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Title:
STRUCTURE COMPRISING AT LEAST TWO INTERCONNECTED STRUCTURAL MEMBERS AND A SEALING SYSTEM, OFFSHORE WIND TURBINE, AND METHOD FOR BUILDING A SEALED STRUCTURE
Document Type and Number:
WIPO Patent Application WO/2019/110086
Kind Code:
A1
Abstract:
A structure comprising at least two interconnected structural members (101, 103), wherein an outer end of a first one (101) of said at least two structural members abuts an outer end of a second one (103) of said at least two structural members, and wherein the outer end of said first structural member (101) is provided with a sealing system (109) for preventing fluid to enter from the environment to the interior of the structure, wherein said sealing system (109) comprises: - a compressible sealing member (111) extending along a surface adjacent the outer end of said second structural member (103); - an expandable expansion member (113) extending along and against said sealing member (111); - an inwardly facing rigid flange surface extending along and against said expansion member (113), wherein said flange surface is rigidly connected to the outer end of said first structural member (101); wherein said expansion member (113) is arranged to, in an expanded state, urge the sealing member (111) against the surface adjacent the outer end of said second structural member (103).

Inventors:
VAN WAARDHUIZEN, Dirk Jan Dingeman (Verlengde Kerkweg 15, 2985 AZ RIDDERKERK, 2985 AZ, NL)
VAN DEN BERG, Leendert Jurriaan (Verlengde Kerkweg 15, 2985 AZ RIDDERKERK, 2985 AZ, NL)
Application Number:
EP2017/081457
Publication Date:
June 13, 2019
Filing Date:
December 05, 2017
Export Citation:
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Assignee:
TRELLEBORG RIDDERKERK B.V. (Verlengde Kerkweg 15, 2985 AZ Ridderkerk, 2985 AZ, NL)
International Classes:
F16J15/46; E02B17/02; F03D13/20; F03D13/25
Foreign References:
DE102014018483A12016-06-16
US3874136A1975-04-01
US3178779A1965-04-20
EP2826932A22015-01-21
US4216981A1980-08-12
Other References:
None
Attorney, Agent or Firm:
VERNOUT, Robert et al. (Arnold & Siedsma, Bezuidenhoutseweg 57, 2594 AC Den Haag, 2594 AC, NL)
Download PDF:
Claims:
Claims

1. A structure comprising at least two interconnected structural members, wherein an outer end of a first one of said at least two structural members abuts an outer end of a second one of said at least two structural members, and wherein the outer end of said first structural member is provided with a sealing system for preventing fluid to enter from the environment to the interior of the structure, said sealing system comprising:

- a compressible sealing member extending along a surface adjacent the outer end of said second structural member;

- an expandable expansion member extending along and against said sealing member;

- an inwardly facing rigid flange surface extending along and against said expansion member, wherein said flange surface is rigidly connected to the outer end of said first structural member; wherein said expansion member is arranged to, in an expanded state, urge the sealing member against the surface adjacent the outer end of said second structural member.

2. The structure according to claim 1 , wherein the structural members are tubular and the sealing member, the expansion member and the flange surface are substantially ring-shaped and extend around the outer surface adjacent the outer end of said second tubular structural member.

3. The structure according to claim 1 or 2, wherein the expansion member comprises an inflatable tube.

4. The structure according to claim 3, wherein the inflatable tube comprises a valve, which is arranged for inserting a medium under pressure for inflating the inflatable tube.

5. The structure according to claim 4, wherein the inflatable tube comprises a multitude of said inflation valves, which are each arranged in a different sector of said inflatable tube along the surface adjacent the outer end of said second structural member.

6. The structure according to claim 4 or 5, wherein the medium is a curable or cured liquid.

7. The structure according to any of the preceding claims 3 - 6, wherein the inflatable tube is inflated with a pressure of at least 3 bar, preferably a pressure between 5 and 10 bar.

8. The structure according to any of the preceding claims, wherein the sealing member comprises two sections with materials having different material properties, wherein a first section of the sealing member, which is arranged to abut the expansion member, comprises a material with higher hardness compared to the material used for a second section of the sealing member, which is arranged to abut the surface adjacent the outer end of the second structural member .

9. The structure according to any of the preceding claims, wherein the sealing member comprises two sections, a first section which is arranged to abut the expansion member having a substantially rectangular cross section and a second section, which is arranged to abut the surface adjacent the outer end of said second structural member, said second section having a rib extending from said first section and tapering towards the surface adjacent the outer end of said second structural member.

10. The structure according to claim 9, wherein the sealing member comprises one and no more than one of said ribs, or wherein the sealing member comprises two and no more than two of said ribs, or wherein the sealing member comprises three and no more than three of said ribs, or wherein the sealing member comprises more than three of said ribs.

11. The structure according to claim 10, wherein the sealing member comprises three or more of said ribs, and wherein the rib arranged substantially in the center of the sealing member has a lower height compared to the ribs arranged substantially at the edges of the sealing member.

12. The structure according to claim 9, 10 or 11, wherein, in the expended state of the expansion member, the sealing member is arranged to abut the surface adjacent the second structural member over substantially the full width of the sealing member.

13. A sealing system for use in a structure according to any of the preceding claims 1 - 12.

14. An offshore wind turbine, comprising a structure according to any of the preceding claims 1 - 12, wherein said structural members are support members for the turbine.

15. A method for building a sealed structure, comprising the steps of:

- providing at least two structural members,

- interconnecting said structural members such that an outer end of a first one of said at least two structural members abuts an outer end of a second one of said at least two structural members, and

- providing a sealing system for preventing fluid to enter from the environment to the interior of the structure, said sealing system comprising: - a compressible sealing member extending along and against a surface adjacent the outer end of said second structural member;

- an expandable expansion member extending along and against said sealing member;

- an inwardly facing rigid flange surface extending along and against said expansion member, wherein said flange surface is rigidly connected to the outer end of said first structural member;

- expanding the expansion member in order to urge the sealing member against the surface adjacent the outer end of said second structural member.

Description:
Structure comprising at least two interconnected structural members and a sealing system, offshore wind turbine, and method for building a sealed structure

The invention relates to a structure comprising at least two interconnected structural members, wherein an outer end of a first one of said at least two structural members abuts an outer end of a second one of said at least two structural members, and wherein the outer end of said first structural member is provided with a sealing system for preventing fluid to enter from the environment to the interior of the structure.

Wind energy is one of the solutions to meet the ever growing demand for renewable energy. At the same time, due to the scarcity of land, a large part of the required capacity of wind energy is to be installed offshore. Therefore, large offshore wind farms, comprising large amounts of offshore wind turbines, are constructed, under construction or in development. A typical offshore wind turbine will comprise of a Rotor-Nacelle-Assembly (RNA) and an offshore support structure, comprising of a tubular tower and offshore foundation. To date, monopile-based foundations make up the largest part of these offshore foundations. In the first stage of installation of such a monopile foundation, a monopile is installed in the seabed and as a second stage, the transition piece, which forms the connection between the monopile and the tubular tower, is installed. Nowadays, the connection between the monopile and transition piece is often a flange connection.

These offshore wind turbines have to deal with the harsh offshore conditions during their entire designed lifetime and, it is not hard to imagine, that corrosion is one of the worst enemies of such a structure. Therefore, it is essential to shield the structure using thick layers of coatings or paint, anodes or other solutions. In addition, any fluid, from for instance waves slamming on the structure, that is allowed to enter from the environment to the interior of the structure typically leads to corrosion on the structural members, thereby negatively influencing the life time of these structural members. It is an object of the invention to address the above mentioned problems.

To that end said sealing system comprises: a compressible sealing member extending along a surface adjacent the outer end of said second structural member; an expandable expansion member extending along and against said sealing member; an inwardly facing rigid flange surface extending along and against said expansion member, wherein said flange surface is rigidly connected to the outer end of said first structural member; wherein said expansion member is arranged to, in an expanded state, urge the sealing member against the surface adjacent the outer end of said second structural member. Hereby, a reliable seal to prevent fluid from entering the flange connection is obtained. Furthermore, the seal is even able to deal with pressurized fluids. The structural members preferably are tubular and the sealing member, the expansion member and the flange surface are substantially ring-shaped and extend around the outer surface adjacent the outer end of said second tubular structural member. Thereby a good fit between the sealing member and structural members is obtained.

The expansion member preferably comprises an inflatable tube. The inflatable tube preferably comprises a valve, which is arranged for inserting a medium under pressure for inflating the inflatable tube. The inflatable tube preferably comprises a multitude of said inflation valves, which are each arranged in a different sector of said inflatable tube along the surface adjacent the outer end of said second structural member. The medium preferably is a curable or cured liquid. The inflatable tube is preferably inflated with a pressure of at least 3 bar, more preferably a pressure between 5 and 10 bar. The valve allows for an easy access to the interior of the inflatable tube, whereby the tube can be inflated to the desired pressure. By applying the magnitude of the inflation valves, the inflatable tube can be evenly pressurized by the applied medium. A curable liquid lead to a more reliable sealing system, as leaks, due to deterioration of the material of the inflatable tube over time, do not substantially influence the performance of the sealing system. The prescribed pressures ensure an adequate seal, even in case a flow of water at higher velocities impacts the sealing system.

The sealing member preferably comprises two sections with materials having different material properties, wherein a first section of the sealing member, which is arranged to abut the expansion member, comprises a material with higher hardness compared to the material used for a second section of the sealing member, which is arranged to abut the surface of the surface adjacent the outer end of the second structural member. The sealing member is preferably made from natural and/or synthetic rubbers. The inflatable tube is also preferably made from natural and/or synthetic rubbers. The choice of materials for the different sections of the sealing member results in an evenly applied pressure from the expansion member onto the sealing member, while also resulting in a reliable seal in case the surface adjacent the outer end of said second structural member has a certain surface roughness.

The sealing member preferably comprises two sections, a first section which is arranged to abut the expansion member having a substantially rectangular cross section and a second section, which is arranged to abut the surface adjacent the outer end of said second structural member, said second section having a rib extending from said first section and tapering towards the surface of the outer end of said second structural member. Such a construction leads to an efficient transfer of the pressure applied by the expansion member onto the sealing member, resulting in a reliable seal.

The sealing member preferably comprises one and no more than one of said ribs, or the sealing member comprises two and no more than two of said ribs, or the sealing member comprises three and no more than three of said ribs, or the sealing member comprises more than three of said ribs. Preferably the sealing member comprises three or more of said ribs, and wherein the rib arranged substantially in the center of the sealing member has a lower height compared to the ribs arranged substantially at the edges of the sealing member. Hereby a stable seal between the sealing member and the structure is obtained, whereby an even more reliable seal is obtained by means of the additional redundancies, in to form of multiple ribs.

In the expended state of the expansion member, the sealing member is preferably arranged to abut the surface adjacent the outer end of the second structural member over substantially the full width of the sealing member. Hereby, only a small cavity is obtained between the structure and the sealing member, further minimizing the risk of corrosion.

The invention also relates to a sealing system for use in a structure according to the invention.

Furthermore the invention relates to an offshore wind turbine, comprising a structure according to the invention, wherein said structural members are support members for the turbine. Application of such a sealing system in an offshore wind turbine, allows for a seal that is able to preventing fluid from entering even under the constant dynamic loading induced by the applied wind and wave loading and also shielding the connections between the different structural members from so called wave run ups along the supporting structure.

The invention furthermore relates to a method for producing a sealed structure, comprising the steps of: providing at least two structural members, interconnecting said structural members such that an outer end of a first one of said at least two structural members abuts an outer end of a second one of said at least two structural members, and providing a sealing system for preventing fluid to enter from the environment to the interior of the structure, said sealing system comprising: a compressible sealing member extending along and against a surface adjacent the outer end of said second structural member; an expandable expansion member extending along and against said sealing member; an inwardly facing rigid flange surface extending along and against said expansion member, wherein said flange surface is rigidly connected to the outer end of said first structural member; expanding the expansion member in order to urge the sealing member against the surface adjacent the outer end of said second structural member. The invention will now be explained in detail with reference to figures illustrated in the accompanying drawings.

Figure 1 shows a cross-section of the sealing system according to a first embodiment in combination with two structural members connected at their respective flanges;

Figure 2 shows a cross-section of the sealing system according to an alternative embodiment in combination with two structural members connected at their respective flanges;

Figure 3 shows a perspective view of the sealing system according to the alternative embodiment in combination with two structural members connected at their respective flanges; and

Figures 4A - 4D show cross-sections of different embodiments of the sealing member, in combination with the expansion member, in an undeformed and uninflated state and in a deformed and inflated state respectively.

Figure 1 shows a cross-section of the sealing system according to a first embodiment in combination with two structural members connected at their respective flanges. The first structural member 1 is for instance a wind turbine tower section or a transition piece. The second structure member 3 is for instance also a wind turbine tower section, transition piece or monopile. The first structural member 1 comprises an internally extending flange 5 and an externally extending sealing system 9. The second structural member 3 also comprises an internally extending flange 7. Both flanges form the flange connection connecting the first and second structural members 1, 3 and are fitted with bolt holes 6, 8 for allowing bolts to be fitted through. After torqueing of the bolts and nuts (not shown) a firm connection between the first and second structural member 1 , 3 is obtained. The sealing system 9 comprises the sealing member 11 , which comprises on a first side a rib-like section comprising a single rib 12 and is arranged to abut an inflatable tube on a second side of the sealing member 13. The cross-section 14 of the sealing member on the second side is substantially rectangular, such that a large contact-area with the inflatable tube 13 is achieved. In this cross-section view one inflation valve 15 for inflating the inflatable tube 13 can be seen. The inflatable tube 13 can be inflated, by insertion through the valve 15, with water, grout, epoxy or any other suitable medium for inflation. In case a curable medium, such as grout or epoxy is used, once the medium is cured the risk of leakage, and thereby a loss of quality of the seal, due to wear and tear over time is largely averted. To support the sealing member 11 and the expandable member, in this case the inflatable tube 13, a supporting structuring 16 for supporting the sealing member 11 and inflatable tube 13 is arranged. The supporting structure 16, which is connected to the first structural member 1, comprises, in the cross-sectional view, a C-shaped holding member 17 for holding the sealing member 11 and inflatable tube 13. Additional supports are 19 are provided for creating a substantially rigid supporting structure 16 which is firmly connected to the first structural member 1. The supporting member 19 and/or supporting structure 16 can be formed integrally with the first structural member 1, but can also be attached at later stage by means of suitable connection means, such as welding, gluing or the like. The inflation valve is fitted through the C-shaped holding member 17, thereby allowing to inflate the inflatable tube 13 after the first and seconder structural member 1, 3 have been connected. After inflation of the inflatable tube 13, the sealing member 11 is urged towards the second structural member, such that a rib 12, formed on an inner side of the sealing member, is urged, under pressure, against an outside surface 21 of the second structural member.

Figure 2 shows a cross-section of the sealing system according to an alternative embodiment in combination with the first and second structural members 101, 103 connected at their respective flanges 105, 107. This alternative embodiment comprises many of the same features of the first embodiment, whereby the difference are listed below. The supporting structure 116 is formed substantially integral with the first structural member. The sealing system 109 is held by the substantially C-shaped holding member 117, the holding member 117 comprising a separate, but connected, locking plate 118 forming one of the legs of the substantially C-shaped holding member 117. Upon installation of the sealing system 109, the locking plate is fitted and connected to the supporting structure 116, thereby locking the sealing system 9 in the substantially C-shaped holding member 117. The locking plate 118 is connected by means of welding, gluing or the like. An inflation valve 115 is again connected to the inflatable tube 113, the valve being fitted with an additional closing member 124. Sealing member 111, comprises two connected sections, either integrally formed or connected by means of a suited welding technique, gluing or the like, having different material properties. The first sealing member section 122 comprises a natural rubber, synthetic rubber or other suitable material with a lower hardness then the second sealing member section 125, which comprises a natural rubber, synthetic rubber or other suitable material.

The sealing member 109 is fitted, on an inner side of the sealing member, with three ribs 123, formed in first sealing member section 122. These ribs 123 are arranged to abut, under pressure, the outside surface 121 of the second structural member. Thereby a reliable and easy to install seal is obtained for protection the flange connection against water and the resulting corrosion. Figure 3 shows a perspective view of the sealing system according to the alternative embodiment, as is also shown in figure 2, in combination with two structural members connected at their respective flanges. Figure 2 shows the tubular shape of the first and second structural members 101, 103. In addition, the bolt holes 106 in the flange of the first structural member 101 are clearly visible. Furthermore a multitude of valves 115 are shown. These valves are arranged in different sectors of the inflatable tube 113.

Figure 4A shows, in a cross-sectional view a sealing member and inflation tube according to the first embodiment comprising a single rib 12, as also shown in figure 1. The left figure of figure 4A shows the sealing member 11 and inflation tube 13 in an undeformed and uninflated state; whereas the right figure of figure 4A shows the sealing member 11 and inflation tube 13 in a deformed and inflated state. In the inflated state, the inflation tube urges the sealing member towards the surface 21 of the structural member. As this is performed under pressure, the sealing member 11 will contact the surface 21 and deform as it is squeezed between the surface 21 and the inflation tube 13. Due to this, the rib, formed in the section of the sealing member preferably comprising the material with the lower hardness, will deform to adjust to the contour and surface roughness of the surface 21. Thereby a reliable seal is obtained that can withstand a high pressure. This embodiment yields the highest maximum contact stress at the sealing interface, compared to the embodiments of Figures 4B-C.

Figure 4B shows, in a cross-sectional view a sealing member 211 and inflation tube 213 according to an alternative embodiment comprising three ribs 231, 232, 233. The left figure of figure 4B shows the sealing member 211 and inflation tube 213 in an undeformed and uninflated state; whereas the right figure of figure 4B shows the sealing member 211 and inflation tube 213 in a deformed and inflated state. The sealing mechanism is equal to as is introduced in figure 4A. It should be noted that the ribs 231, 233 formed near the edges of the seal have a greater height hi, compared to the height h2 of the rib 232 formed substantially in the center of the sealing member. As a result the contact pressure between the ribs 231, 233 and the surface 221 is, in the deformed and inflated state, higher than the contact pressure between the center rib 232 and the surface 221. Again note that the ribs 231, 232, 233 are preferably formed in the section of the rib comprising material of the lower hardness. This embodiment prevents trapped air from entering the flange opening, as the tip of the seal is pressed into the flange opening, while the contact stress is only slightly less than with the embodiment of Figure 4A.

Figure 4C shows, in a cross-sectional view a sealing member 111 and inflation tube 113 according to the alternative embodiment of figure 2 and 3, comprising a three ribs 123. The left figure of figure 4C shows the sealing member 111 and inflation tube 113 in an undeformed and uninflated state; whereas the right figure of figure 4C shows the sealing member 111 and inflation tube 113 in a deformed and inflated state. The sealing mechanism is equal to as is introduced in figure 4A. The three ribs 123 have substantially the same height and are preferably formed in the section of the rib comprising material of the lower hardness. Hence, a significantly smaller difference in contact pressure exists in between the three ribs in the deformed and inflated state. This embodiment prevents trapped air from entering the flange opening, as the tip of the seal is pressed into the flange opening, while the contact stress is only slightly less than with the embodiment of Figure 4A, and the configuration may be more robust and stable than the embodiment of Figure B.

Figure 4D shows, in a cross-sectional view a sealing member 311 and inflation tube 313 according to an alternative embodiment comprising a three ribs 331, 332, 333. The left figure of figure 4D shows the sealing member 311 and inflation tube 313 in an undeformed and uninflated state; whereas the right figure of figure 4D shows the sealing member 311 and inflation tube 313 in a deformed and inflated state. The sealing mechanism is equal to as is introduced in figure 4A. In this specific embodiment, the ribs are formed such that, in the deformed and inflated state, the sealing member 311 is in contact with the surface 321 over substantially the full width wl of the sealing member. The ribs are preferably formed in the section of the rib comprising material of the lower hardness. This embodiment completely prevents air from being present in the sealing region, but has a lower contact stress than the embodiments of Figures 4A-C.

Note that all the different embodiments of the sealing member, as shown in figures 4A - 4D, can be combined with the embodiments of the structures, as shown in figures 1 -3.

The invention has thus been described by means of preferred embodiments. It is to be understood, however, that this disclosure is merely illustrative. Various details of the structure and function were presented, but changes made therein, to the full extent extended by the general meaning of the terms in which the appended claims are expressed, are understood to be within the principle of the present invention. The description and drawings shall be used to interpret the claims. The claims should not be interpreted as meaning that the extent of the protection sought is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims. For the purpose of determining the extent of protection sought by the claims, due account shall be taken of any element which is equivalent to an element specified therein. An element is to be considered equivalent to an element specified in the claims at least if said element performs substantially the same function in substantially the same way to yield substantially the same result as the element specified in the claims.