A submersible support structure configured to support an elongated member, a submersible support system comprising the support structure, a submersible support assembly and a method of removing growth and / or corrosion from an elongated member surface

Abstract

The invention relates to a submersible support structure (1) configured to support at least one pressure vessel (20) which comprises an elongated member (23), the elongated member (23) comprising an elongated member surface (23'), the support structure (1) comprising an axially extending glide member (24) comprising a glide surface (4) configured to support the elongated member (23), wherein the support structure (1) comprises: - at least one scraper member (6,7) on at least one axial side of the glide surface (4) configured to scrape against the elongated member surface (23') and remove any growth and / or corrosion building on the elongated member surface (23 '). The invention further relates to a submersible support system (100) and a submersible support assembly (50), as well as a method of removing growth and / or corrosion from an elongated member surface (23') of an elongated member (23.

Description

[0001] A SUBMERSIBLE SUPPORT STRUCTURE CONFIGURED TO SUPPORT AN ELONGATED MEMBER, A SUBMERSIBLE SUPPORT SYSTEM COMPRISING THE SUPPORT STRUCTURE, A SUBMERSIBLE SUPPORT ASSEMBLY AND A METHOD OF REMOVING GROWTH AND / OR CORROSION FROM AN ELONGATED MEMBER SURFACE

[0002] Technical Field

[0003] The present disclosure relates to a submersible support structure configured to support at least one pressure vessel, a submersible support system comprising at least one pressure vessel and the submersible support structure, a submersible support assembly and a method of removing growth and / or corrosion from an elongated member surface of an elongated member supporting the pressure vessel in the support structure.

[0004] Background

[0005] As is known in the art, there exist different types of pressure vessels, commonly referred to as type I, type II, type III, type IV and type V pressure vessels. As is known in the art, the pressure chamber of a type I pressure vessel comprises an all-metal tank, e.g. an all-steel or an all-aluminium tank. The pressure chamber of a type II pressure vessel comprises mostly steel or aluminium and have a glass-fibre composite overwrap in the hoop direction. The pressure chamber of a type III pressure vessel comprises a metal liner having a full composite overwrap, generally an aluminium liner with a carbon fibre composite overwrap. The pressure chamber of a type IV pressure vessel, finally, comprises a liner, e.g. a polymer liner, and filaments, e.g. carbon fibre or glass fibre reinforced with epoxy, wound round the liner to reinforce the same. A type IV pressure vessel is sometimes referred to as a glass fibre reinforced pressure vessel (GRP). These different types of pressure vessels are discussed in “ Pressure vessel tank types’" by Michael Legault, published on 7 / 2 / 2012 and available at https: / / www.compositesworld.com / articles / pressure-vessel-tank-types.

[0006] Type IV pressure vessels are used in many land-based systems, e.g. in hydrogen vehicles, since they are resistant to corrosion and can remain in use for a long period of time before requiring replacement. These are advantageous features also in a subsea setting. However, a Type IV pressure vessel normally has a positive buoyancy. Therefore, a subsea hydrogen storage module made from Type IV pressure vessels may need to be weighted or held down in order for the buoyancy to be controlled.

[0007] It exists solutions for storing hydrogen in pressure vessels subsea. One such solution is described in US 20240142055 AL

[0008] Once the pressure vessels are submerged, and filled with a fluid (gas or liquid) subsea or topside, they will experience expansion and retraction resulting from changes in pressure and / or temperature. Dependent on the size of the pressure vessel, the pressuredifferences, the temperature differences etc., the expansion and retraction can be in the range of e.g. 1 to 20 centimetres, or even more. There is a risk that the forces resulting from said expansion and retraction damages other equipment, such as any frame structure supporting the pressure vessels.

[0009] It is therefore an objective of the invention to provide a solution that solves, or at least reduce, at least one of the aforementioned problems or challenges.

[0010] Summary of the invention

[0011] The invention is defined in the attached claims.

[0012] In general, the invention relates to a submersible support structure which allows axial expansion and retraction of a pressure vessel supported therein. In particular, due to the nature from pressure and temperature changes of the fluids within the pressure vessel, the pressure vessel will experience expansion and retraction. Furthermore, equipment and installation arranged under water are subject to marine growth and corrosion. In order for the support structure to be able to allow for the axial expansion, the marine growth and corrosion should not influence the glide surface of the support structure, which glide surface functions as a bearing and support against the pressure vessel and allows the axial movement of the pressure vessel. Therefore, the support structure comprises a scraper member which is configured to scrape against an elongated member surface of an elongated member connectable to the pressure vessel.

[0013] In accordance with a first aspect of the invention, it is described a submersible support structure configured to support at least one pressure vessel which comprises an elongated member, the elongated member comprising an elongated member surface,

[0014] the support structure comprising an axially extending glide member comprising a glide surface configured to support the elongated member,

[0015] wherein the support structure comprises:

[0016] - at least one scraper member on at least one axial side of the glide surface configured to scrape against the elongated member surface and remove any growth and / or corrosion building on the elongated member surface.

[0017] The submersible support structure prevents particles formed by e.g. growth and / or corrosion from damaging the glide surface by preventing material removed from the elongated member surface from passing from one side of the at least one scraper member to the opposite side of the at least one scraper member.

[0018] Typically, installations or structures which are submerged in salt water, e.g. offshore or in harbor basins, are said to be installed subsea. Similarly, installations or structures which are installed in fresh water, e.g. in lakes, rivers or land-based water-filled tanks, are said to be submerged.The submersible support structure according to the first aspect can be a subsea support structure. Alternatively or additionally, the support structure can be a submerged support structure.

[0019] The elongated member may be a shaft and the elongated member surface can be the surface of the shaft or a surface of a sleeve enclosing the shaft. The sleeve can be put on or formed, e.g. by shrinking, on an outside of the shaft thereby forming a tight fit to the shaft. If the shaft has a circular cross-section, the sleeve is on a radial outside of the shaft. The elongated member may form part of an attachment member. The attachment member may comprise the elongated member and a support flange. The support flange may be connectable to an end boss of the pressure vessel.

[0020] The end boss, the support flange and the elongated member can be formed, e.g. by molding or casting, in one piece.

[0021] Alternatively, the support flange and the elongated member may be formed in one piece whereas the end boss is a separate piece, and where the one piece is secured to the end boss by fastening means.

[0022] In yet another alternative, the end boss, the support flange and the elongated member can be formed in separate pieces and connected together by fastening means.

[0023] Since the elongated member surface moves relative to the at least one scraper, and thus is more subject to wear, it can be of another material than the shaft. Although it could be possible to manufacture the shaft and the elongated member surface in one piece, i.e. of the same material (e.g. a superduplex material), it will be a question of e.g. cost and / or complexity whether the shaft shall be manufactured of a relative expensive material or a relative cheap material. For example, in order to save cost without compromising on the function and durability of the shaft and the elongated member surface over time, the shaft can be manufactured of a relative cheaper material (such as e.g. steel) and the piece with the elongated member surface can be of a relatively expensive material (e.g. a superduplex material).

[0024] If the elongated member surface is on a sleeve, the sleeve can be made of a super-duplex material, or at least a part of the sleeve in contact with the glide surface can be of a superduplex material.

[0025] The submersible support structure allows the elongated member to move in the axial direction resulting from changes in pressure and / or temperature of the pressure vessel. If the elongated member is not allowed to move freely in the axial direction, the elongated member, the pressure vessel and / or the support structure may be damaged due to the expansion and retraction forces.

[0026] The at least one scraper member may comprise a scraper edge.The scraper edge may be formed on an outer edge of the scraper member. In other words, the scraper edges may face away from the glide surface. As such, any growth or corrosion removed from the surface of the elongated member is kept away from the glide surface.

[0027] Said at least one scraper member may comprise a first scraper member on a first axial side of the glide surface and a second scraper member on a second axial side of the glide surface.

[0028] The elongated member may have a cross-section and the at least one scraper member may have a complementary cross-section. The cross-section of the elongated member can be circular. Alternatively, the elongated member may have a polygonal cross-section such as triangular, square etc., and the first and second scraper members may have a complementary polygonal cross-section.

[0029] Said at least one scraper member may circumferentially enclose said elongated member. If there is a scraper member on both the first axial side each side and the second axial side of the glide member, the glide member is circumferentially enclosed and protected from dirt, corrosion and / or marine growth / fouling.

[0030] The at least one scraper member, on a side facing away from the glide surface, may comprise a concave surface section terminating in said scraper edge. In other words, the part of the scraper member terminating in the scraper edges may have a plough-shape, collecting and distributing any material removed from the elongated member surface of the elongated member.

[0031] The glide member may be made from a self-lubricating material. The self-lubricating material may thus be configured to feed or lubricate the glide surface thereby reducing the friction between the glide surface and the elongated member surface of the elongated member.

[0032] The self-lubricating material may comprise a bronze-graphite alloy.

[0033] The glide surface may have a semi-circular shape.

[0034] Since most pressure vessels have positive buoyancy in water the subsea support system may be weighted with e.g. weights in order to ensure that the subsea support system maintains subsea even if all of the support structures support a pressure vessel. That is, the overall buoyancy of the subsea support system, when arranged subsea and with pressure vessels supported therein, is negative.

[0035] Due to the high positive buoyancy of type IV pressure vessels 20 in water, the glide member does not necessarily have to extend around the whole circumference of the elongated member surface since the contact area between the glide member and the elongated member surface will be on an upper part of the circumference of the elongatedmember surface and an underside of the glide surface. For example, if the elongated member surface is circular, the glide member may be a semicircle which forms 45 - 120 degrees of a full circle.

[0036] The submersible support structure comprises a body, and the at least one scraper member may be supported by said body such that the at least one scraper member is configured to move relative said body.

[0037] The relative movement may be achieved by providing the at least one scraper member with a larger connection hole than a diameter of a fastening means running through the connection hole and fixing the scraper member to the body. Consequently, when the fastening means runs through the connection hole, the at least one scraper member is allowed to move in a direction perpendicular to longitudinal axis of the fastening means. As such, the scraper members may align themselves relative the elongated member even in situations where the pressure vessel, and thus the elongated member is somewhat inclined relative to the support structure. In other words, if the support structure is in the horizontal plane, the movable support allows that a centre axis of the pressure vessel forms a few degrees inclination relative to the horizontal plane.

[0038] The relative movement may be up and down, i.e. in a vertical plane.

[0039] Alternatively, the at least one scraper member may be secured to the body of the support structure such that the scraper member is prevented from moving relative to the body. The scraper member may comprise a scraper surface may extend between an inner edge and an outer edge. The outer edge will then form the scraper edge.

[0040] Said inner edge may have a radius. In other words, the inner edge is not a right edge and is prevented from acting as a scraper edge thereby reducing the risk of growth or particles collecting between the first and second scraper members.

[0041] According to a second aspect of the invention it is described a subsea support system comprising:

[0042] - at least one pressure vessel comprising an elongated member comprising an elongated member surface, and

[0043] - a submersible support structure as defined above configured to support the at least one pressure vessel.

[0044] The submersible support structure may form part of a support frame. The support frame may be configured to support a plurality of pressure vessels. The other end of the pressure vessel may be axially and rotationally locked to the support frame in order to be connectable to e.g. tubing or piping.

[0045] The elongated member can be a shaft extending from a support flange. The support flange can be connected to an end boss of the pressure vessel.The pressure vessel may be a composite pressure vessel, i.e. a pressure vessel having a pressure chamber made from different types of components and materials.

[0046] The composite pressure vessel may be a type IV pressure vessel.

[0047] The pressure vessel may be formed of a glass reinforced epoxy (GRE).

[0048] The pressure vessel may be filled with hydrogen before or after it is installed subsea. The pressure vessel may be connected to a pipe or hose for filling and / or draining of hydrogen. The filling and / or draining of hydrogen may be performed during the lifetime of the pressure vessel, e.g. hydrogen is filled into the pressure vessel during periods when the production is higher than the demand, and hydrogen is drained from the pressure vessel during periods when the production is lower than the demand.

[0049] Similar to the submersible support structure according to the first aspect, the submersible support system according to the second aspect can be a subsea support system which is submersible in salt water. Alternatively or additionally, the submersible support system can be a submerged support system which is submersible in fresh water.

[0050] According to a third aspect of the invention it is described a submersible support assembly comprising:

[0051] - an attachment member attachable to a pressure vessel, the attachment member comprising an elongated member comprising an elongated member surface, - an axially extending glide member comprising a glide surface configured to support the elongated member,

[0052] wherein the support assembly comprises:

[0053] - at least one scraper member on at least one axial side of the glide surface configured to scrape against the elongated member surface and remove any growth and / or corrosion building on the elongated member surface.

[0054] Similar to the submersible support structure according to the first aspect and the submersible support system according to the second aspect, the submersible support assembly according to the third aspect can be a subsea support assembly which is submersible in salt water. Alternatively or additionally, the submersible support assembly can be a submerged support assembly which is submersible in fresh water.

[0055] According to a fourth aspect of the invention it is described a method of removing growth and / or corrosion from an elongated member surface of an elongated member, the elongated member being connected to a pressure vessel, and wherein the method comprises:

[0056] - providing a support structure to an underwater location, wherein the support structure comprises an axially extending glide member comprising a glide surface; - installing the pressure vessel in the support structure such that the elongated member surface is supported by the glide surface;- bringing at least one scraper member on at least one axial side of the glide surface; - scraping, by using said at least one scraper member, against the elongated member surface to remove any growth and / or corrosion therefrom.

[0057] Upon expansion and retraction of the pressure vessel, and thus the axially movable elongated member, the growth, such as e.g. marine growth, and / or corrosion present on the elongated member surface is removed by scraping against the elongated member surface. Thus, the pressure vessel moves relative the at least one scraper member.

[0058] The method may comprise a step of, prior to the step of providing a support structure to a subsea location, a step of providing a support frame to a subsea location.

[0059] The step of providing a support structure to a subsea location may comprise connecting the support structure to the support frame and positioning the pressure vessel in the support structure.

[0060] The underwater location can be a subsea location, i.e. in salt water, and / or a submerged location, i.e. in fresh water.

[0061] In order to avoid potential explosion, the pressure vessel(s) are typically filled with inert gas before being shipped from production site. Similarly, the pressure vessel(s) may be lowered subsea filled with inert gas. Once installed on the seabed, the inert gas can be replaced by e.g. hydrogen.

[0062] In addition to supporting pressure vessels, the support structure can be used in systems where there are relative axial movement between components, in contact with water such as:

[0063] connections to and from a subsea separator,

[0064] supporting flexible jumper,

[0065] PLET (PipeLine End Termination), e.g. on an end of flowline which expands and retracts due to change in pressure and / or temperature. For example, if the PLET is not allowed to slide on the seabed (e.g. due to very soft seabed) and the flowline needs to be connected to a support instead, a solution according to the invention which allow axial movement may be used.

[0066] connection points on floating piers / bridges,

[0067] anchor connections for semi-submersible objects (e.g. weather buoys),

[0068] - wave energy systems,

[0069] mooring turrets.Above-discussed preferred and / or optional features of each aspect of the invention / disclosure may be used, alone or in appropriate combination, in the other aspects of the invention / disclosure.

[0070] The claimed invention is specified in the independent claims of this application.

[0071] Advantageous adaptations and versions of the claimed invention are specified in the dependent claims.

[0072] Description of the drawings

[0073] Following drawings are appended to facilitate the understanding of the claimed invention:

[0074] Fig. 1 shows a subsea support system comprising a number of submersible support structures supporting pressure vessels, each of the pressure vessels comprising an elongated member and the elongated member comprising an elongated member surface;

[0075] Fig. 2A is a side perspective view of a submersible support structure and a submersible support assembly supporting an elongated member surface of a pressure vessel, where the support structure and the pressure vessel are cut along a vertical plane which is parallel to a longitudinal axis of the pressure vessel;

[0076] Fig. 2B is a partly exploded view of the components forming the submersible support structure, the submersible support assembly and the pressure vessel of Fig. 2A;

[0077] Fig. 2C shows details of a scraper member in Figs. 2A and 2B;

[0078] Fig. 3 A is a similar view as Fig. 2A, however the submersible support structure, the support assembly and the pressure vessel are seen from the side;

[0079] Fig. 3B is an enlarged view of section A-A in Fig. 4A;

[0080] Fig. 4A is an example of a scraper member where only a scraper edge of the scraper member is in contact with the elongated member surface;

[0081] Fig. 4B is an example of a scraper member comprising a scraper surface extending between an inner edge and an outer edge, and where the scraper surface and the scraper edge are in contact with the elongated member surface.

[0082] Figs. 5A-5C show different relative positions between the submersible support structure and the elongated member surface of the pressure vessel in Figs. 1, 2A and 2B, where:

[0083] Fig. 5A the pressure vessel is fully expanded,

[0084] Fig. 5B the pressure vessel is retracted compared to Fig. 5A, and

[0085] Fig. 5C the pressure vessel is fully retracted;It should be understood, however, that the drawings are not intended to limit the claimed invention to the subject-matter depicted in the drawings.

[0086] In the drawings, like reference numerals have been used to indicate common parts, elements or features unless otherwise explicitly stated or implicitly understood by the context.

[0087] Detailed description

[0088] In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementationspecific decisions must be made to achieve the developer’s specific goals, such as compliance with system and / or business-related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.

[0089] It is clear that features described in relation to the structure are equally valid for the system, the assembly and the method, and vice versa.

[0090] Fig. 1 shows a subsea support system 100 comprising a support frame 101 comprising a number of submersible support structures 1 supporting pressure vessels 20, each of the pressure vessels 20 comprising an elongated member 23 and the elongated member 23 comprising an elongated member surface 23’.

[0091] The illustrated subsea support system 100 features a frame structure with a number of dedicated storage positions therein. Each of the storage positions comprising a submersible support structure 1 supporting one of the pressure vessels 20.

[0092] Since most pressure vessels 20 have positive buoyancy in water (at least the type IV pressure vessels) the support frame 101 may be weighted with e.g. weights in order to ensure that the subsea support system 100 maintains subsea even if all of the support structures 1 support a pressure vessel 20. That is, the overall buoyancy of the subsea support system 100, when arranged subsea and with pressure vessels 20 supported therein, is negative.

[0093] Fig. 2A is a side perspective view of a submersible support structure 1 and a submersible support assembly 50 supporting an elongated member surface 23’ of a pressure vessel 20,where the support structure 1 and the pressure vessel 20 are cut along a vertical plane which is parallel to a longitudinal axis A of the pressure vessel 20.

[0094] Fig. 2B is a partly exploded view of many of the components forming part of the submersible support structure 1, the submersible support assembly 50 and the pressure vessel 20 of Fig. 2A. It shall be noted that Fig. 2B shows an additional component compared to Fig. 2A, including a support ring 11. If the elongated member surface 23’ is on a sleeve which is arranged on a radial outside of the elongated member 23, the support ring 11 provides a function of preventing axial movement of the sleeve with the elongated member surface 23’ relative to the elongated member 23.

[0095] Referring to Figs 2A and 2B, the pressure vessel 20 features an end boss 21. The elongated member 23 is shown as a shaft extending from the support flange 22 and which is fixedly connected to the end boss 21. The elongated member surface 23’ is shown as a sleeve fixedly connected on a radial outside of the shaft of the support flange 22. The illustrated elongated member surface 23’ is circular. The support flange 22 is connectable to the end boss 21 via appropriate fastening means such as a bolt or screw.

[0096] The support flange 22, the elongated member 23 and the elongated member surface 23’ may form part of an attachment member 10 of the submersible support assembly 50. The remaining features of the submersible support assembly 50 are similar to the features described in relation to the submersible support structure 1 and will not be repeated herein.

[0097] The support structure 1 comprises an axially extending glide member 24 comprising a glide surface 4 configured to support the elongated member 23.

[0098] The glide member 24 is supported by a bearing carrier 5. The bearing carrier 5 is connected to an upper support 3. In Fig. 2B the glide member 24 has a semicircular shape and the glide surface 4 is formed on a radial inside thereof. The bearing carrier 5 has a corresponding semicircular shape for accommodating the glide member 24 therein. The shape of the bearing carrier 5 and the glide member 24 are adapted to the shape of the elongated member surface 23’ of the pressure vessel 20. It shall be understood that the glide member 24 and the bearing carrier 5 may have other shapes dependent on the shape of the elongated member surface 23’ of the elongated member 23. Due to the high positive buoyancy of type IV pressure vessels 20 in water, the glide member 24 does not have to extend around the whole circumference of the elongated member surface 23’ since the contact area between the glide member 24 and the elongated member surface 23’ will be on an upper part of the circumference of the elongated member surface 23’. For example, if the elongated member surface 23’ is circular, the glide member 24 may be a semicircle which forms 45 - 120 degrees of a full circle.

[0099] The bearing carrier 5 is supported by an upper support 3. The upper support 3 is arranged above the elongated member 23. The upper support 3 is formed by two semicircular partswith free ends. The two parts are connectable to the bearing carrier 5 from opposite sides, forming a sandwich construction with the bearing carrier 5 in the middle.

[0100] A lower support 2 is arranged below the elongated member 23. The free ends of the upper support 3 are connectable to the lower support 2 via fastening means such as pin, screw or bolt. The upper support 3 and the lower support 2 are configured to be fixedly connected to the support frame 101. The support ring 11 can be connectable to an end face 28 of the elongated member 23 via appropriate fastening means such as a bolt or screw and prevents, in the event the elongated member surface 23’ is on a separate piece (e.g. a sleeve) outside the elongated member 23, relative axial movement between the elongated member surface 23’ and the elongated member 23.

[0101] The end boss 21 may comprise a flange connection point 27 for connection of a flange (not shown), thereby providing fluid connection between an inside of the pressure vessel 20 and the flange (not shown).

[0102] In Fig. 2B, two scraper members 6,7 are shown, where the scraper member with reference number 6 is shown separated from the elongated member surface 23’ the scraper member with reference number 7.

[0103] Fig. 2C shows details of a scraper member 6,7 in Figs. 2A and 2B. The scraper member 6,7 is illustrated as a continuous ring with a scraper edge 6’, 7’ along an inner circumference thereof. The scraper member 6,7 in Fig. 2C thus has a circular crosssection with a through-going hole along a longitudinal axis for accommodating the elongated member 23. The inner diameter of the ring is complementary to the outer diameter of the elongated member 23. In order to ensure that the scraper member 6,7 is in contact with the elongated member surface (not shown in Fig. 2C), the scraper member 6,7 is formed on the part of the ring having the smallest diameter. The scraper member 6,7 in Fig. 2C comprises a scraper surface 25 extending between an inner edge 6”, 7” and an outer edge (i.e. the scraper edge 6’, 7’, see details in Figs. 3B and 4B). The scraper member 6,7 features scraper member holes 26 for connection to the bearing carrier 5 and the lower support 2.

[0104] Fig. 3 A is a similar view as Fig. 2A, however the submersible support structure 1, and a submersible support assembly 50 and the pressure vessel 20 are seen from the side.

[0105] Fig. 3B is an enlarged view of section A-A in Fig. 4A. As seen in the Figure, both of scraper members 6,7, on a side facing away from the glide surface 4, comprises a concave surface section 6” ’,7’” terminating in the scraper edge 6’, 7’. The concave surface sections 6” ’,7’” have a plough-shape, collecting and distributing any material removed from the elongated member surface 23’ of the elongated member 23.

[0106] Fig. 4A is an example of a scraper member 7 where only a scraper edge 7’ of the scraper member 7 is in contact with the elongated member surface 23’. In the example scrapermember 7 in Fig. 4A the inner edge 7” has a radius. This means that the inner edge 7” is not a right edge and is prevented from acting as a scraper edge thereby reducing the risk of growth or particles collecting between the first and second scraper members 6,7. Furthermore, the scraper surface 25 between the inner edge 7” and the outer edge 7’ is not in contact with the elongated member surface 23’.

[0107] Fig. 4B is an example of a scraper member 6,7 comprising a scraper surface 25 extending between an inner edge 6”, 7” and an outer edge 7’, 7”. The outer edge 6’, 7’ forms the scraper edge 6’, 7’. Similar to the example of scraper member in Fig. 4A, the inner edge 7” has a radius meaning that it does not act as a scraper edge. In Fig. 4B, the scraper surface 25 and the outer edge (i.e. the scraper edge 6’, 7’) are in contact with the elongated member surface 23’.

[0108] Figs. 5A-5C show different relative positions between the submersible support structure 1 and the elongated member surface 23’ of the pressure vessel in Figs. 1, 2A and 2B. In Fig. 5A the pressure vessel 20 is fully expanded. In Fig. 5B the pressure vessel 20 is retracted compared to Fig. 5A, and Fig. 5C the pressure vessel 20 is fully retracted. The easiest way of comparing the relative positions may be to look at the relative relationship between the support ring 11 (which follows axial expansion and retraction of the pressure vessel 20) and the upper support 3 which is fixedly connected to the stationary support frame 101. It can be seen that the support ring 11 is closer to the upper support 3 in Fig. 5B than in Fig. 5A, and even closer to the upper support in Fig. 5C than in Fig. 5B. The expansion and retraction of the pressure vessel 20 in the axial direction resulting from changes in pressure and / or temperature of the pressure vessel 20.

[0109] Referring to Figs. 1-5, the invention also relates to a method of removing growth and / or corrosion from a pressure vessel 20. wherein the pressure vessel 20 comprises an elongated member 23 comprising an elongated member surface 23’, and wherein the method comprises:

[0110] - providing a support structure 1 to a subsea location, wherein the support structure 1 comprises an axially extending glide member 24 comprising a glide surface 4; - installing the pressure vessel in the support structure 1 such that the elongated member surface 23’ is supported by the glide surface 4;

[0111] - bringing at least one scraper member 6,7 on at least one axial side of the glide surface 4;

[0112] - scraping, by using said at least one scraper member 6,7, against the elongated member surface 23’ to remove any growth and / or corrosion therefrom.

[0113] Upon expansion and retraction of the pressure vessel, and thus the axially movable elongated member 23, the growth, such as e.g. marine growth, and / or corrosion present on the elongated member surface 23’ is removed by scraping against the elongated member surface 23’. Thus, the pressure vessel 20 moves relative the at least one scraper member 6,7.The method may comprise a step of, prior to the step of providing a support structure 1 to a subsea location, a step of providing a support frame 101 of a subsea support system 100 to the subsea location. The step of providing a support structure 1 to a subsea location may comprise connecting the support structure 1 to the support frame 101.

[0114] In the preceding description, various aspects of the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the structure, the system, the assembly and its workings. For example, features described in relation to the submersible support structure may also form part of the submersible support system, the submersible support assembly and the method, and vice versa.

[0115] However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiments, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims.

Claims

CLAIMS1. A submersible support structure (1) configured to support at least one pressure vessel (20) which comprises an elongated member (23), the elongated member (23) comprising an elongated member surface (23’),the support structure (1) comprising an axially extending glide member (24) comprising a glide surface (4) configured to support the elongated member (23), characterized in that the support structure (1) comprises:- at least one scraper member (6,7) on at least one axial side of the glide surface (4) configured to scrape against the elongated member surface (23’) and remove any growth and / or corrosion building on the elongated member surface (23’).

2. The submersible support structure (1) according to any of the preceding claims, wherein the at least one scraper member (6,7) comprises a scraper edge (6’, 7’).

3. The submersible support structure (1) according to claim 2, wherein the scraper edge (6’, 7’) is formed on an outer edge of the scraper member (6,7).

4. The submersible support structure (1) according to any of the preceding claims, wherein said at least one scraper member (6,7) comprises a first scraper member (6) on a first axial side of the glide surface (4) and a second scraper member (7) on a second axial side of the glide surface (4).

5. The submersible support structure (1) according to any of the preceding claims, wherein the elongated member (23) has a cross-section and the at least one scraper member (6,7) has a complementary cross-section.

6. The submersible support structure (1) according to any of the preceding claims, wherein said at least one scraper member (6,7) circumferentially encloses said elongated member (23).

7. The submersible support structure (1) according to claim 2, or any one of claims 3-6 when dependent upon claim 2, wherein the at least one scraper member (6,7), on a side facing away from the glide surface (4), comprises a concave surface section (6”’, 7’”) terminating in said scraper edge (6’, 7’).

8. The submersible support structure (1) according to any of the preceding claims, wherein the glide member (24) is made from a self-lubricating material.

9. The submersible support structure (1) according to any of the preceding claims, wherein the glide surface (4) has a semi-circular shape.

10. The submersible support structure (1) according to any of the preceding claims, wherein the submersible support structure (1) has a body, and wherein the at least one scraper member (6,7) is supported by said body such that the at least one scraper member (6,7) is configured to move relative said body.

11. The submersible support structure (1) according to any of the preceding claims, wherein the scraper member (6,7) comprises a scraper surface (25) extending between an inner edge (6”, 7”) and an outer edge (6’, 7’).

12. The submersible support structure (1) according to claim 11, wherein said inner edge (6”, 7”) has a radius.

13. A submersible support system (100) comprising:- at least one pressure vessel (20) comprising an elongated member (23) comprising an elongated member surface (23’), and- a submersible support structure (1) according to any of the preceding claims configured to support the at least one pressure vessel (20).

14. A submersible support assembly (50) comprising:- an attachment member (10) attachable to a pressure vessel (20), the attachment member (10) comprising an elongated member (23) comprising an elongated member surface (23’),- an axially extending glide member (24) comprising a glide surface (4) configured to support the elongated member (23),characterized in that the support assembly (50) comprises:- at least one scraper member (6,7) on at least one axial side of the glide surface (4) configured to scrape against the elongated member surface (23 ’) and remove any growth and / or corrosion building on the elongated member surface (23 ’).

15. A method of removing growth and / or corrosion from an elongated member surface (23’) of an elongated member (23), the elongated member (23) being connected to a pressure vessel (20), and wherein the method comprises:- providing a support structure (1) to an underwater location, wherein the support structure (1) comprises an axially extending glide member (24) comprising a glide surface (4);- installing the pressure vessel (20) in the support structure (1) such that the elongated member surface (23’) is supported by the glide surface (4);16- bringing at least one scraper member (6,7) on at least one axial side of the glide surface (4);- scraping, by using said at least one scraper member (6,7), against the elongated member surface (23’) to remove any growth and / or corrosion therefrom.

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