CA2207895A1 - Method and structural device for mono-mooring ships in open sea - Google Patents
Method and structural device for mono-mooring ships in open seaInfo
- Publication number
- CA2207895A1 CA2207895A1 CA 2207895 CA2207895A CA2207895A1 CA 2207895 A1 CA2207895 A1 CA 2207895A1 CA 2207895 CA2207895 CA 2207895 CA 2207895 A CA2207895 A CA 2207895A CA 2207895 A1 CA2207895 A1 CA 2207895A1
- Authority
- CA
- Canada
- Prior art keywords
- tanker
- mooring
- flexible
- fluid
- rotatable sleeve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Electrophonic Musical Instruments (AREA)
Abstract
This invention provides a single-point mooring method, advantageously suitable for forming a tanker terminal, in which there are provided a fixed structure anchored to the sea bed, a mooring chain or cable and at least one flexible pipeline, said method enabling the translational and rotational movements of the tanker to. be compensated by rotations of elements connected together. The invention also provides a structural device for the practical implementation of the method, comprising a universal joint, an articulated arm, and a rotatable sleeve.
Description
~t ~~ CA 0220789~ 1997-0~-29 ;
METHOD AND STRUCTURAL D~VICE FOR MONO-MOORING SHI~S IN OPEN S~A
This invention relates to a single-point mono-mooring method for ships, preferably tankers, and a structural device for impLementing the method. More particularLy, said device comprises in advantageous cooperation a universal Joint, an articulated mooring arm, and a hollow rotatable sleeve. That method o~
mooring tankers in open sea which best satis~ies ship safety and operating requirements, in that with the advent of giant tankers it becomes increasingly more difficuLt to find ports of sufficient depth to en~ble such t~nkPr~ to be mocred, is to moor these tankers on buoys to enable the fluid to be loaded and unloaded.
Moreover, moorings in open sea are often advantageous, i~ not indeed essential, when drawing fluid fueL extracted ~rom deposits Located in the sea bed. In this respect, it should be noted that in the description and claims, the term "~1uid" is meant to include gas, liquids and their mixtures. In loading and unloading fluids between tankers and dry land, so-called mono-mooring has been known ~or some time, this as the name suggests using a single mooring and in particular a ~10ating buoy to which the tanker is moared and an adequate pipeLine is secured for trans~erring the fluid from the tanker to land storage and vice versa. The basic .~ CA 0220789~ 1997-0~-29-.
operational aspect of mono-mooring is to enable the operations involved in transfer to be performed even under adverse atmospheric conditions, when the tanker, urged by wind and currents, orientates itself in the natural direction, which can continuously change as the environmental conditions vary. In thls case, although the tanker remains moored, it in fact moves by rotating about the mono-mooring, while maintaining the same orientation to this latter. The operating structure for mono-mooring is ~herefore required to satis~y two basic ~unctions, the first involving the anchoring cable or chain, ie coupling to the tanker a cable anchored to the sea bed and consequently reacting to the pull on the tanke.r, the second involving ~luid transfer between the pipeLines originating ~rom the tanker or arriving at the tanker and the pipelines connected to land storage. As the tanker is mobile while the connections to land are fixed, it is evident that this secand function require.d af the. mono-mooring is the more severe, in that the fLexible pipeline extending from the tanker tQ the huoy structure anchored ta the sea bed, and which carries the Li.~uid ~eed, may ke subject to rapid wear not only because af the continuous stresses caus.ed ky the movement o~ the sea but also because by the action o~ the sea it Qften comes into contact wLth the mooring chain. Moreuver, in many cases, this ~1exible pipeLine twists about the buoy structure anchored to the ~ea bed, putting the loading and unloading station out Qf action ~or a considerabLe time. In this respect, it is evident that even under the worst operating conditions the anchorage must provide mA~;m~lm guarantees and m~im1lm possible sa~ety, because the sudden .- CA 0220789~ 1997-0~-29 yielding of a buoy while the tanker is loading or unloading can cause damage of unimaginable gravity. Again, it is apparent that the provision of a safe mooring system means the availability of a loading and unloading station which will be much used, and hence resulting in practice in considerable economical advantages.
Various mooring buoys have been developed in the past, but these have been invariably complicated overall, and hence of costly construction. Moreover, such mooring buoys do not allow the tanker sufficient movement, nor enable the normal mooring forces to be satisfactorily absorbed. An object Qf the present invention is therefore to provide a mooring buoy which is sufficLently easy to handle, and which can be constructed e~fectively and at low cost. A further object of the present invention is to provide a structure suitable for berthing in open sea, such as to enable the berthed tanker to assume at any moment the most convenient direction Qn thé basis of the ~;nPnt wind and the sea conditions, so that the tanker can move in a complete circLe, thus enabLing it to always remain with lts bow into the blowing wind.
further object of the present invention is to provide structuraL
elements which support the mooring forces within a unified structure which enables the tanker to move wLthout imposing mooring stresses on the structure, on the flexibLe pipeline Qr Qn the tanker. A further object of the present invention is to provide structural berthing elements which are particularly simple and hence relatively economical. These and further considerable advantages, particularly with regard to practicality, operating safety, the practicaL elimination of determined breakage and .~ CA 0220789~ l997-0~-29 damage risks, and simplification of the operations involved in berthing the tanker, are attained by the single-point mooring method of the present invention, in which there are provided a fixed structure anchored to the sea bed, a mooring chain or cable and at least one flexible pipeline, said mooring method comprising compensating the translational and rotational movements of the tanker by means o~ a universal joint flanged to an articulated arm connected to a rotatable sleeve acting as the connector for flexible pipes, which in their entry branches assume a helical configuration and which at their exit, by pass.ing through the central space of the rotatable hollow sleeve in the form of an axially symmetrical rotating member, meet the ~1uid line o~ the flexible pipeline connected to the moored tanker, said rotatable sleeve being also the anrh~ring member for the mooring cable bridles. In its practical implementation, the single-point mooring method o~ the present invention is characterised in that the tensile. stresses in the tanker mooring chain are nullified via the ~ixing s.tructuraL for the universal joint. The single-point mooring methQd o~ the present invention is further characterised by rendering the fluid trans~er fLexible pipeLines ~ree from tensil.e and/or torsional stresses. The device used ~or the practical implementation of the method of the present invention comprises:
- a universal joint rigidly fixed tQ a large rigid immersed foundation structuraL ~ixed to the sea bed;
- an articulated mooring arm flanged at its lower end to the universaL joint and fixed at its upper end to a holl.ow rotatable CA 0220789~ l997-0~-29 sleeve;
- a hollow rotatable sleeve supported by and connected to the underlying articulated arm via an axiaL thrust bearing shaped upperly with axially symmetrical projections for coupling the mooring cable bridLes;
- at least one flexible pipe which along its entry branch between the sea bed pipeline and the hollow rotatable sleeve assumes an advantageous helical configuration;
- a fluid-tight connector within the rotatable sleeve into which the ~1uids Qf the ~1exible entry pipes flow and from which the fluids of the flexible exit pipelines depart to transfer the fluid products to and/or from the moored tanker.
The invention is described in detail hereinafter on the basis of the embodiment repres.ented schematlcaLly on the figure oi the single accompanying drawing, together with the clari~ication of further details and characteristics, in which respect it should be noted that any variatLons in the relative positLons of the elements and the conseguent simpli~icatians which may derive therefrom are to be considered as faLLing within.the reguested protection as cQnstructional modifications included in the generaL
Ldea .
The s.ingle accompanying drawing shows in schematic fQrm that part of an embodiment of the invention reguiring an explanation of the s.eparatian ~etween the tensiLe mooring action and the fluid transfer. actLon through the fLexibLe pipeLines.
The figure of the drawing is an axonometric perspective view of the structuraL device of the present invention showing the base frame CA 0220789~ l997-0~-29 surmounted by the structural elements on which there are superposed a universal joint, an articulated mooring arm and a hoLlow rotatable sleeve, and further schematically showing the flexible pipes, the rigid base pipeline and the mooring cable bridles.
In the accompanying figure, identical elements or elements with identical functions carry identical reference characters for simplicity.
With re~erence to the ~igure, the tanker mooring and fluid transfer structure a~ the present invention is shown resting on the sea bed. Although the structure of the present invention is described herein as located on the sea bed, it is e~ually of use in other waters. The structure consists essentially of a large soLid fixed plat~orm indicated overaLL by 1, constructed on piles driven into the sea bed cr resting thereon by gravity, and depending on thé depth of the sea ked can be partly or totaLly encased. OtheL types c~ fixing can be used. Said fixed plat~Qrm 1 centrally houses the rigld structure 7 which as a rigid support provides a ~ixed suppart ~Qr the universaL joint 3 Qf known type, located in a substantiaLly horizontaL position. The universal jQint 3 supports, and is sultabLy connected by flanging to, an articulated mooring arm 5 of cylindricaL shape. Said articulated arm 5 ifi fixed at its upper end to a rotatable sleeve 4, which can rotate about its barycentric axis. The rotatable sLeeve 4 i5 supported by and cQnnected tQ the underlying articulated arm 5 by means of an axial thrust bearing, said rotatabLe sLeeve 4 being shaped upperly with axially symmetrical projections 14 for CA 0220789~ l997-0~-29 ., , coupling the rings 8, which embrace the end eyes of the bridles 9 for the mooring cable 10, which maintains the tanker in position for the entire time required for transferring the fluid. The connection between the hollow rotatable sleeve 4 and the articulated arm 5 allows free angular oscillation between the universal joint 3 and the flexible fluid transfer pipeline 12, with the precise and innovative result o~ eliminating practically any flexural and/or fLexo-torsional stress on the flexible pipeLine 12, especiaLLy in that portion thereof passing fre~ly through the central space of the sleeve 4. The bearing arrangement Joining the arm 3 to the sleeve 4 allows free angular positioning of the flexible pipeline 12 for the variable angular positions of the universal joint 3, which oscillates variably on the basis of the pulling direction of the mooring chain 10. A
feed Line 11 is positioned on the sea bed 15 and has an end sealedly connected to at least one. flexible pipe 2. The ~langed connections must ensure a per~ect seaL ~or the fLuid transferred unde.r pres.sure. At its othe.r end, not shown, the feed Line 11 Leads to a storage accessory, aLso not shown hut hahituaLLy locate.d on the near shore. This storage accessory can also be Located out at sea, for exampLe close to a welL Located offshore.
~he fLexibLe entry pipes 2 assume an advantageous heLicaL
con~iguration to the side o~ the universaL joint 3 to achieve Linear compensation for any rotary movement and anguLar displacement of the articulated arm 5 and rotatabLe sLeeve 4.
Said flexible pipe portions 2 are connected by flanging to pre~erably rigid connector pipe pieces 6 inserted in a perfectly - CA 0220789~ l997-0~-29 ' ..
sealed manner into the rotatable sleeve 4, to feed the fluids into the flexible pipeline 12 which conveys them to the tanker moored on the surface. The operations involved in mooring the tanker wilL now be described. It should be noted that the fixed structure and the elements connected to it must in aLl cases be dimensioned to withstand the mooring stresses of any loaded tanker subjected to the various sea and wind conditions. In the case of typical berthing, the tanker, approaching under the mos~ suitable prevailing wind, halts in proximity to the berth and being kedged 10 in this position by its own means, or with the aid of a tug, takes the mooring chain 10 and anchors it rigidly to the tanker bow.
Mooring is implemented in accordance with the known art as long used in arriving at the berthing point. Having terminated mooring, the tanker is connected to the sea line by the flexible pipeline system, and the loading and/or unloading of the fluid being trans~erréd commences. During the loading and-unloading, the ta~ker remains free to move about its mooring, foLlowing without reaction the force o~ the wind or sea, the tanker hence assuming that orientation which the direction of the wind and possib~e sea current impose on it. From the a~oregoing it is apparent that the method of the present invention has the significant advantage o~ separating the two ~unctions normally inherent in a berthing point, namely that of mooring the tanker and that Qf transmitting the fluid to be handled from the tanker to the underwater Line 11 or vice versa. In this manner the mooring pull by the tanker directly stresses the anchoring base 1 via the chain 10, without minimaLLy involving the fLexibLe CA 0220789~ l997-0~-29 _ g _ pipelines handling the ~uid. The structure of the invention can be implemented in a simple and economical manner. The mooring chain 10 is ~ixed to the anchoring base 1 by elemen~s which allow rotation about axes orientated in several directions, said elements advantageously assuming the operational ~unctions of a ball joint. There is there~ore no impact danger in the case of collision between the tanker and the surface e~uipment, and the tanker is free to orientate itseLf in the best direction according tQ the prevaiLing wind and the sea conditions at that moment.
Consequently unmooring caused by the sea conditions is obviated, and the flexible pipeLine 12 is not subjected to any substantiaL stress so that the welL-known problems deriving ~rom possibLe fracture of this pipeLine are avoided. Unmooring is per~ormed in the opposite manner to mooring, and under unloaded conditions the ~LexibLe pipeLine 12 and the mooring chain 10 are Left hanging in the verticaL position, parked under the sea surface with their ends connected to known means and probes which enabLe them tQ be ~ecovered on board. ALthough the present invention has been described with re~erence to determined embodiments, numerous modifications can be made to the constructional ~orms o~ the operationaL eLements, in which respect any changes in the relative positions Qf the eLements and any consequent simpLificatians deriving therefrom are to be considered as iaLling within the requested protection as constructional modifications incLuded within the generaL idea.
METHOD AND STRUCTURAL D~VICE FOR MONO-MOORING SHI~S IN OPEN S~A
This invention relates to a single-point mono-mooring method for ships, preferably tankers, and a structural device for impLementing the method. More particularLy, said device comprises in advantageous cooperation a universal Joint, an articulated mooring arm, and a hollow rotatable sleeve. That method o~
mooring tankers in open sea which best satis~ies ship safety and operating requirements, in that with the advent of giant tankers it becomes increasingly more difficuLt to find ports of sufficient depth to en~ble such t~nkPr~ to be mocred, is to moor these tankers on buoys to enable the fluid to be loaded and unloaded.
Moreover, moorings in open sea are often advantageous, i~ not indeed essential, when drawing fluid fueL extracted ~rom deposits Located in the sea bed. In this respect, it should be noted that in the description and claims, the term "~1uid" is meant to include gas, liquids and their mixtures. In loading and unloading fluids between tankers and dry land, so-called mono-mooring has been known ~or some time, this as the name suggests using a single mooring and in particular a ~10ating buoy to which the tanker is moared and an adequate pipeLine is secured for trans~erring the fluid from the tanker to land storage and vice versa. The basic .~ CA 0220789~ 1997-0~-29-.
operational aspect of mono-mooring is to enable the operations involved in transfer to be performed even under adverse atmospheric conditions, when the tanker, urged by wind and currents, orientates itself in the natural direction, which can continuously change as the environmental conditions vary. In thls case, although the tanker remains moored, it in fact moves by rotating about the mono-mooring, while maintaining the same orientation to this latter. The operating structure for mono-mooring is ~herefore required to satis~y two basic ~unctions, the first involving the anchoring cable or chain, ie coupling to the tanker a cable anchored to the sea bed and consequently reacting to the pull on the tanke.r, the second involving ~luid transfer between the pipeLines originating ~rom the tanker or arriving at the tanker and the pipelines connected to land storage. As the tanker is mobile while the connections to land are fixed, it is evident that this secand function require.d af the. mono-mooring is the more severe, in that the fLexible pipeline extending from the tanker tQ the huoy structure anchored ta the sea bed, and which carries the Li.~uid ~eed, may ke subject to rapid wear not only because af the continuous stresses caus.ed ky the movement o~ the sea but also because by the action o~ the sea it Qften comes into contact wLth the mooring chain. Moreuver, in many cases, this ~1exible pipeLine twists about the buoy structure anchored to the ~ea bed, putting the loading and unloading station out Qf action ~or a considerabLe time. In this respect, it is evident that even under the worst operating conditions the anchorage must provide mA~;m~lm guarantees and m~im1lm possible sa~ety, because the sudden .- CA 0220789~ 1997-0~-29 yielding of a buoy while the tanker is loading or unloading can cause damage of unimaginable gravity. Again, it is apparent that the provision of a safe mooring system means the availability of a loading and unloading station which will be much used, and hence resulting in practice in considerable economical advantages.
Various mooring buoys have been developed in the past, but these have been invariably complicated overall, and hence of costly construction. Moreover, such mooring buoys do not allow the tanker sufficient movement, nor enable the normal mooring forces to be satisfactorily absorbed. An object Qf the present invention is therefore to provide a mooring buoy which is sufficLently easy to handle, and which can be constructed e~fectively and at low cost. A further object of the present invention is to provide a structure suitable for berthing in open sea, such as to enable the berthed tanker to assume at any moment the most convenient direction Qn thé basis of the ~;nPnt wind and the sea conditions, so that the tanker can move in a complete circLe, thus enabLing it to always remain with lts bow into the blowing wind.
further object of the present invention is to provide structuraL
elements which support the mooring forces within a unified structure which enables the tanker to move wLthout imposing mooring stresses on the structure, on the flexibLe pipeline Qr Qn the tanker. A further object of the present invention is to provide structural berthing elements which are particularly simple and hence relatively economical. These and further considerable advantages, particularly with regard to practicality, operating safety, the practicaL elimination of determined breakage and .~ CA 0220789~ l997-0~-29 damage risks, and simplification of the operations involved in berthing the tanker, are attained by the single-point mooring method of the present invention, in which there are provided a fixed structure anchored to the sea bed, a mooring chain or cable and at least one flexible pipeline, said mooring method comprising compensating the translational and rotational movements of the tanker by means o~ a universal joint flanged to an articulated arm connected to a rotatable sleeve acting as the connector for flexible pipes, which in their entry branches assume a helical configuration and which at their exit, by pass.ing through the central space of the rotatable hollow sleeve in the form of an axially symmetrical rotating member, meet the ~1uid line o~ the flexible pipeline connected to the moored tanker, said rotatable sleeve being also the anrh~ring member for the mooring cable bridles. In its practical implementation, the single-point mooring method o~ the present invention is characterised in that the tensile. stresses in the tanker mooring chain are nullified via the ~ixing s.tructuraL for the universal joint. The single-point mooring methQd o~ the present invention is further characterised by rendering the fluid trans~er fLexible pipeLines ~ree from tensil.e and/or torsional stresses. The device used ~or the practical implementation of the method of the present invention comprises:
- a universal joint rigidly fixed tQ a large rigid immersed foundation structuraL ~ixed to the sea bed;
- an articulated mooring arm flanged at its lower end to the universaL joint and fixed at its upper end to a holl.ow rotatable CA 0220789~ l997-0~-29 sleeve;
- a hollow rotatable sleeve supported by and connected to the underlying articulated arm via an axiaL thrust bearing shaped upperly with axially symmetrical projections for coupling the mooring cable bridLes;
- at least one flexible pipe which along its entry branch between the sea bed pipeline and the hollow rotatable sleeve assumes an advantageous helical configuration;
- a fluid-tight connector within the rotatable sleeve into which the ~1uids Qf the ~1exible entry pipes flow and from which the fluids of the flexible exit pipelines depart to transfer the fluid products to and/or from the moored tanker.
The invention is described in detail hereinafter on the basis of the embodiment repres.ented schematlcaLly on the figure oi the single accompanying drawing, together with the clari~ication of further details and characteristics, in which respect it should be noted that any variatLons in the relative positLons of the elements and the conseguent simpli~icatians which may derive therefrom are to be considered as faLLing within.the reguested protection as cQnstructional modifications included in the generaL
Ldea .
The s.ingle accompanying drawing shows in schematic fQrm that part of an embodiment of the invention reguiring an explanation of the s.eparatian ~etween the tensiLe mooring action and the fluid transfer. actLon through the fLexibLe pipeLines.
The figure of the drawing is an axonometric perspective view of the structuraL device of the present invention showing the base frame CA 0220789~ l997-0~-29 surmounted by the structural elements on which there are superposed a universal joint, an articulated mooring arm and a hoLlow rotatable sleeve, and further schematically showing the flexible pipes, the rigid base pipeline and the mooring cable bridles.
In the accompanying figure, identical elements or elements with identical functions carry identical reference characters for simplicity.
With re~erence to the ~igure, the tanker mooring and fluid transfer structure a~ the present invention is shown resting on the sea bed. Although the structure of the present invention is described herein as located on the sea bed, it is e~ually of use in other waters. The structure consists essentially of a large soLid fixed plat~orm indicated overaLL by 1, constructed on piles driven into the sea bed cr resting thereon by gravity, and depending on thé depth of the sea ked can be partly or totaLly encased. OtheL types c~ fixing can be used. Said fixed plat~Qrm 1 centrally houses the rigld structure 7 which as a rigid support provides a ~ixed suppart ~Qr the universaL joint 3 Qf known type, located in a substantiaLly horizontaL position. The universal jQint 3 supports, and is sultabLy connected by flanging to, an articulated mooring arm 5 of cylindricaL shape. Said articulated arm 5 ifi fixed at its upper end to a rotatable sleeve 4, which can rotate about its barycentric axis. The rotatable sLeeve 4 i5 supported by and cQnnected tQ the underlying articulated arm 5 by means of an axial thrust bearing, said rotatabLe sLeeve 4 being shaped upperly with axially symmetrical projections 14 for CA 0220789~ l997-0~-29 ., , coupling the rings 8, which embrace the end eyes of the bridles 9 for the mooring cable 10, which maintains the tanker in position for the entire time required for transferring the fluid. The connection between the hollow rotatable sleeve 4 and the articulated arm 5 allows free angular oscillation between the universal joint 3 and the flexible fluid transfer pipeline 12, with the precise and innovative result o~ eliminating practically any flexural and/or fLexo-torsional stress on the flexible pipeLine 12, especiaLLy in that portion thereof passing fre~ly through the central space of the sleeve 4. The bearing arrangement Joining the arm 3 to the sleeve 4 allows free angular positioning of the flexible pipeline 12 for the variable angular positions of the universal joint 3, which oscillates variably on the basis of the pulling direction of the mooring chain 10. A
feed Line 11 is positioned on the sea bed 15 and has an end sealedly connected to at least one. flexible pipe 2. The ~langed connections must ensure a per~ect seaL ~or the fLuid transferred unde.r pres.sure. At its othe.r end, not shown, the feed Line 11 Leads to a storage accessory, aLso not shown hut hahituaLLy locate.d on the near shore. This storage accessory can also be Located out at sea, for exampLe close to a welL Located offshore.
~he fLexibLe entry pipes 2 assume an advantageous heLicaL
con~iguration to the side o~ the universaL joint 3 to achieve Linear compensation for any rotary movement and anguLar displacement of the articulated arm 5 and rotatabLe sLeeve 4.
Said flexible pipe portions 2 are connected by flanging to pre~erably rigid connector pipe pieces 6 inserted in a perfectly - CA 0220789~ l997-0~-29 ' ..
sealed manner into the rotatable sleeve 4, to feed the fluids into the flexible pipeline 12 which conveys them to the tanker moored on the surface. The operations involved in mooring the tanker wilL now be described. It should be noted that the fixed structure and the elements connected to it must in aLl cases be dimensioned to withstand the mooring stresses of any loaded tanker subjected to the various sea and wind conditions. In the case of typical berthing, the tanker, approaching under the mos~ suitable prevailing wind, halts in proximity to the berth and being kedged 10 in this position by its own means, or with the aid of a tug, takes the mooring chain 10 and anchors it rigidly to the tanker bow.
Mooring is implemented in accordance with the known art as long used in arriving at the berthing point. Having terminated mooring, the tanker is connected to the sea line by the flexible pipeline system, and the loading and/or unloading of the fluid being trans~erréd commences. During the loading and-unloading, the ta~ker remains free to move about its mooring, foLlowing without reaction the force o~ the wind or sea, the tanker hence assuming that orientation which the direction of the wind and possib~e sea current impose on it. From the a~oregoing it is apparent that the method of the present invention has the significant advantage o~ separating the two ~unctions normally inherent in a berthing point, namely that of mooring the tanker and that Qf transmitting the fluid to be handled from the tanker to the underwater Line 11 or vice versa. In this manner the mooring pull by the tanker directly stresses the anchoring base 1 via the chain 10, without minimaLLy involving the fLexibLe CA 0220789~ l997-0~-29 _ g _ pipelines handling the ~uid. The structure of the invention can be implemented in a simple and economical manner. The mooring chain 10 is ~ixed to the anchoring base 1 by elemen~s which allow rotation about axes orientated in several directions, said elements advantageously assuming the operational ~unctions of a ball joint. There is there~ore no impact danger in the case of collision between the tanker and the surface e~uipment, and the tanker is free to orientate itseLf in the best direction according tQ the prevaiLing wind and the sea conditions at that moment.
Consequently unmooring caused by the sea conditions is obviated, and the flexible pipeLine 12 is not subjected to any substantiaL stress so that the welL-known problems deriving ~rom possibLe fracture of this pipeLine are avoided. Unmooring is per~ormed in the opposite manner to mooring, and under unloaded conditions the ~LexibLe pipeLine 12 and the mooring chain 10 are Left hanging in the verticaL position, parked under the sea surface with their ends connected to known means and probes which enabLe them tQ be ~ecovered on board. ALthough the present invention has been described with re~erence to determined embodiments, numerous modifications can be made to the constructional ~orms o~ the operationaL eLements, in which respect any changes in the relative positions Qf the eLements and any consequent simpLificatians deriving therefrom are to be considered as iaLling within the requested protection as constructional modifications incLuded within the generaL idea.
Claims (4)
1. A single-point mooring method, suitable for forming a tanker terminal, in which there are provided a fixed structure anchored to the sea bed, a tanker mooring chain or cable and at least one flexible pipeline for transferring the fluid to and/or from the moored tanker, said mooring method being characterised by compensating the translational and rotational movements of the tanker by means of a universal joint flanged to an articulated arm connected to a rotatable sleeve acting as the connector for flexible pipes, which in their entry branches assume a helical configuration and which at their exit, by passing through the central space of the rotatable hollow sleeve in the form of an axially symmetrical rotating member, meet the fluid line of the flexible pipeline connected to the surface-moored tanker.
2. A single-point mooring method as claimed in claim 1, characterised in that the tensile stresses in the tanker mooring chain are nullified via the fixing structure for the universal joint.
3. A single-point mooring method, suitable for forming a tanker terminal as claimed in claim 1, characterised by rendering the fluid transfer flexible pipeline free from tensile and/or torsional stresses.
4. A structural device for implementing the method claimed in claim 1, characterised by comprising:
- a universal joint rigidly fixed to a large rigid immersed foundation structural fixed to the sea bed;
- an articulated mooring arm flanged at its lower end to the universal joint and fixed at its upper end to a hollow rotatable sleeve;
- a hollow rotatable sleeve supported by and connected to the underlying articulated arm via an axial thrust bearing shaped upperly with axially symmetrical projections for coupling the mooring cable bridles;
- at least one flexible pipe which along its entry branch between the sea bed pipeline and the hollow rotatable sleeve assumes an advantageous helical configuration;
- a fluid-tight connector within the rotatable sleeve into which the fluids of the flexible entry pipes flow and from which the fluids of the flexible exit pipelines depart to transfer the fluid products to and/or from the tanker moored on the sea surface.
-
- a universal joint rigidly fixed to a large rigid immersed foundation structural fixed to the sea bed;
- an articulated mooring arm flanged at its lower end to the universal joint and fixed at its upper end to a hollow rotatable sleeve;
- a hollow rotatable sleeve supported by and connected to the underlying articulated arm via an axial thrust bearing shaped upperly with axially symmetrical projections for coupling the mooring cable bridles;
- at least one flexible pipe which along its entry branch between the sea bed pipeline and the hollow rotatable sleeve assumes an advantageous helical configuration;
- a fluid-tight connector within the rotatable sleeve into which the fluids of the flexible entry pipes flow and from which the fluids of the flexible exit pipelines depart to transfer the fluid products to and/or from the tanker moored on the sea surface.
-
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ITMI96/A001203 | 1996-06-13 | ||
| IT96MI001203A IT1284008B1 (en) | 1996-06-13 | 1996-06-13 | MONOREGGIO METHOD AND STRUCTURAL APPARATUS FOR VESSELS IN THE OPEN SEA |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2207895A1 true CA2207895A1 (en) | 1997-12-13 |
Family
ID=11374419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2207895 Abandoned CA2207895A1 (en) | 1996-06-13 | 1997-05-29 | Method and structural device for mono-mooring ships in open sea |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2207895A1 (en) |
| FI (1) | FI972298A (en) |
| IT (1) | IT1284008B1 (en) |
-
1996
- 1996-06-13 IT IT96MI001203A patent/IT1284008B1/en active IP Right Grant
-
1997
- 1997-05-29 CA CA 2207895 patent/CA2207895A1/en not_active Abandoned
- 1997-05-30 FI FI972298A patent/FI972298A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| IT1284008B1 (en) | 1998-05-08 |
| FI972298A0 (en) | 1997-05-30 |
| FI972298A (en) | 1997-12-14 |
| ITMI961203A1 (en) | 1997-12-13 |
| ITMI961203A0 (en) | 1996-06-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |