WO2023012179A1

WO2023012179A1 - Mould for coating pipeline sections

Info

Publication number: WO2023012179A1
Application number: PCT/EP2022/071738
Authority: WO
Inventors: Michael George; Jason Montgomery
Original assignee: Pipeline Induction Heat Ltd.
Priority date: 2021-08-05
Filing date: 2022-08-02
Publication date: 2023-02-09
Also published as: GB2609489A

Abstract

A mould for coating, e.g. with polymer material, a section of a pipeline, e.g. a field joint between two pipe sections of the pipeline, comprises at least first and second mould portions. The mould portions are arranged to be fitted together around a pipeline section exterior to enclose the pipeline section and to form an assembled mould cavity. The mould cavity is provided between the pipeline section exterior and an interior surface of the mould. The first and second mould portions are configured such that there is at least one join between them when assembled in use. The first mould portion includes at least one seal member protruding therefrom and arranged to overlap part of the mould-interior surface of the second mould portion in use. The seal member substantially covers the join between the first and second mould portions at the interior surface of the mould, to prevent or reduce egress of molten polymer material.

Description

MOULD FOR COATING PIPELINE SECTIONS

The present invention relates to moulds for coating sections of pipelines, and especially for coating joints between pipe sections of pipelines. The invention has particular utility in the coating of oil or gas pipeline field joints, especially by injection-moulding of polypropylene or other polymer materials, but at least in its broadest aspects, the invention is applicable to mould-coating pipeline sections more generally.

Pipelines in the oil and gas industry are typically formed from multiple lengths of steel pipe sections that are welded together end-to-end as they are being laid. To prevent corrosion of the steel pipe sections and to reduce heat loss of fluids transported by the pipelines, the pipe sections are coated with one or more protective and/or insulative layers, typically a multi-layer coating comprising, for example, an epoxy bottom layer (especially fusion-bonded epoxy, FBE) followed by one or more polyethylene (e.g. polypropylene and/or modified polypropylene) outer layer(s). The pipe sections are usually coated at a factory remote from the location in which they are to be laid. This is often referred to as factory-applied coating and it is generally more cost effective than coating pipe sections on site where they are laid. (“On site”, generally known as “in the field”, may be on land, or at sea from a pipe-laying ship.) At the factory, the coating is applied to the outside of the pipe sections and a short length is left uncoated at each end of the pipe section. Each end region of the coating is typically machined to provide a chamfer prior to the field joint coating being applied, and thus the uncoated regions are commonly called “cut-back” regions. The uncoated ends are necessary to enable the steel pipe sections to be welded together to form the pipeline in the field. The welded uncoated ends, known as field joints, must be coated in order to provide the necessary protection and/or insulation, and such coating is known as the field joint coating.

Field joints are commonly coated by means of an injection-moulded polypropylene (“IMPP”) coating process. The IMPP coating process typically commences by blastcleaning the exposed steel pipe section ends and hand-machining (by handheld power tools) the factory coating end portion chamfers to remove oxidation and dirt. The exposed steel pipe section ends are then heated, e.g. by induction heating. A layer of powdered fusion-bonded epoxy primer is then typically applied to the heated pipe section ends, and a thin layer of polypropylene is typically applied to the FBE primer during the FBE curing time. The end regions of the factory-applied coating, including the chamfers, are then heated, e.g. by means of radiant (infrared) heating. The field joint is then completely enclosed in a heavy-duty mould that defines a cavity around the welded pipe joint, the uncoated ends of the pipe sections, and the end regions of the factory-applied coating. Heated molten polypropylene (or modified polypropylene) is then injected into the mould cavity, to fill the cavity, and is allowed to cool. Once the injection-moulded polypropylene has cooled and solidified, the mould is removed from the field joint, leaving the solidified polypropylene field joint coating in place. Extraneous portions of solidified polypropylene due to some mould cavity leakage during the moulding process (mould flashing), and from the polypropylene injection port(s) of the mould, then need to be removed, by hand-machining using handheld power tools.

Other types of field joint coating processes are also known. For example, the injection-moulded polyurethane (IMPII) coating process uses a chemically curable urethane material instead of injecting polypropylene as the mould-infill material around the field joint. Typically, the initial step in the IMPII coating process is to apply a liquid polyurethane primer onto the exposed blast cleaned surface of the welded pipe end sections. Once the primer has been applied, a mould is positioned to enclose the field joint in a cavity and the chemically curable (typically two-component) polyurethane precursor material is injected into the cavity defined by the mould. When the curing process is sufficiently advanced, the mould is removed and the field joint coating is left in place. Older known techniques of moulding a field joint coating are also known, in which the mould infill material (e.g. polyurethane, or other polymer material, or polymer precursor material) is gravity-fed or poured, rather than injected, into the mould. In each case, extraneous portions of solidified moulded polymer material (mould flashing, etc.) need to be removed by hand-machining.

EP 2590794 discloses known methods and apparatus for coating pipeline field joints, including IMPP, and cast-moulded polyurethane (CMPLI) techniques.

US 10,357,907 discloses a system and method for factory-coating pipe sections of a pipeline. In order to reduce the amount of flashing that forms at parting lines between mould portions, radially outwardly extending flange members are secured to the mould portions at the parting lines, the flange members providing a plurality of longitudinal grooves containing resiliently deformable elongate gaskets, to seal between the flange members when the mould is closed. However, it is apparent that, because the flange members and their gaskets are secured radially outwardly of the mould portions, a degree of mould flashing is still to be expected, from a degree of radially outward extrusion of liquid mouldable material at the parting line. Additionally, this document discloses the use of a restriction member in the form of an elongate strip of steel extending along the length of the mould in an upper elongate vent created by a gap at an upper parting line between mould portions. The restriction member provides a non-sealing barrier that partially obstructs the flow of fluids through the vent while still permitting the venting of gas from the mould interior, and is positioned at the top edge of the longitudinal vent I parting line gap so that the liquid mouldable material is still able to expand into the lower portion of the vent / parting line gap, thereby creating a significant amount of mould flashing.

There is a need to improve the process of moulding coatings onto pipes and pipelines, e.g. the moulding of field joint coatings, e.g. to reduce or eliminate the amount of mould flashing that is produced and thereby to reduce or eliminate post-moulding handmachining operations.

The present invention seeks to provide improved mould arrangements.

In a first aspect, the present invention provides a mould for coating a section of a pipeline, according to Claim 1 of the appended claims.

Preferred, and other optional, features of the invention are defined and described in the dependent claims.

Accordingly, the invention provides a mould for coating a section of a pipeline, comprising at least first and second mould portions arranged to be fitted together around a pipeline section exterior to enclose the pipeline section and to form an assembled mould cavity between the pipeline section exterior and an interior surface of the mould, the first and second mould portions configured such that there is at least one join between them when assembled in use, wherein the first mould portion includes at least one seal member protruding therefrom and arranged to overlap part of the mould-interior surface of the second mould portion in use, thereby substantially to cover the join between the first and second mould portions at the interior surface of the mould.

The pipeline section preferably comprises a joint region, e.g. a field joint, between two pipe sections of a pipeline.

Preferably, a mould-interior surface of the seal member is configured to be substantially flush with the mould-interior surface of the first mould portion. Advantageously, a mould-interior surface of the seal member is configured to be substantially flush, in use, with the mould-interior surfaces of the assembled first and second mould portions.

In preferred embodiments of the invention, the mould-interior surface of the second mould portion includes a recess configured to receive the protruding seal member therein.

Preferably, the seal member protrudes in the form of a protruding elongate strip, preferably along substantially the entire length of the mould cavity.

In preferred embodiments of the invention, the mould-interior surface of each of the first and second mould portions is formed by a mould lining layer. In some embodiments of the invention, the seal member comprises part of the mould lining layer of the first mould portion. More preferably, the seal member comprises an elongate strip, most preferably extending along substantially the entire length of the mould cavity. Advantageously, the mould lining layer of each of the first mould portion and the second mould portion may provide a recess in the mould-interior surface of each of the first and second mould portions, in which recess the seal member is configured to be located when the mould portions are assembled in use. The mould lining layer preferably is formed from steel, preferably stainless steel. The remainder of the mould may be formed from steel. The seal member preferably is formed from metal, more preferably steel, especially spring steel. Advantageously, the seal member may be welded to the first mould portion. The interior surface of the assembled mould preferably substantially comprises a right circular cylinder, preferably an elongate right circular cylinder. Preferably, the mouldinterior surface of each of the first and second mould portions comprises a longitudinal section of the cylinder. The join preferably is elongate and substantially parallel to the longitudinal axis of the cylinder.

In preferred embodiments, the mould further comprises at least one external support frame arranged to support the mould portions. The external support frame preferably is configured to enable relative movement between the first and second mould portions, more preferably comprising relative pivoting movement, to cause the first and second mould portions to be fitted together around a pipeline section exterior, in use, and preferably also to cause the mould portions to be separated from each other once the moulding process has finished. Advantageously, the external support frame may include one or more actuators, preferably hydraulic actuators, arranged to cause the relative movement between the first and second mould portions, in use. A controller may be configured to control the actuators and/or other components and/or systems and/or processes of the mould and the moulding process.

In at least some preferred embodiments of the invention, the mould further comprises at least a third mould portion. Preferably the second and/or third mould portion includes a said seal member.

Preferably, there is the same number of joins, seal members and mould portions, in the mould according to the invention. That is, when there are two mould portions, preferably there are two joins between the mould portions in use, and two seal members arranged substantially to cover the joins at the interior surface of the mould, for example. When there are three mould portions, preferably there are three joins between the mould portions in use, and three seal members arranged substantially to cover the joins at the interior surface of the mould, for example.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 (a) and (b) show views of a known mould for coating a section of a pipeline;

Figure 2 shows a perspective view of an embodiment of a mould according to the invention, with the mould open and the mould portions separated from each other;

Figures 3(a) and (b) show, respectively, an end view of the mould shown in Figure

2, and a detail thereof, the mould being fully open and the mould portions fully separated from each other;

Figure 4 shows an end view of the mould as shown in Figure 2, in an open configuration;

Figure 5 shows an end view of the mould shown in Figure 2, in the closed configuration.

Figure 1 (a) shows a perspective view, and Figure 1 (b) shows an end view, of a known mould 1 for coating a section of a pipeline, e.g. a field joint between two pipeline sections. As shown schematically in Figure 1(b), in use, the mould portions 3 are fitted together around the exterior 5 of a field joint between pipeline sections 7 to enclose the field joint, and to form an assembled mould cavity 9 between the exterior 5 of the pipeline sections and an interior surface 11 of the mould 1 . The longitudinal ends of the mould cavity 9 are defined by circumferential metal (preferably steel) seals 13, for sealing between the interior surface 11 of the mould 1 and the exterior surfaces 5 of the pipeline sections 7. Molten coating material, e.g. polypropylene and/or another polymer, is then injected or poured into the mould to fill the mould cavity, and allowed to solidify. The mould 1 is then removed from the pipeline sections 7 by separating and/or opening-out the mould portions

3, to expose the coated field joint.

Figure 2 shows a perspective view of an embodiment of a mould 15 according to the invention, for coating a field joint between sections 7 of a pipeline, with the mould 15 open and the mould portions separated from each other. Specifically, the illustrated mould 15 comprises a first mould portion 17, a second mould portion 19, and a third mould portion 21 , but the mould according to the invention can instead comprise two, or more than three, mould portions. The first mould portion 17 comprises a substantially semi-cylindrical longitudinal section of a right circular cylinder, and is arranged to be positioned adjacent to an underside of a pipeline field joint. Each of the second 19 and third 21 mould portions comprises a substantially quarter-cylindrical longitudinal section of a right circular cylinder, and is arranged to be positioned adjacent to an upper side of the pipeline field joint, to complete the generally cylindrical shape of the assembled mould portions. As shown in Figure 5, the mould portions 17, 19 and 21 are arranged to be fitted together around the exterior of the jointed pipeline sections (not shown in Figure 5, but shown schematically in Figure 1) to enclose the field joint and to form an assembled mould cavity 9 between the exterior 5 of the pipeline sections and an interior surface 23 the mould 15. The longitudinal ends of the mould cavity 9 are defined by circumferential metal (preferably steel) seals 24, for sealing between the interior surface 23 of the mould 15 and the exterior surface 5 of the pipeline sections 7. In use, molten polymer material (e.g. polypropylene) is injected into the mould cavity 9 via a pair of inlet ports 26 (a single inlet port 26, or a larger number of ports, could instead be employed).

The mould portions 17, 19 and 21 are configured such that there are longitudinal joins 25 between them when assembled in use. In the illustrated embodiment, the first mould portion 17 includes two seal members 27 protruding therefrom along opposite edges of the first mould portion 17, to seal the joins 25 between the first 17 and second 19 mould portions, and between the first 17 and third 21 mould portions, respectively. The second mould portion 19 also includes a longitudinal seal member27 for sealing the join 25 between the second 19 and third 21 mould portions. The third mould portion 21 does not include any longitudinal seal members, because the joins it forms with the first 17 and second 19 mould portions are sealed by the seal members carried by those mould portions. It is apparent that there is the same number of joins 25, seal members 27 and mould portions, in the mould 15, i.e. three of each, in the illustrated embodiment.

As shown in figures 3(b) and 5, each seal member 27 carried by a mould portion is arranged to overlap part 29 of the mould-interior surface 23 of the other mould portion with which the seal member-carrying mould portion forms a join 25, in use, thereby substantially to cover the join 25 at the interior surface 23 of the mould 15. Thus the seal members 27 carried by the first mould portion 17 are arranged to overlap part 29 of the mould-interior surface 23 of the second 19 and third 21 mould portions, and the seal member 27 carried by the second mould portion 19 is arranged to overlap part 29 of the mould-interior surface 23 of the third 21 mould portion. As can be seen from figures 3(b) and 5, the mould-interior surface 31 of each seal member 27 is configured to be substantially flush with the mouldinterior surface 23 of the mould portion which carries the seal member. This may be achieved, as shown, by attaching (preferably by welding) the seal member 27 to its carrier mould portion in a recess 33 provided in the mould lining 35. A corresponding recess 33 may be provided, as shown, in the mould lining 35 of the other mould portion forming the join 25, so that the protruding part (strip) of the seal member 27 fits into the recess 33 in the other mould portion when the two mould portions are fitted together around the pipeline section. This results, as shown in Figure 5, in the mould-interior surface 31 of the seal member 27 being substantially flush, in use, with the mould-interior surfaces 23 of both joined mould portions.

In some alternative embodiments of the invention, each seal member 27 comprises a protruding part of the mould lining layer 35 of its mould portion. However, it is generally preferred for each seal member 27 to comprise an elongate strip, the mould-interior surface 31 of which is configured to be substantially flush with the mould-interior surface 23 of the mould lining layer 35. The mould lining layer 35 preferably is formed from metal, more preferably steel, especially stainless steel. The remainder of the mould 15 may be formed from steel or other metal, for example. Each seal member 27 preferably is formed from metal, more preferably steel, especially spring steel. Advantageously, each seal member 27 may be welded to its mould portion.

As shown in figures 2 to 5, the mould 15 of the invention further comprises an external support frame 37 arranged to support the mould portions 17, 19, 21. The external support frame 37 is configured to enable relative movement between the mould portions, in particular by pivoting movement by the second 19 and third 21 mould portions, about pivots 39, relative to a substantially stationary first mould portion 17, to cause the mould portions to be fitted together around a pipeline field joint. The external support frame 37 includes a plurality of actuators 41 , preferably hydraulic actuators, arranged to cause such pivoting movement of the second 19 and third 21 mould portions. The actuators 41 also cause the mould portions to be separated from each other once the moulding process has finished. A controller (not shown) may be configured to control the hydraulic actuators 41 and/or other components and/or systems and/or processes of the mould 15 and the moulding process.

The seal members 27, which overlap the joins 25 at the interior surface 23 of the mould cavity 9, prevent or reduce the egress of molten polymer material through the joins 25 between the mould portions, thereby reducing or eliminating the resultant mould flashing which needs to be removed by hand machining once the mould 15 is removed from the pipeline field joint.

It will be understood that the above description and the drawings are of a particular example embodiment of the invention, but that other implementations and embodiments of the invention are included in the scope of the claims.

Claims

1. A mould for coating a section of a pipeline, comprising at least first and second mould portions arranged to be fitted together around a pipeline section exterior to enclose the pipeline section and to form an assembled mould cavity between the pipeline section exterior and an interior surface of the mould, the first and second mould portions configured such that there is at least one join between them when assembled in use, wherein the first mould portion includes at least one seal member protruding therefrom and arranged to overlap part of the mould-interior surface of the second mould portion in use, thereby substantially to cover the join between the first and second mould portions at the interior surface of the mould.

2. A mould according to Claim 1 , wherein a mould-interior surface of the seal member is configured to be substantially flush with the mould-interior surface of the first mould portion.

3. A mould according to Claim 1 or Claim 2, wherein a mould-interior surface of the seal member is configured to be substantially flush, in use, with the mould-interior surfaces of the assembled first and second mould portions.

4. A mould according to any preceding claim, wherein the mould-interior surface of the second mould portion includes a recess configured to receive the protruding seal member therein.

5. A mould according to any preceding claim, wherein the seal member protrudes in the form of a protruding strip.

6. A mould according to any preceding claim, wherein the seal member comprises an elongate strip.

7. A mould according to any preceding claim, wherein the mould-interior surface of each of the first and second mould portions is formed by a mould lining layer.

8. A mould according to Claim 7, wherein the seal member comprises part of the mould lining layer of the first mould portion.

9. A mould according to Claim 7, wherein the mould lining layer of each of the first mould portion and the second mould portion provides a recess in the mould-interior surface of each of the first and second mould portions, in which recess the seal member is configured to be located when the mould portions are assembled in use.

10. A mould according to Claim 7 or any claim dependent thereon, wherein the mould lining layer is formed from steel, preferably stainless steel.

11. A mould according to any preceding claim, wherein the interior surface of the assembled mould substantially comprises a right circular cylinder, preferably an elongate right circular cylinder.

12. A mould according to Claim 11 , wherein the mould-interior surface of each of the first and second mould portions comprises a longitudinal section of the cylinder.

13. A mould according to Claim 11 or Claim 12, wherein the join is elongate and substantially parallel to the longitudinal axis of the cylinder.

14. A mould according to any preceding claim, wherein the seal member is formed from metal, preferably steel, more preferably spring steel.

15. A mould according to any preceding claim, wherein the seal member is welded to the first mould portion.

16. A mould according to any preceding claim, further comprising at least one external support frame arranged to support the mould portions.

17. A mould according to Claim 16, wherein the external support frame is configured to enable relative movement between the first and second mould portions, preferably comprising relative pivoting movement, to cause the first and second mould portions to be fitted together around a pipeline section exterior, in use.

18. A mould according to Claim 17, wherein the external support frame includes one or more actuators, preferably hydraulic actuators, arranged to cause the relative movement between the first and second mould portions.

19. A mould according to any preceding claim, further comprising at least a third said mould portion.

20. A mould according to any preceding claim, wherein there is the same number of joins, seal members and mould portions.

21. A mould according to any preceding claim, wherein the pipeline section comprises a joint region between two pipe sections of the pipeline.