WO2012177144A1

WO2012177144A1 - Tubular body coated with an internal wear coating and method of manufacturing such a coating

Info

Publication number: WO2012177144A1
Application number: PCT/NO2012/050113
Authority: WO
Inventors: Kjell Egil REPPEN; Arvid Ophaug
Original assignee: PU TEKNIKK AS
Current assignee: PU TEKNIKK AS
Priority date: 2011-06-23
Filing date: 2012-06-21
Publication date: 2012-12-27
Anticipated expiration: 2013-12-23
Also published as: NO20120721A1

Abstract

A lengthy channel (1) comprising a jacket (2) and being provided with an internal polymer coating (3) comprised of a polymer material chosen from a group comprised of polyurethane and silicone, wherein an inner mantel surface (21) of the lengthy channel (1) is provided with a primer in at least one end portion (11, 12), and wherein the inner mantel surface (21) is free of primer in a central portion (13). A method of internally coating a lengthy channel (1) with a polymer coating (3) comprised of a polymer material chosen from a group comprised of polyurethane and silicone is provided, wherein the method comprises the steps of: a) positioning the channel (1) in a jig structured in a manner allowing it to rotate the channel (1) about a longitudinal axis (10) thereof, and the jig is further structured in a manner allowing it to correct deviations in the longitudinal direction of the channel ( i ); b) applying a primer to an inner mantel surface (21) of the channel (1) in at least one end portion (11, 12) and maintaining a central portion (13) of the channel (1) free of primer; c) positioning the polymer material within the channel (1); and d) rotating the channel (1) about the longitudinal axis (10) thereof until the polymer material is form-stable within the channel (1).

Description

TUBULAR BODY COATED WITH AN INTERNAL WEAR COATING AND METHOD OF MANUFACTURING SUCH A COATING

This invention concerns a lengthy, hollow body, wherein the internal mantel surface is coated with a coating in order to increase the resistance of the lengthy body against wear from a fluid flowing through the lengthy body. More particularly, the invention concerns a tubular body coated with a polymer material on the internal mantel surface, and wherein the coating exhibits a smooth or closed structure. The invention also concerns a method of coating such a lengthy body with such an internal coating.

All channels being used for transport of fluids become affected, more or less, by the fluid on surfaces being in contact with the fluid. For example, water may cause corrosion. Fluid containing particles will cause frictional wear. In many cases, maintenance of such channels is costly. Transport of the fluid must be discontinued and, in many cases, the channel or a portion of the channel must be replaced due to the wear damages inflicted. In order to restrict the damages, and in order to extend the effective life of the channels, it is known to apply another material better suited to resist the influence of the fluid being transported in the channels. It is known in the field to coat the internal mantel surface with a Teflon coating in order to avoid corrosion. It is further known to apply a plastics material by spraying and to glue rubber mats or rubber hoses to the mantel surface in order to avoid mechanical loads, such as e.g. frictional wear. Such application of a protective coating or material is carried out manually, which results in varying quality. Moreover, the materials are not sufficiently adequate for a number of uses.

Norwegian patent application NO 762309 describes a method of coating metal pipes internally with a protective coating. The protective coating may be comprised of a thermoplastic resin, such as e.g. fluorine resin, polyacid resin, polyethylene, polystyrene, acrylic acid resin, polyolefine and polyvinyl chloride. The protective coating may be further comprised of a thermosetting resin, such as e.g. phenolic resin, urea resin, melamine resin, polyester resin and silicone resin. Such curable resins may be sprayed into the pipes. The pipes are heated to between 220 and 300 °C and are rotated in such a manner that the resin melts and attaches to the inner mantel surface. Air is removed from the inside of the pipe, and such that the coating is carried out at pressure which is lower than the ambient atmospheric pressure. In order to prevent the injection-sprayed material from being sucked out, patent publication NO 762309 concerns an improved method in which resin material is introduced into the pipe formed as a rod or as a cylinder having a knitted or braided shape before air is sucked out and the pipe is heated and rotated. In the exemplary embodiments, the produced coating is between 0.2 and 1.0 mm thick.

Patent publication GB 1260961 concerns coating of inner surfaces of short, cylindrical objects. The coating may be comprised of a plastic material, such as e.g. phenolic resins, epoxy resins, polyester resins, acrylic- and methacrylic resins, urethane, amides, aromatic polyesters, terephtalates, phenoxy resins, and polycarbonates. The object is placed within a spindle, which is heated to between 100 and 300 °C. After heating and application of the plastic material, which is distributed across the inner mantel surface of the object by means of centrifuging, bubbles are removed by carrying a wire back and forth across the surface of the plastic material in the axial direction of the object. In one exemplary embodiment, the plastic coating is 0.4 mm thick. In another exemplary embodiment, the plastic coating is 0.25 mm and 0.5 mm thick.

Patent publication GB 437755 concerns coating of the inner surface of a steel pipe with a coating comprised of bitumen. The method comprises immersing the pipe in a warm bitumen solution in such a manner that the pipe is also heated to between 110 and 220 °C, and positioning the pipe with residues of the bitumen solution within the pipe and on a rotary device which rotates the pipe slowly about a longitudinal axis thereof until the bitumen solution has hardened.

Patent publication US 4107254 concerns coating of the inner surface of a metal pipe with a polyurethane coating. A suitable binding agent for binding metal to

polyurethane is applied to the inside of the pipe. Liquid polyurethane is distributed evenly on the inside of the pipe by rotating the pipe. Any gas bubbles intermixed in the liquid polyurethane mass may be removed by blowing warm air having a temperature of 250 °C ± 10 °C into the pipe for a period of 40 - 50 seconds at the onset of rotation. Patent publication GB 1596305 also concerns coating of the inner surface of a metal pipe with a polyurethane coating. A suitable binding agent is applied to the inside of the pipe. Liquid polyurethane is supplied to the pipe at a speed preventing air from being mixed into the polyurethane mass. Liquid polyurethane is distributed evenly on the inside of the pipe by rotating the pipe.

Patent publication WO 01/02503 concerns coating of the inner surface of a metal pipe with one insulation layer. The insulation layer may be comprised of epoxy or of glass or ceramic material. First a suitable binding agent is applied to the inside of the pipe. A wear coating may be applied to the insulation layer.

The object of the invention is to remedy or to reduce at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art.

The object is achieved by virtue of features disclosed in the following description and in the subsequent claims.

The invention concerns coating lengthy channels forming a continuous sidewall, for example a pipe, with a coating of thermosetting plastics, polyurethane or silicone on the channels inner mantel surface. The coating will protect an inner mantel surface of the channel against damages and wear. The coating is carried out by virtue of filling a measured amount of the desired material into a horizontally-oriented channel which is rotating about a longitudinal axis thereof at room temperature. Setting takes place during ongoing, constant rotation of the channel about the longitudinal axis of the channel. The rotational speed is adapted to the material type and the cross sectional dimension of the channel. A coating having an even surface and a desired thickness may be constructed under controlled setting of the material.

In a first aspect, the invention concerns a lengthy channel comprising a jacket and being provided with an internal polymer coating comprising a polymer material chosen from a group comprised of polyurethane and silicone, wherein the inner mantel surface of the lengthy channel is provided with a primer in at least one end portion, and wherein the inner mantel surface is free of primer in a central portion. The inner mantel surface of the channel may be coated with a thermally insulating coating between the jacket and the polymer coating. The thermally insulating coating may be comprised of a polymer material chosen from a group comprised of polyurethane and silicone. The internal polymer coating of the channel may be smoothed. The channel may be comprised of a pipe.

In a second aspect, the invention concerns a method of internally coating a lengthy channel with a polymer coating comprising a polymer material chosen from a group comprised of polyurethane and silicone, wherein the method comprises the steps of: a) positioning the channel in a jig structured in a manner allowing it to rotate the channel about a longitudinal axis thereof, and the jig is further structured in a manner allowing it to correct deviations in the longitudinal direction of the channel;

b) applying a primer to an inner mantel surface of the channel in at least one end portion and maintaining a central portion of the channel free of primer;

c) positioning the polymer material within the channel; and

d) rotating the channel about the longitudinal axis thereof until the polymer material is form-stable within the channel.

The method may further comprise a step e) of carrying an open flame along an internal surface of the form-stable polymer material and parallel to the longitudinal axis of the channel in order to smooth the surface after step d). As an alternative, step e) may comprise carrying an electric heating element along an internal surface of the form-stable polymer materials and parallel to the longitudinal axis of the channel. The method may further comprise a step bO) of providing the channel with a thermally insulating coating before step c) .

In an alternative embodiment, the method may further comprise the steps of:

bl) providing the channel with sealing end plugs after step b);

cl) evacuating air from the interior of the channel after step c); and

dl) equalizing the pressure within the channel after step d).

In the alternative embodiment, the method may further comprise a step e) of carrying an open flame along an internal surface of the form-stable polymer material and parallel to the longitudinal axis of the channel in order to smooth the surface after step dl). As an alternative, step e) may comprise carrying an electric heating element along an internal surface of the form-stable polymer material and parallel to the longitudinal axis of the channel. The method may further comprise a step f) of rotating the channel about the longitudinal axis thereof after step e) in order to further increase the firmness of the form-stable polymer material to allow the end plugs to be removed. The method may further comprise a step b2) of providing the channel with a thermally insulating coating before step c).

The method may be carried out at an ambient temperature. The method may further comprise tempering the channel to a temperature between 10 and 50 °C, such as e.g. 25, 30, 35, 40, or 45 °C.

Hereinafter, examples of preferred embodiments are described and are depicted in the accompanying drawings, where: Figure 1 schematically shows a cross sectional view of a channel coated with a wear coating in accordance with the invention;

Figure 2 schematically shows the same as Figure 1 of a channel coated with a

thermally insulating coating and a wear coating; and

Figure 3 schematically shows an isometric perspective view of the channel shown in Figure 1.

In the Figures, reference numeral 1 denotes a channel in the form of a pipe. The pipe

1 comprises an outer jacket 2. On an inner mantel surface 21 thereof, the outer jacket

2 is coated with a polymer coating 3, hereinafter termed a wear coating 3. On an internal surface 31 thereof, the wear coating 3 is formed with a smooth surface.

Figure 2 shows a pipe 1 within which the inner mantel surface 21 is coated with a thermally insulating coating 4. On an inner surface 41 thereof, the thermally insulating coating 4 is coated with a wear coating 3. On the internal surface 31 thereof, the wear coating 3 is formed with a smooth surface.

The pipe 1 forms a first end portion 11, a second end portion 12 and a central portion 13, as shown in Figure 3.

A closed channel, exemplified by a pipe 1 which is open at both ends, is placed in a jig (not shown). Each end portion 11, 12 of the pipe 1 rests on a rotary mechanism of a type known per se, and which is structured to keep a central axis of the pipe 1 at rest. At least one of the rotary mechanisms is structured in a manner allowing it to rotate the pipe about a longitudinal axis 10 thereof. The jacket 2 of the pipe 1 has the same temperature as the ambient temperature. The jig is further provided with an alignment mechanism. The alignment mechanism may be formed in the same manner as the rotary mechanism, and in such a manner that one or more wheels or rollers support the pipe 1 at the central portion 13 of the pipe 1, and wherein one or more wheels or rollers exert a force against an outer mantel surface 22 of the pipe 1. By so doing, one achieves that potential warps or deviations in the longitudinal direction of the pipe 1 are corrected when the pipe 1 is rotated about the longitudinal axis 10 thereof.

At each open end, the pipe 1 is provided with a sealing first and second end plug (not shown). The first end plug is provided with a connector to a vacuum pump (not shown). In a first embodiment, the connector is a swivel connector of a type known per se. By so doing, an underpressure may be formed within the pipe 1 while the pipe 1 is being rotated in the jig. In another embodiment, the connector is provided with a rapid coupling to a vacuum pump. By so doing, an underpressure may be formed within the pipe 1 when the rotation of the pipe 1 is stopped for a short time. The connector is further provided with a valve (not shown) to admit air into the pipe 1 to allow the pressure between the inside and the outside of the pipe 1 to be equalized.

The first and second end plugs are provided each with a removable central plug. The central plug may be removed when the pressure has been equalized. Then, the end plug will form a ring around the jacket 2 of the pipe 1, and a heating element (not shown) may be carried into and out of the pipe 1 through the central opening in one of the end plugs.

A primer is applied onto the inner mantel surface 21 in a portion at each end portion 11, 12 of the pipe 1. Suitable primers are known in the field and are not discussed in further detail. The primer will form a strong bond between the mantel surface 21 and the wear coating 3. Application of the primer at each end portion 11, 12, but not across the entire inner mantel surface 21, for example not in the central portion 13, provides the advantage of allowing the wear coating 3 to be separated from the jacket

2 by virtue of mechanically detaching the wear coating 3 at the end portions 11, 12 and then pulling the wear coating 3 out of the pipe 1.

After application of a primer by means of brushing, spraying or pouring, a measured amount of polymer material in liquid form, hereinafter termed a wear coating material, is filled into the pipe 1. The wear coating material may be a mixture of polyurethane and a setting agent or an accelerator, as known in the field. The pipe 1 rotates in order to distribute the wear coating evenly across the inner mantel surface 21. The rotational speed depends on the diameter of the pipe and on the properties of the wear coating material. A rotational speed between 1 m/s and 5 m/s peripheral speed has proven advantageous. It has proven further advantageous to evacuate air from the interior of the pipe 1 by means of a vacuum pump. The advantage thereof is that the setting process progresses faster and that gasses and air in the wear coating material rise more readily to the surface in the still liquid wear coating material.

Pumping out of air may be carried out before setting the pipe 1 into rotation or after having set the pipe 1 into rotation. The pressure internally in the pipe 1 may be between 0.9 and 0.001 of atmospheric pressure, more advantageously between 0.5 and 0.01 of atmospheric pressure, further more advantageously between 0.25 and 0.02 of atmospheric pressure, and further more advantageously between 0.1 and 0.02 of atmospheric pressure. After a few minutes of rotation, the rotation is stopped and air is admitted into the pipe 1. It has proven advantageous for the rotation to last between 2.5 minutes and 15 minutes, more advantageous for the rotation to last between 5 minutes and 12 minutes, and further advantageous for the rotation to last between 7.5 minutes and 12 minutes, for example 10 minutes. The central plug is removed from the first and the second end plug. At that point in time, the wear coating material is form-stable, for example as a jelly, but not hardened. The heating element is introduced through the opening in the second end plug and is activated within the pipe 1. The heating element is carried along the surface 31 once and parallel to the longitudinal axis 10 of the pipe. The advantage thereof is that gas forming bubbles in the still adhesive wear coating material will burst, whereby the gas escapes and the bubbles are closed. The heat from the heating element will also smooth the surface 31. In one embodiment, the pipe 1 is at rest while the heat treatment is ongoing. In an alternative

embodiment, the pipe 1 rotates while the heat treatment is ongoing. The heating element may be comprised of an electric heating element. The heating element may be comprised of a gas burner, which produces an open flame. The gas burner may be a propane gas burner.

Having completed the heat treatment, the heating element is removed from the pipe 1. The pipe 1 rotates further until the wear coating material is sufficiently form-stable to allow the end plugs to be removed. The pipe 1 is stored until the wear coating material is finally hardened. At that point in time, a wear coating 3 has formed on the inner mantel surface 21. The wear coating 3 is fixed firmly to the end portions 11, 12 of the pipe. The wear coating 3 exhibits a smooth surface 31 and the wear coating 3 exhibits an even thickness. The even thickness is achieved by correcting any deviations along the longitudinal axis 10 of the pipe 1 by means of the alignment mechanism of the jig.

In an alternative embodiment, the pipe 1 may be coated at first with a thermally insulating material 4. The method is the same as described above, however potentially with another primer, as is known in the field. The surface 41 of the thermally insulating coating 4 is not heat-treated. Advantageously, the surface 41 is not completely even given that this provides better adhesion for the wear coating 3 being applied to the surface 41. In one embodiment, the wear coating material is distributed across the surface 41 before the thermally insulating coating 4 is fully hardened . The advantage thereof is that good adhesion is achieved between the thermally insulating coating 4 and the wear coating 3. In an alternative embodiment, a primer of a type known per se is applied to the entire surface 41 when the thermally insulating coating 4 is fully hardened. The wear coating is distributed across the surface 41 and the process is repeated.

In a further alternative embodiment, an inner coating may be constructed in the pipe 1, wherein the coating comprises several further layers.

The thickness of the thermally insulating coating 4 and the wear coating 3 is determined by the amount of material positioned within the pipe 1. The rotational speed and setting time are adapted thereto. As such, the thickness of the wear coating 3 may be between 0.5 mm and 50 mm. The thickness may be 10, 15, 20, 25, 30, 35, 40 and 45 mm. The thickness may also exceed 50 mm if the inner diameter of the pipe 1 allows this. The thickness of the wear coating is also determined by the desired open cross-sectional area after the coating. Analogously, the thermally insulating coating may be between 20 mm and 50 mm thick, for example 25, 30, 35 and 45 mm thick.

Example 1

A tubular body 1, which is referred to as a riser in the petroleum field, is coated with polyurethane on an inner mantel surface 21 thereof. An outer jacket 2 of the riser may be comprised of metal, such as e.g . carbon steel or titanium, or of a composite material, for example a fibre-reinforced plastics material, as is known in the field. The jacket 2 of the riser 1 is structured in a manner allowing it to withstand external mechanical loads, for example impacts, torsion, bending and pressure, and internal loads in the form of overpressures.

On the inner mantel surface 21 thereof, the riser 1 is coated with a wear coating 3 comprised of polyurethane. The wear coating 3 is 10 mm thick. The inner surface 31 of the wear coating 3 is heat-treated with an open flame in order for the surface 31 to form a smooth, continuous surface. The wear coating 3 resists wear from the liquid flow (not shown) conducted through the riser 1, and wear from particles located in the liquid flow.

Example 2

A riser 1 is coated, on the inner mantel surface 21 thereof, with a thermally insulating coating 4. The thermally insulating coating 4 is comprised of polyurethane. In an alternative embodiment, the thermally insulating coating 4 is comprised of silicone. The thermally insulating coating 4 is covered by a wear coating 3 comprised of polyurethane, as described in example 1. Example 3

A transport pipe 1 for transport of petroleum products, for example oil and gas, is comprised of an outer jacket 2. The outer jacket 2 of the transport pipe 1 may be comprised of a metal, a thermoplastic, a thermosetting plastic or composite materials, for example fibre-reinforced thermosetting plastics or fibre-reinforced thermoplastics. The jacket 2 of the transport pipe 1 is structured in a manner allowing it to withstand external loads and internal mechanical loads in the form of an overpressure or an underpressure relative to the ambient pressure.

The jacket 2 of the transport pipe 1 is coated, on the inner mantel surface 21 thereof, with a thermally insulating coating 4. The thermally insulating coating 4 is comprised of polyurethane. In an alternative embodiment, the thermally insulating coating 4 is comprised of silicone. The thermally insulating coating 4 is covered, on the inner surface 41 thereof, by a wear coating 3 comprised of polyurethane, as described in example 1.

Claims

1. A lengthy channel (1) comprising a jacket (2) and being provided with an

internal polymer coating (3) comprising a polymer material chosen from a group comprised of polyurethane and silicone, c h a r a c t e r i z e d i n that an inner mantel surface (21) of the lengthy channel (1) is provided with a primer in at least one end portion (11, 12), and wherein the inner mantel surface (21) is free of primer in a central portion (13).

2. The channel (1) according to claim 1, wherein the inner mantel surface (31) of the channel (1) is coated with a thermally insulating coating (4) between the jacket (2) and the polymer coating (3).

3. The channel (1) according to claim 1, wherein the internal polymer coating (3) of the channel (1) is smoothed.

4. The channel (1) according to claim 1, wherein the channel (1) is comprised of a pipe.

5. A method of internally coating a lengthy channel (1) with a polymer coating (3) comprising a polymer material chosen from a group comprised of polyurethane and silicone, wherein the method comprises the steps of:

a) positioning the channel (1) in a jig structured in a manner allowing it to rotate the channel (1) about a longitudinal axis (10) thereof, and the jig is further structured in a manner allowing it to correct deviations in the longitudinal direction of the channel (1);

b) applying a primer to an inner mantel surface (21) of the channel (1) in at least one end portion (11, 12) and maintaining a central portion (13) of the channel (1) free of primer;

c) positioning the polymer material within the channel (1); and

d) rotating the channel (1) about the longitudinal axis (10) thereof until the polymer material is form-stable within the channel (1).

6. The method according to claim 5, wherein the method further comprises the steps of:

bl) providing the channel (1) with sealing end plugs after step b);

cl) evacuating air from the interior of the channel (1) after step c) ; and dl) equalizing the pressure within the channel (1) after step d).

7. The method according to claim 5, wherein the method further comprises a step e) of carrying an open flame along an internal surface (31) of the form-stable polymer material and parallel to the longitudinal axis (10) of the channel (1) in order to smooth the surface (31) after step d).

8. The method according to claim 5, wherein the method further comprises a step e) of carrying an electric heating element along an internal surface (31) of the form-stable polymer material and parallel to the longitudinal axis (10) of the channel (1) in order to smooth the surface (31) after step d).

9. The method according to claim 6, wherein the method further comprises a step e) of carrying an open flame along an internal surface (31) of the form-stable polymer material and parallel to the longitudinal axis (10) of the channel (1) in order to smooth the surface (31) after step dl).

10. The method according to claim 6, wherein the method further comprises a step e) of carrying an electric heating element along an internal surface (31) of the form-stable polymer material and parallel to the longitudinal axis (10) of the channel (1) in order to smooth the surface (31) after step dl).

11. The method according to any one of claims 9-10, wherein the method further comprises a step f) of rotating the channel (1) about the longitudinal axis (10) thereof after step e) in order to further increase the firmness of the form-stable polymer material to allow the end plugs to be removed.

12. The method according to claim 5, wherein the method further comprises a step bO) of providing the channel (1) with a thermally insulating coating before step c).

13. The method according to claim 6, wherein the method further comprises a step b2) of providing the channel (1) with a thermally insulating coating before step c).

14. The method according to claim 5, wherein the method further comprises

tempering the channel (1) to a temperature between 10 and 50 °C.

15. The method according to claim 5, wherein the method further comprises

tempering the channel (1) to an ambient temperature.