EP3600694A1

EP3600694A1 - Method for coating a pipe and coating system

Info

Publication number: EP3600694A1
Application number: EP18714219.5A
Authority: EP
Inventors: Jörg Doege; Otmar Becker; Lars Möller
Original assignee: Inprocoat Holding GmbH
Current assignee: Inprocoat Holding GmbH
Priority date: 2017-03-31
Filing date: 2018-03-26
Publication date: 2020-02-05
Anticipated expiration: 2038-03-26
Also published as: CN110494227A; DE102017106979A1; AR111395A1; WO2018177984A1; CN110494227B; EP3600694B1

Abstract

The present invention relates to a method for coating the exterior of a pipe (2) having an interior coating (3), more particularly an interior plating, comprising: providing the pipe (2) in a coating system (1), locally heating an exterior surface region of the pipe (2) to be coated using 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 threshold temperature (TG1) is not exceeded and in the exterior surface region to be coated, a second threshold temperature (TG2) is not undershot, coating the heated exterior surface region by means of a coating device (8), and a coating system (1) for carrying out such a method.

Description

METHOD OF PIPE COATING AND

COATING LINE

TECHNICAL AREA

The present invention relates to a method for coating a pipe with an interior lining, in particular an interior cladding.

TECHNICAL BACKGROUND

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

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 contents and higher concentrations of hydrogen sulphide (H2S) and carbon dioxide (CO2). Such increasingly corrosive products often need to be transported over long distances in remote areas and under increased pressure.

Suitable tubes for such media are steel tubes with an inner coating, an inner lining or an inner cladding, which offer cost advantages over tubes made of corrosion-resistant steels.

In particular, plated steel pipes provided with an inner cladding of a corrosion resistant steel are successfully used for the transportation of wet and corrosive petroleum and natural gas products. Corrosion-resistant steel grades such as 316L, Alloy 825, Alloy 625 or even duplex steel grades with high strength and good corrosion resistance are used as the cladding material (cladding).

There are two basic methods for producing internally-plated tubes:

On the one hand, so-called metallurgically clad pipes are known which consist of a rolling or

blast-plated starting material (plates, sheets) are made from the then by deformation (W alzen, edges) and welding a tube is made. The steel material and the corrosion-resistant support material are firmly metallurgically bonded together by a diffusion bridge.

On the other hand, there are mechanically clad pipes in which a corrosion-resistant inner pipe is drawn into a steel outer pipe and mechanically formed by means of a hydroforming process. The inner tube and the outer tube are expanded together by water pressure. When reducing the water pressure is due to the greater elastic springback rate of Outside tube the inner tube in a compressive residual stress state - the inner tube is immersed in the outer tube.

In continuations of this classic expansion method, the so-called "rolled lined" methods have been developed, starting from the flat metal sheet (two sheets) or from the pipe (outer pipe and inner pipe) by mechanical pressing by moving the sheets during the forming or in the inner tube In all cases, there is a strong mechanical connection between the inner and outer tubes, but there is no strong metallurgical connection via a diffusion bridge, but this method is considerably less expensive than the production of metallurgically plated tubes.

In addition, there are also internally coated pipes provided with organic corrosion protection (see for example DE 2 348 751 A). Such inner coatings may be, for example, liquid-applied epoxy layers or else multilayer melt coatings in which epoxy resin mixtures in powder form are applied to the inner surface of the heated tube. Although such organic coatings are relatively resistant to corrosion, their lifetime is limited in abrasive media flowing through such pipes.

For oil and gas pipelines, the pipe sections are prefabricated and externally completely coated at the factory. The coating used is a three-layer polyolefin (polyethylene or polypropylene) coating (cf ISO 21809-1). For this purpose, however, the outer surface of the tube must be heated to temperatures between 150 ° C and 250 ° C, because only at these temperatures, the powdered epoxy components go into a melt, mix with each other, react in the desired manner with each other and then after a so-called gel Solidify and finally harden and thus form the basis for the further layer structure.

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

In this coating process, the tubes are passed through annular induction coils that heat a complete tube section. Organic interior coatings usually do not withstand such temperatures. Also plated pipes and in particular mechanically clad pipes are also only limited suitable for such a preparatory heat treatment, as affected by the different thermal expansion coefficients of the outer tubes (carbon-manganese steel material) and the inner tubes (corrosion-resistant steel quality), the connection between the tubes or even can be completely solved. Thus, the best practices for thermally assisted application of durable exterior coatings for such pipes can not be used and, if necessary, less resistant external coating systems must be used.

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

SUMMARY

According to a first aspect, the present invention provides a method for exterior coating a pipe with an inner coating, in particular an inner plating, comprising:

Providing a pipe in a coating plant,

locally heating an outer surface area of the pipe to be coated with a heating device,

Local cooling of the inner coating with a cooling device in the region of the heated outer surface area, so that there is not exceeded in a transition zone between the pipe and lining a first temperature limit and in the outer surface area to be coated does not fall below a second limit temperature, and

Coating the heated outer surface area with a coating device.

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

a heating device,

a cooling device,

a coating device,

a temperature sensor and

a controller.

Other aspects and features will become apparent from the dependent claims, the accompanying drawings and the following description of embodiments.

BRIEF DESCRIPTION OF THE DRAWING

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

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

2 shows the coating system shown in FIG. 1 in another view, Fig. 3 is an enlarged sectional view of a pipe to be coated (detail A of Fig. 2) with a schematic representation of a temperature profile over the pipe wall cross section and

4 shows a schematic representation of a method according to the invention for pipe coating.

DESCRIPTION OF EMBODIMENTS

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

In one embodiment of the method according to the invention according to the first aspect of the invention, the following method steps are performed first of all in succession and simultaneously in the retracted process: First, a tube is provided in a coating installation. An outside surface area of the pipe to be coated is locally heated with a heater. 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 chosen so that below this temperature neither the inner lining suffers nor the connection between the inner lining (inner tube) and pipe material (outer tube). This is particularly important for metallic inner linings that have been applied to the inner wall of the tube in a plating process. At the same time, the local heating and the local cooling are coordinated so that a second limit temperature is not undershot in the (heated) outer surface area to be coated. This limit temperature is an essential process parameter for the coating itself. It is particularly important in powder coatings that are melted onto the pipe surface, as this temperature is responsible for the required melting and curing process.

With suitably adjusted parameters (first limit temperature and second limit temperature), the coating of the heated outer surface area is effected with a coating device.

The term "inner liner" covers primarily metallic linings, ie claddings, of corrosion-resistant steel grades such as duplex steels, super-duplex steels and alloys such as 316L, Alloy 625, Alloy 825 and cupronickel 9010 (in accordance with relevant material standards and piping standards). Oil and gas standards / standards: eg API 5LD, Saudi Aramco, etc.) The term "inner lining" should not be limited to such linings in the context of the present application, but also such linings or Coatings which are either applied in sheets by lining, melted or applied liquid. These include, for example, liquid epoxy prints, antirust coatings 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. For organic coatings or paints, this temperature may also be lower.

The second limit temperature which must be reached in order to provide a high quality outer coating (for example a FBE primer) is 150 ° C to 250 ° C. For other coating materials, however, this temperature may also be higher or lower.

There are methods in which the heat transfer is assisted by the setting of a relative feed movement between the tube on the one hand and the heating device, cooling device and / or coating device on the other. In the first instance, the tube to be coated is guided past these above-mentioned devices by means of a feed movement. This feed movement can be, for example, a spiral movement in which a rotational movement about the tube axis is combined with a feed movement in the direction of the tube axis. However, the feed movement can also be carried out step by step, 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 advancing 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 embodiments, but also partial movements of the above devices themselves can be performed. For example, the rotational movement of the tube can be adjusted via a suitable slewing gear, while the corresponding translational movement is carried out by means of movable aggregate carriers on the outside of the tube or in the interior of the tube. For this purpose, movable supports or rails can be provided.

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

The use of gases or gas mixtures has the advantage that they can be used without additional outflow or collecting devices. In particular, an air flow is for cooling with Minimal effort available and available without additional gas supply. There are only the systems for pressure build-up and possibly for controlling the temperature of the cooling air required.

A water cooling is possibly more efficient, since with a water flow, a higher cooling effect can be achieved and the cooling water can be easily removed through the pipe and recycled into a cycle, so that here too the water consumption can be kept relatively low.

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 may then be used in a controller to adjust the advancing movement, the cooling fluid flow, and the cooling fluid temperature to maintain the first and / or second limit temperatures within a desired range. The term "control" in this context is broad and includes not only controls in the strict sense, but also control operations or regulations in which the desired reference variables are set fed back.

The controller is designed and set up in such a way that it selectively detects, adjusts and possibly changes individual or any combinations of the following parameters:

Surface temperature of the tube in the effective range of the heater, the cooling device and the coating device. In this case, both temperatures on the outer wall and on the inner wall of the tube can be detected, processed and / or adjusted. Multi-axial relative feed movement of the tube (rotational and / or translational), distance control of the heater, coating device and / or the cooling device;

Controlling a coating mass flow.

There are embodiments in which the cooling device is arranged on a running inside the pipe to be coated carrier. Thus, the positioning of the cooling device can be made relative to the coating device and heater in a simple manner. The cooling device may also be arranged to be movable and / or adjustable on this support, so that a relative movement of the cooling device to the pipe can be realized via the movability.

There are embodiments in which an adjusting device is provided on the cooling device, via which the position and / or an orientation of the cooling device are adjustable. This further improves the setting options of the cooling device and thus an improvement of the cooling parameters. There are embodiments 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 partially converted into heat by the specific electrical resistance and leads to heating of the tube. Such a heat source generates the desired heat in a geometrically tight manner in the region of the magnetic flux precisely predetermined by induction coils. In this way, a precisely localized heat supply can take place. Also, the shape of the heat affected zone (for example, round, angular, oval) and / or their number and distribution can be accurately determined with an inductively operating heater.

Additionally or alternatively, however, more or less conventional gas burner devices or other flow or radiant heat sources (hot air, infrared radiator) can be provided to perform the desired heat or a preheating of the material. Radiation heat sources may have electrically or with fossil fuels heated radiant surfaces.

Embodiments in which the temperature sensor (s) are designed as laser pyrometers permit rapid and non-contact temperature determination. They can be mounted and adjusted in almost any location to monitor the temperature in different locations (for example, in the area of the heater, in the area of the cooler or in the coating area). In this way, temperature profiles can also be determined in critical regions (for example between the heating device and the coating device on the outside of the device)

Pipe or also between the heating device and the cooling device on the inside of the pipe) so as to determine and adjust a precise compliance with the relevant limit temperatures on the outside of the pipe and in the transition region in the transition zone between pipe and liner. In alternative embodiments, suitable Kontakttemperaturfüh- 1er can be used.

There are embodiments in which the coating installation is equipped with a pipe conveying 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, via a suitable large-diameter rotary mechanism, with which the rotational movement largely controlling the coating for controlling the coating application can be set. Such a pipe receiving slewing can in turn be made movable again to perform the additional longitudinal movement, so that a spiral feed movement (continuous feed) is realized. In other embodiments, this longitudinal feed along the tube axis can also be done in stages, ie piece by piece in a coating in several rings. In other embodiments, the coating system is provided with one or more adjustable device carriers 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 translational movement. In such an embodiment, the device (s) then move translationally along the outer or inner surface of the tube (continuously and / or in stages), thus assuming the execution of a component of relative feed motion. With such an embodiment, apart from the rotational movement during the coating process, the tube may be received stationary. This facilitates, for example, the realization of a cooling water circuit in conjunction with the internal cooling, for which substantially more compact water collecting and circulating devices can be realized.

Returning to FIGS. 1 and 2, these show an embodiment of a coating system 1 according to the invention, which is used for the outer coating of a tube 2 with an inner coating 3, which is designed here as an inner cladding. The tube 2 is made of an oil and / or gas-conforming steel material (so-called X-grades such as X65) and typically has one

Wall thickness of 12.7mm to 60mm and is classically used as a pipeline in the oil and gas production industry. The internal cladding is made of an austenitic stainless steel, a duplex steel or a nickel-based alloy in a wall thickness of 2mm to 6mm.

The coating installation 1 comprises a turning and conveying system 4, which comprises rotating rollers 5 for rotating the tube, as well as 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 this purpose to perform a translational movement along the axis of rotation 7.

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

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 helix or a ring line. The helix is generated by the two components 9a and 9b in a relative feed motion. The component 9a designates a rotational component and the component 9b a translation component of this relative advancing movement of the tube 2 to the coating device 8.

The coating material is applied in powder form and fuses on the heated tube outer surface 2a. For heating the pipe outer surface 2a is a heater 10, which serves as Inductor is formed and the pipe outer surface or the tube 2 heats up so far that the desired temperature of 190 ° C in the region of the coating device 8 (second limit temperature TG2) is reached and not fallen below, so that the desired reflow occurs.

Furthermore, a cooling device 11 (see FIG. 2) is provided inside the tube, which is arranged on a carrier 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 TGI) of 35 ° C is not exceeded.

For temperature detection is a temperature sensor 15, which is designed as an infrared pyrometer and detects the surface temperature of the tube in the region of the heater 10. The carrier 12 is optionally coupled in the direction of arrow 16 adjustably with a support 17, which comprises an adjusting mechanism which adjusts the carrier 12 in the vertical direction 16.

Additionally or alternatively, the cooling device 11 is arranged pivotable in the direction 18 (also adjustment of the cooling device) about the rotation axis 7, so that the coolant flow K (see 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).

To control the coating system 1, a controller 19 is provided, which via signal and control lines 20 with the rotating and conveying system 4, the adjustment of the support 17, the heater 10, the coating device 8, the temperature sensor 15 and (not shown) of the cooling device 11 is coupled. The controller 19 adjusts (or controls) 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 heater 10,

the discharge amount of the coating material or coating stream B from the coating device 8 (see also B in FIG.

the amount of fluid and / or the fluid temperature of the discharged from the cooling device 11 fluid flow (K, see Fig. 3) and

the adjustment of the cooling device in the direction of the 18th The controller 19 controls and regulates these parameters so that the required for coating second boundary temperature T _{G2 is achieved} on the outer surface of the tube 2 and the first limit temperature TGI in the transition zone 14 between the inner wall of the tube 2 and the

Internal plating or the inner coating 3 is not exceeded. For the first limit temperature T _GI , a temperature range from 60 ° C. to 80 ° C. applies to metallic interior plating and a temperature range from 150 ° C. to 250 ° C. for the second limit temperature TGI at the pipe outer surface 2 a.

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

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

For different inner coatings 3 or inner claddings or inner linings 3, different limit temperatures TGI may also be required, which optionally can be selected and set via the controller 19. The same applies to the second limit temperature T _G2 , which may be different for different coating materials.

The second limit temperature TG2 on the outer surface of the tube is determined primarily by the heating effect H, while the first limit temperature TGI is adjustable primarily by the cooling effect K.

4 shows schematically a method according to the invention for coating the outside of the tube 2, comprising the following steps:

Sl providing a pipe in a coating plant, 52 local heating of an outer surface area of the pipe to be coated with a heating device,

53 local cooling of the inner coating with a cooling device in the region of the heated outer surface area, so that in a Uberganszone between the pipe and liner a first temperature limit (TG _I ) is not exceeded and in the outer surface area to be coated, a second temperature limit (TG_) is not exceeded

54 coating the heated outer surface area with a coating apparatus, and optionally (replacing or supplementing) the steps:

55 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,

56 applying a cooling fluid with the cooling device to the inner lining,

57 setting a cooling fluid flow and / or a cooling fluid temperature,

58 detecting a surface temperature of the tube with a temperature sensor in an effective range of the heating device, the cooling device and / or the coating device,

Using a controller to set one of the variables: feed motion, cooling flow, cooling fluid temperature taking into account at least one sensed surface temperature value, the first limit temperature and / or the second limit temperature.

Further alternatives and variants of the present invention will become apparent to those skilled in the scope of the claims.

LIST OF REFERENCE NUMBERS

1 Installation instructions

2 pipe

2a outside pipe surface

3 inner coating (internal plating)

3a pipe inner wall

4 turning and conveying system

5 spinning reel

6 longitudinal conveyor element

7 axis of rotation

8 coating device

9a rotational component

9b translation component

10 heating device

11 cooling device

12 carriers

14 transition zone

15 temperature sensor

16 adjustment direction

17 Support

18 Construction Cooling device

19 control

20 signal and control line

22 T he sealing melt e

23 interface

T _G , first limit temperature

TG2 second limit temperature

Tso temperature outside pipe surface

TsG temperature interface

Tsi temperature pipe inner wall

H heating effect

B Coating current

K coolant flow / cooling effect

Claims

1. A method for external coating of a tube (2) with an inner coating (3), in particular internal plating, with:

Providing the tube (2) in a coating installation (1),

local heating of an outer surface region of the pipe (2) to be coated with a heating device (10),

Local cooling of the inner coating (3) with a cooling device (1 1) in the region of the heated outer surface area, so that there in a transition zone (14) between the tube (2) and inner coating (3) a first limit temperature (T _GI ) is not exceeded, and in the outer surface area to be coated, a second limit temperature (T _G I) is not exceeded,

Coating the heated outer surface area by means of a coating device (8),

2. The method of claim 1 comprising:

Setting a relative feed movement (9a, 9b) between the tube (2) on the one hand and heating device (10), cooling device (1 1) and / or coating device (8) on the other.

3. The method according to claim 1 or 2 comprising:

Applying a cooling fluid to the cooling device (1 1) on the inner coating (3),

Adjusting a coolant flow and / or a cooling fluid temperature.

4. The method of claim 1, 2 or 3 comprising:

Detecting a surface temperature (Tso) of the tube (2) with a temperature sensor (15) in an effective range of the heating device (10), the cooling device (1 1) and / or the coating device (8),

Use of a controller (19) for adjusting one of the following variables: advancing movement (9a, 9b), coolant flow (K), cooling fluid temperature taking into account at least one detected surface temperature value (Tso, Tsi), the first limit temperature (T _GI ) and / or second limit temperature (Tcz) -

5. coating system (1) for carrying out the method according to one of claims 1 to

4 comprehensively

a heating device (10), a cooling device (11), a coating device (8), a temperature sensor (15) and a controller (19).

6. Coating plant (1) according to claim 5, wherein the cooling device (1 1) is arranged on a in the interior of the pipe to be coated pipe (2) extending support (12).

7. Coating system (1) according to claim 6, wherein the cooling device (1 1) comprises an adjusting device for adjusting the cooling device (l 8), via which a layer and / or a

Alignment of the cooling device (11) is adjustable.

8. Coating plant (1) according to claim 5, 6 or 7, wherein the heating device (19) comprises an induction device, a gas burner device and / or a radiant heat source.

9. Coating plant (1) according to claim 5, 6, 7 or 8, wherein the temperature sensor (15) is designed as a laser pyrometer.

10. Coating plant (1) according to one of claims 5 to 9, with a pipe conveyor (4) for carrying out at least one component (9a, 9b) of the relative feed movement, in particular a rotational movement (9a).

1 1. Coating installation (1) according to one of claims 5 to 10 with an adjustable device carrier (12) for receiving the heating device (10), the cooling device (1 1), the coating device (8) and / or the temperature sensor (15 ) for carrying out at least one component of the relative feed movement (9a, 9b), in particular a translational movement (9b).