US3412981A

US3412981A - Marine platform support assembly

Info

Publication number: US3412981A
Application number: US582984A
Authority: US
Inventors: George T Richardson
Original assignee: Offshore Co
Current assignee: SONAT OFFSHORE DRILLING Inc
Priority date: 1966-09-29
Filing date: 1966-09-29
Publication date: 1968-11-26
Anticipated expiration: 1985-11-26
Also published as: ES344868A1; BE704549A; DE1634510C3; GR34308B; SE319731B; DK139199B; DK139199C; JPS4939473B1; DE1634510A1; DE1634510B2; NL6712834A; GB1147293A; NO125150B

Description

Nov. 26, 1968 i ,1, c npscjN 3,412,981

MARINE PLATFORM SUPPORT ASSEMBLY.-

Filed Se t/-29. 1966 3 Sheets-Sheet 1 I I NVENTOR. Gsones T'. Rlcnnnosm Nov. 26, 1968 T. RICHARDSON 3,412,981

MARINE PLATFORM SUPPORT ASSEMBLY Filed Sept. 29, 1966 s Sheets-Sheet 2 INVENTOR. GeoneeT. RmHAnosou Nov. 26, 1968 Filed Sept. 29, 1966 G. T. RICHARDSON MARINE PLATFORM SUPPORT ASSEMBLY I X 12 .d u l' 0 N 2 x 998 F\ I N Q z. o Q \l o o m \9 O o N I5 Sheets-Sheet 3 ""WTTIIIIIM',

Q/ g g? l vEN R GEORGE T. RICHARDSON United States Patent 3,412,981 MARINE PLATFORM SUPPORT ASSEMBLY George T. Richardson, Houston, Tex., assignor to The Offshore Company, Houston, Tex., a corporation of Delaware Filed Sept. 29, 1966, Ser. No. 582,984 13 Claims. (Cl. 254106) This invention relates to a marine platform support assembly. More particularly, the invention relates to a marine platform support assembly having a rigid support leg comprised of a plurality of tubes to extend between the marine platform and a marine bottom. Still more particularly the invention relates to a horseshoe or crescent-like jacking assembly for such a multitube support leg of a marine platform.

Marine platforms, such as dock or offshore oil well drilling barges which are buoyant and adapted to be towed or otherwise propelled to a marine site are frequently provided with openings through which a corresponding number of supporting legs are arranged to be extended These supporting legs have been constructed of single tubes which have been raised and lowered relative to the platforms by jacking assemblies which completely enveloped the tubes. However when used in deep water, for example, in depths over 100 feet, with the supporting legs embedded in the marine bottom and the platform raised on the supporting legs to an operative position above wave action, such tubes have had a long unsupported length extending between the marine bottom and the platform. Thus, the tubes have been subjected to high bending forces created by wave, wind or current action, particularly during storms, creating a condition which in some circumstances may be unsafe as well as unstable.

In order to satisfactorily brace the tubes against the forces causing the high bending forces, proposals have in some cases been made to increase the dimensional extent of the tubes to provide a greater section modulus against bending. This has also been accompanied by proposals to increase the weight of the tubes. However, such would not only cause the handling of these tubes to be extremely diflicult but would also make the tubes too cumbersome to be manipulated by a jacking mechanism of practical size. Also, increasing the dimensional extent has increased the possibility of localized buckling of sections of the tubes. Further, strengthening of the tubes by increasing the cross section would not adequately solve the platform stabilizing problem occasioned by increased leverage of the platform with respect to the tubes at greater water depths. Other proposals have been made to interconnect the tubes by auxiliary bracing after the platform has been erected. However, such is also not a wholly satisfactory solution as it cannot be readily accomplished underwater where it is most needed without the use of divers. Similarly, providing the platform with a set of temporary supporting legs and a set of permanent interconnected supporting legs is also not wholly satisfactory as not only are structures of excessive bulk and weight needed but also a greater erection time is required for proper positioning of the platform.

Generally, this invention provides a marine platform with a support assembly having a plurality of supporting legs constructed of a plurality of tubular members interconnected by bracing which are raised and lowered relative to the platform by jacking assemblies of horseshoe or crescent-like shape mounted on the platform. Each supporting leg is sized to pass through a cut-out in the deck of the platform and is of sufficient rigidity to withstand the bending loads imposed by the wind, wave or current action when embedded in a marine bottom to support the marine platform. The crescent-like jacking as- 3,412,981 Patented Nov. 26, 1968 ice semblies are each constructed of a pair of vertically spaced horseshoe or crescent-like yokes which are disposed longitudinally of a tubular member of the support leg and movable relative to each other by a vertical jack means. Each yoke has a pair of hydraulic pin cylinder devices mounted at the ends which are adapted to cooperate with apertures in or apertured racks on a tubular member of a support leg. The jacking assemblies are shaped so as to move transversely of a leg when being mounted or dismantled for maintenance without interfering with the bracing connecting the tubular members of a support leg. In addition, each jacking assembly has a guide means removably secured thereon which maintains the jacking assembly on the associated tubular member and guides the jacking assembly during longitudinal movement relative to the associated tubular member. The guide means is secured in place after a jacking assembly is brought into position on a tubular member.

The jacking assemblies are mounted on the support legs between a platform and a jackhouse and actuated in unison to move relative to the support leg. Each jacking assembly is of such dimensions so as to resist skewing on a support leg tubular member. Since the jacking assemblies do not completely surround the tubular members, the jacking assemblies are of reduced weight. Consequently, each jacking assembly can be handled with greater ease and portability.

Accordingly, it is an object of the invention to provide a jacking assembly for a marine platform support leg of multi-member construction.

It is an other object of the invention to provide a jacking assembly of crescent-like shape for cooperation with a tube of a multitube support leg of a marine platform.

It is another object of the invention to provide a crescent-like jacking assembly for a multitube support leg which is portable.

It is another object of the invention to provide a jacking assembly of crecent-like shape for a support leg of a marine platform which is readily movable transversely of the support leg.

It is another object of the invention to provide a jacking assembly for a support leg of a marine platform which is of reduced weight.

It is another object of the invention to provide a crescent-shaped jacking assembly for engaging a leg support of a marine platform at points apart.

It is another object of the invention to provide a jacking assembly which utilizes the same power in both directions of travel relative to a leg support of a marine platform.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a perspective schematic view of a marine platform with a support leg according to the invention;

FIG. 2 illustrates a segmented schematic view of a support leg of the invention passing through the deck of a marine platform;

FIG. 3 illustrates a partially broken front view of a jacking assembly of the invention on a tubular member of the support leg;

FIG. 4 illustrates a plan view of the jacking assembly of FIG. 3 on the tubular member of the support leg; and

FIG. 5 illustrates a view taken on line 55 of FIG. 4.

Referring to FIGS. 1 and 2, a marine platform 10 constructed in accordance with the invention includes a support assembly having a plurality of leg supports 11, for example, four passing through cut-outs 12 in the deck 13 of the marine platform 10 to support the platform 10* on a marine bottom. Each support leg 11 is formed of three elongated tubular members 14 which are interconnected by lateral bracing 15 to form a single rigid leg. The tubular members 14 are arranged in a triangular fashion with respect to each other in order to present a support leg which is able to resist the high bending forces imparted by wind and water, for example, during periods of storm or when the legs extend through great depths of water to support the platform 10. The bracing 15 is secured to the tubular members 14 in any suitable manner such as by welding and may consist of pipes, rods, angles or other conventional bracing members.

The 'leg supports 11 are moved in a vertical direction relative to the platform by means of jacking assemblies 16 mounted on each of the tubular members 14 in order to raise or lower the leg supports 11 relative to a marine bottom or to raise or lower the platform 10 on the leg supports 11 when supported on the marine bottom. The jacking assemblies are mounted in a floating condition on the tubular members between the deck 13 and a jackhouse 17 positioned above the deck 13. Each jacking assembly 16 is independent of fixed connection with the deck 13 and jackhouse 17 (FIG. 2).

Referring to FIGS. 3, 4 and 5, each tubular member 14 is of cylindrical cross section, although any suitable polygonal cross section can be utilized, and is provided with a pair of racks 18 extending longitudinally along the exterior of member 14. Each rack 18 is provided with an aligned series of apertures 19 disposed along the length of the rack for cooperation with a jacking assembly 16. Alternatively, the racks 18 can be omitted and the apertures can be formed in the tubular member 14. Also, other types of known rack devices can be used such as gear types. The racks 18 are disposed on the tubular mem ber 14 outside the points of connection of the bracing interconnecting the tubular member 14 with the remaining tubular members of the leg support 11 so as to provide a suflicient clearance between the jacking assembly 16 and bracing 15. For example, where three tubular members are used in equilateral fashion, the racks are disposed 180 apart.

Each jacking assembly 16 is of crescent-like or horseshoe shape so as to be moved transversely of a tubular member 14 during mounting of the jacking assembly on the tubular member or removal therefrom. This shape permits separate jacking assemblies 16 to be mounted individually on each of the tubular members 14 of a leg support 11 instead of using a single massive jacking assembly to envelop the entire support leg circumferentially. The jacking assembly 16 is mounted between the deck 13 and jackhouse 17 in floating relation for abutment with a resilient buffer means 20 secured to the upper surface of the deck 13 and the underside of the jack'house 17. Depending on the operation of the marine platform, that is, whether the leg supports 11 are being raised or lowered relative to a marine bottom or whether the platform 10 is being raised or lowered on the leg supports 11, the jacking assembly 16 is in abutment with one of the buffer means 20.

The jacking assembly 16 includes a pair of vertically spaced crescent-like yokes 21 disposed longitudinally of the tubular member 14 opposite the bracing 15, a pair of hydraulic pin cylinder devices 22, similar to the hydraulic pin cylinder apparatus disclosed in copending US. patent application Ser. No. 562,400, filed July 1, 1966-, mounted at the ends of each yoke 21 for cooperation with the racks 18 and a vertical jack means 23- for moving the yokes 21 relative to each other.

The yokes 21 are constructed of metal plates 24, such as steel plates which are welded together, in tubular form with a substantially square cross section (FIG. 5) which is suitably stiffened by interior stiffener plates (not shown). Each yoke is shaped with a substantially straight intermediate section and arcuate-like end sections to form a substantially crescent-like or horseshoe shape. However, any suitable shape can be used for the yokes provided the pin cylinder devices are in cooperation with a pair of apertured racks and the yokes are able to resist skewing on the tubular member, for example, a block C, L or arcuate shape. The term crescent-like is thus used to provide a generic definition for these various shapes.

The pin cylinder devices 22 are connected to the ends of the yokes 21 as by welding so as to be disposed opposite the racks 18 of the tubular member 14. Each pin cylinder device 22 has a hydraulically operated reciprocally mounted pin 25 which, as described in the above mentioned patent application, is adapted to be reciprocated into and out of the apertures 19 of the racks 18 for moving the tubular member 14 relative to the deck 13. In addition, each pin cylinder device 22 is provided with a limit switch mechanism 26 and an electrical circuit (not shown) which is integrated with similar structure of the other pin cylinder devices 22 of the jacking assemblies 16 so that all the jacking assemblies are operated in unison in a manner similar to the system described in patent application Ser. No. 562,401, filed July 1, 1966.

The vertical jack means 23 consists of a pair of telescoping jacks, as disclosed in the above mentioned patent application, each of which is secured to a vertically aligned pair of pin cylinder devices 22 to connect the yokes 21 together for relative movement to each other.

In addition, each jacking assembly 16 is provided with a guide means for maintaining and guiding the jacking assembly 16 on the tubular member 14. The guide means includes a guide bracket 27 (FIG. 4) removably mounted, as by bolts 28, on each pin cylinder device 22 on a side opposite the yoke 21. Each guide bracket 27 includes a bearing pad 29, such as a brass pad, on the face disposed opposite to and in slightly spaced relation to the side of a rack 18 to the other side of the yoke 21. The guide brackets 27 are each mounted on the respective pin cylinder devices 22 after the jacking assembly has been brought into mounting position on the tubular member 14 with each pin 25 in a retracted position. Conversely, when the jacking assembly 16 is to be removed from the tubular member 14, the guide brackets 27 are eac removed.

Also, each jacking assembly 16 is provided with bumpers 30 centrally of each yoke 21 for guiding the jacking assembly 16 along the tubular member 14. The bumpers 30 are arranged in pairs on the upper and lower surfaces of each yoke 21 and disposed in the direction of the tubular member 14. Each bumper 30 consists of a generally L shaped bracket 31 which is mounted by bolts 32 to a mounting plate 33 fastened to the yoke surface as by welding. The face of the bracket 31 depends along the inside of the yoke 21 in opposition to the tubular member 14 and has a projecting bearing plate 34 secured thereon by bolts 35 in slightly spaced relation to the tubular member 14. The bumpers 30 serve with the guide bracket 27 to guide the jacking assembly 16 on the tubular member 14 during use.

Alternatively, the bumpers may be omitted and the yokes shaped to conform substantially to the shape of the tubular member, with or without pads between the yokes and tubular member.

The invention thus provides a marine platform with a support assembly having a multi-rnernber support leg which is able to resist the high bending forces imparted to the support legs during towing of the platform as well as during adverse wind and water conditions when erected at a marine site. The members of the support legs are each sized of smaller cross section than a single tube which has been used before for the same water depths and thus allow an easier handling of the support leg. Additionally, the jacking assembly of the support assembly is of a size and shape so as to be easily positioned and secured on the members of the support leg. It is seen from the foregoing how these and other objects of the invention referred to herein may be achieved by the invention.

Having thus described the invention, it is not intended that it be so limited as changes may be readily made therein without departing from the scope of the invention. Accordingly, it is intended that the subject matter described above and shown in the drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In combination with a support leg of a marine platform having a plurality of spaced elongated members in interconnected braced relation; a plurality of jacking assemblies, each of said jacking assemblies being disposed on a respective one of said members, each of said jacking assemblies including a pair of spaced crescent-like yokes disposed longitudinally of said member, a jack means connecting each of said yokes in movable relation to each other, and a pair of pin cylinder devices mounted at respective ends of each of said yoke for removable engagement with said member.

2. The combination as set forth in claim 1 wherein each said member includes a pair of apertured racks thereon for removable engagement with said pin cylinder devices.

3. The combination as set forth in claim 2 wherein each said jacking assembly includes a removable guide means for maintaining said jacking assembly on said member and for guiding said jacking assembly on said member during relative movement thereto.

4. The combination as set forth in claim 1 wherein each said jacking assembly includes bumper means mounted on each of said yokes in opposition to said member for guiding said jacking assembly on said member.

5. The combination as set forth in claim 1 wherein each member is tubular.

6. The combination as set forth in claim 1 wherein said pair of pin cylinder devices are disposed substantially 180 apart.

7. The combination as set forth in claim 1 wherein said support leg is formed of at least three tubular members.

8. In combination with a marine platform having a deck, a vertically spaced jackhouse above said deck, and a plurality of support legs passing through said deck for supporting the platform on a marine bottom, each support leg having a plurality of spaced tubular members in interconnected braced relation and each support tubular member having a pair of longitudinally disposed racks thereon; a jacking assembly on each of said tubular members between said deck and jackhouse for movement relative to said tubular member, said jacking assembly comprising a pair of spaced crescent shaped yokes disposed longitudinally of said tubular member, a jack means conmeeting said yokes for relative movement to each other, a pair of hydraulic pin cylinder devices mounted at respective ends of each of said yokes for removable engagement with said racks on said tubular member, said devices being disposed substantially 180 to each other, and removable guide means on each of said devices at one side of a respective rack for maintaining said jacking assembly on said tubular member and for guiding said jacking assembly on said tubular member during relative movement thereto.

9. The combination as set forth in claim 8 wherein each said jacking assembly further includes bumper means mounted on each said yoke for guiding said jacking assembly on a tubular member.

10. The combination as set forth in claim 9 wherein said support leg has at least three equi-spaced tubular members.

11. A jacking assembly for an elongated member including a pair of spaced crescent-like yokes, a jacking means connecting each of said yokes in movable relation to each other, and a pair of pin cylinder devices mounted at respective ends of each said yokes for removable engagement with the elongated member.

12. A jacking assembly as set forth in claim 11 further including a removable guide means for maintaining and guiding said jacking assembly on said elongated member.

13. A jacking assembly as set forth in claim 11 wherein said pin cylinder devices are disposed substantially 180 apart.

References Cited UNITED STATES PATENTS 2,992,812 7/ 196 1 Rasmussen et a1. 254--107 3,171,259 3/1965 Roussel 254- X FOREIGN PATENTS 949,420 2/ 1964 Great Britain.

OTHELL M. SIMPSON, Primary Examiner.

Claims

1. IN COMBINATION WITH A SUPPORT LEG OF A MARINE PLATFORM HAVING A PLURALITY OF SPACED ELONGATED MEMBERS IN INTERCONNECTED BRACED RELATION; A PLURALITY OF JACKING ASSEMBLIES, EACH OF SAID JACKING ASSEMBLIES BEING DISPOSED ON A RESPECTIVE ONE OF SAID MEMBERS, EACH OF SAID JACKING ASSEMBLIES INCLUDING A PAIR OF SPACED CRESCENT-LIKE YOKES DISPOSED LONGITUDINALLY OF SAID MEMBER, A JACK MEANS CONNECTING EACH OF SAID YOKES IN MOVABLE RELATION TO EACH OTHER, AND A PAIR OF PIN CYLINDER DEVICES MOUNTED AT RESPECTIVE ENDS OF EACH OF SAID YOKE FOR REMOVEABLE ENGAGEMENT WITH SAID MEMBER.