GB2526631A - Underwater pipeline repair by automated composite lamination - Google Patents

Abstract

An apparatus for repairing pipelines or the like under water, comprising an enclosure (1) which is adapted to be placed around a pipeline section (4) to be repaired and form an enclosed chamber between the pipeline section (4) and the enclosure (1). A lamination tool (6) for applying a repair chemical, typically epoxy, and a sheet material is adapted to orbit around the circumference of the pipeline section. The enclosure on the inside surface of the enclosure is equipped with at least two pitch racks (5a, 5b) along which the lamination tool (6) is moveable. A method for applying is described whereby the repair chemical is provided with magnetic particles to attract the chemical to the surface of the pipe. The repair chemical per se is also claimed.

Description

Underwater Pipeline Repair by Automated Composite Lamination The present invention relates to an apparatus and a method for repairing pipelines or the like under water, according to the preamble of the subsequent claims 1 and 8, respectively. It also relates to a repair chemical having the ability to adhere to a metallic surface according to the preamble of claim 15.

Pipeline repair using epoxy or other types of repair chemicals, such as polymers, has become useful due to its numerous benefits. Some of the benefits are cost reduction compared to other types of repair, the possibility to perform the repair at the pipeline location, reduced weight of repair components, the fact that epoxy may be used that is environmentally friendly, and minimal need for surface preparation.

In general repair using epoxy or similar is recommended for aged pipelines as application of local compressive stress is not required.

Many types of epoxy are environmentally friendly. This has further increased the interest in using epoxy as a component for pipeline repair.

The-state-of-art related technology for underwater pipeline repair has been more of pipeline strengthening than for through-hole repair. It is therefore a need for effectively repairing through-holes, cracks, and damages. However, at the same time the repair technique should also be used for pipeline strengthening both in marine and surface conditions.

The state-of-the-art composite application can take different models. Some applications apply a spiral structure with epoxy on the pipeline and the repair is then bound by clips or similar components. For land pipelines, it is common to strengthen pipes by coating locations with epoxy and then pull manually over with composite sheets in several layers. In other cases, a chamber is cupped round a pipeline and epoxy is injected. This chamber could be formed within two half clamps. There have also been tests using clamp-in-clamps technique with epoxy filling in-between. Use of the injection method on a pipeline where there is an open hole, will result in injection of the epoxy into the pipeline through the hole, thereby endangering the use of the pipeline further. The use of the clamp-in-clamp technique will pose challenges in avoiding pores, though it is noted that the pore problems may be avoided by using high-pressure injection pumps.

An apparatus for automatic repair of a pipeline is known from EP 2600051. It shows a device that is adapted to establish a sealed chamber around a section of a pipeline and is capable of draining water from the chamber. It also comprises ring gears that acts to roll a coil of sheet material around the perimeter of the pipeline section to wrap the pipeline section with the sheet material. The ring gears are coupled to a respective disc that rotates with the ring gear. These discs carry the coil of sheet material.

A roller is arranged to press the sheet material against the outer wall of the pipeline. The roller has holes for supply of air or a repair chemical. The coils may be pre-impregnated by a repair chemical to enhance adhesion and solidification. The repair chemical can be a polymer or a resin. The repair chemical is deposited on the sheet material by the roller, or the sheet material has a pre-preg of repair chemical.

The device of EP 2600051 is complicated and bulky. It also requires that a chamber around the pipeline section that is to be repaired be evacuated of water.

US 4061513 describes an apparatus for applying sheet material to a pipe, especially at joints of pipes. The apparatus comprises a plurality of wheels that have the pipe clamped there-between. The rollers act to orbit a coil of sheet material around the pipe while the coil feeds out the sheet material onto the pipe. As this apparatus is open to the environment, it is not suitable for use under water. It is also highly adapted to a specific diameter of pipe, and the same apparatus cannot be used on pipes with different diameters. There are no means for applying epoxy or other types of matrix material.

WO 2009/157748 describes an apparatus similar to US 4061513. This apparatus forms a spiraled sleeve that has a distance to the pipe, so that an annular chamber is formed between the pipe and the sleeve. The chamber is subsequently filled with a filling material that creates a bond between the pipe and the sleeve. As this apparatus is open to the environment, it is not useful for performing repairs under water.

Other prior art examples are known from US 2004129373, RU 2484359, ON 103542227 and ON 101457115.

A first aspect the object of the present invention is to provide a lightweight and simple apparatus with few moving parts, which can be used to repair pipelines or the like under water. The apparatus comprise an enclosure that forms a chamber around the pipeline and a lamination tool for applying a repair chemical and a sheet material. The lamination tool is adapted to orbit around the circumference of the pipeline section.

This object is achieved by providing tha enclosure on its inside surface with at least two pitch racks along which the lamination tool is moveable.

The chamber does not need to be evacuated of water, although it may be evacuated in certain applications.

In a preferred embodiment, the lamination tool comprises a repair chemical applicator and a rolled sheet material feeder. Thereby the repair chemical and the sheet material can be applied independently of each other.

In a further embodiment, the repair material applicator and the sheet material feeder are arranged on a common carriage, which has one electric motor at each end, said motors being coupled to a respective gear that engages with a respective pitch rack. This simplifies the construction down to only one unit that has to be moved within the enclosure.

In a further preferred embodiment, the carriage is at each end equipped with a journal or guide pin that is adapted to engage with a track to hold the carriage against the pitch racks. Thereby a simple and reliable arrangement for moving the carriage has been achieved.

In a still further embodiment, the lamination tool comprises a stopper blade that is adapted to swipe along the sheet material and distribute the repair chemical evenly along the surface of the pipeline section. This will ensure even distribution and a consistent layer of the repair chemical.

In a still further embodiment, the lamination tool comprises a smoothing roller that is adapted to squeeze the sheet material against the repair chemical.

Thereby good contact between the sheet material and the repair chemical is ensured.

In a further embodiment, the enclosure comprises three parts that are hinged together. This provides an apparatus that easily can be fitted around the pipeline with minimal excavation.

In second aspect of the present invention, the object is to ensure that the repair chemical adheres to the surface of the pipeline. The method comprises arranging an enclosure around a pipeline section to be repaired, and orbiting a repair chemical applicator around the circumference of the pipeline section while applying a repair chemical. The object is achieved by providing the repair chemical with magnetic particles that causes the repair chemical to adhere to the surface of the pipeline section.

In a further embodiment, the method comprises applying a sheet material on top of the repair chemical. Thereby the repair chemical is both reinforced and held in place until it has been cured.

In a further embodiment, further layers of repair chemical and sheet material are applied. This further increases the strength of the repair.

By wrapping the sheet material on top of the repair material immediately after the repair material has been applied to the surface of the pipeline, it is ensured that the repair material is held in place.

By using a stopper blade and/or a smoothing roller to distribute the repair chemical evenly, a consistent thickness is ensured and thereby also a predictable strength.

In a preferred embodiment, the repair chemical is an epoxy. Epoxy is environmentally friendly, cures without external influences and forms a reliable and hard shell when cured.

In a preferred embodiment, the sheet material is a fibreglass sheet. Fibreglass works very well in combination with epoxy. It is relatively cheap, strong, and non-degradable.

In a third aspect of the present invention, the object is to ensure that the repair chemical adheres to the surface onto which it is to be applied. The object is achieved by a repair chemical for application onto a metallic surface, which contains magnetic particles, which are attracted to the metallic surface and hence attract the repair chemical to the metallic surface.

In one embodiment of the invention, the repair chemical is a pad of a composite material containing reinforcing fibres. Thereby a strong and durable repair is ensured.

In a further embodiment, the reinforcing fibres are of a magnetisable material.

Thereby two objects are achieved by the same additive.

In another embodiment, the fibres are in the form of a sheet material adapted to be applied on top of the repair chemical. Thereby is also ensured that the repair chemical is held in place until it has cured.

Preferably, the repair chemical is an epoxy, due to the unique characteristics that epoxy can be provided with.

The present invention also aims at offering an improvement in repairing open holes in underwater and surface conditions and for strengthening pipes by an automated process. In the present invention the repair chemical, such as epoxy, is applied directly onto the pipe wall. This can be done without the use of high-pressure pumps, as the method of the present invention effectively removes the challenges of pores in the repair chemical.

Whereas the existing technology for repair mainly relies on the strength of the sheet material as the layers of epoxy or other types of sticking substances are very thin and cannot withstand high-pressure condition on perforated pipelines.

In contrast, the present invention is robust. The repair chemical that is sandwiched between the layers of sheet material, e.g. fiberglass sheets, carbon fibre sheets, Kevlar® sheets, or other types of reinforcing fibres, is incompressible when hardened. The sandwich of fiberglass sheet with hard and tough epoxy provides sufficient strength against high-pressure conditions.

The apparatus of the present invention may also be made self-contained, unlike the existing state of the art. It may be provided with a battery-powered system that is remotely controlled. The only external assistance required is to position the tool to the application location.

The repair chemical will stick to the pipe body by magnetic particle inclusion within the repair chemical.

The invention will now be described in detail, referring to a preferred embodiment shown in the accompanying drawings, in which: Figure 1 shows the apparatus of the present invention in perspective view in open state, Figure 2 shows the apparatus of the invention in closed state where the outer shell has been made transparent, Figure 3 shows the device for applying: sheet material, and repair chemical, and Figure 4 shows a cross section through the device for applying sheet material and repair chemical, and a part of the outer shell.

When in orientation terms, such as upper and lower or upwards and downwards are used, this refers to the device of the invention in the normal orientation when being used, as shown in figure 1. It should be understood that the device also could be used in other orientations.

Figure 1 shows the device of the invention in perspective view. The device has three main parts, an upper shell half 1 and two lower shell quarters 2 and 3. The lower shell quarters 2 and 3 are hinged at the longitudinal sides to the upper shell half 1. Figure 1 shows the device in open state, where the lower shell quarters 2, 3 have been swung upwards. In this state the upper half 1 can be placed upon a pipeline section 4 to be repaired. After the upper half 1 has been placed against the outer wall of the pipeline section 4, the lower quarters 2, 3 will be swung downwards until they meet one another below the pipeline section 4. In this state the quarters 2, 3 will be secured to one another by well-known securing means that are readily available for the person of skill.

It should be understood that the upper half 1 can extend over a smaller part of the outer circumference of the pipeline section that half a circle, and that the lower quarters 2, 3 can extend over a larger part of a the outer circumference of the pipeline section 4 than a quarter circle. It is also possible that the device comprises two halves instead of one half and two quarters, or more than three main parts. However, the main parts 1, 2, 3 will, irrespective of their number and sizes, form a full circle around the pipeline section 4 when assembled. a

The main parts 1, 2, 3 each have end walls, of which only the end walls la, 2a, 2b, 3a are visible in figure 1. These end walls form the end closures of an annular chamber between the pipeline section 4 and the inside of the main partsl,2,3.

At the inside of the main parts 1, 2, 3, toothed sections 5a and 5b are formed.

When the device is in the closed state, the toothed sections form a full circular pitch rack 5 close to each end of the device.

Next to each pitch rack 5a, 5b is a respective track 7a, 7b, which will be explained further below.

Figure 2 shows the device in a closed state. The main parts 1, 2, 3 have been made transparent, so that the internal parts are visible. Consequently, the two pitch racks 5a and Sb are shown. A laminating tool 6 extends between the pitch racks 5a, Sb. The laminating toot 6 is a single carriage and has a journal or guide pin 8a, 8b at each end, which extends into the tracks 7a, 7b, and acts to guide the tool 6 along the pitch racks 5a, Sb.

The laminating tool 6 is shown separately in figure 3. It is equipped with two battery-powered motors 9a and 9b that rotate driving gears I Oa and I Ob. The driving gears lOa, lOb each mesh with a respective one of the pitch racks Sa, 5b. With the journals Ba, 8b hooked into the tracks 7a, 7b, the tool 6 is held against the pitch racks 5a, 5b. The journals 8a, 8b may have rotating bearings that wilt run easily along the tracks 7a, 7b or they may be provided with grease.

The motors 9a, Yb are synchronized so that the tool is oriented parallel to the longitudinal axis of the device at all times. To secure this, sensors (not shown) may be used.

The toot comprises a carriage frame 16 that carries the motors 9a, Yb. The tool is also is equipped with a laminating roll 11, which sits on the same shaft 12 as the gears 1 Oa, 1 Ob. The laminating roll 11 preferably contains a sheet material comprising fiberglass. A smoothening roller 13 is arranged a short distance from the laminating roll 11. The smoothening roller 13 is also arranged in a position where it will be close to the outer surface of the pipeline 4. The roller 13 is rotatable around a shaft 14, which is suspended in a first pair of arms ISa, 15b, which are adapted to move in a radial direction with respect to the pipeline 4. To this end, the arms iSa, 15b are suspended in the frame 16. The arms 15a, 15b are biased by springs 18a, lBb to push the smoothening roller against the pipeline surface.

A second pair of arms 19a, lYb extends radially outwardly from the frame 16 and each have small wheels 17a, 17b at their distal end. The small wheels 17a, 17b are also biased with springs 20a, 20b.

Referring also to figure 4, which shows a cross section of the device close to one end of the tool 6, the tool 6 will be further described. At the opposite side of the frame 16 from the roller 13 is arranged a repair chemical application device 21. The repair chemical is a chemical or mixture of chemicals that are filling and curable. The preferred chemical is epoxy, but other types of chemicals, such as polymers, synthetic or natural rubber, resins or polypropylene. The chemicals may harden due to an internal chemical reaction, by UV light, by the use of a catalyst, heat, removal of solvent or by other means well-known to the skilled person. When in the following, epoxy is exemplified, it should be noted that other types of repair chemicals may be used instead.

The repair chemical may also contatn reinforcing fibres, such as glass fibres, carbon fibres, Kevlar®, metal thread, etc. If a magnetisable material is used as reinforcement fibres, the reinforcement fibres can also be used as magnetic particles.

The application device 21 has a serIes of nozzles or alternatively a narrow slit 22 (shown in figure 4) at its end closest to the pipeline surface. The epoxy will be ejected from these nozzles or the slit 22 onto the pipeline surface.

The laminating tool 6 is also equipped with a stopper blade 23 (see figure 4), which is suspended in the frame between two journals 24a, 24b. The stopper blade is biased against the surface of the pipeline 4.

Having now described the structure of the apparatus according to the invention, the function of the apparatus will now be described, referring again to figures 1 -4.

The apparatus of the invention may be lowered down to the repair site by a crane, an ROV or by divers and be placed as a stand-alone device around the pipeline, but it may also form a part of an ROy. The apparatus will be placed in an open state against the pipeline, with the upper main part 1 resting on top of the pipeline, as shown in figure 1. Before closing the device around the pipeline, any soil under the pipeline at the repair site has to be removed, so that the two lower main parts 2, 3 can close securely around the whole perimeter of the pipeline section in question.

The laminating tool will already have been loaded with a sheet material coil and epoxy. The batteries are at this stage fully charged.

The epoxy or other type of repair chemical also contains an inclusion of magnetic particles, such as magnetized iron. These particles may be magnetic nanoparticles. The magnetic particle content is high enough for the epoxy to stick to the pipeline 4 (which of course has to be of a magnetically attractive material, such as steel).

In order to avoid the epoxy sticking to the tool 6, the parts, such as the blade 23, roller, 13, applicator 21, frame 16 etc. are made of a non-magnetic material, such as plastic, to an as large as possible extent.

The magnetic particles will cause the epoxy to adhere to the pipeline surface even when there is water present within the chamber between the apparatus and the pipeline. The epoxy will stay on the pipeline surface while the sheet material is being applied. It is also possible to apply a thicker layer of epoxy than if the epoxy has to stick by adhesion only. A ticker epoxy layer will provide increased strength of the repair. The epoxy will also adhere to the surface even if the surface is not completely clean. This means that only a fairly rough cleaning will be necessary to remove marine growth and thick layers of debris.

Corrosion and thin layers of grease will not prevent the epoxy from sticking to the surface.

At the start of the operation, the motors 9a, 9b will drive the gears 1 Oa, lob, and hence the coil 11, anticlockwise as seen in figure 4. This will move the carriage or tool 6 in a clockwise direction as seen in figure 4 along the pitch racks 5a, 5b.

The epoxy with particles of magnetic material is ejected from the applicator 21 onto the pipeline surface. The stopper blade 23 will swipe along the pipeline surface and distribute the epoxy evenly over the surface. When rotating in this direction, the stopper blade 23 will not trap the outer edge ha of the sheet material, so that the application of epoxy can take place without also applying sheet material. The application of epoxy will be done for at least one complete revolution. However, it is also envisaged that epoxy may be applied in several revolutions to make a thicker layer.

After the epoxy has been applied, the rotation is reversed. Now, as the coil 11 is driven in the clockwise direction, the stopper blade 23 will trap the outer edge 11 a of the sheet material that is being fed from the coil 11. The sheet material will glide over the surface of the stopper blade 23 and into the gap between the stopper blade 23 and the smoothening roller 13, under the roller 13 and onto the layer of epoxy at the pipeline surface. The sheet material will stick to the epoxy by adhesion.

While the sheet material is applied, the epoxy application continues, so that epoxy is applied between each layer of sheet material. A total of 5 -15 layers of sheet material is applied, dependirg on the required strength, which in turn depends on the desired pressure within the pipeline.

The magnetic particles should, when the epoxy has been cured, be completely embedded in the epoxy, so that they are not exposed to the environment, and 12 I hence are protected against any corrosion. In addition, it is also possible to add layers of epoxy without magnetic particles after the first layer of sheet material has been applied. It is also possible to add a final layer of epoxy without magnetic particles.

The action of the stopper blade and the smoothening roller 13, which follows the stopper blade 23, will squeeze out some of the water trapped between the epoxy and the pipeline surface and the epoxy and the sheet material. As the curing of the epoxy is an exothermic process, the heat will boil out the remaining water from the laminate.

The small wheels 17a, 17b will roll along the inner surface of the main parts 1, 2, 3 of the apparatus and thereby press the smoothing roller against the pipeline surface. The springs 18a, 18b, 20a, 20b will take up any unevenness on the surface of the pipeline and secure an even pressure on the sheet material during the lamination process.

The tool 6 completes at least one full round along the perimeter of the pipeline 4. However, it is an advantage if more than one layer of epoxy and sheet material is laminated onto the pipeline 4. The number of layers may be varied depending on the pressure that the pipeline must endure and the amount of other strains that will act on the pipeline.

The amount of the sheet material on the roll for a given pipeline required is determined in advance. The system is adapted automatically to stop the rotation once the roll is exhausted. Suitable sensors may be arranged to detect this, or a counter may be used to count the number of revolutions.

Although, the lamination process can be performed without evacuating the chamber between the apparatus and the pipeline of water, there may be arranged vents in the main parts 1, 2, 3 through which water can be evacuated and air can be forced in.

When the lamination has been completed, the apparatus will be opened again and brought to the surface. The curing of the laminate will proceed over some time after the lamination has been completed. After the epoxy has cured, the pipeline should be pressurized and checked for any leaks.

It will be understood that the exact configuration of the apparatus could vary depending on the configuration of the structure to be laminated. The common operational characteristic however, will be substantially the same as described above.