GB2521922A

GB2521922A - Mounting arrangement for offshore structure

Info

Publication number: GB2521922A
Application number: GB1420299.8A
Authority: GB
Inventors: Gregory Van Hinsbergh
Original assignee: Tekmar Energy Ltd
Current assignee: Tekmar Energy Ltd
Priority date: 2013-11-15
Filing date: 2014-11-14
Publication date: 2015-07-08
Also published as: GB201420299D0; GB201320251D0

Abstract

A mounting combination for mounting a longitudinally extensive protection apparatus 200 to an offshore structure is disclosed. The mounting combination comprises: a first combination part 136 to which an upper end portion of the a longitudinally extensive protection apparatus 200 is securable in use and a second combination part 128 securable in use to the offshore structure 520, first and second combination parts 136, 128 each including a complementary spherical surface 130, wherein the spherical surface 130 of the first combination part 136 rests in use on the spherical surface of the second combination part 128 such that the first combination part 136 is supported by the second combination part 128, the spherical surface 130 of the second combination part 128 contains an aperture 142 configured to allow passage therethrough of the longitudinally extensive protection apparatus 200, and wherein the mounting combination can in use accommodate angular movement of the a longitudinally extensive protection apparatus by relative movement of one spherical surface with respect to the other.

Description

P212619GB1 Mounting Arrangement for Offshore Structure [0001] This invention relates to apparatus and method for mounting a longitudinally extensive protection apparatus, which can contain a longitudinally extensive service member, to a location on an offshore structure. The longitudinally extensive service member can be permitted to move laterally and/or rotationally.

BRIEF SUMMARY OF THE DISCLOSURE

[0002] In accordance with the present invention there is provided a mounting combination for mounting a longitudinally extensive protection apparatus to an offshore structure, the mounting combination comprising: a first combination part to which an upper end portion of the a longitudinally extensive protection apparatus is securable in use and a second combination part securable in use to the offshore structure, first and second combination parts each including a complementary spherical surface, wherein the spherical surface of the first combination part rests in use on the spherical surface of the second combination part such that the first combination part is supported by the second combination pad, the spherical surface of the second combination part contains an aperture configured to allow passage therethrough of the longitudinally extensive protection apparatus, and wherein the mounting combination can in use accommodate angular movement of the longitudinally extensive protection apparatus by relative movement of one spherical surface with respect to the other.

[0003] In some preferred embodiments the mounting combination can in use accommodate angular movement of the longitudinally extensive protection apparatus by movement of the spherical surface of the first combination part on the spherical surface of the second combination part. The spherical surface of the second combination part can remain stationary. The second combination part can preferably be fixedly secured to the offshore structure.

[0004] In some preferred embodiments the spherical surface of the first combination part can be a spherically convex outer surface and the spherical surface of the second combination part can be a spherically concave outer surface.

[0005] In some preferred embodiments the first combination part can include a lower portion including said spherical surface and defining a central aperture, a collar upstanding from the margin of the aperture and configured to receive therein a leading end of the P212619GB1 longitudinally extensive protection apparatus. The collar can be substantially cylindrical.

In particular, the collar can define a substantially cylindrical inner surface [0006] In some preferred embodiments the mounting combination can further comprise a cooperating locking or latching formation configured to cooperate with a complementary locking or latching formation arranged at a leading end of the longitudinally extensive protection apparatus for retaining the longitudinally extensive protection apparatus in fixed relation to the collar in use. Said locking or latching formation of the mounting combination can be disposed within said collar.

[0007] In some preferred embodiments the first combination part can include a lower portion including said spherical surface and defining a central aperture, a collar upstanding from the margin of the aperture and a cooperating locking or latching formation configured to cooperate with a complementary locking or latching formation arranged at a leading end of the longitudinally extensive protection apparatus for retaining the longitudinally extensive protection apparatus in fixed relation to the collar in use.

[0008] According to a second aspect of the present invention there is provided a mounting assembly comprising a mounting combination defined in the first aspect of the invention and a longitudinally extensive protection apparatus having a leading end portion thereof secured to the first combination part. Said leading end portion can pass through the aperture of the second combination part.

[0009] In some preferred embodiments the first combination part can include a lower portion including said spherical surface and defining a central aperture and a collar upstanding from the margin of the aperture and wherein a leading end of the longitudinally extensive protection apparatus is received in said collar through said central aperture.

[0010] In some preferred embodiments the mounting assembly can further comprise a cooperating locking or latching formation which cooperates with a complementary locking or latching formation arranged at a leading end of the longitudinally extensive protection apparatus to retain the longitudinally extensive protection apparatus in fixed relation to the collar. The leading end of the longitudinally extensive protection apparatus can thus be fixedly retained within the collar.

[0011] In some preferred embodiments the longitudinally extensive protection apparatus can be suspended from the first combination part.

[0012] In some preferred embodiments the longitudinally extensive protection apparatus can be a longitudinally extensive flexible pipe or tube.

[0013] In some preferred embodiments the longitudinally extensive protection apparatus can comprise or consist of a polymeric material.

P212619GB1 [0014] In some preferred embodiments the mounting assembly can further comprise a longitudinally extensive service member arranged within the longitudinally extensive protection apparatus.

[0015] In some preferred embodiments the longitudinally extensive service member can comprise one or more cables for the transmission of electricity and/or information.

[0016] In some preferred embodiments the longitudinally extensive service member can extend upwardly of the first combination part.

[0017] In some preferred embodiments the leading end portion of said longitudinally extensive protection apparatus can be retained within an annular interface component and wherein the annular interface component comprises on an external face thereof a cooperating locking or latching formation configured to cooperate with the complementary locking or latching formation of the collar of the first combination part to retain the longitudinally extensive protection apparatus in fixed relation to the collar in use.

[0018] In some preferred embodiments the mounting assembly can further comprise a pulling head attached to the leading end portion of the longitudinally extensive protection apparatus and configured for pulling of the longitudinally extensive protection apparatus upwardly into the first combination part.

[0019] In some preferred embodiments the pulling head can extend forwardly of the leading end of the longitudinally extensive protection apparatus and comprises a sealed chamber in which are disposed pre-terminated ends of one or more cables of a longitudinally extensive service member.

[0020] According to a third aspect of the present invention there is provided an offshore structure including a mounting combination as defined in the first aspect of the invention, the offshore structure having a supporting surface on which the second combination part is mounted, said surface including an aperture configured for passage of a longitudinally extensive protection apparatus and arranged in alignment with the aperture of said second combination part.

[0021] According to a fourth aspect of the present invention there is provided an offshore structure including a mounting assembly as defined in the second aspect of the invention, the offshore structure having a supporting surface on which the second combination part is mounted, said surface including an aperture through which the longitudinally extensive protection apparatus passes and arranged in alignment with the aperture of said second combination part, the longitudinally extensive protection apparatus extending downwardly from said mounting combination towards the seabed.

P212619GB1 [0022] In some preferred embodiments the offshore structure can be maintained in substantially fixed positional relation to the seabed.

[0023] In some preferred embodiments said offshore structure can be fixedly mounted to the seabed.

[0024] In some preferred embodiments said offshore structures can be a floating structure.

[0025] In some preferred embodiments said supporting surface can be arranged above the sea surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 is a partially cut-away view of a mounting assembly according to embodiments of the present invention including a pulling head; Figure 2 is a section along the line A-A of Figure 1; Figure 3 shows in more detail a portion of the mounting assembly according to embodiments of Figure 1 in a first configuration; Figure 4 shows in more detail a portion of the mounting assembly of Figure 1 in a second configuration; Figure 5 shows a general view of an offshore apparatus including a mounting assembly according to embodiments of the present invention; and Figure 6 illustrates a spherical cap formed from a sphere.

DETAILED DESCRIPTION

[0027] Referring now to the drawings, a mounting assembly 100 is shown with a longitudinally extensive protection apparatus 200 and a pulling (or pull-in) head 300.

[0028] Longitudinally extensive protection apparatus 200 can serve to protect a longitudinally extensive service member 400 arranged within the longitudinally extensive protection apparatus 200. In a typical arrangement the longitudinally extensive service member 400 can approach an offshore structure 500 along the seabed 10. In some useful arrangements the longitudinally extensive service member 400 can be buried beneath the seabed 10 for its protection.

[0029] The longitudinally extensive service member is required to ascend at the location of the offshore structure 500 from the seabed 10 to a location on the offshore structure 500, such as a platform level 520, above the water surface 20 at which it can terminate. The P212619GB1 longitudinally extensive service member 400 can be connected or coupled to such apparatus or equipment arranged on the offshore structure 500 as may be required.

[0030] For the ascent of the longitudinally extensive service member 400 from the seabed to its end location at a relatively upper part of the offshore structure 500, such as platform level 520, the longitudinally extensive service member 400 can be protected for example, from damage caused by contact with other objects and/or adverse environmental conditions, by means of a longitudinally extensive protection apparatus 200. The longitudinally extensive protection apparatus can be mounted to a foundation part 510 of the offshore structure. The foundation part 510 can extend from the seabed 10 to a location above the water surface 20. In other constructions, the foundation 510 can be a floating foundation which can extend from below the water surface to a location above the water surface 20.

[0031] In co-pending applications the applicant proposes that the longitudinally extensive protection apparatus can be in the form of a longitudinally extensive flexible pipe or tube.

Such a flexible pipe or tube can have significant advantages as compared with a conventional arrangement in which a longitudinally extensive service member is contained in an I-tube or J-tube for its ascent from the seabed. For comparison or reference only, a J-tube is indicated at "J" in Figure 5. Accordingly, embodiments of the present invention provide that the longitudinally extensive protection apparatus is a longitudinally extensive flexible pipe or tube. The longitudinally extensive service member can be contained for its protection within the flexible pipe or tube. In some preferred embodiments, the longitudinally extensive flexible pipe or tube can be formed from a polymeric material such as polyethylene, in particular high density polyethylene (HDPE).

[0032] In some embodiments, the longitudinally extensive service member 400 can comprise one or more cables. The one or more cables can include cable for the transmission of electricity and/or cable for the transmission of information or data such as fibre optic cable.

[0033] In one example the offshore structure can be a wind turbine generator (WTG) and its associated foundation, or a structure required for a group of VVTGs such as a substation or collection station and associated foundation. In such arrangements the one or more cables of the longitudinally extensive service member can, for example, be for the transmission of electricity generated by the WTG or for the transmission to or from the WTG of signals or data required for monitoring or control of the operation of the WTG or associated apparatus or equipment.

[0034] In other examples the offshore structure can be a structure associated with the offshore oil and gas extraction industries such as an oil or gas rig. In these cases, the P212619GB1 longitudinally extensive service member 400 can also be a cable, such as for the transmission or data or information or electricity. In other embodiments the longitudinally extensive service member can be a pipe for the transmission of fluids associated with oil and gas extraction, such as water or production fluids, including oil, gas and downhole fluids.

[0035] At some times, such as during the installation of the longitudinally extensive protection apparatus and/or installation of the longitudinally extensive service member within the longitudinally extensive protection apparatus, it can be necessary to suspend the longitudinally extensive protection apparatus, or a portion thereof from the offshore structure, such as from platform level 520, without fixedly or permanently attaching the longitudinally extensive protection apparatus to the foundation 510, or prior to such attachment. In such cases, it can be necessary to suspend the longitudinally extensive protection apparatus from a suitable suspension apparatus arranged on the offshore structure 510, such as at a platform level 520. In such circumstances the suspension apparatus must be strong enough to bear the weight of the longitudinally extensive service member.

[0036] The portion of the longitudinally extensive protection apparatus below the suspension apparatus while suspended is free to move. Such movement can include lateral movement (so, that, for example the longitudinally extensive protection apparatus moves away from a vertical alignment), bending and twisting in response to torsional loads. Embodiments of the present invention seek to provide a suspension or mounting arrangement which can accommodate such movement of the longitudinally extensive protection apparatus.

[0037] A mounting combination 120 according to embodiments of the present invention can comprise a first combination part 122 and a second combination part 124. Second combination component 124 is fixedly located on a supporting part of the offshore structure such as a platform level 520. Second combination part 124 includes a through aperture 126 through which a leading end portion 220 of the longitudinally extensive protection apparatus can pass. Aperture 126 is sized and configured to have a greater width or diameter than the width or diameter of the leading end 220 of the longitudinally extensive protection apparatus 200, such that movement of the longitudinally extensive protection apparatus 200 can be accommodated. That is, the aperture can be configured so that the margin of the aperture 126 does not unnecessarily restrict lateral movement of the longitudinally extensive protection apparatus. Displacement of the longitudinally extensive protection apparatus 200 from a substantially vertical configuration by such lateral movement can be seen from the orientation of the longitudinally extensive protection P212619GB1 apparatus in Figure 4, as compared with the nominally vertical orientation thereof in Figure 3.

[0038] Second combination part 124 can include a body portion 128 having a generally planar underside which can rest on the platform level 520. Second combination part 124 can be secured to the platform level 520 by any suitable means, as required. Body portion 128 can define an upper spherical surface 130, that is, an upper surface which is shaped as a portion of the surface of a sphere. In some preferred embodiments the circumference of the said upper surface can be circular such that (with the exception of the aperture 126) the surface 130 forms the spherical surface part of a spherical cap. With reference to Figure 6, a spherical cap 610 can be defined as a portion of a sphere 600 cut off by a plane 620. In some preferred embodiments the height h and radius p of the spherical cap are less than the radius r of the sphere. In some preferred arrangements, radius r of the sphere can be about 5 to 20 times greater than height ii of the spherical cap, such as about 10 times greater.

[0039] First combination part 122 can comprise a body portion 132 having a lower portion 134 and a collar 136. Lower portion 134 can define an aperture 140 from which collar 136 can extend upwardly to define a through passageway 142. Passageway 142 is, in some preferred embodiments, substantially cylindrical. Lower portion 134 can also define a lower spherical surface 138, that is, a lower surface which is shaped as a portion of the surface of a sphere. In some preferred embodiments the circumference of the said lower surface can be circular such that (with the exception of the aperture 140) the lower surface 138 forms the spherical surface part of a spherical cap.

[0040] The spherical surfaces 138, 130 of the first and second combination parts 122, 124 can be complementary such that juxtaposed portions of the respective surfaces can sit in full contact. The complementary spherical surfaces 130, 138 can be formed from spheres of nominally the same radius.

[0041] Through passageway 142 of collar 136 can be sized to accommodate the leading end 220 of the longitudinally extensive protection apparatus 200 within the passageway.

[0042] In some preferred embodiments the leading end 220 of the longitudinally extensive protection apparatus has mounted thereon an annular interface component 144. The interface component 144 can be secured to the leading end 220 by suitable means such as bonding with adhesive, moulding, fusing or the like. Thus in preferred embodiments, annular interface component 144 can include an internal passageway which is sized and shaped to conform to the external profile of leading end 220 of longitudinally extensive protection apparatus 200 on which it is mounted.

P212619GB1 [0043] Interface component 144 can have an outer surface which is sized and shaped to conform to the inner surface of passageway 142 of collar 146. Interface component can be substantially annular having substantially cylindrical inner and outer (external) surfaces.

External surface of annular interface component 144 can include an inward taper at its leading (upper) or trailing (lower) ends.

[0044] As will be described further below, leading end 220 of longitudinally extensive protection apparatus 220 can be drawn into the passageway 142 of collar 136 from below.

Leading end 220 and collar 136 can include one or more cooperating locking or latching arrangements which, when the leading end 220 reaches its intended position of use, can automatically adopt a locking or latching configuration which prevents a withdrawal of the leading end 220 in -at least -a downward direction. In this way, the leading end 220 can be retained in fixed relation to the collar 136. In some preferred arrangements, when the longitudinally extensive protection apparatus 220 is in the locked or latched configuration, a leading portion thereof can extend upwardly beyond the uppermost extent of collar 136.

[0045] In particular arrangements, the locking or latching arrangement of the leading end 220 can be located at an outer surface of the annular interface component 144. In some embodiments, an internal wall of the collar 136 which defines the passageway 142 can include an annular groove or recess. Annular interface component can also include an annular groove or recess in its external surface. One of the respective grooves can have arranged therein a locking or latching arrangement in the form of a snap ring which can extend radially out of the groove. Where the snap ring is arranged in a groove of the annular interface component 144, on entry of the annular interface component 144 into the passageway 142 the snap ring can be radially compressed by the wall of the passageway 142 and can expand to enter the groove in the wall of the passageway 142 when the leading end 220 reaches its use position. In some preferred embodiments, where the snap ring is arranged in a groove of the wall of the passageway 142, on entry of the annular interface component 144 into the passageway 142 the snap ring can be radially expanded by the interface component 144 and can contract to enter the groove in the wall of the annular interface component 144 when the leading end 220 reaches its use position.

[0046] Arranged within the longitudinally extensive protection apparatus can be the longitudinally extensive service member 400. Longitudinally extensive service member can, in some embodiments, comprise multiple components, such as a plurality of cables.

In the illustrated example, the longitudinally extensive service member contains at least three cables 402a, 402b, 402c (402c is not visible in the drawings). Each cable 402a,b,c can terminate at its upper end in a pre-terminated cable end 404a,b,c.

P212619GB1 [0047] For movement of the leading end 220 of longitudinally extensive protection apparatus 200 into its desired position in the mounting combination 100, the leading end 220 can be connected to a pulling head 300 (sometimes known as a pull-in head). Pulling head 300 can be connected, by way of an eye 302 or other suitable connecting formation, to a cable or line which is in turn connected to a suitable pulling apparatus such as a crane or winch. The pulling head 300 can thus be used for pulling of the leading end 220 from a location below the platform level 520 in a generally upward direction. Fulling head can pass through aperture 126 of the second combination pad 124 and through the through passageway 142 of the collar 136 of the first combination part 122. At least a major part of the pulling head can emerge upwardly from the passageway 142 before the leading end 220 reaches its final intended position, which can preferably be the locked or latched configuration of the longitudinally extensive protection apparatus 220.

[0048] In some preferred embodiments, pre-terminated cable ends 404a,b,c can be contained within the pulling head 300. Pulling head 300, can in some pieferred embodiments, form a closed or sealed chamber or capsule around the pre-terminated cable ends 404a,b,c. Thus the pre-terminated cable ends 404a,b,c can be maintained in a closed and protected environment until the leading end 220 reaches its position of use.

The pre-terminated cable ends 404a,b,c are thus protected from damage by impact, water penetration or the like before they are in a position to be brought into use.

[0049] The pulling head and/or the longitudinally extensive seivice member 400 can be securely attached to the leading end of the longitudinally extensive protection apparatus and a seal can be formed between the longitudinally extensive service member 400 (such as the one or more cables 402) and/or pulling head 300 and the leading end 220. For example, an adhesive bond may be formed between the respective components. In some embodiments, an annular interface component 222 can be provided between the leading end 220 and the longitudinally extensive service member 400 or the puling head 300. In one or more of these ways a sufficiently strong union can be formed between the leading end 220 of the longitudinally extensive protection apparatus 200 and the pulling head 300 to allow the leading end 220 to be pulled into the mounting combination 100.

[0050] With particular reference to Figures 3 and 4, when the leading end 220 has been received into the passageway 142, so that the locking or latching arrangement adopts its locking or latching configuration, the longitudinally extensive protection apparatus can hang downwardly from the mounting combination 100. In other words, the longitudinally extensive protection apparatus -which can have the longitudinally extensive service member contained therein -can be suspended from the mounting combination 100.

P212619GB1 [0051] In this configuration the longitudinally extensive protection apparatus 200 can be displaced from a substantially vertical configuration such as by action of water currents, or by deliberate movement thereof, such as for securing of the longitudinally extensive protection apparatus to the foundation 510. In another case, a distal end of the longitudinally extensive protection apparatus 200 (i.e. the end remote from the leading end 220) may be moved for the purpose of inserting the longitudinally extensive service member 400 into the longitudinally extensive protection apparatus 200. For example, said distal end may be taken on board an adjacent service vessel. Displacement of the longitudinally extensive protection apparatus 200 along its length to, or near to, the leading end 220 can result. The longitudinally extensive protection apparatus 200 can also experience torsional (twisting) loads resulting in a rotational movement. The mounting apparatus 100 can accommodate such angular (lateral and/or twisting) movements.

[0052] These above angular movements can be accommodated by movement of the spherical surface 138 of the first combination part on the spherical surface 130 of the second combination part. An example of the result of such movement is shown in Figure 4. Because of the respective surfaces 130, 138 are spherical movement in any direction, including rotational movement, can be accommodated. It is noted that if surfaces 130 and 138 are taken as defining respective spherical caps then the maximum diameter of the spherical cap formed by surface 130 is greater than the maximum diameter of the spherical cap formed by surface 138. Since surface 130 is of greater dimension than surface 138, surface 138 has freedom to move on surface 130. In some configurations, movement of surface 138 on surface 130 can be constrained when a side wall 130a extending upwardly from surface 130 comes into contact with a side wall 138a extending downwardly from surface 138 and/or when an external surface of annular interface component 144 contacts a wall of body portion 128 which defines aperture 126.

[0053] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0054] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this P212619GB1 specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.

The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0055] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

CLAIMS1. A mounting combination for mounting a longitudinally extensive protection apparatus to an offshore structure, the mounting combination comprising: a first combination pad to which an upper end portion of the a longitudinally extensive protection apparatus is securable in use and a second combination pad securable in use to the offshore structure, the first and second combination parts each including a complementary spherical surface, wherein the spherical surface of the first combination pad rests in use on the spherical surface of the second combination pad such that the first combination pad is suppoded by the second combination pad, the spherical surface of the second combination part contains an aperture configured to allow passage therethrough of the longitudinally extensive protection apparatus, and wherein the mounting combination can in use accommodate angular movement of the a longitudinally extensive protection apparatus by relative movement of one spherical surface with respect to the other.
2. A mounting combination claimed in claim 2 wherein the spherical surface of the first combination part is a spherically convex outer surface and the spherical surface of the second combination pad is a spherically concave outer surface.
3. A mounting combination as claimed in claim 1 or 2 wherein the first combination pad includes a lower podion including said spherical surface and defining a central aperture, a collar upstanding from the margin of the aperture and configured to receive therein a leading end of the longitudinally extensive protection apparatus
4. A mounting combination as claimed in claim 1, 2 or 3 further comprising a cooperating locking or latching formation configured to cooperate with a complementary locking or latching formation arranged at a leading end of the longitudinally extensive protection apparatus for retaining the longitudinally extensive protection apparatus in fixed relation to the collar in use.
5. A mounting assembly comprising a mounting combination as claimed in claim 1 or 2and a longitudinally extensive protection apparatus having a leading end portion thereof passing through the apedure of the second combination pad and secured to the first combination pad.
6. A mounting assembly as claimed in claim 5 wherein the first combination pad includes a lower podion including said spherical surface and defining a central aperture and a collar upstanding from the margin of the aperture and wherein a leading end of the longitudinally extensive protection apparatus is received in said collar through said central aperture.
7. A mounting assembly as claimed in claim 5 or 6 further comprising a cooperating locking or latching formation which cooperates with a complementary locking or latching formation arranged at a leading end of the longitudinally extensive protection apparatus to retain the longitudinally extensive protection apparatus in fixed relation to the collar.
8. A mounting assembly as claimed in claim 5, 6 or 7 wherein the longitudinally extensive protection apparatus is suspended from the first combination part.
9. A mounting assembly as claimed in any of claims 5 to 8 wherein the longitudinally extensive protection apparatus is a longitudinally extensive flexible pipe or tube.
10. A mounting assembly as claimed in claim 9 wherein the longitudinally extensive protection apparatus comprises or consists of a polymeric material.
11. A mounting assembly as claimed in any of claims 5 to 10 further comprising a longitudinally extensive service member arranged within the longitudinally extensive protection apparatus.
12. A mounting assembly as claimed in claim 7 wherein the longitudinally extensive service member comprises one or more cables for the transmission of electricity and/or information.
13. A mounting assembly as claimed in claim 11 or 12 wherein the longitudinally extensive service member extends upwardly of the first combination part.
14. A mounting assembly as claimed in any of claims 5 to 14 when dependent on claim 4 wherein the leading end portion of said longitudinally extensive protection apparatus is retained within an annular interface component and wherein the annular interface component comprises on an external face thereof a cooperating locking or latching formation configured to cooperate with the complementary locking or latching formation of the collar of the first combination part to retain the longitudinally extensive protection apparatus in fixed relation to the collar in use.
15. A mounting assembly as claimed in any of claims 5 to 14 further comprising a puling head attached to a the leading end portion of the longitudinally extensive protection apparatus and configured for pulling of the longitudinally extensive protection apparatus upwardly into the first combination part.
16. A mounting assembly as claimed in claim 15 wherein the pulling head extends forwardly of the leading end of the longitudinally extensive protection apparatus and comprises a sealed chamber in which are disposed pre-terminated ends of one or more cables of a longitudinally extensive service member.
17. An offshore structure including a mounting combination as claimed in claim 1,2, 3 or 4, the offshore structure having a supporting surface on which the second combination part is mounted, said surface including an aperture configured for passage of a longitudinally extensive protection apparatus and arranged in alignment with the aperture of said second combination part.
18. An offshore structure including a mounting assembly as claimed in any of claims 5 to 16 the offshore structure having a supporting surface on which the second combination part is mounted, said surface including an aperture through which the longitudinally extensive protection apparatus passes and arranged in alignment with the aperture of said second combination part, the a longitudinally extensive protection apparatus extending downwardly from said mounting combination towards the seabed.
19. An offshore structure as claimed in claim 17 or 18 wherein the offshore structure is maintained in substantially fixed positional relation to the seabed.
20. An offshore structure as claimed in claim 19 wherein said offshore structure is fixedly mounted to the seabed.
21. An offshore structure as claimed in claim 19 wherein said offshore structure is a floating structure.
22. An offshore structure as claimed in any of claims 17 to 20 wherein said supporting surface is arranged above the sea surface.
23. A mounting combination or a mounting assembly substantially as hereinbefore described with reference to any of Figures ito 4.