US3894567A - Offshore vessel mooring - Google Patents

Abstract

The invention relates to a ship''s mooring of the single point type for an offshore location, including a liquid cargo loading facility. The mooring comprises a foundation member such as a pile or the like which is imbedded in the offshore substratum with a portion projecting thereabove. A buoyant casing extending to the water''s surface is operably engaged at its lower end with the foundation member to enclose and protect a liquid carrying conduit. Said conduit is communicated either with a shore based source of liquid to be transferred to a transport vessel, or is coupled with a floating storage vessel such as a tanker or barge. In the latter instance, the storage or transport vessel is positioned by a rotatable connection at the foundation member whereby to limit movement of the vessel during a liquid transfer operation.

Description

United States Patent Mott et al. 1 July 15, 1975 ['5 OFFSHORE VESSEL MOORING 3,501,173 3/1970 Petersen et a1. 285/114 3,515,182 6/1970 Dickson et a1 137/236 )1 1751 "Vemorsi Gemge Metarei 3,527,481 9/1970 Lewis 285/114 Ratcliff, Gretna, both of La.

Assignee: Texaco Inc., New York, N.Y.

Filed: Sept. 8, 1971 Appl. No.: 178,831

Related US. Application Data [63] Continuation of Ser. No. 886,140, Dec. 18, 1969,

abandoned.

[52] US. Cl. 141/388; 9/8 P, 137/236 [51] Int. Cl. B651) 3/04 [58] Field of Search 9/8 P; 61/46, 46.5; 114/230; 137/236, 236.5, 141/279, 284, 387, 388; 166/.5, .6; 285/114, 226, 229, 236

[56] References Cited UNITED STATES PATENTS 2,196,676 4/1940 Johnson et al 285/226 3,311,142 3/1967 Bergstrom.............. 137/236 X 3,366,088 1/1968 Gibson 114/230 3,372,409 3/1968 Manning 141/279 X 3,407,416 10/1968 Brickhouse.. 9/8 OP 3,434,442 3/1969 Manning 9/8 OP X 3,472,032 10/1969 Howard 166/.5 X

Primary ExaminerHouston S. Bell, Jr.

Assistant ExaminerFrederick R. Schmidt Arlomey, Agent, or F1'rmT. H. Whaley; C. G. Ries; Robert B. Burns [57] ABSTRACT The invention relates to a ships mooring of the single point type for an offshore location, including a liquid cargo loading facility. The mooring comprises a foundation member such as a pile or the like which is imbedded in the offshore substratum with a portion projecting thereabove. A buoyant casing extending to the waters surface is operably engaged at its lower end with the foundation member to enclose and protect a liquid carrying conduit. Said conduit is communicated either with a shore based source of liquid to be transferred to a transport vessel, or is coupled with a floating storage vessel such as a tanker or barge. 1n the latter instance, the storage or transport vessel is positioned by a rotatable connection at the foundation member whereby to limit movement of the vessel during a liquid transfer operation.

4 6 Claims, 3 Drawing Figures OFFSHORE VESSEL MOORING This is a continuation. Ser. No. 886.140, tiled Dec. 18, I969, now abandoned.

BACKGROUND OF THE INVENTION The use of offshore moorings for positioning large vessels such as barges. tankers. super-tankers and the like. is becoming more necessary as the size and capacity of the vessels becomes greater. The floatable mooring is normally positioned in a water depth sufficient to accommodate a tanker and yet permit a degree of movement to the latter in response to varying wind and wave conditions. As a matter of practicality. the float is often provided not only with a ship mooring facility, but also with means for transferring a liquid cargo such as crude or refined petroleum products between the vessel and a land based source.

To function properly under all Conditions, the offshore mooring must be adequate to permit uninterrupted flow or transfer of the liquid between the storage area and the tanker over an extended period of time. However. it must also be sufficiently massive to maintain the floating position of the tanker with a reasonable degree ofimmobility. Due to the uncertainty of weather conditions and to the certainty of tidal changes. there is a constant tendency for the moored vessel to be pivotally swung around its mooring point. Preferably, this swinging motion is about the ships bow which is normally tethered in a relatively fixed position in order that the liquid cargo carrying lines may be maintained between the mooring and the ship without damage in spite of movement of the vessel.

It is therefore one of the objectives of the invention to provide an improved, ships mooring for an offshore location. A further object is to provide a tanker anchoring and cargo transfer facility adapted to effectively receive and hold a tanker without entangling cargo transfer conduits. A still further object is to provide a single point mooring for securely holding a floating vcsscl whereby to transfer a liquid cargo to or from the latter.

DESCRIPTION OF THE DRAWINGS .FIG. 1 is a side elevation view illustrating the presently disclosed offshore facility when unoccupied by a floating vessel.

FIG. 2 is similar to FIG. 1 showing the disposition of the mooring means as related to a tanker.

FIG. 3 is an enlarged view in cross section of the disclosed mooring device.

In achieving the foregoing objectives, there is presently provided a single point mooring for use at an offshore location. The mooring includes a foundation member or anchor pile which is fixedly imbedded in the underwater substrate. The foundation member is in the form of an elongated, open ended pile which is usually buried in the substratum by driving, jetting or other appropriate means, with the upper end protruding upwardly from the substrate.

A buoyant casing, which maintains a normally upright position in the water. is operably engaged to the foundation member upper end to permit restrained movement of the casing. Said casing surrounds and protects one or more conduits, carrying liquid cargo to be transferred between the floating vessel and the shore facility.

Fastening collars capable of 360 rotation are secured to the buoyant casing and the foundation memher respectively. to permit the floating vessel to rotate around the buoyant casing and foundation member. Two or more pipe swivels disposed 90 apart are mounted in the cargo carrying conduit near the top of the buoyant casing to permit the cargo loading hose to also rotate 360 around the buoyant casing. A series of flexible connections secures the buoyant casing to the tixed foundation member. whereby the former is free to oscillate in the water independently of the foundation member.

A mooring of the type contemplated is shown in FIG. 2 wherein a floating tanker 10 is tethered bymooring line 6 to the protruding upper end of an imbedded foundation member I3. It is appreciated that in the following description the term tankcr will be used to illustrate the invention. In actuality, any floating vessel such as a ship. barge or similar water borne unit would apply as well to function as a cargo transfer vehicle. Further, the present mooring is usually anchored immediately offshore in a bay or adjacent to a refinery. or tank field but could be used near at producing offshore field with an oil storage vessel. However. the terminology ocean and ocean floor will be used to illustrate any underwater section wherein the facility is disposed.

FIG. 2 illustrates an embodiment of the instant mooring means wherein a shore based source of liquid 9 is communicated with the offshore positioned vessel III. The means of communication usually consists of a plurality ofrigid conduits 15 preferably imbcddcd beneath the substratum to avoid damage or breakage. The cargo transfer system is provided with necessary valve and manifold means normally used to controllably di rect a variety of liquids between tanker II) and the storage facility 9. The shore based facility may as mentioned be a refinery. a tank farm or merely the gathering point ofa number ofdispersed well heads which de liver streams of crude liquid product thereto.

The mooring facility is positioned in a body of water a sufficient distance from the shore to permit the mooring to be safely approached by a tanker without fear of grounding or other damage. The tanker is preferably secured to the mooring by abow line 6 extending from the tanker forward end to the ocean floor. and thence to permanently imbedded foundation member 13. The latter for convenience is provided with a buoy or float 7 connected to theanchor line 6 by pendant line 8 to locate the latter prior to its being connected to the tanker and while lying at the ocean floor. In a similar manner, hose 4] is secured to line 45 which is fixedly connected to float 5 so that tanker [0 may easily locate and connect tohose 41.

Foundation member 13 is formed preferably of an elongated metallic cylindrical piling imbedded a predetermined depth into the substratum. The actual depth of imbedmcnt will be determined in advance of the imbedding operation by coring or other means to determine the consistency of the substratum. Foundation pile 13 can be installed in any of the usual ways and may be made of concrete, steel or other material of the necessary strength to accommodate the proposed mooring loads.

Pile 13 is imbedded in a substratum to a depth which permits the upper portion to extend above the floor of the ocean. Said upper portion is provided with a pair of circular thrust rings I4 and 16 spaced a determined distance apart to define an annular channel or track 17 therebetween.Rings 14 and 16 are preferably welded to the exterior of the pile when the latter is metallic. but can be bolted or otherwise positioned.Lower ring 16 is fixedly welded in place. whereas upper ring l4 may be split and assembled to the pile by bolting thereby facilitating replacement. Collar I8 is disposed in track 17 between therespective rings 14 and 16 and can thus be readily assembled within the channel or track 17.

Upper ring 14 includes two or more pad eyes or rings 22 spaced about the ring edge. havingopenings 12 adapted to receivefastening shackles 34 or the like. Similarly the outer surface ofcollar 18 is provided with one or more pad eyes or staples ll adapted to hold the end of anchoringchain 6.

Collar 18 may be provided with peripheral rubbing surfaces along the upper. lower. as well as inner faces. Said surfaces are relatively smooth and adapted to posi tion the collar by sliding contact with the adjacent retaining rings 14 and 16. The rubbing faces may be equipped with non-corrosive bearing inserts to prevent the collar from binding. Theinner opening 23 ofcollar 18. and the external surface of pile 13 define sufficiently wide spacing therebetween to allow the collar to be rotatably moved about the pile within the conlines of rings [4 and 16. In that the entire unit will be submerged beneath the sea. a degree of lubrication is provided by the watery environment. However. since movement ofcollar 18 is very slow additional lubrication although not essential, can be utilized.

The upper end of pile I3 is further provided with an elongated aperture 2] which allows one or more cargo carrying conduits l access to the pile interior. The conduits may be imbeddcd beneath the surface of the ocean and terminate within the pile hollow interior. While the present illustration describes but a single cargo carrying conduit for the purpose of disclosing the invention. it is appreciated that a plurality ofsuch conduits 15 may terminate within the confines of the pile and thereafter be directed upwardly by vertical risers to connect with swivels above the waters surface. If more than one conduit is utilized. a multi-product type swivel is utilized.

Conduit l5 comprises in effect an articulated cargo carrying member. Said conduit is communicated byelbow 19 to ashort riser 20. Aflexible connection 26 further communicates riser to anelongated riser 27 disposed withincasing 28 and which extends to and beyond the upper end of the latter.

Casing 28 comprises an elongated hollow member preferably formed in a cylindrical configuration. A cylindrical housing 29 depends from the inner wall of casing 28, being spaced from the latter to form an elongated passage extcnding substantially the length ofcas ing 28. A plurality of longitudinally spaced. fluid tighttransverse panels 30 proportion said annular passage into discrete fluid tight chambers 3l.

To balance thefloatable casing 28 against the buoying effect of said chambers 31 during installation. the lower chamber orchambers 32 can be flooded or provided with a ballasting means accessible from the sur face. The unit is thus caused by the weight at the lower end to submerge to the desired depth for making the underwater connections. Subsequently, the ballast water may be removed by pumping or air pressure thereby permitting a constant buoyancy to be applied tocasing 28.

Riser 27 may further include upper and lower stop blocks 24 and 25 secured to the end walls ofriser 27 to prevent said riser from moving up or down beyond desired limits.

Casing 28 as noted. operably engages the foundation pile 13 in such manner that the lower end of the casing is secured throughflexible lines 33 to the upper end of the foundation pile. One embodiment of a connection means which provides the desired flexibility. yet rcstrained movement. comprises a plurality of lines orcables 33 extending between and connected to therespective casing 28 and foundation pile 13. Eachline 33 is provided terminally with connectingshackles 34 and 35 or similar connections which removably although flexibly retain the movable casing with respect to the fixed foundation member.

Lines 33 are connected at their lower ends tomooring staple 22 byshackles 34. Similarly. the upper ends oflines 33 are operably engaged to the lower end of casing 28 by way of radially projectingbrackets 36 havingopenings 37 in whichshackles 35 are received.

As thecollar 18 is caused to rotate within its confining channel 17 by a displacing movement of the moored vessel at a Waters surface, thebuoyant casing 28 will remain fixed to pile l3 and will therefore be restrained from rotating.

The upper end of liquid carryingriser 27 is provided with a universal joint consisting of two swivels disposed at right angles to each other to assure continuous liquid cargo flow without interruption in spite of movement of vessel 10. Representative of such pipe swivels are theelbows 38 and 39 connected through anipple 40. Said connection represents any of a number of couplings suitable to the application which are available commercially. However. the said coupling is communicated to a flexible hose orsimilar member 41 which extends to a moored tanker. and is adapted to rcmovably couple to pumps or other fluid conducting manifolds.Hose 41 is supportably retained by thecasing 28 to permit freedom of movement of thehose 41 as the tanker 10 is swung about its moored forward end.

Thus, the upper end of casing 28 is provided with a pair of spaced thrust rings 42 and 43 together with a rotatable collar 44 disposed therebetween. The general disposition and structure of the respective ring and collar are similar to the description of the rings and collar previously described with respect to the anchoring pile 13. The function of said collar 44 however. is to supportably position hose 4] by way of flexible connecting means such as cable orother line 45 which depends from collar 44, and connects tobands 46 and 47 deposed alonghose 41.

Obviously. many modifications and variations of the invention. as hereinafter set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

I. A vessel mooring and liquid transfer apparatus for an offshore body of water being adapted to moor and communicate a floating vessel with a submerged source of liquid cargo. which transfer apparatus includes;

an elongated column disposed normally in a substantially upright disposition with said body of water and having an upper buoyant portion and a lower anchoring section. the latter being embedded into the floor beneath said body of Water.

flexible coupling means operably connecting said respective lower section and upper buoyant portions.

to permit limited pivotal movement of the latter about said anchoring section. an articulated conduit disposed within said elongated column having a pivotal segment extending beyond the upper end of said column and having means on said the ends of conduit to engage said floating vessel for transferring liquid cargo between said vessel and said liquid cargo source. said conduit including a flexible connection therein to permit pivotal movement of the conduit in response to pivotal movement of said column buoyant portion. and vessel mooring means depending from said anchoring section at a point adjacent to the floor of said body of water. and spaced vertically downwardly from said conduit end. being rotatably carried on said anchoring section operable to removably engage a mooring line extending to said vessel whereby to permit limited movement of the latter about said transfer apparatus during acargo transfer operation 2. In an apparatus as defined in claim I. wherein said flexible coupling means includes; a plurality of flexible lines interconnecting the respective upper portion and lower anchoring sections to permit said limited pivotal movement therebetween.

3. In an apparatus as defined inclaim 1, wherein said lower anchoring section includes; at least one eloiv gated foundation member substantially embedded along its length into the substrate beneath said body of water. the upper end thereof being disposed above the surface of said floor. said vessel mooring means including a collar rotatably carried on said anchoring section at the end thereof extending above the ocean floor.

4. In an apparatus as defined inclaim 3. wherein said lower anchoring section includes; at least one elongated cylindrical pile having the lower end thereof embedded in the substrate. and the pile upper end extending beyond the floor of said body of water. and means forming a circumferential track about said pile extending upper end. said collar being guidably received within said track to permit circumferential movement of the collar about said pile when the collar is connected to said vessel.

5. In an apparatus as defined in claim 4, wherein said pile upper end projecting above the substrate includes a pair of longitudinally spaced circumferential rings defining a channel thcrebetwecn. said collar being slidably received within said channel to permit circumferential movement of the collar about the pile outer surface when said collar is connected to a floating vessel.

6. In an apparatus as defined inclaim 1. wherein said lower anchoring section includes: at least one clongated cylindrical pile cinbedded into the substrate beneath said body of water in a substantially upright position.

Claims (6)

1. A vessel mooring and liquid transfer apparatus for an offshore body of water being adapted to moor and communicate a floating vessel with a submerged source of liquid cargo, which transfer apparatus includes; an elongated column disposed normally in a substantially upright disposition with said body of water and having an upper buoyant portion and a lower anchoring section, the latter being embedded into the floor beneath said body of water, flexible coupling means operably connecting said respective lower section and upper buoyant portions, to permit limited pivotal movement of the latter about said anchoring section, an articulated conduit disposed within said elongated column having a pivotal segment extending beyond the upper end of said column and having means on said the ends of conduit to engage said floating vessel for transferring liquid cargo between said vessel and said liquid cargo source, said conduit including a flexible connection therein to permit pivotal movement of the conduit in response to pivotal movement of said column buoyant portion, and vessel mooring means depending from said anchoring section at a pOint adjacent to the floor of said body of water, and spaced vertically downwardly from said conduit end, being rotatably carried on said anchoring section operable to removably engage a mooring line extending to said vessel whereby to permit limited movement of the latter about said transfer apparatus during a cargo transfer operation.

2. In an apparatus as defined in claim 1, wherein said flexible coupling means includes; a plurality of flexible lines interconnecting the respective upper portion and lower anchoring sections to permit said limited pivotal movement therebetween.

3. In an apparatus as defined in claim 1, wherein said lower anchoring section includes; at least one elongated foundation member substantially embedded along its length into the substrate beneath said body of water, the upper end thereof being disposed above the surface of said floor, said vessel mooring means including a collar rotatably carried on said anchoring section at the end thereof extending above the ocean floor.

4. In an apparatus as defined in claim 3, wherein said lower anchoring section includes; at least one elongated cylindrical pile having the lower end thereof embedded in the substrate, and the pile upper end extending beyond the floor of said body of water, and means forming a circumferential track about said pile extending upper end, said collar being guidably received within said track to permit circumferential movement of the collar about said pile when the collar is connected to said vessel.

5. In an apparatus as defined in claim 4, wherein said pile upper end projecting above the substrate includes a pair of longitudinally spaced circumferential rings defining a channel therebetween, said collar being slidably received within said channel to permit circumferential movement of the collar about the pile outer surface when said collar is connected to a floating vessel.

6. In an apparatus as defined in claim 1, wherein said lower anchoring section includes; at least one elongated cylindrical pile embedded into the substrate beneath said body of water in a substantially upright position.

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