NL2030213B1

NL2030213B1 - Method and connecting ring for mounting a tower to a foundation pile, and a wind turbine generator

Info

Publication number: NL2030213B1
Application number: NL2030213A
Authority: NL
Inventors: Antoin Marie Kurstjens Michel; Petrus Hendrik Everts Stefan; Jan Goverse Hermanus
Original assignee: Sif Holding N V
Priority date: 2021-12-22
Filing date: 2021-12-22
Publication date: 2023-06-29
Also published as: WO2023121457A1

Abstract

Method for mounting a tower for a wind turbine generator to a foundation pile, wherein the tower is provided with a metal connecting ring at a lower end and is positioned on an upper end of the foundation pile, where after: - the metal connecting ring is welded to the upper end of the foundation pile from one of an outer side of the foundation pile or an inner side of the foundation pile, forming a first peripheral weld at a first level; - a groove is formed at the level of the weld from the other one of the inner side of the foundation pile or the outer side of the foundation pile; and - a second peripheral weld is formed in said groove. or wherein the foundation pile is provided with a metal connecting ring at an upper end and the tower is positioned on an upper end of the foundation pile, where after: - the metal connecting ring is welded to the lower end of the tower from one of an outer side of the tower or an inner side of the tower, forming a ﬁrst peripheral weld at a first level; - a groove is formed at the level of the weld from the other one of the inner side of the tower or the outer side of the tower; and - a second peripheral weld is formed in said groove.

Description

P130162NL00

Title: Method and connecting ring for mounting a tower to a foundation pile, and a wind turbine generator

The invention relates to a method for mounting a tower to a foundation pile.

It is known in the art to mount a tower, for example of a wind turbine generator, to a foundation pile, by using cooperating flanges extending horizontally, radially from a lower end of the tower and an upper end of the foundation pile. These flanges are bolted together by a series of bolts and nuts, each bolt extending through the flanges and secured by a nut. With increasing diameters of the towers and foundation piles, due to increasing diameter of the rotor of the wind turbine generators and hence of the height of the towers, and due to the increasing forces exerted on these towers and therefore on the connection between tower and foundation pile, the number of bolts used as well as the size of the bolts, especially diameters of the bolts also have increased dramatically and are still increasing with new towers built. This makes it more and more difficult to handle these bolts and nuts, both during placement of the tower on the foundation pile and during maintenance, and costly. One of the problems of such nut-and- bolt connection is that regular maintenance is necessary, during which the tension in each bolt has to be measured, and if necessary amended. The tension in the bolts regularly diminishes due to for example movement of the tower due to forces of the rotor blades. This means that at regular intervals in time a crew has to go to the installed wind turbine generator, approach each bolt, assess the overall condition of and the tension in the bolts, which may require replacement of bolts and nuts and/or adjusting, if necessary, tension in the bolts. Such regular maintenance is time consuming and costly, and may be hazardous, especially for off-shore constructions. An additional problem is that it is difficult to accurately measure tension in the bolts, for example because of corrosion of the bolts and nuts, which will especially but not exclusively be a problem in off-shore applications, because of a salt water environment. Therefore the risk occurs that even after maintenance the tension in some or all of the bolts is incorrect and does not correspond to the tension as prescribed, which may lead to reduced fatigue life of the bolted connection. Moreover, with increasing tower dimensions designing and manufacturing flanges which can accommodate the required number and sizes of bolts, especially complying with the strict tolerances necessary, reaches the limits of what is technically and economically feasible.

It is an aim of the present disclosure to provide for an alternative method for mounting a tower to a foundation pile. It is an aim of the present disclosure to provide for a method for mounting a tower to a foundation which provides for a mounting which requires little maintenance. It is an aim of the present disclosure to provide for a mounting of a tower to a foundation pile which is relatively easy to provide and to maintain.

At least some of these and other aims are at least in part obtained by a method and mounting according to the present disclosure.

In an aspect a method according to the disclosure for mounting a tower for a wind turbine to a foundation pile, is characterized by the tower being provided with a metal connecting ring at a lower end which is positioned on an upper end of the foundation pile. After said positioning the metal connecting ring is welded to the upper end of the foundation pile from one of an outer side of the foundation pile or an inner side of the foundation pile, forming a first peripheral weld at a first level. A groove is formed at the level of the weld from the other one of the inner side of the foundation pile or the outer side of the foundation pile and a second peripheral weld is formed in said groove.

Alternatively in an aspect a method according to the disclosure for mounting a tower for a wind turbine to a foundation pile, is characterized by the foundation pile being provided with a metal connecting ring at an upper end and the tower being positioned on an upper end of the foundation pile.

After said positioning of the tower the metal connecting ring is welded to the lower end of the tower from one of an outer side of the tower or an inner side of the tower, forming a first peripheral weld at a first level. A groove is formed at the level of the weld from the other one of the inner side of the tower or the outer side of the tower, and a second peripheral weld is formed in said groove.

In the present disclosure mainly the first method will be discussed, in which the connecting ring is first welded to the tower. However, any feature discussed and explained with regards to this method or a generator obtained with such method should also be understood as disclosed with respect to the second method, in which the connecting ring is first welded to the foundation pile.

A method according to the disclosure allows for mounting a tower to a foundation pile, by welding the two together. The welding can be done in situ. After welding the tower to the foundation very little to no maintenance will be necessary for maintaining the mounting, compared to prior art mounting in which a bolted connection is used for said mounting. A method according to the present disclosure can for a large part be done semi automatically, using for example a machining robot and/or a welding robot, which means that less manual labor may be required compared to using a bolted connection between the tower and the foundation as known in the prior art. An additional advantage of using robots for machining and/or welding may be that the quality of the connection can be even better ensured.

A method according to the disclosure is especially but not exclusively suitable for mounting a tower to a foundation off-shore.

In an aspect a method according to the disclosure can further comprise forming the groove such that at least part of the first weld 1s removed, wherein the second weld is formed against the remaining part of the first weld. By such method it can be ensured that an optimal welding is achieved, in which from opposite sides of the connection a weld is provided, which welds are thoroughly connected to each other.

In an aspect a method according to the disclosure can further comprise forming the first weld such that it extends substantially through the full thickness of at least one of the connecting ring and the upper end of the foundation pile. To this end for example the connecting ring and/or the upper end of the foundation can be provided with a chamfer, such that a welding groove, such as a substantially V-shaped welding groove is formed between the connecting ring and the upper end of the foundation in which the first weld can be formed. Such chamfer can be pre-formed or can be formed after positioning of the tower on the foundation, for example by grinding, milling or the like known suitable method. Such method can provide for an optimal first weld.

In such method it can be advantageous when the first weld extends such that an end thereof is provided near or in the surface opposite the surface from which the first weld is provided, such that said end can be removed by forming the groove from said opposite side.

In an aspect a method according to the disclosure can comprise the step of providing the connecting ring with a support portion, such that the support portion extends at least partly alongside an inner or outer surface of the upper end of the foundation pile, at a side opposite the side from which the first weld is to be welded.

Such support portion in embodiments forms a backing for forming the first weld. In embodiments the foundation pile is provided with at least one support, wherein at least during forming of the first weld the support portion of the connecting ring is supported by the at least one support. Thus at least some of the forces acting on the tower and foundation can be borne by said supports, at least during forming of the first weld.

In an aspect in embodiments the support portion is connected to the at least one support at least during forming of the first weld, preferably by a bolt or clamp connection. Thus the tower can at least temporarily fixed to the foundation, at least until the first weld has been formed. 5 In an aspect in embodiments of a method of the disclosure comprises the step of forming the groove through the connecting ring, after having formed the first weld. Said groove can be formed through a support portion, if provided for, since the first weld at that point in time firmly connects the tower to the foundation.

In an aspect a method according to the disclosure tools can be supported by the connecting ring, for machining parts of the tower and/or the foundation. For example in embodiments a welding tool is supported on a rail system provided by the connecting ring, during welding of the first weld and/or the second weld. In embodiments a groove forming tool is supported on a rail system provided by the connecting ring during forming of the groove. The rail system can be provided on an inside or outside of the tower and/or foundation, or both on the inside and outside thereof.

In embodiments the connecting ring can be welded to the tower on- shore, where after the tower is shipped to the foundation pile. Then the connecting ring is welded to the foundation pile, which can be off-shore.

In an aspect the present disclosure is directed to a connecting ring for mounting a tower to a foundation pile, wherein the connecting ring is made of a weldable metal. The connecting ring comprises at a first longitudinal end a first connecting configuration for connecting the connecting ring to an end of a tower and at a second longitudinal end longitudinally opposite the first longitudinal end comprises a second connecting configuration for connecting the connecting ring to a metal foundation pile. The second connecting configuration comprises at least a welding surface for welding the connecting ring to the foundation pile,

wherein at the second longitudinal end further a support portion is provided, extending in longitudinal direction beyond the welding surface.

A connecting ring according to the disclosure allows for easy mounting of a tower to a foundation pile, using welding technique.

Preferably the connecting ring is provided with support rails, extending from an inner side or an outer side of the connecting ring, preferably extending radially. In embodiments that connecting ring comprises rails extending radially inward and extending radially outward.

The rails can during use support tooling, like welding tools and machining tools, such as for example a grinder or milling tool.

In embodiments the first connection configuration is directly longitudinally opposite the welding surface, whereas the support portion extends to a side of the welding surface. Such arrangement provides for a direct lead through of forces from the tower to the foundation after welding, whereas the support portion allows proper mounting of the tower to the foundation pile.

In an aspect the present disclosure is directed to a wind turbine generator tower, provided with a connecting ring according to the disclosure.

Preferably the tower has a cylindrical inner surface and a cylindrical outer surface at the lower end of the tower, wherein the support portion extends outside a cylinder defined by the outer surface or inside a cylinder defined by the inner surface, such that when the connecting ring is placed on a foundation pile having substantially the same inner and outer dimensions as the tower, the support portion abuts against an inner surface of the foundation pile or against an outer surface of the foundation pile.

In this aspect cylindrical should be understood as including truncated conical having a central rotational, longitudinal axis, at least in which the relevant inner or outer surface has an angle relative to the longitudinal axis of between 0 and 20 degrees, more specifically between 0 and 15 degrees, such as between 0 and 10 degrees.

In an aspect the present disclosure is directed to a wind turbine generator comprising a tower mounted to a foundation pile, wherein between the tower and the foundation pile a mounting connecting ring is provided, wherein the mounting connecting ring has been welded to the foundation pile and to the tower. The connecting ring preferably is a connecting ring according to the disclosure. The tower of the wind turbine generator preferably is mounted to the foundation pile using a method according to the disclosure.

It will be clear that different aspects of the embodiments discussed here before and hereafter can be combined, as for example defined by the appending claims.

For a better understanding of the disclosure embodiments of a method, press system and computer program product according to the disclosure will hereafter be described, by way of example only, with reference to the drawings. Therein shows:

Fig. 1A schematically a wind turbine generator, comprising a tower mounted on a foundation pile, wherein in fig. 1A by way of example an off- shore wind turbine generator (WTG) is shown, with a mid-section of the tower broken away;

Fig. 1B schematically a cross sectional view along the line IB — IB in fig. 1A;

Fig. 2 — 7 different steps of a method according to the disclosure, for mounting a tower to a foundation pile, showing a cross sectional part along the line A — Ain fig. 1B;

Fig. 8 schematically a connection between a tower and a foundation pile of a wind turbine generator, for example as shown in fig. 1A or formed with the steps of fig. 2 — 7, in cross sectional view along the line VIII — VIII in fig. 1B;

Fig. 9A and B schematically a connecting ring with a rail system, supporting tooling for machining and welding.

The embodiments shown in the drawings and described hereafter are shown only by way of example and should not be considered limiting the scope of the disclosure.

In this description by way of example an off-shore wind turbine generator 1 is shown and described, also referred to a wind generator 1 or wind turbine 1, mounted to a foundation pile 2 off-shore, as schematically shown in fig. 1. The wind turbine generator 1 shown by way of example only comprises a tower 3, supporting a nacelle 4 with a generator (not shown) and a propeller 5, as known in the art. In fig. 1A a mid-section of the tower 1 has been broken away, indicated by broken lines M and N. It will be clear that the wind turbine generator 1 can also be an on shore wind turbine generator 1.

The tower 3 in the embodiment shown as a metal tower, as known in the art, for example made of a series of interconnected substantially cylindrical elements. Substantially cylindrical should be understood as comprising truncated conical, such that the segments have a longitudinal axis X — X and an inner surface 6 and an outer surface 7, both inclining relative to the axis X — X at a relatively shallow angle a, for example between 0 and 20 degrees, such as for example between 0 and 15 degrees, such as between 0 and 10 degrees. The tower 3 preferably has a substantially circular cross section over most of its height, but may also have a different cross section, such as polygonal. The tower 3 has a lower end 11.

In the embodiment shown the foundation pile 2 is a metal, substantially cylindrical monopile, as known in the art, driven into or otherwise supported by the bedding of a water in which the foundation pile 2 1s provided, as known in the art. Alternatively the foundation pile can be provided differently, for example made of concrete with a weldable upper end, for example made of metal, such as steel. The upper end 8 of the foundation pile 2 is preferably hollow, such that it comprises an inner volume V with an inner surface 9 at the upper end 8. The upper end 8 preferably comprises or is formed by a metal cylindrical portion 10, which in the embodiments shown is an upper end of a metal monopile 2. In the embodiments disclosed the inner and outer diameters of the upper end 8 of the pile 2 are comparable to the inner and outer diameters of the lower end 11 of the tower, such that the lower end 11 of the tower 3 extends directly above the upper end 8 of the foundation pile 2. If the diameters differ the connecting ring 12 as will be discussed hereafter can be amended for compensating for such difference.

Substantially cylindrical should again be understood as comprising truncated conical, such that the pile has a longitudinal axis X — X and an inner surface 9 and an outer surface 13, both parallel to or inclining relative to the axis X — X at a relatively shallow angle B, for example between 0 and 20 degrees, such as for example between 0 and 15 degrees, such as between 0 and 10 degrees. The pile 2 preferably has a substantially circular cross section, as shown in fig. 1B, over most of its height, but may also have a different cross section, such as polygonal.

According to the present disclosure at the lower end 11 of the tower 3 connecting to the upper end 8 of the pile 2 a connecting ring 12 is provided. The connecting ring 12 in the embodiments shown is connected to the tower 3 and the pile 2 by welding. In preferred embodiments the connecting ring 12 is welded to the lower end 11 of the tower 3 first, for example on-shore, and is subsequently welded to the upper end 8 of the foundation pile 2 in situ, here shown off-shore. By connecting the tower 3 to the foundation pile 2 by welding it for example can be prevented that during use bolts have to be tightened periodically, as is necessary for bolted connections as known in the art. It is also prevented that bolts and/or nuts have to be replaced because of for example corrosion or fatigue.

Fig. 2 — 8 show an embodiment of the present disclosure, in which a connecting ring 12 is provided, which can for example be forged and/or can assembled from different parts, forming an integral connecting ring 12. In embodiments the connecting ring 12 has a cylindrical shape, preferably symmetrical around the longitudinal axis X — X, as shown in fig. 1B.

The connecting ring 12 is made of a weldable metal, such as for example steel. The connecting ring 12 generally has a ring shape, and comprises at a first longitudinal end 14 a first connecting configuration 15 for connecting the connecting ring 12 to the lower end 11 of a tower 3. At a second longitudinal end 16 longitudinally opposite the first longitudinal end 14 the connecting ring 12 comprises a second connecting configuration 17 for connecting the connecting ring 12 to a metal upper end 8 of the foundation pile 2. The second connecting configuration 17 comprises at least a welding surface 18 for welding the connecting ring 12 to the foundation pile 2.

In the embodiment shown in fig. 2 — 8 the first connecting configuration 15 comprises a substantially flat first welding surface 19, which can be welded, for example butt welded to the lower end 11 of the tower 3. As shown in fig. 3, the flange 12 is welded from the outer surface 7 and from the inner surface 6, for forming an inner and outer base weld 20A, 20B, together forming a base weld 20. It will be clear that any suitable welding technique can be used for forming the base weld 20. By welding the flange 12 to the tower 3 on-shore, this can be done easily, for example with the tower 3 lying down, the axis X — X substantially horizontal, with easily controlled welding properties.

The connecting ring 12 in embodiments comprises radially extending support rails 21, for supporting tooling 24, as will be discussed.

The support rails 21 in the embodiments shown comprises outer rails 21A and inner rails 21B. In fig. 2 — 8 the rails 21 are shown schematically, as upper and lower radially outward extending rail flanges 22A and B and upper and lower radially inward extending rail flanges 23A and 23B. The flanges 22, 23 extend circumferential to the connecting ring 12, such that the tooling 24 can be supported by the rails 21 and can be guided around the outside and/or inside of the flange 12, for example for grinding or milling and for welding, as will be discussed.

In embodiments a support flange 25 is provided at the inner surface 13 of the pile 2, below the rim 26 of the upper end 8 of the pile 2.

The support flange 25 can for example be welded to the pile 2. The second longitudinal end 16 the connecting ring 12 can then be provided with a support portion 27, extending in longitudinal direction beyond the welding surface 18. The support portion 27 is provided such that it can rest on the support flange 25, such that the welding surface 18 is close to the rim 26.

In embodiments the welding surface 18 extends at an angle Ô relative to the longitudinal axis X — X, such that a substantially wedge shaped welding gap 28 is provided between the welding surface 18 and the rim 26. As shown the gap 28 can be open to the outer periphery of the connecting ring 12 and the pile 2. The gap 28 can have any suitable shape and dimensions.

The support portion 27 can be provided with an inward reaching connecting flange 29, which can rest on the support flange 25. A series of openings 30 can be provided extending through the connecting flange 29 and support flange 25, through which at least during mounting of the tower 3 to the pile 2 bolds 31 can extend, for at least temporarily bolting the flanges 25, 29 together. The support portion 27 can comprise an outward facing surface portion 32 between the welding surface 18 and the lower end 33 of the support portion 27, which during use can abut against the inner surface 9 of the pile, for increasing stability and fitting.

A tower 3 can be mounted according to the disclosure to the pile 2 as follows.

The connecting ring 12 is welded to the lower end 11 of the tower 3, for example butt welded, as discussed, preferably on-shore, as is schematically shown in fig. 2 and 3. Then the tower 3, including the connecting ring 12 is shipped to a mounting location, for example off-shore,

where a foundation pile 2 as discussed has been provided, in a known manner, for example driven into a sea bed or otherwise supported on and/or in the ground, such as a water bedding. At the mounting location the tower 3 is lifted upright, and lowered onto the upper end 8 of the pile, as shown schematically in fig. 3 by indicating arrow F, such that the mounting portion 27 is lowered into the pile 2, to such extend that the connecting flange 29 comes to rest on top of the support flange 25. Thus the welding gap 28 is formed, circumferential to the tower 3 and pile 2. The welding gap 28 can also be modified or provided for after placing the tower 3 on the pile 2, as schematically shown in fig. 9A.

Then the connecting flange 29 is bolted to the support flange, in order to at least temporarily secure the tower 3 to the pile 2. Then the tower 3 can, if desired, be released from the equipment (not shown) with which it has been lifted and lowered onto the pile 2, if still attached. This position is schematically shown in fig. 4.

As schematically shown in fig. 5 and 9B a welding tool 34 is provided on the outer rails 21A, with which a first weld 35 is formed in the welding gap 28, between the welding surface 18 and the rim 26. As can be seen in e.g. figs. 5 and 9A, B, the first weld 35 can extend over substantially the full thickness D of the rim 26, such that it reaches from the outside surface 13 to approximately the inside surface 9 of the pile 2. The first weld 35 is provided circumferential by moving the welding tool 34 over the rails 21A. The welding tool 34 can be remotely controlled, can be programmed for the welding or can be manually operated, or a combination thereof.

Then, after forming the first weld 35, a machining tool 36 is provided at the inside of the tower 3 and pile 2, supported by the inner rails 21B. The machining tool 36 can for example be or comprise a grinder or a milling tool or similar tooling for forming a peripheral groove 37 from the inside surface 9. The machining is used for removing part of the first weld 35, as schematically shown in fig. 6. The groove 37 is open towards the inner volume V of the tower 3 and pile 2. In the embodiment as for example shown in fig. 2 — 8 the groove 37 is formed through the support element 27, disconnecting the remaining support element 27 from the connecting ring 12. This is acceptable since the first weld 35 has been provided, connecting the tower 3 to the pile 2.

Then the machining tool 36 is replaced by a welding tool 34, for example as previously used for the first weld 35, with which welding tool 34 a second weld 38 is formed in the groove 37, connecting the connecting ring 12 further to the pile 2. The second weld 38 connects to and is preferably welded against the first weld 35. The second weld 38 thus can form a counter weld to the first weld 35, as is schematically shown in fig. 7. It will be understood that the machining tool 36, such as a grinder or milling tool, can also be combined with a welding tool 34, such that the groove 37 can be formed and the second weld 38 can be formed in a continuous process.

As can be seen in fig. 8 thus a firm, welded connection is provided for between the tower 3 and the pile 2, which does not rely on a bolted connection.

The support portion 27 during welding of the first weld can act as a backing. The support flange 25 and the connecting flange 29 preferably extend over the full periphery of the pile 2, although they could also be provided as a series of sections, brackets or the like. Instead of or additionally to a temporary bolting connection between the support flange and the support element 27, as discussed, using bolts 30, also other systems can be used, such as clamps, or welding of the support portion 27 to the pile 2 and/or support flange 25.

In the embodiments discussed here before the connecting ring 12 is provided with the support rails for supporting the tooling, such as welding tools and machining tools. It should be understood that such tooling could also be provided for differently, for example supported on scaffolding provided outside and/or inside the tower 3 and pile 2.

In the embodiments discussed here before the tower 3 is provided with the connecting ring 12 at the lower end 11 and is then positioned on the upper end 8 of the foundation pile, where after the metal connecting ring is welded to the upper end of the foundation pile from an outer side of the foundation pile, forming the first peripheral weld 35 at a first level, where after the groove is formed at the level of the first weld 35 from the inner side of the foundation pile and the second peripheral weld 38 is formed in said groove 37.

It should be clear that according to the disclosure this could also be reversed, in the sense that the tower 3 is provided with the connecting ring 12 at the lower end 11 and is positioned on an upper end 8 of the foundation pile 2, where after the connecting ring is welded to the upper end 8 of the foundation pile from the inner side 13 of the foundation pile 2, forming the first peripheral weld 35at a first level. Then the groove 37 is formed at the level of the first weld 35 from the outer side of the foundation pile 2 and the second peripheral weld 38 is formed in said groove, from the outside. In such embodiment, if provided for, the support portion 27 will preferably extend alongside the outer surface 9 of the pile 2.

In alternative embodiments the connecting ring 12 can be first connected to the pile 2, where after the tower 3 can be mounted to the connecting ring 12 and thus to the pile 2. In such method the foundation pile 1s provided with the metal connecting ring 12 at the upper end 8 and the tower is positioned on the upper end of the foundation pile, where after the metal connecting ring 12 is welded to the lower end 11 of the tower 3 from one of an outer side 7 of the tower 3 or an inner side 6 of the tower 3, forming a first peripheral weld 35 at a first level. The groove 37 is the formed at the level of the first weld 35 from the other one of the inner side 6 of the tower 3 or the outer side 7 of the tower3 and the second peripheral weld 38 is formed in said groove 37.

In fig. 9 A and B schematically an embodiment is shown of the rail system 21 as can be used in a system and method according to the disclosure, with tooling supported on said rail system. In fig. 9A and B each of the outer rail system 21A and the inner rail system 21B is provided with two rails 22A, B and 23A, B respectively, provided above each other. The tooling 24, such as the welding tool 34 and the machining tool 36 or a combined machining and welding tool 34, 36 comprises a body 40, supported on the upper and lower rail 22A, 22B or 23A, 23B by sets of wheels 41. The sets of wheels 41 are designed such that the tool 24 can run over the rails along the outer or inner periphery of the pile 2, ring 12 and/or tower 3, but is prevented from releasing from the rail unintentionally. The sets of wheels 41 can be designed in a known manner, for example as bogies or wheel sets as used in rail guided vehicles like stair lifts or roller coasters. The tooling 24 is designed such that it can be placed on and removed from the rails 21, preferably such that the same tools can be used both on the inside and on the outside of the ring 12, tower 3 and/or pile 2.

In the embodiment show in fig. 9A and B, by way of example only, a grinder 36 and a welding torch 34 are mounted to a lower side of the body 40, such that they are at least radially movable, as indicated by the arrow 42, and preferably also in an up- and down direction, as indicated by arrow 43. Thus the welding grooves and welds can be provided for as desired. The welding tool and the machining tool can be exchangeable, entirely or in part.

For example a grinder and the torch can be exchangeable, such that the same body can be used. Additionally or alternatively they can be placed next to each other on the same body 40.

It will be clear that the design of the rail system 21 and tooling 24 can be designed in many different ways, as will be known to the skilled person.

In a system and method according to the disclosure the tower 3 and/or pile 2 and/or ring 12 can be coated, in a known manner, with a water resistant, especially salt water resistant, coating preventing damage to and especially preventing corrosion of these parts. The coating preferably also is provided covering the or each weld between the ring 12 and the tower 3 and/or pile 2.

The invention 1s by no means limited to the embodiments shown in the drawings, which are shown by way of example only. Many variations thereof are possible within the claims.

For example the connecting ring can be an integral part of the tower or pile, such that it only has to be welded as claimed to the other of the tower and pile. The rail systems can be provided in part or entirely on the pile and/or on the tower, instead of or additional to to the ring. In stead of or additional to using tools supported by rail systems as described tooling can be used in a different manner, for example hand held tools operated by workers on scaffolding, platforms, support vehicles or vessels or the like.

Also rail systems for supporting tools can be provided in different ways, for example mounted to the ring, for example by welding or bolting, or made integral with the ring. The ring can be made using suitable methods, like rolling, casting, forging or the like.

These any many such variants within the scope of the appending claims should as be considered as disclosed in this disclosure.

Claims

Conclusions

CLAIMS 1. A method of fixing a tower for a wind turbine generator to a foundation pile, wherein the tower is provided with a metal connecting ring at a lower end and positioned on an upper end of the foundation pile, after which! - the metal connecting ring is welded to the top end of the foundation pile of either an outer side of the foundation pile or an inner side of the foundation pile, forming a first peripheral weld at a first level; - a groove is formed at the level of the weld of the other of the inside of the foundation pile or the outside of the foundation pile; and - a second peripheral weld is formed in said groove, or in which the foundation pile is provided with a metal connection ring on an upper end and the tower is positioned on an upper end of the foundation pile, after which: - the metal connection ring is welded to the lower end of the tower of one of an outer side of the tower or an inner side of the tower, forming a first peripheral weld at a first level; - one groove is formed at the level of the weld of the other of the inside of the tower or the outside of the tower; and - a second peripheral weld is formed in said groove.

The method of claim 1, wherein the groove is formed so that at least a portion of the first weld is removed, the second weld being formed against the remaining portion of the first weld.

The method of claim 1 or 2, wherein the first weld is formed to extend substantially through the full thickness of at least one of the connecting ring and the top end of the foundation pile.

A method according to any one of the preceding claims, wherein the connecting ring is provided with a supporting portion such that the supporting portion extends at least partially adjacent an inner or outer surface of the top end of the foundation pile, on a side opposite to the side from which the first weld must be welded.

The method of claim 4, wherein the support portion forms a support for forming the first weld.

6. Method as claimed in claim 4 or 5, wherein the foundation pile is provided with at least one support, the supporting part of the connecting ring being supported by the at least one support at least during the formation of the first weld.

A method according to any one of claims 4-6, wherein the support portion is connected to the at least one support at least during the formation of the first weld, preferably by a bolt or clamp connection.

A method according to any one of the preceding claims, wherein the groove is formed extending through the connecting ring, in particular by a supporting portion thereof.

A method according to any one of the preceding claims, wherein a welding machine is supported on a rail system provided by the connecting ring, during welding of the first weld and/or the second weld.

A method according to any one of the preceding claims, wherein a groove forming device is supported on a rail system provided by the connecting ring during groove formation.

A method according to any one of claims 1 - 10, wherein the connecting ring is welded to the tower on shore and the connecting ring is welded to the foundation pile offshore.

A method according to any one of the preceding claims, wherein the method is performed for securing a tower to a pile offshore.

13. Connecting ring for securing a tower to a foundation pile, the connecting ring being made of a weldable metal and comprising at a first longitudinal end a first connection adapted to connect the connecting ring to one end of a tower and to a second longitudinal end longitudinally opposite the first longitudinal end comprises a second connecting device for connecting the connecting ring to a metal foundation pile, the second connecting device comprising at least one welding surface for welding the connecting ring to the foundation pile, the second longitudinal further provided at the end is a supporting portion which extends in longitudinal direction beyond the welding surface.

14. Connecting ring according to claim 13, wherein the connecting ring 1 is provided with radially extending support rails.

Connecting ring according to claim 13 or 14, wherein the connecting ring has a cylindrical shape, preferably symmetrical about a longitudinal axis.

A connecting ring according to any one of claims 13-15, wherein the at least one welding surface extends at an angle to a longitudinal axis of the connecting ring.

A connecting ring according to any one of claims 13-16, wherein the first connecting device is directly longitudinally opposite the weld surface

1 is provided, with the supporting portion extending to one side of the welding surface.

A wind turbine generator tower provided at a lower end of a connecting ring according to any one of claims 13-17.

A wind turbine generator tower according to claim 18, wherein the tower has a cylindrical inner surface and a cylindrical outer surface at the lower end of the tower, the supporting portion extending outside a cylinder defined by the outer surface or within a cylinder defined by the inner surface, such that when the connecting ring is placed on a foundation pile having substantially the same inner and outer dimensions as the tower, the supporting portion bears against an inner surface of the foundation pile or against an outer surface of the foundation pile.

20. Wind turbine generator comprising a tower mounted on a foundation pile, wherein a fastening connecting ring is provided between the tower and the foundation pile, the fastening connecting ring being welded to the foundation pile and the tower.

A wind turbine generator according to claim 20, wherein the connecting ring is according to any one of claims 13-17.

A wind turbine generator according to claim 20 or 21, wherein between the connecting ring and the foundation pile a first peripheral weld is provided between a first from the inside and the outside and a second second weld is provided from the other from the inside and the outside, wherein the second weld is welded to the first weld 1s.

A wind turbine generator according to any one of claims 20-22, wherein a groove extends through the support portion after welding of the first and second welds.