Coating current

K

Coolant flow / cooling effect

Claims (11)

1. A method for coating the exterior of a pipe (2) having an interior coating (3), more particularly an interior cladding, comprising:

   - providing the pipe (2) in a coating system (1),

   - locally heating an exterior surface area of the pipe (2) to be coated with a heating device (10),

   - locally cooling the interior coating (3) using a cooling device (11) in the region of the heated exterior surface area, such that in a transition zone (14) between the pipe (2) and the interior coating (3), a first limit temperature (T_G1) is not exceeded and, in the exterior surface area to be coated, the temperature does not fall below a second limit temperature (T_G2),

   - coating the heated exterior surface area by means of a coating device (8).
2. The method according to claim 1, including:
   setting a relative feed motion (9a, 9b) between the pipe (2), on the one hand, and heating device (10), cooling device (11) and/or coating device (8), on the other hand.
3. The method according to claim 1 or 2, including:

   spreading a cooling fluid with the cooling device (11) over the interior coating (3),

   setting a coolant flow and/or a cooling fluid temperature.
4. The method according to claim 1, 2 or 3, including:

   detecting a surface temperature (T_S0) of the pipe (2) with a temperature sensor (15) in an effective range of the heating device (10), the cooling device (11) and/or the coating device (8),

   using a controller (19) to adjust one of the variables: feed motion (9a, 9b), coolant flow (K), cooling fluid temperature taking into account at least one detected surface temperature value (T_S0, T_S1), the first limit temperature (T_G1) and/or the second limit temperature (T_G2).
5. A coating system (1) for carrying out the method according to any of claims 1 to 4, comprising
   a heating device (10), a cooling device (11), a coating device (8), a temperature sensor (15) and a controller (19).
6. The coating system (1) according to claim 5, wherein the cooling device (11) is arranged on a carrier (12) running inside the pipe (2) to be coated.
7. The coating system (1) according to claim 6, wherein the cooling device (11) comprises an adjusting device for adjusting the cooling device (18), by means of which a position and/or an orientation of the cooling device (11) can be adjusted.
8. The coating system (1) according to claim 5, 6 or 7, wherein the heating device (19) has an induction device, a gas burner apparatus and/or a radiant heat source.
9. The coating system (1) according to claim 5, 6, 7 or 8, wherein the temperature sensor (15) is designed as a laser pyrometer.
10. The coating system (1) according to any of claims 5 to 9, comprising a pipe conveying apparatus (4) for carrying out at least one component (9a, 9b) of the relative feed motion, in particular a rotational movement (9a).
11. The coating system (1) according to any of claims 5 to 10, comprising an adjustable device carrier (12) for receiving the heating device (10), the cooling device (11), the coating device (8) and/or the temperature sensor (15) for carrying out at least one component of the relative feed motion (9a, 9b), in particular a translational movement (9b).

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