Key information

Title
A method and apparatus for protecting subsea structures
Application number
20230629
Case type
National
Status
03.03.2025 Patent meddelt (B1)
Filed
02.06.2023
Effective date
02.06.2023
Publicly available
03.12.2024
Next annual fee due
30.06.2027
Applicant
Subsea 7 Norway AS (NO)
Owner
Subsea 7 Norway AS (NO)
Inventor
Christian Linde Olsen (NO) et al.
Agent
BRYN AARFLOT AS (NO)
Granted
03.03.2025
Patent number
348526
Expiry date
02.06.2043

Abstract and drawing

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.
An elongate subsea element, such as a pipeline, is covered by a series of cover units that each comprise a rigid shell arranged to bridge over the element and inner mudmats that are movable relative to side walls of the shell. When one of the cover units is suspended in water or in air, the inner mudmats are moved relative to the shell from a stowed configuration into a deployed configuration in which the inner mudmats extend inwardly toward each other from the side walls. The cover unit is then landed on the seabed over the element with the element disposed between the side walls and the inner mudmats.

Publications

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Documents

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Date
 Date Doc. No. Process Case number In/Out Journal description To/from
 02.05.2025 11-01 Saksbehandling 20230629(348526) UT PT Varsel om betaling av første årsavgift (3317) (PT20230629) BRYN AARFLOT AS
 06.03.2025 10-01 Saksbehandling 20230629(348526) UT PT Registreringsbrev nasjonal patent (15) (PT20230629)
25.11.2024 09-01 Saksbehandling 20230629 UT Intention to grant BRYN AARFLOT AS
 20.11.2024 08-03 Saksbehandling 20230629 INN 143275NO_ Claims NO_143275NO BRYN AARFLOT AS
 20.11.2024 08-02 Saksbehandling 20230629 INN 143275NO Response NIPO_22 November 2024 BRYN AARFLOT AS
 20.11.2024 08-01 Saksbehandling 20230629 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 22.10.2024 07-01 Saksbehandling 20230629 UT Substantive examination BRYN AARFLOT AS
 19.06.2024 06-06 Saksbehandling 20230629 INN Response NIPO BRYN AARFLOT AS
 19.06.2024 06-05 Saksbehandling 20230629 INN P73518NO - Amended description pg1-5a_clean BRYN AARFLOT AS
 19.06.2024 06-04 Saksbehandling 20230629 INN P73518NO - Amended description pg1-5_tracked_143275NO BRYN AARFLOT AS
 19.06.2024 06-03 Saksbehandling 20230629 INN P73518NO - Amended claims - tracked_143275NO BRYN AARFLOT AS
 19.06.2024 06-02 Saksbehandling 20230629 INN P73518NO - Amended claims - clean BRYN AARFLOT AS
 19.06.2024 06-01 Saksbehandling 20230629 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 19.12.2023 05-02 Saksbehandling 20230629 UT PT report 01:46:44
19.12.2023 05-01 Saksbehandling 20230629 UT 20230629_1793333_PT 08 Eng BRYN AARFLOT AS
 13.06.2023 04-03 Saksbehandling 20230629 INN Norway Declaration signed BRYN AARFLOT AS
 13.06.2023 04-02 Saksbehandling 20230629 INN General power of attorney signed BRYN AARFLOT AS
 13.06.2023 04-01 Saksbehandling 20230629 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 02.06.2023 03-01 Saksbehandling 20230629 UT Formal Examination 1 BRYN AARFLOT AS
 02.06.2023 02-01 Saksbehandling 20230629 UT Informasjon til oppfinner Christian Linde Olsen
 02.06.2023 01-05 Saksbehandling 20230629 INN P73518GB Drawings BRYN AARFLOT AS
 02.06.2023 01-04 Saksbehandling 20230629 INN P73518GB Description BRYN AARFLOT AS
 02.06.2023 01-03 Saksbehandling 20230629 INN P73518GB Claims BRYN AARFLOT AS
 02.06.2023 01-02 Saksbehandling 20230629 INN P73518GB Abstract BRYN AARFLOT AS
 02.06.2023 01-01 Saksbehandling 20230629 INN Søknadsskjema Patent BRYN AARFLOT AS

Description, claims and drawings

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content. Description
This invention relates to the mechanical protection of subsea structures, in particular elongate elements laid on the seabed. Examples of such elements are rigid or flexible pipelines, spools, umbilicals and cables as used in the subsea oil and gas industry and in the offshore renewable energy industry.When laid on the seabed, especially in shallow seas, elongate subsea elements such as pipelines, spools, umbilicals and cables may require protection against damage from dropped objects or overtrawling. In shallow seas, lightweight elongate elements are also susceptible to movement across the seabed due to sea movement, particularly during exceptional storms or under rapid tidal flow.In the context of the invention, 'shallow' means that the seabed is close enough to the surface as to be influenced, at least occasionally, by near-surface sea motions such as wind-driven movement. For illustration but without limitation, depths of up to, say, 90 to 100 metres may therefore be considered shallow in some sea areas. The North Sea is an example of shallow water of particular relevance to the subsea oil and gas industry, whose seabed is also characterised by very soft clay.Conventional subsea protection solutions include burying an elongate element in a trench or placing concrete mattresses or dumping a berm of crushed graded rock fragments over an element previously laid on the seabed. These solutions anchor the element to the seabed and particularly resist lateral movement of the element, hence stabilising the element in addition to protecting it.Whilst it is desirable to limit or control movement of an elongate element across the seabed, a lack of compliance is disadvantageous where the element needs some freedom of movement. A prime example is where the element carries hot or cold fluids in use and so has to handle the expansion and contraction of thermal cycling. In these circumstances, a rigidly-constrained element would impart enormous loads to tie-in support structures and could itself buckle under such loads. Also, sliding movement of an elongate element relative to the rocks of a surrounding static berm could damage a protective or insulative sleeve or coating of the element. This could lead to corrosion of the element or undermine thermal insulation of hot or cold fluids that the element carries in use. Where an elongate element is likely to move considerably in service due to thermal fluctuations or sea movement, it is preferred to protect the element with a cover system that maintains a clearance gap around the element. The cover system bears against the seabed on opposite sides of the element and bridges over the element to protect it from damage. The clearance gap allows the element to move relative to the cover system and the seabed, and to do so without suffering damage from contact with a rock berm. Yet, to stabilise the element, lateral movement of the element is limited by the sides of the cover system so that excessive lateral movement is prevented.Typical pipeline cover systems comprise a rigid upper shell that sits on the seabed to cover the top and surround the sides of a pipeline, for example as shown in KR 10-1444171. Such cover systems usually comprise multiple cover units that can be connected to each other in series as an assembly to define a cover system of any desired length. The cover units may be made of steel, concrete or, most commonly, of a reinforced polymer composite such as GRP (glass-reinforced plastics) or other fibrereinforced plastics. Where cover units are of a lightweight polymeric material such as GRP, rock dumping may be used after their installation on the seabed to stabilise them against sliding or overturning and to add further protection.To increase the capacity of the seabed soil to support a cover system including any dumped rock, rock gravel may be pre-laid on the seabed around the pipeline path before installing the cover units on top of the gravel-reinforced soil. Also, for use on soft soils, wing-like mudmats may be added outside the shell of a cover unit, potentially with other structural features such as those shown in US 8702347, NO 341517 or WO 2016/188923. In another approach disclosed in WO 2022/221422, guillotine-like blades can be deployed downwardly from peripheral skirts of mudmats to engage the seabed soil. More conventionally, especially where cover units are of lightweight materials such as GRP, an advantage of external mudmats is the possibility to dump rock on top of the mudmats to increase the stability of the cover system.Further to explain the prior art, reference is now made to Figures 1 to 4 of the accompanying drawings. Figure 1 shows a cover system 10 comprising two cover units 12 of moulded GRP that are used together to protect an elongate subsea element, exemplified here by a subsea pipeline 14 shown lying on the seabed 16 after pre-installation.Each cover unit 12 comprises an open-ended arched shell 18 that defines a hollow interior dimensioned to provide clearance all around the pipeline 14 within. In this example, the shell 18 is defined by upwardly-convergent side walls 20 joined by a top wall 22. In other examples, the shell 18 could have a continuously-curved arch section. The shell 18 has lifting points 24 mounted on each side wall 20.The cover units 12 are identical so as to fit together with adjoining cover units 12 in successively overlapping relation to form a longitudinal series along the path of the pipeline 14. Thus, once the cover units 12 are installed to form the cover system 10, the hollow interiors of their successive bodies 18 conjoin as a long open-ended tube to form a continuous elongate part-cylindrical tunnel extending across the seabed 16 around and along the pipeline 14.The shell 18 of each cover unit 12 is flanked to both sides by integral outer mudmats 26 that extend outwardly from the base of respective side walls 20. The outer mudmats 26 are flat, flange-like lateral projections that extend in a common horizontal plane to lie flat upon the seabed 16, in the manner of feet, upon installation of the cover units 12. Ballast weights 28 are disposed on top of the outer mudmats 26.The outer mudmats 26 of the cover units 12 serve as footings to support the cover system 10 on a soft seabed 16. They also facilitate stabilisation of the cover system 10 by rock-dumping. In this respect, Figure 2 shows berms of crushed rock 30 dumped along both sides of the cover system 10. Consequently, the outer mudmats 26 extending outwardly from the bodies 20 of the units 12 are sandwiched between the rock 30 and the seabed 16. The weight of the rock 30 therefore presses the outer mudmats 26 against the seabed 16 and so stabilises the cover system 10 against movement relative to the seabed 16.For ease of illustration, the pipeline 14 and hence the cover system 18 are shown as being straight in Figures 1 and 2 but they could instead be curved in plan view, that curvature being accommodated by articulation between adjoining overlapping cover units 12. Figure 3 shows a stack 32 of the cover units 12 to exemplify how each cover unit 12 is stackable with like cover units 12 for compactness of storage and for ease of transportation together. For this purpose, the upwardly-convex outer side of the shell 18 of a lower unit 12 of the stack 32 can be received as a complementary fit within the downwardly-concave inner side of the shell 18 of an upper unit 12 of the stack 32. Indeed, conveniently, a stack 32 of the cover units 12 can be lowered to the seabed 16 before being lifted one-by-one from the stack 32 as the cover system 10 is assembled underwater from those cover units 12 over a pre-installed pipeline 14 or other elongate element.Where cover units 12 are used on very soft soils, the size of their outer mudmats 26 may have to be increased to the extent that the cover units 12 become difficult to transport and handle offshore. The alternative of dumping more rock 30 is expensive and could even be counterproductive if the resulting weight bearing down on the outer mudmats 26 exceeds the bearing capacity of the soil of the seabed 16 beneath. There is a need to improve the stability of a pipeline cover system 10 without over-reliance upon dumping rock 30.Thus, Figure 4 shows a variant of the cover system 10 shown in Figures 1 and 2 in which the cover units 12 further include integral inner mudmats 34 that extend inwardly from the base of respective side walls 20, parallel to or coplanar with the outer mudmats 26. Like the outer mudmats 26, the inner mudmats 34 are flat, flange-like projections that extend in a common horizontal plane to lie flat upon the seabed 16upon installation of the cover units 12.Inner mudmats 34 may particularly be required where the seabed 16 comprises very soft clay. In that respect, the critical design issue is that stabilising the system 10 against overtrawling could require so much rock 30 to be dumped on the outer mudmats 26 that there is a risk of bearing failure due to the weight of the rock 30. Increasing the size and hence the bearing area of the outer mudmats 26 will not help because the weight of rock 30 on top of the outer mudmats 26 will then increase commensurately.In contrast, the inner mudmats 34 increase the bearing area without a commensurate increase in weight as they do not support any rock 30. In this respect, it will be noted that as the inner mudmats 34 are disposed within the shell 18 of the unit 12, they are separated by the side walls 20 from the rocks 30 dumped on top of the outer mudmats 26.The presence of inner mudmats 34 creates a problem, however, which is that they preclude compact nested stacking of cover units 12 in the manner shown in Figure 3. Specifically, the inner mudmats 34 prevent the downwardly-concave inner side of the shell 18 receiving the upwardly-convex outer side of the shell 18 of the underlying cover unit 12 in a stack. The inability to stack them increases the cost and reduces the practicality of storing, transporting and installing the cover units 12. For example, there is no possibility of lowering a stack of the cover units 12 to the seabed 16 to be lifted from the stack in turn as a cover system 10 is assembled underwater.Additional examples of disclosures that contribute to the state of the art include GB 2410758, US 4329084 and NO 20150337.Against this background, the invention resides in a cover unit for covering an elongate subsea element. The unit comprises a rigid shell having side walls in mutual opposition and inner mudmats that are movable, for example pivotable, relative to the side walls from a stowed configuration into a deployed configuration. In the deployed configuration, the inner mudmats extend inwardly from the side walls. Conversely, in the stowed configuration, the inner mudmats lie outside a chamber defined between the side walls and may splay apart downwardly.The unit may further comprise outer mudmats that extend outwardly from the side walls. In that case, when in the deployed configuration, the inner mudmats can be coplanar with or parallel to the outer mudmats.The outer mudmats may be movable with the inner mudmats with respect to the side walls. For example, the inner and outer mudmats may be pivotable in mutual opposition about pivot axes that lie between them and that extend parallel to the respective side walls. In that case, when the inner mudmats are in the stowed configuration, the outer mudmats can lie against the side walls. Latches can then act between the outer mudmats and the side walls to hold the inner mudmats in the stowed configuration. Each inner mudmat may be part of a plate that further comprises at least one wing that is opposed to the inner mudmat and that extends through the shell. When the inner mudmats are in the stowed configuration, the wings can lie against the side walls and
Claims
Claims1. A cover unit (12) for covering an elongate subsea element (14), the unit (12) comprising a rigid shell (18) having side walls (20) in mutual opposition and inner mudmats (34), characterised in that the inner mudmates (34) are movable relative to the side walls (20) from a stowed configuration into a deployed configuration in which the inner mudmats (34) extend inwardly from the side walls (20).2. The unit (12) of Claim 1 wherein, in the stowed configuration, the inner mudmats (34) lie outside a chamber defined between the side walls (20).3. The unit (12) of Claim 1 or Claim 2 wherein, in the stowed configuration, the inner mudmats (34) splay apart downwardly.4. The unit (12) of any preceding claim, wherein the inner mudmats (34) are pivotable with respect to the side walls (20).5. The unit (12) of any preceding claim, further comprising outer mudmats (26) that extend outwardly from the side walls (20).6. The unit (12) of Claim 5, wherein in the deployed configuration, the inner mudmats (34) are coplanar with or parallel to the outer mudmats (26).7. The unit (12) of Claim 5 or Claim 6, wherein the outer mudmats (26) are movable with the inner mudmats (34) with respect to the side walls (20).8. The unit (12) of Claim 8, wherein the inner and outer mudmats (34, 26) are pivotable in mutual opposition about pivot axes (44) that lie between them and that extend parallel to the respective side walls (20).9. The unit (12) of Claim 8, wherein when the inner mudmats (34) are in the stowed configuration, the outer mudmats (26) lie against the side walls (20).10. The unit (12) of Claim 9, further comprising latches (48) acting between the outer mudmats (26) and the side walls (20) to hold the inner mudmats (34) in the stowed configuration.11. The unit (12) of any of Claims 1 to 6, wherein each inner mudmat (34) is part of a plate that further comprises at least one wing (40) that is opposed to the inner mudmat (34) and that extends through the shell (18).12. The unit (12) of Claim 11, wherein when the inner mudmats (34) are in the stowed configuration, the wings (40) lie against the side walls (20).13. The unit (12) of Claim 12, further comprising latches (48) acting between the wings (40) and the side walls (20) to hold the inner mudmats (34) in the stowed configuration.14. The unit (12) of any of Claims 11 to 13, wherein the wings (40) are movable away from the side walls (20) in response to movement of the inner mudmats (34) from the stowed configuration into the deployed configuration.15. The unit (12) of Claim 14, wherein when the inner mudmats (34) are in the deployed configuration, the wings (40) lie on top of outer mudmats (26) that are fixed integrally to the side walls (20).16. The unit (12) of any preceding claim, wherein when the inner mudmats (34) are in the stowed configuration, the shell (18) of the unit (12) is nestable with a shell (18) of a like unit (12) disposed above or below in a stack (32).17. The unit (12) of Claim 16, wherein when in the stowed configuration, the inner mudmats (34) lie outside a width of the shell (18) as measured between bottom edges of the side walls (20).18. The unit (12) of Claim 17, wherein when in the deployed configuration, spacing between the inner mudmats (34) is less than the width of the shell (18) as measured between the bottom edges of the side walls (20).19. The unit (12) of any of Claims 16 to 18, wherein when in the stowed configuration, the inner mudmats (34) lie outside a width of a top wall (22) of the shell (18) that joins the side walls (20).20. The unit (12) of Claim 19, wherein when in the deployed configuration, spacing between the inner mudmats (34) is less than the width of the top wall (22) of the shell (18).21. The unit (12) of any preceding claim when installed on a seabed (16) with the inner mudmats (34) in the deployed configuration lying parallel to the seabed (16).22. The unit (12) of Claim 21 when dependent on Claim 5 or Claim 6, further comprising ballast (30) deposited on the outer mudmats (26).23. The unit (12) of Claim 21 when dependent on Claim 15, further comprising ballast (30) deposited on the wings (40) and sandwiching the wings (40) between the ballast (30) and the outer mudmats (26).24. A stack (32) of the units (12) of any of Claims 1 to 20 with their shells (18) in nested relation.25. A method of covering an elongate subsea element (14), the method comprising:suspending a cover unit (12) that comprises a rigid shell (18) and inner mudmats (34) that are movable relative to side walls (20) of the shell (18);moving the inner mudmats (34) relative to the shell (18) from a stowed configuration into a deployed configuration in which the inner mudmats (34) extend inwardly from the side walls (20); andlanding the cover unit (12) over the element (14) with the element (14) disposed between the side walls (20) of the shell (18).26. The method of Claim 25, comprising subsequently placing ballast (30) onto outward extensions (40) of the inner mudmats (34) that extend outwardly beyond the shell (18) and are movable with the inner mudmats (34) relative to the side walls (20).27. The method of Claim 26, comprising sandwiching the outward extensions (40) between the ballast (30) and outer mudmats (26) that extend outwardly from the side walls (20).28. The method of Claim 26, wherein the outward extensions (40) are outer mudmats (26) that extend outwardly from the side walls (20) when the inner mudmats (34) are in the deployed configuration.29. The method of any of Claims 26 to 28, comprising latching the outward extensions (40) to the side walls (20) to hold the inner mudmats (34) in the stowed configuration.30. The method of Claim 29, comprising unlatching the outward extensions (40) from the side walls (20) to release the inner mudmats (34) for movement into the deployed configuration.31. The method of any of Claims 25 to 30, comprising moving the inner mudmats (34) from the stowed configuration into the deployed configuration when the cover unit (12) is suspended above a body of water.32. The method of any of Claims 25 to 30, comprising moving the inner mudmats (34) from the stowed configuration into the deployed configuration when the cover unit (12) is submerged in a body of water.33. The method of Claim 32, comprising lowering a stack (32) of the cover units (12) to a submerged location with their shells (18) in nested relation, and moving the inner mudmats (34) from the stowed configuration into the deployed configuration after separating each cover unit (12) from the stack (32).P A T E N T K R A V1. Dekkingsenhet (12) for å dekke et avlangt undersjøisk element (14), hvor enheten (12) innbefatter et stivt skall (18) med innbyrdes motstående sidevegger (20) og indre muddermatter (34), karakterisert ved at de indre muddermattene (34) er bevegelige i forhold til sideveggene (20) fra en lagret konfigurasjon til en utplassert konfigurasjon der de indre muddermattene (34) strekker seg innover fra sideveggene (20).2. Enhet (12) ifølge krav 1, hvori de indre muddermattene (34) i den lagrede konfigurasjonen ligger utenfor et kammer definert mellom sideveggene (20).3. Enhet (12) ifølge krav 1 eller krav 2, hvori de indre muddermattene (34) i den lagrede konfigurasjonen spriker fra hverandre nedover.4. Enhet (12) ifølge hvilket som helst av de foregående krav, hvori de indre muddermattene (34) er svingbare i forhold til sideveggene (20).5. Enhet (12) ifølge hvilket som helst av de foregående krav, videre omfatter ytre muddermatter (26) som strekker seg utover fra sideveggene (20).6. Enheten (12) ifølge krav 5, hvori de indre muddermattene (34) i den utplasserte konfigurasjonen er i samme plan med eller parallelle med de ytre muddermattene (26).7. Enheten (12) ifølge krav 5 eller krav 6, hvori de ytre muddermattene (26) er bevegelige med de indre muddermattene (34) i forhold til sideveggene (20).8. Enheten (12) ifølge krav 8, hvori de indre og ytre muddermattene (34, 26) er svingbare i innbyrdes motstående opposisjon rundt svingaksler (44) som ligger mellom dem og som strekker seg parallelt med de respektive sideveggene (20).9. Enheten (12) ifølge krav 8, hvori de ytre muddermattene (26) ligger mot sideveggene (20) når de indre muddermattene (34) er i den lagrede konfigurasjonen.10. Enheten (12) ifølge krav 9, videre omfatter låser (48) som virker mellom de ytre muddermattene (26) og sideveggene (20) for å holde de indre muddermattene (34) i den lagrede konfigurasjonen.11. Enheten (12) ifølge hvilket som helst av kravene 1 til 6, hvori hver indre muddermatte (34) er en del av en plate som videre omfatter minst én vinge (40) som er motsatt den indre muddermatten (34) og som strekker seg gjennom skallet (18).12. Enheten (12) ifølge krav 11, hvori vingene (40) ligger mot sideveggene (20) når de indre muddermattene (34) er i den lagrede konfigurasjonen.13. Enheten (12) ifølge krav 12, videre omfatter låser (48) som virker mellom vingene (40) og sideveggene (20) for å holde de indre muddermattene (34) i den lagrede konfigurasjonen.14. Enheten (12) ifølge hvilket som helst av kravene 11 til 13, hvori vingene (40) er bevegelige bort fra sideveggene (20) i respons til bevegelse av de indre muddermattene (34) fra den lagrede konfigurasjonen til den utplasserte konfigurasjonen.15. Enheten (12) ifølge krav 14, hvori vingene (40) ligger på toppen av ytre muddermattene (26) som er fast integrert med sideveggene (20) når de indre muddermattene (34) er i den utplasserte konfigurasjonen.16. Enheten (12) ifølge hvilket som helst av de foregående krav, hvori skallet (18) til enheten (12) er nestbar med et skall (18) til en lignende enhet (12) plassert over eller under i en stabel (32) når de indre muddermattene (34) er i den lagrede konfigurasjonen.17. Enheten (12) ifølge krav 16, hvori de indre muddermattene (34) ligger utenfor en bredde av skallet (18) målt mellom bunnkantene til sideveggene (20) når de er i den lagrede konfigurasjonen.18. Enheten (12) ifølge krav 17, hvori avstanden mellom de indre muddermattene (34) er mindre enn bredden av skallet (18) målt mellom bunnkantene til sideveggene (20) når de er i den utplasserte konfigurasjonen.19. Enheten (12) ifølge hvilket som helst av kravene 16 til 18, hvori de indre muddermattene (34) ligger utenfor en bredde av en toppvegg (22) til skallet (18) som forbinder sideveggene (20) når de er i den lagrede konfigurasjonen.20. Enheten (12) ifølge krav 19, hvori avstanden mellom de indre muddermattene (34) er mindre enn bredden av toppveggen (22) til skallet (18) når de er i den utplasserte konfigurasjonen.21. Enheten (12) ifølge hvilket som helst av de foregående krav når den er installert på en havbunn (16) med de indre muddermattene (34) i den utplasserte konfigurasjonen liggende parallelt med havbunnen (16).22. Enheten (12) ifølge krav 21 når den er avhengig av krav 5 eller krav 6, videre omfatter ballast (30) deponert på de ytre muddermattene (26).23. Enheten (12) ifølge krav 21 når den er avhengig av krav 15, videre omfatter ballast (30) deponert på vingene (40) og klemme vingene (40) mellom ballasten (30) og de ytre muddermattene (26).24. En stabel (32) av enhetene (12) ifølge hvilket som helst av kravene 1 til 20 med deres skall (18) i et nestet forhold.25. Fremgangesmåte for å dekke et avlangt undersjøisk element (14), fremgangesmåten omfattende:å sette ut en dekkingsenhet (12) omfattende et stivt skall (18) og indre muddermattene (34) som er bevegelige i forhold til sideveggene (20) av skallet (18);å bevege de indre muddermattene (34) i forhold til skallet (18) fra en lagret konfigurasjon til en utplassert konfigurasjon der de indre muddermattene (34) strekker seg innover fra sideveggene (20); ogå sette av dekkingsenheten (12) over elementet (14) med elementet (14) plassert mellom sideveggene (20) til skallet (18).26. Fremgangesmåte ifølge krav 25, omfattende å plassere ballast (30) på utvidelser (40) av de indre muddermattene (34) som strekker seg utover skallet (18) og er bevegelige med de indre muddermattene (34) i forhold til sideveggene (20).27. Fremgangesmåte ifølge krav 26, omfattende å anbringe utvidelsene (40) mellom ballasten (30) og ytre muddermattene (26) som strekker seg utover fra sideveggene (20).28. Fremgangesmåte ifølge krav 26, hvori utvidelsene (40) er ytre muddermatter (26) som strekker seg utover fra sideveggene (20) når de indre muddermattene (34) er i den utplasserte konfigurasjonen.29. Fremgangesmåte ifølge hvilket som helst av kravene 26 til 28, omfattende å låse utvidelsene (40) til sideveggene (20) for å holde de indre muddermattene (34) i den lagrede konfigurasjonen.30. Fremgangesmåte ifølge krav 29, omfattende å låse opp utvidelsene (40) fra sideveggene (20) for å frigjøre de indre muddermattene (34) for bevegelse til den utplasserte konfigurasjonen.31. Fremgangesmåte ifølge hvilket som helst av kravene 25 til 30, omfattende å bevege de indre muddermattene (34) fra den lagrede konfigurasjonen til den utplasserte konfigurasjonen når dekkingsenheten (12) er opphengt over en vannmasse.32. Fremgangesmåte ifølge hvilket som helst av kravene 25 til 30, omfattende å bevege de indre muddermattene (34) fra den lagrede konfigurasjonen til den utplasserte konfigurasjonen når dekkingsenheten (12) er nedsenket i en vannmasse.33. Fremgangesmåte ifølge krav 32, omfattende å senke en stabel (32) av dekkingsenhetene (12) til en nedsenket plassering med deres skall (18) i nestet forhold, og å bevege de indre muddermattene (34) fra den lagrede konfigurasjonen til den utplasserte konfigurasjonen etter å ha skilt hver dekkingsenhet (12) fra stabelen (32).
Drawings

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Patent classes

IPC classesE21B 33/037F16L 1/12CPC classesE21B 33/037F16L 1/123

Citations

GB 2410758 A (A)US 4329084 A (A)NO 20150337 A1 (A1)NO 20130296 A1 (A1)WO 9829611 A1 (A1)

Applicants, owners and inventors

Owners
Subsea 7 Norway AS
Kanalsletta 9 4033 STAVANGER NO (STAVANGER Municipality, Rogaland county)Org. number: 936742475Inventors
Christian Linde Olsen
Krokusstien 4 4022 STAVANGER NO (STAVANGER Municipality, Rogaland county)
Xiaoming Gu
Brattebøveien 35 4336 SANDNES NO (SANDNES Municipality, Rogaland county)

Agent

BRYN AARFLOT AS
BRYN AARFLOT AS

Org. number: 979993269

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Open in The Brønnøysund Register Centre
Stortingsgata 8 0161 OSLO NO (OSLO Municipality, Oslo county)
Org. number: 979993269
Reference: 143275NO

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