Patent Grant
7527450
1. Field of the Invention
The invention relates to the apparatus and a method for the construction and installation of floating oilfield production structures having their main structural elements pin-connected. More particularly, the present invention relates to the pin assembly used to interconnect the structural elements of the floating oilfield production structures.
2. Description of the Related Art
Pinning structures in underwater applications is often performed by robots, by personnel working from some distance utilizing submersible craft with remote manipulators, or by personnel in underwater suits. Currently used pins for engaging and disengaging structural connections between different components of a floating offshore platform are solid cylindrical pins that engage cylindrical socket bores.
A need exists for pinned connections that are easy to stab and which can have the gaps between the mating elements minimized or eliminated when the pins are engaged.
A further need exists for pinned connections that can be accessed for maintenance and repair underwater.
In addition, a need exists for robust pinned connections that have very low stress levels in operation so that metal fatigue and contact surface galling or fretting are not a problem.
The present invention relates to pins that may be selectably operated to engage and disengage socket bores in the assembly and disassembly of large structures, such as floating offshore platforms for deepwater applications. The pin connections can be engaged or disengaged robotically or under direct operator control. The construction and installation of structures utilizing the pin connections will typically use multiple sets of selectably operable pins to connect, support and stabilize the structural components of the structure.
One aspect of the present invention is a pin assembly comprising: (a) a pair of pin sockets mounted on a first structure, wherein the pin sockets are spaced apart and have opposed coaxially aligned pin receiving bores; (b) a second structure having a pin mounting bore; (c) a pair of opposed pins, reciprocably mounted in the pin mounting bore, the pins being coaxial and comateable with the pin receiving bores, wherein each pin includes (i) a hollow pin casing, (ii) at least one internal diaphragm to support the casing, and (iii) a pressure equalization means for equalizing a pressure in the pin casing with an environmental pressure outside the pin casing; (d) a sealing means for sealing a gap between the pin casing and the pin mounting bore, and (e) a selectably operable, bidirectional pin actuator mounted on a first end of each pin.
A second aspect of the present invention is a pin assembly comprising: (a) a pair of pin sockets mounted on a first structure, wherein the pin sockets are spaced apart and have opposed coaxially aligned pin receiving bores; (b) a second structure having a longitudinal midline and a through bore penetrating a distal end of the second structure, wherein the through bore has a through bore diaphragm coplanar with the midline of the second structure and fixedly mounted in the through bore; (c) a pair of opposed pin members, with one pin member positioned on each side of the through bore diaphragm, wherein the pin members are coaxially aligned in the through bore and the pin members are reciprocably comateable with the pin receiving bores, wherein each pin member has a hollow pin casing and at least one pin diaphragm to support the casing; (d) a pin chamber bounded by the pin member, the through bore and the through bore diaphragm; (e) a sealing means for sealing a gap between the pin casing and the through bore, (f) a flow passage communicating between an inside of the pin chamber and an outside of the pin chamber; (g) a selectably operable valve, wherein whenever the valve is open flow is permitted through the flow passage and whenever the valve is closed flow is prevented through the flow passage; and (h) a pair of selectably operable, reciprocable actuators, each actuator fixedly attached at a first end to the through bore diaphragm and at a second end to the pin member.
Another aspect of the present invention is a pin assembly comprising: (a) a pair of pin sockets mounted on a first structure, wherein the pin sockets are spaced apart and have opposed coaxially aligned pin receiving bores; (b) a second structure having a longitudinal midline and a through bore penetrating a distal end of the second structure, wherein the through bore has a through bore diaphragm coplanar with the midline and fixedly mounted in the through bore; (c) a pair of opposed pin members, with one pin member positioned on each side of the through bore diaphragm, wherein the pin members are coaxially aligned in the through bore and the pin members are reciprocably comateable with the pin receiving bores, wherein each pin member has a hollow pin casing and three pin diaphragms including an end transverse diaphragm closing a first end of the pin casing, and a first and second transverse diaphragm fixedly attached to the pin casing and spaced apart from the end diaphragm and from each other; (d) a pin chamber bounded by the pin member, the through bore and the through bore diaphragm; (e) a sealing means for sealing a gap between the pin casing and the through bore, (f) a flow passage communicating between an inside of the pin chamber and an outside of the pin chamber; (g) a selectably operable valve, wherein whenever the valve is open flow is permitted through the flow passage and whenever the valve is closed flow is prevented through the flow passage; (h) a selectably openable access passage in the end transverse diaphragm of the pin member, wherein the access passage passes from the outside of the pin chamber to the inside of the pin chamber; (i) a pair of selectably operable, reciprocable actuators, each actuator fixedly attached at a first end to the through bore diaphragm and at a second end to the pin member, wherein the actuator reciprocates between a first position and a second position such that when the actuator is in the first position the pin member is partially extended from the through bore and when the actuator is in the second position the pin member is within the through bore and an external face of the pin member is substantially flush with an outer end of the through bore; () a pumping means for selectably pumping fluid into or out of the pin casing; and (k) a lubricant injection port for injecting lubricant into a lubricant distribution groove in an external surface of the pin casing.
Yet another aspect of the present invention is a method for using a pin assembly to interconnect structural components, the method comprising the steps of: (a) mounting a pair of pin sockets on a first structure, the pin sockets being spaced apart and having opposed coaxial pin receiving bores; (b) mounting a pair of opposed coaxially aligned pins in a pin mounting bore positioned in one end of a second structure, wherein each pin includes a hollow pin casing, a sealing means for sealing a gap between the casing and the pin mounting bore, at least one internal diaphragm to support the casing, and a pressure equalization means for equalizing a pressure in the pin casing with an environmental pressure outside the pin casing, and wherein a distal end of the pins is extendable from the pin mounting bore and retractable into the pin mounting bore; (c) positioning the pins in the pin mounting bore of the second structure between the pin sockets such that the pin receiving bores and the pins are coaxially aligned; and (d) extending the pins into the pin receiving bores to rotatably connect the first structure to the second structure.
Still yet another aspect of the present invention is a method for using the pin assembly described above to interconnect structural components, the method comprising the steps of: (a) positioning the pin members in the pin mounting bore of the second structure between the pin sockets mounted on the first structure such that the pin receiving bores and the pin members are coaxially aligned; (b) injecting lubricant into the lubricant distribution groove of the pin members to lubricate the gap between the pin casing and the through bore; (c) opening the valve to allow pressure equalization between an inside and an outside of the pin chambers; (d) moving the actuators to a first position to extend the pin members into the pin receiving bores; (e) closing the valve to prevent fluid from leaving the pin chamber; and (f) locking the pin members into the pin receiving bores using a keeper pin.
Another aspect of the present invention is a method for disconnecting structural components connected using the pin assembly described above, the method comprising the steps of: (a) unlocking the pin members extended into the pin receiving bores by removing a keeper pin; (b) injecting lubricant into the lubricant distribution groove to lubricate the gap between the pin casing and the through bore; (c) opening the valve to allow pressure equalization between an inside and an outside of the pin chamber; (d) moving the actuators to a second position to retract the pin members into the pin mounting bore; and (e) closing the valve.
Yet another aspect of the present invention is a method for using the pin assembly described above to interconnect structural components, the method comprising the steps of: (a) positioning the pin members in the pin mounting bore of the second structure between the pin sockets mounted on the first structure such that the pin receiving bores and the pin members are coaxially aligned; (b) injecting lubricant into the lubricant distribution groove of the pin member to lubricate the gap between the pin casing and the through bore; (c) closing the valve, if the valve is open; (d) moving the actuators to a first position while pumping fluid into the pin chambers of the pin members to extend the pin members into the pin receiving bores; and (e) locking the pin members into the pin receiving bores using a keeper pin.
Still yet another aspect of the present invention is a method for disconnecting structural components connected using the pin assembly of claim 62, the method comprising the steps of: (a) unlocking the pin members extended into the pin receiving bores by removing a keeper pin; (b) injecting lubricant into the lubricant distribution groove to lubricate the gap between the pin casing and the through bore; (c) closing the valve, if the valve is open; (d) releasing the hydraulic cylinder; (d) moving the actuators to a second position while pumping fluid out of the pin chamber so that the differential in hydrostatic pressure external to the pin chamber and pressure within the pin chamber urge the pin members to retract into the pin mounting bore.
The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed might be readily utilized as a basis for modifying or redesigning the structures for carrying out the same purposes as the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The present invention relates to pins that may be selectably operated to engage and disengage socket bores in the assembly and disassembly of large structures, such as floating offshore platforms for deepwater applications. The pin connections can be engaged or disengaged robotically or under direct operator control. The construction and installation of structures utilizing the pin connections will typically use multiple sets of selectably operable pins to connect, support and stabilize the structural components of the structure. For example, the pins are useful in the assembly and disassembly of a new type of floating moored oilfield offshore platform for deepwater applications. This new platform type is described in a copending U.S. patent application Ser. No. 11/051,691 entitled “Inclined Leg Floating Production Platform with a Damper Plate”, filed Feb. 4, 2005.
The pin connections are used for the assembly and disassembly of the offshore platform described below. The construction and installation of the described floating oilfield drilling and production structure utilizes multiple sets of inclined buoyant legs in which are mounted selectably operable pins to connect, support and stabilize the deck structure and a subsurface damping plate.
The pin connections are selectably engagable and disengagable connectors between the subassemblies of structural components of the floating oilfield production structure. The structure components are initially assembled and configured in relatively shallow water, and then the preassembled structure is towed to a deepwater location and reconfigured to its operational configuration.
The illustrated platform operates in a manner similar to a folding table, in that its pins serve as rotationally free hinge connections. For purposes of illustration of the need for and operation of the pins, the operation of the platform using the first embodiment 100 of the pin connections of the present invention is discussed herein.
Platform 10 has multiple parallel buoyant leg pairs 25, each pair consisting of a leg 26 and a leg 43 pivotably interconnected by a permanent pin 70. The legs are internally compartmented down their lengths and the compartments are interconnected by ballast piping to permit selectable adjustment of their buoyancy. Opposed pairs of selectably extendable and retractible pins 101 are positioned in pin mounting bores 136 in the upper and lower leg ends 36 of the legs 26 and 43 of the platform. Adjacent legs 26 are transversely interconnected by diagonal braces 78, as are the adjacent legs 43. The legs 26 are all coplanar in a plane containing the axes of their coaxial permanent pins 70. The legs 43 are also all coplanar in a plane containing the axes of their coaxial permanent pins 70.
The axes of the permanent pins 70 and the selectably operable pins 101 located in the leg ends 36 are always parallel. The legs in each pair 25 are crossed as seen in
Initially, platform 10 is preassembled inshore by means of the half of the selectably operable pins of the present invention that are located in the leg ends 36 of the legs 26. The platform deck 11, the leg pairs 25 with their pins 101, and the damper plate are separately fabricated and completed prior to preassembly. The preassembly consists of arranging the separate deck 11, leg pairs 25, and damper plate 90 components as shown in
In the preassembled condition of
Upon arrival at its installation location, the platform 10 is reconfigured in a two-step sequence by means of controlled buoyancy adjustments of the legs and further engagement of previously disengaged pins.
The components of the main structural elements of the novel floating production platform 10 of the present invention are typically constructed of steel. The design of the structural platform uses tubular members, stiffened shells, frames, and stiffened plate structures commonly found in shipyard and offshore construction. Welding is the primary means of assembly for the structural components of the individual subassemblies. Components related to the pins, such as connecting pins, pin mountings, and pin sockets, require closer tolerances and are typically machined. Standard shipyard, steel fabrication, and machining techniques are available for the manufacture of each of the primary structural components, such as the deck 11, the legs 26 and 43, and the damper plate 90. Other than for application to the pins of the present invention, the manufacturing techniques for those platform components are well known to those skilled in the art and are not discussed herein.
The pins of the pin embodiments 100, 200, 300, 400, 500, and 600 may be cast in one piece and then machined. In such a case, the pin material would probably be a ductile iron or an austempered ductile iron. Alternatively, the pins could be made of a combination of rolled plate rings and either cast or forged disks and rings, with steel being used throughout for weldability. For the fabricated pins, the pins would be machined following welding. Lathe or horizontal boring mill turning is necessary for the exterior of the pins in order to carefully control their size and configuration.
Typically, the pin sockets 118 are welded from plate, but cast and machined subassemblies alternatively could be used around the bores of the pin sockets. In all cases, the pin mounting bores 136 of each group of the leg ends 36 at the upper and lower ends of legs 26 and 43 must all be machined to be coaxial. This machining generally will be performed in situ with portable boring equipment when the leg pairs 25 are finally assembled by their permanent pins 70 and the diagonal braces 78. The final assembly of the set of leg pairs 25 in the fabrication yard requires that adjacent legs 26 from separate leg pairs be interconnected by diagonal braces 78 and that, additionally, adjacent legs 43 from separate leg pairs be interconnected by other diagonal braces 78. Likewise, the mounted pin sockets of each group must be machined to be coaxial. This machining in most cases will have to be done after assembly of the legs and assembly of the sockets to either the deck or the damper-plate in order to ensure proper fit.
In
The deck is supported by a leg system consisting of multiple buoyant leg pairs 25. Each leg pair includes similar legs 26 and 43 cojoined by a permanent pin 70 which is located in the central portion of the legs and which serves as a hinge or pivot. The first leg 26 and the second leg 43 of a leg pair are laterally offset from each other in the direction of the axis of the permanent pin 70, to permit them to freely rotate in parallel planes relative to each other about permanent pin 70. The permanent pins 70 of the set of leg pairs 25 are coaxial, with all of the first legs 26 of the leg system coplanar in a plane containing their longitudinal axes and their permanent pins 70, and with the second legs 43 similarly mutually coplanar in a separate plane.
The selectably extendable and retractible field mateable pin assemblies of the present invention are mounted in opposed pairs in the pin mounting bores 136 of the distal leg ends 36 of each leg 26 and 43. Each pin assembly embodiment 100 includes a pin and a comateable pin socket.
The first embodiment of the pin assembly 100 has a hollow pin 101 with a coaxial internal double-acting hydraulic cylinder 60 and an access flange assembly 55 as its major subassemblies as shown in
The leg system consisting of multiple leg pairs 25 is transversely connected and fixedly spaced apart by tubular diagonal braces 78 in order to maintain the leg pairs mutually parallel and so that loads may be efficiently transferred between adjacent leg pairs. The combination boat landing and strongback 84 is a tubular truss rigidly attached to the legs 26 just above the operational waterline for the platform 10. The combination boat landing and strongback 84 serves as a strongback when it is also temporarily connected to the legs 43 during towout of the platform 10. This temporary connection maintains the legs 43 parallel to the legs 26 during towout, thereby avoiding overstress of the permanent pin 70 interconnecting the legs 26 and 43 of each leg pair 25.
The damper plate assembly 90 primarily serves to provide a large hydrodynamic mass to contribute to lower platform response to wave action, but it also interconnects the bottom end of the leg pairs 25 to help rigidize the platform 10 in the planes perpendicular to the axes of the permanent pins 70.
Prior to the connection of the last set of corresponding pins on the linkage, the linkage is not rigid. The diagonal braces 78 assist the pin connection joints formed by the field mateable pin sockets 118 with the field mateable pin assemblies 101 in maintaining the overall rigidity of the platform in the transverse vertical secondary plane containing the axes of the permanent pins 70. Additionally, a combination boat landing and strongback 84 is used to further connect the legs 26 of the platform 10 on one side of the platform. If a second, optional combination boat landing and strongback 84 is used on the other side of the platform, it also further connects the legs 43.
Preassembly and Assembly of the Platform
Referring to
In contrast to most platform types, the preassembly, shown in
Referring to
For this preassembly arrangement, the pins 101 at the upper ends of the legs 26 are engaged with the pin sockets 118 on the first side of the fully outfitted deck 11 so that the legs 26 are rotatably connected thereto. The pins 101 at the lower end of the legs 26 are rotatably engaged with the pin sockets 118 at the first side of the damper plate 90. The damper plate 90 is lifted into position for connection to the legs 26 by cranes or, alternatively, floated into position with its first side ballasted down. This preassembled arrangement of the platform 10 is rigid in the horizontal plane, but is articulated about its pins 101 engaged in the pin sockets 118 of the deck 11 and the damper plate 90.
When towing offshore, the damper plate 90 is normally restrained from movement relative to the legs 26 by tiedowns or hydraulic cylinders or both. As shown in
After arrival at or near the installation location for the platform 10, the second step of the platform assembly can be performed. To prepare for this second step of the platform assembly, the temporary connections of the legs 43 to the combination boat landing and strongback 84 are removed and arrangements for controlled adjustment of the ballast in the legs 26 and 43 are made. In addition, any fixed restraints used to hold the damper plate 90 rigid relative to the legs 26 during towout are removed and the structure of the damper plate is made free-flooding.
Following these preparatory steps, the transition of the linked primary elements of the platform 10 from the preassembled state shown in
The legs 43 are caused to rotate to the position shown in
The installed position of the travel stops 128 is such that when the leg end 36 abuts the travel stop, the pins 101 are aligned or substantially aligned with the bore of their sockets 118. At this time, the selectably operable opposed pins 101 of the lower ends 36 of the legs 43 are extended outwardly to fully engage their corresponding sockets 118. This pinning of the legs 43 to the damper plate 90 rigidizes the combination of the leg pairs 25 and the damper plate. In this rigidized condition shown in
The transition from the completed second assembly step shown in
The adjustment of the ballast in the legs 26 and 43 is necessary so that a clockwise torque about the pinned connection of the legs to the deck is always acting on the combination. Again, the net buoyancy of the leg-damper plate combination is maintained at neutral or slightly negative during the rotation. When the leg-damper combination is fully rotated, as shown in
After the alignment produced by the abutment of the leg ends on the travel stops is achieved, the pins 101 at the upper end 36 of legs 43 are fully or nearly aligned with their respective bores in the pin sockets 118 on the second side of the deck 11. At this time, the remaining unengaged pins 101 at the upper end of the legs 43 are extended into full engagement with their corresponding sockets 118 and the platform 10 is fully rigidized and floating on the water surface 86 shown in
The various constituents of the first pin assembly embodiment 100 are shown in
1. Field Mateable Pins
The pins are mounted in coaxial outwardly extending opposed pairs which, when extended, are cantilevered from their housings in the pin mounting bores 136 of the leg ends 36. In addition,
Each side of the field mateable pin assembly 100 consists of a pin 101, an access flange assembly 55, a hydraulic cylinder assembly 60, and a spacer block 65, all mounted to the central diaphragm 138 of the leg end 36 by means of threaded mounting studs 66 with nuts 67 assembled through comating holes in the cylinder base flange, the spacer block 65, and the diaphragm 138. As an example of a typical case, the diameter of the pin 101 is approximately 120 inches (3.28 m) so that sufficient space can be provided for personnel access inside. The diameter of the pin typically will be from 27% to 32% of the diameter of the leg end 36 in which the pin is housed, and the diameter of the manway passage 109 is 24 inches (0.656 m).
The pin 101 has a right circular cylindrical outer body or casing with an outer cylindrical surface 102 which is a close slip fit to the bore 136 and which has an external annular O-ring groove 103 containing O-ring 52 adjacent its open interior end. O-ring 52 sealingly mates with pin mounting bore 136 of the field mateable pin leg end 36. At its outer end, pin 101 has a slightly reduced diameter concentric entry cylindrical outer surface 105. A short concentric frustro-conical transition section 111 connects outer cylindrical surface 102 with the entry cylindrical outer surface 105. Although it is not shown here, the pin 101 is restrained against rotation about its longitudinal axis by means of a key and comating keyway or other similar means. The diameter of the pin 101 is such that it is a slip fit into and freely rotatable within a bore 119 of a pin socket 118.
A large bevel is provided on each external end of the external cylindrical body of each pin 101, and the pins are lubricated at assembly into their mounting bores 136. The outer end of pin 101 has an integral thick transverse end diaphragm 106 and a relatively thicker integral transverse annular ring middle diaphragm 107 positioned coaxially with the cylindrical pin body 101 and spaced inwardly from the end diaphragm. The distance between the distal side of the end diaphragm 106 and the transverse midplane of the middle diaphragm 107 is approximately equal to the axial thickness of the pin socket 118. End diaphragm 106 has an off-center externally counterbored hole 109 parallel to its axis for the mounting of access flange assembly 55. The hole 109 for flange 55 is made large enough to serve as a manway. Drilled and tapped holes are provided on the outwardly facing transverse face between the bore and counterbore in end diaphragm 106 consistent with the bolt hole pattern in the access flange 56. Additionally, the inner side of the end diaphragm 106 has a concentric drilled and tapped hole 112 for the attachment of the threaded rod end 63 of the hydraulic cylinder 60.
Close to the interior open end of pin 101 is located transverse interior end diaphragm 108, which is a thinner, relatively to diaphragms 106 and 107, annular right circular ring concentrically attached to the inner wall of the casing, or cylindrical body, of pin 101. Intermediate between the end diaphragm 106 at the outer end of pin 101 and middle diaphragm 107 is an interior boss reinforcing the cylindrical wall and sealing thereto to prevent leakage through a mutually concentric external blind radial locking pin socket 113 which is engageable by threaded keeper pin 125 of the field mateable pin socket 118.
The cylindrical body 102 of pin 101 is provided with multiple radial through holes 115, which serve as lubricant injection ports. Ports 115 are drilled and tapped on their interior ends and intersect corresponding shallow circumferential annular lubricant distribution grooves 104 on the cylindrical exterior 102 of pin 101. These grooves 104, shown in
Access flange 56 of the access flange assembly 55 shown in
A selectively operable ball valve 57 and hydraulic quick connect fittings 58 are threadedly and sealingly mounted to the ends of the through holes on the outward side of flange 56 and are recessed within the counterbores of those holes. The valve 57 and the quick connect fittings 58 do not extend outwardly past the transverse outer face of the access flange 56. The thickness of the radially outwardly extending flange of the access flange 56 is such that the heads of the bolts 59 do not extend outwardly of the outer face of the end diaphragm 106 of pin 101. Additionally, the interior ends of the through holes in flange 56 accommodating the outer quick connect fittings 58 are also tapped, thereby permitting the installation of a corresponding number of quick connect fittings 58 on the interior side of the flange 56. These quick connect fittings permit independent external supply of grease through hoses (not shown) to the quick connects in the lubricant injection ports 115, as well as permitting external powering and control of the hydraulic cylinder assembly 60.
The ball valve is selectably operated externally so that hydraulic lock of the pin 101 in the pin mounting bore 136 of the leg end 36 is avoided by permitting pressure equalization between the exterior and interior of pin 101 when shifting the pin position. The ball valve 57 is closed following completion of a pin move. For example, for underwater operations the ball valve may be opened to allow water into the pin casing to equalize the pressure with the water in the exterior environment.
The access flange assembly 55 is placed where it can be accessed and operated by a diver or a remotely operated vehicle (ROV) if underwater or by conventional means if it is above the water surface. This accessibility permits the connection and disconnection of hydraulic control lines, grease supply lines, and a valve operating means so that the ball valve 57 and the hydraulic cylinder 60 can be operated externally. Additionally, grease can be injected as required in order to lubricate the pin. Alternatively, the ball valve 57 and the quick connect fittings 58 may be mounted directly in the outer transverse diaphragm 106 if it is anticipated that the access flange assembly 55 will be utilized regularly.
The hydraulic cylinder 60 is of conventional double-acting design, with an outwardly extending transverse base mounting flange having mounting holes in a regular bolt hole pattern on the inner end of its generally hollow cylinder body 61. The flange permits cylinder mounting to the spacer blocks 65 and the bore middle diaphragm 138 by means of mounting studs 66 and hex nuts 67, as shown in
2. The Field Mateable Pin Sockets
Mounted on the pin socket mounting surfaces of both the deck 11 and the damper plate assembly 90 and extending perpendicularly thereto are a series of multiple pairs of parallel, spaced-apart, antisymmetric, coaxially mounted field mateable pin sockets 118 used to attach the leg ends 36, as described in more detail below. The number and positioning of the pairs of pin sockets 118 corresponds to the number and positioning of leg ends 36 attaching to the deck 11 or the damper plate assembly 90. The sockets 118 are rigidly connected to internal supporting structures (not shown) inside the deck and damper sections. The spacing of the leg sockets 118 in a pair is such that they are a relatively close fit to the external flats 131 of the leg ends 36, with only 0.125 to 0.25 inch (3 to 6 mm) of clearance gap. The corners of the sockets 118, which the leg ends 36 must pass during entry of the leg ends, are chamfered to ease entry. While not shown herein, the pin sockets 118 alternatively also may be structurally connected on their outer sides to their mounting surfaces with transverse lateral supports such as buttresses and knees in order to strengthen them for resistance to transverse loadings in the direction of their bore axes, as may be readily understood by those skilled in the art.
The field mateable pin sockets 118 are arranged in antisymmetrical pairs of buttress construction, so that they closely straddle a leg end 36 when a connection is made. The sockets 118 in a pair are perpendicular to the axis of the pins 101. The sockets 118 in a pair have coaxial horizontal axis straight bores 119 extending from their inner sides (which face the sides of the leg ends 36) most of the way through their thicknesses. The thickness of the sockets will be on the order of 50 inches (1.27 m). The bores 119 are parallel to the axes of the pins 101.
For simplicity, the lefthand socket shown in profile in
As may be seen in
Each pair of the field mateable pin sockets 118 are optionally provided with a pair of horizontal travel stops 128 welded on their interior facing transverse sides, as shown in
Referring to
3. Mateable Pin Leg End
Each leg 26 and 43 of platform 10 has a leg end 36 with a pair of field mateable pins 101 at each of its distal ends. A cross-section through both the longitudinal axis of the field mateable pins 101 mounted in a leg end 36 and the longitudinal axis of the leg end is shown in
A constant diameter through hole intersecting the leg longitudinal axis and normal to midplane A is adjacent the outer end of the leg end 36 and penetrates from one outside plate 131 to the other. The outer end 140 of the leg end 36 is radiused about the axis of the flat-to-flat through hole. The outer periphery of leg end 36 consists of the arcuate distal portion of the radiused leg end 140 adjacent its intersection with the flats formed by outside plates 131. This outer periphery is abutted by the abutting surfaces 129 of the travel stops 128 of the field mateable pin sockets 118 when a leg end 36 is being aligned for engagement of its pin assemblies 100. A pair of symmetrical plate flats 132 flare outwardly from the outside plates 131 of the leg ends 36 to intersect the cylindrical portion 130 of the leg ends.
Mounted by welding in the transverse through hole of the leg end 36 is a heavy wall right circular cylindrical tube 135 having a concentric latch pin bore 136, as shown in
Extending in the midplane A from the outer diameter of tube 135 to the interior of the outer shell of leg end 36 is a stiffened central diaphragm 139. Symmetrically spaced apart from and parallel to the central diaphragm 139 are two intermediate inboard longitudinal diaphragms 137 which extend outwardly from the outer cylindrical wall of the transverse tube 135 to the interior of the shell wall of the leg end. The intermediate diaphragms 137 are positioned so that when the transverse midplane of the middle diaphragm 107 of the pin 101 is at the outer end of the pin mounting bore 136, the intermediate diaphragms are substantially coplanar with the interior end diaphragm 108 of the pin.
One or more transverse bulkheads 133, 134 are positioned in the interior of leg end 36 perpendicular to the midplane A. One transverse bulkhead 133 is positioned where the outside plates 131 intersect the flaring symmetrical flats 132 of the leg end. Typically, a second transverse bulkhead 134 would be located close to the end of the flaring symmetrical flats 132 near to where the leg end 36 connects to the central leg body. The middle diaphragm 139, the intermediate diaphragms 137, and the transverse bulkheads 133, 134 are shown with plate construction, but may be stiffened plates, watertight bulkheads, or double walled shells with interior reinforcing. The transverse tube 135 may be locally thickened as required; the outside plates 131 and the intermediate diaphragms 137 may be locally reinforced and thickened at their intersections with the tube 135.
The middle diaphragm 138 of the tube 135 is provided with multiple through bolt holes in a pattern consistent with the mounting base flange of the body 61 of the hydraulic cylinder assemblies 60 which are used to latch by extending and unlatch by retracting the field mateable pin 101. The mounting bolt holes are positioned concentrically with the axis of the latch pin bore 136.
An O-ring type groove 141 is provided near the mouth of each side of the latch pin bores 136. An inflatable seal 142 is mounted in each of the grooves 141 and used to seal between the exterior of the pin 101 and the leg end 36. A pin cavity is formed between the pin mounting bore 136, the bore middle diaphragm 138, and the pin 101 and is sealed by the pin O-ring 52. This cavity is sealed so that the ball valve 57 on the access flange 55 of the pin 101 must be open in order to permit the pin to be moved freely in its pin mounting bore 136 without experiencing hydraulic lock.
The second embodiment 200 of the pin assembly of the present invention is shown in
Pin 201 has a cylindrical outer surface 202 which is a close sliding fit with the bore 136 of leg end 36. Adjacent the outer end of pin 201 and extending for a length of slightly less that the through thickness of the second pin socket embodiment 218 is a entry cylindrical outer surface 205 which has a slightly smaller diameter than surface 202. For instance, if the outer diameter of surface 202 is 120 inches, the outer diameter of surface 205 might be 118 inches. The central portion of the surface 205 has slightly undercut surface 216 with a diameter less than that of surface 205 for the purpose of reducing the chances of binding during insertion of pin 201 into socket 218. A short frustro-conical transition 211 is located between the entry cylindrical outer surface 205 and the main cylindrical outer surface 202.
The pins 201 are shown assembled into the leg end 36 in
The second pin socket embodiment 218, shown in
Referring to
The third embodiment 300 of the pin assembly of the present invention is shown in
Pin 301 has a cylindrical outer surface 302, which is a close slip fit with the bore 136 of the leg end 36. Frustro-conical section 311, which is the entire outer tip of pin 301, has an external frustro-conical taper which uniformly reduces in diameter from approximately the middle of interior transverse diaphragm 107 to the outer end of pin 301 at the outer transverse diaphragm 106. The single-side angle of taper is typically 4 degrees or less. The outer tip of the pin 301 is chamfered. As seen in
The third pin socket embodiment 318 differs from pin socket 118 only in having its bore uniformly tapered, as shown in
The fourth embodiment 400 of the pin assembly of the present invention is shown in
The basic differences are that the pin 401 has a constant diameter external cylindrical surface section 402 throughout its length, and the pin socket 418 has a constant diameter through bore 419. The exterior surface 402 of pin 401 is a close slip fit to the bore 419 of the pin socket 418.
The fifth embodiment 500 of the pin assembly of the present invention is shown in
The basic difference from the other embodiments for pin 501 is that the pin, seen in simplified form in
Starting at the outer end of cylindrical surface 502 at approximately the middle of the thickness of intermediate transverse diaphragm 107 and moving toward the outer end of pin 501, the diameter is reduced from that of section 502 in intermediate frustro-conical transition section 503. Frustro-conical intermediate section 503 is adjoined at its outer end by outwardly extending intermediate cylindrical surface 505. At the outer tip of pin 501, outer frustro-conical surface 504 further reduces the diameter. All of the cylindrical and frustro-conical external surfaces of pin 501 are concentric.
The lengths of the frustro-conical sections 503 and 504 are slightly more than the contact bearing lengths which will be established with pin 501 by the set of first wedges 522 and set of second wedges 524 of the pin socket 518 when the pin is engaged. The single-side taper angles of the frustro-conical sections are typically 4 degrees or less, and the taper angles of surfaces 503 and 504 are typically the same. As before, the inflatable seal 142 will have to be expanded to seal between retracted pin 501 and leg end 36.
Pin socket 518 has a straight cylindrical bore 519 which is interrupted by a radially inwardly projecting transverse annular ring intermediate guide 520 intermediate to its length. At the outer end of the bore 519 of socket 518, an integral radially outwardly projecting annular spacer ring having an inner diameter equal to or greater than bore 519 is lapped onto and welded to the exterior of the outside end side plate 527. The spacer ring mounts a welded-on annular ring reaction plate 521 on its outer side. The bore of reaction plate 521 is less than that of bore 519, but slightly more than the intermediate cylindrical surface 505 of the pin 501. Multiple through holes parallel to and equally offset from the axis of bore 519 on a regular bolt hole circle pattern coaxially penetrate both reaction plate 521 and intermediate guide 520. Plate radial braces 526 serve to further reinforce and stiffen the attachment of the spacer plate and the reaction plate 521 to the outside side plate 527.
Referring to
A drilled and tapped through hole is centrally positioned on the radial midplane of the first wedge 522. First wedge actuator screw 523 has, from its outer end, a hex head for wrench engagement, an outwardly extending transverse flange, a continuation of its shank, a second outwardly extending transverse flange spaced apart from the first by slightly more than the thickness of reaction plate 521, and at its distal end its helically threaded shank. The threads of a screw 523 are engaged with the female threads of each first wedge 522. Every other hole of reaction plate 521 mounts a first wedge actuator screw 523 where the screws project towards the entry end of bore 519. The shaft of each screw 523 between its upset flanges is engaged in its mounting hole in reaction plate 521 so that its flanges can resist inward or outward reactions by bearing on the transverse faces of the ring reaction plate when the screw is torqued. Turning the first screw 523 in a first direction advances the first wedge 522 toward the leg end 36, while turning the screw in its opposed second direction withdraws the first wedge from the leg end. Disk shaped plain bearings can be provided between the screw flanges and the reaction plate 521 to reduce the friction there. These structural features permit the first wedge actuator screws 523 to serve as screw jacks for the first wedges 522.
The second wedges 524 are similar in construction to the first wedges 522, but they are supported on second wedge actuator screws 525 and their frustro-conical inner faces are a close fit to the intermediate frustro-conical transition surface 503 of pin 501. The cylindrical outer surfaces of the second wedges 524 are positioned against the bore 519 spaced apart from but adjacent the inner or entry end of the pin socket 518. The second wedge actuator screws 525 are longer than the screws 523, but otherwise are of the same double-flanged construction. The screws 525 are inserted into the holes in reaction plate 521 between the screws 523 and extend also through the holes in the intermediate guide 520 to where they are threadedly engaged with the tapped holes of the second wedges 523.
The second wedge actuator screws 525 extend through the gaps between adjacent first wedges 522, so that the radial midplanes of the first 522 and second wedges 524 alternate when seen from an axial direction. Turning the second screw 525 in a first direction-advances the second wedge 524 toward the leg end 36, while turning the screw in its opposed second direction withdraws the second wedge from the leg end. The weight of the second wedges 524 is largely supported by reactions of the second wedge actuator screws 525 with the holes in the intermediate guide plate 520. These structural features permit the second wedge actuator screws 525 to serve as screw jacks for the second wedges 524.
When the pin 501 is fully extended into the bore 519 of pin socket 518, it has its frustro-conical surfaces 503 and 504 positioned inside of and radially slightly inwardly of the retracted wedges 522 and 524 prior to tightening of the connection. Additionally, the frustro-conical surfaces of the first and second wedges 522 and 524, respectively, are axially slightly spaced apart from their respective comatable frustro-conical surfaces 504 and 503. This condition is shown in
Advancing the first and second wedges 522 and 524 towards the leg end 36 by means of the screws 523 and 525, respectively, causes the wedges to encounter and firmly engage against the frustro-conical surfaces 504 and 503, respectively. This tightening eliminates radial play in the made-up connection. Further, since the wedges 522 and 524 are segmented, advancing the wedges until refusal can treat an off-center positioning of the pin 501. In such a case, the wedges will travel different distances to tighten between the bore 519 and the eccentric pin 501, but the eccentric joint will still be stabilized by being firmly wedged by both sets of wedges. The screws 523 and 525 can be rotated in reverse from their rotation for tightening the wedges 522 and 524 in order to loosen the connection 500 for pin retraction.
The sixth embodiment 600 of the pin assembly of the present invention is shown in
Pin 601 has a right circular cylindrical outer surface 602 which extends for slightly more than half of its length from its open inner end, which is on the righthand side of
Near the outer tip of pin 601 and starting at the outer end of cylindrical surface 605, outer frustro-conical surface 604 further reduces the diameter. The lengths of the frustro-conical sections 603 and 604 are slightly more than the contact bearing lengths which will be established by pin 601 with their corresponding and comatable frustro-conical surfaces 620 and 621 of the pin socket 618 when the pin is engaged. The taper angles of frustro-conical surfaces 603 and 604 are the same. As before, the inflatable seal 142 will have to be expanded to seal between retracted pin 501 and leg end 36.
The sixth pin socket embodiment 618, shown in
The diameter of frustro-conical transition section 620 at its pin entry end is the same as or slightly larger than the bore 136 of the leg end 36. The taper angle of frustro-conical bore 621 is the same as surface 604 of pin 601, and the axial length of the bore 621 is approximately the thickness of the outer side plate of the socket 618. The tolerances for the machining of the pin 601 and the socket 618 are such that pin frustro-conical surface 604 abuts or very nearly abuts socket frustro-conical surface 621 when pin frustro-conical surface 603 fully abuts socket frustro-conical surface 620.
Thus, the only radial gaps in the connection of pin 601 to socket 618 of embodiment 600 are between pin 601 and its housing bore 136 in the leg end 36 and, possibly, in the region of frustro-conical pin surface 604 and socket surface 621. Both gaps are maintained small due to the selection of operational clearances and careful monitoring of machining tolerances. Referring to
Alternate Bore Middle Diaphragm Assembly for Leg End 36
Although not shown in
A pipe vent line 164 is located on Midplane A of the leg end 36 and connects to the upper end of the leg 26 or 43 at its first end and has a teed vent line branch 165 projecting perpendicularly through each of the outer plates 160 of the alternative diaphragm 159. On the outer end of each vent line branch 165 is located a two-position ball valve 166 controlled by a selectably operable rotary actuator 167. The control lines for the rotary actuator are not shown for clarity, but extend to the exterior of the leg end 36 in which the diaphragm 159 is mounted so that the valve 166 can be remotely controlled.
A pin cavity formed between the pin mounting bore 136, the alternate bore middle diaphragm 159, and the pin O-ring 52 seals the pin. When it is desired to move the pin assembly operated by the hydraulic cylinder 60, the ball valve 166 is opened so that the pressure inside the pin cavity can be equalized with the pressure outside of the pin cavity, to avoid hydraulic lock and permit pin movement. Pipe vent line 164 and its-valves 166 are able to perform the same function as the ball valve 57 on the access flange assembly 55 of the pin. Provision of this second means of providing flow communication with the pin cavity offers operational convenience and redundancy.
A second pipe serves as a control and lubrication line conduit 170 from the leg end 36 of the leg 26 or 43 to the middle diaphragm 159. Control and lubrication lines 175 from the deck 11 and/or leg end 36 extend down through conduit 170 to the diaphragm 159. Conduit 170 intersects two branching tee lines, the control and lubrication conduit first branch 171 and second branch 172, extending perpendicularly through the outer plates 160 of the diaphragm 159 into the pin cavities on either sides.
Control and lubrication flexible hose lines 176 from the quick connects 58 on the interior of access flange 55 of the pin extend to the conduit first branch 171 on either side and there connect to the corresponding control and lubrication lines 175 from the leg end 36. The connections can be made with simple tee connections, with shuttle valves, or with more involved valved connections so that applying pressure to one set of lines (either 175 or 176) permits-overriding control from the other set of lines.
The alternative middle diaphragms 159 of the leg ends are provided with multiple through bolt holes in a pattern consistent with the spacer blocks 65 and the mounting base of the hydraulic cylinder assemblies 60 which are used to latch by extending and unlatch by retracting the field mateable pin 101. The mounting bolt holes are positioned concentrically with the axis of the latch pin bore 136. The cylinders 60 are mounted to the spacer blocks 65 and the diaphragm 159 by means of mounting studs 66 and hex nuts 67.
A first hydraulic power system consists of major components pump 801, tank 802, four-way valve 803, and shuttle valve 816. Hydraulic pump 801 draws hydraulic fluid from tank 802 and delivers the fluid to a solenoid-controlled three-position four-way valve 803 with its outlet ports drained to the tank when the valve is centered. The return line 808 from four-way valve 803 flows back to the tank 802.
Valve 803 is selectably controlled by its solenoids. The valve 803 typically would be spring-centered and detented, although this is not shown for sake of clarity. The outlet lines from valve 803 are 809 and 810, which are each respectively connected to the preferred inlet/return ports of double-pilot-operated two-position spring-biased three-way valves 820 and 880. Lines 814 and 815 respectively are connected at their first ends to intermediate points of the outlet lines 809 and 810 from valve 803 and at their second ends to the inlet ports of shuttle valve 816. The outlet line 817 from shuttle valve 816 serves as a pilot line and connects to the first pilot port of valve 820 to urge the valve 820 in the same direction as its spring bias. Pilot line 830 is branched from line 817 at an intermediate point and connects to the first pilot port of valve 880 to urge the valve 880 in the same direction as its spring bias. Thus shuttle valve 816 provides a first pilot pressure to each of the valves 820 and 880.
A second hydraulic power system consists of major components pump 840, tank 843, four-way valve 848, and shuttle valve 868. This second hydraulic power system is assumed to act through the flow passages provided by the quick connects 58 on the access flange assembly 55. Hydraulic pump 840 draws hydraulic fluid from tank 843 and delivers the fluid to a solenoid-controlled three-position four-way valve 848 with its outlet ports drained to the tank when the valve is centered. The return line 842 from four-way valve 848 flows back to the tank 843. Valve 848 is selectably controlled by its solenoids. The valve 848 typically would be spring-centered, although this is not shown for sake of clarity.
The outlet lines from valve 848 are 851 and 852, which are each connected to two of the quick connects 58 on the exterior side of access flange assembly 55 and corresponding quick connects 58 on the interior side of the flange. The flange assembly 55 is schematically indicated by the dashed ellipse on
The outlet port from valve 880 is connected to the cylinder retract line 178 and the outlet port from valve 820 to the cylinder extend line 182 of the actuator cylinder 60 for the pin 101. The flows in the lines 178 and 182 and the valves 820 and 880 can be bidirectional, depending on the positions of the valves 803 and 848. As arranged in
The operation of the inclined leg floating production platform 10 that utilizes the pin assembly embodiments of the present invention is largely concerned with the assembly of the structural system from its component subassemblies. There are three main subassemblies: the deck structure 11, the set of cojoined buoyant legs 25, and the damper plate assembly 90. Two types of pins connect these main subassemblies: the field mateable pin assemblies 100, 200, 300, 400, 500, or 600, and the permanent hinge pins 70. Additionally, cross bracing from the diagonal braces 78, as well as the combination boat landing and strongback 84, are also needed to complete the structural preassembly of the platform 10.
For the purposes of general operational description, either the deck 11 or the damper plate 90 is considered as a first structure for the mounting of the pin sockets of the different embodiments. Similarly, the leg ends 36 of the legs 26 or 43 are considered as a second structure for the mounting of the pins of the different embodiments. The pins are used for interconnecting the first and second structures.
Once the platform is preassembled as shown in copending U.S. patent application Ser. No. 11/051,691: “Inclined Leg Floating Production Platform with a Damper Plate”, filed Feb. 4, 2005, it can be towed to a deep water location at or in route to its final installation site for its final assembly. The assembly operations for platform 10 can be fully or partly reversed at any step of the operation, unlike the situation for other types of floating platforms. This capability is due to the reversibility of the pin connection procedure, which is based on the pins of the present invention.
This flexibility permits the platform to be readily salvaged, refurbished, reconfigured, or moved on a heavy lift vessel long distances to new locations. The reconfiguration of the platform 10 in the sequence of steps described earlier is also due to the ability of the pins to be rotated relative to their sockets, thereby permitting the linked primary platform subassemblies to be moved relative to each other.
A critical operation in the preassembly of the legs 26 and 43 is the insertion of the field mateable pin assemblies into the bores 136 of the field mateable pin leg end 36. This assembly is described for the first pin embodiment 100, but the procedures are common to the other pin embodiments. This assembly is done by preassembling the hydraulic cylinder assemblies 60 to the interior drilled and tapped holes 112 on the centerlines of the end diaphragms 106 of the pins 101 and then aligning the cylindrical bodies 102 of the pins with the bores 136 of the field mateable pin leg end 36 of the leg 26 or 43.
After the pins 101 are well into the bore 136, the hydraulic cylinder assembly 60 and the spacer block 65 for each pin are attached to the middle diaphragm 138 or 159 of the field mateable pin leg end 36 using studs 66 and nuts 67. Access to the interior of the pins 101 is available through the access holes 109 in their end diaphragms 106 after removal of their access flange assemblies 55.
For the first embodiment of the pin assembly 100, the pinning operation proceeds as follows. The travel stops 128 on the interior faces of the pin sockets 118 abut and centralize the leg end 36 of a leg brought into the gap between a pair of pin sockets. The leg can be steered and roughly positioned in the gap between the sockets 118 by means of a pulling cable.
Following the positioning of the leg in the detent for the periphery of the leg end 36 formed y the arcuate abutting surfaces 129 of the travel stops 128 on the interior faces of the sockets 118, the ball valve 57 in the access flange assembly 55 of each pin 101 is opened or, alternatively, the ball valves 166 mounted on the alternative bore middle diaphragm assembly 159 are opened by their respective actuators 167. The opening of the ball valves 57 or 166 permits the pin cavities on the interior sides of the pins 101 to be hydrostatically pressure-balanced so that the differential of the hydrostatic forces on the opposed sides of the end diaphragms 106 of the pins 101 is minimized.
This hydrostatic balancing ensures that the forces exerted on the pins 101 by their cylinders 60 will be fully available to overcome friction and misalignment induced forces between the pins and the bores of the sockets 518 during the pin insertion process. After the leg ends 36 are positioned by the travel stops 128 so that the pins 101 are coaxial or nearly coaxial with the bores of their corresponding pin sockets 118, the opposed pins 101 are extended outwardly from their pin mounting bores 136 in the leg end 36 by applying hydraulic pressure to the piston side of the hydraulic cylinders 60 affixed to the pin. The pressure can be applied through connections attached to the appropriate fittings 58 on the access flange 55 of the pin or by lines extending through the leg of the platform 10, using the hydraulic circuit of
Lubricant is injected into the interface between the pin 101 and the pin mounting bore 136 during pin extension, and the socket 118 is assumed to be prelubricated. The lubricant is supplied through connections attached to the appropriate fittings 58 on the access flange 55 of the pin or by lines extending through the leg of the platform 10.
In the event of slight axial misalignment, the chamfer at the exposed outer end of the pin 101 aids in the initial stabbing of the pin 101 into the straight bore 119 of the socket 118. As the pin advances into the straight bore 119, its conical transition section 111 may possibly abut the entrance of the straight bore 119, further aiding in producing axial alignment of the pin and socket. The cylindrical outer surface 102 of pin 101 is a close fit to bore 119 of the socket, so that axial alignment is fairly closely obtained when the outer surface 102 of the pin has entered bore 119.
Pin extension is complete when the frustro-conical section 111 of pin 101 has abutted the frustro-conical bore transition 127 of the socket 118. When this abutment occurs between frustro-conical section 111 of pin 101 and the frustro-conical bore transition 127 of socket 118, the joint is tightened on the outer side of the socket. The inner end of the pin 101 is slightly loose in the straight bore 119 of the socket 118 due to the need for sliding clearance, so that some relative movement can be experienced in the event of load reversals. Additionally, sliding clearance is necessary between the pin 101 and the pin housing bore 136 of the leg end 36. Again, this clearance permits relative movement in the event of load reversals. For this reason, the first pin assembly embodiment 100 is best used when load reversals are uncommon and the connection is not highly loaded.
Resistance to loads on the leg end 36 in the direction of the axis of pins 101 normally is provided by the abutment of frustro-conical surfaces 111 of the pin and 127 of the socket. This abutment of frustro-conical surfaces is also common to pin assembly embodiments 200, 300, 500, and 600. In the case of embodiment 500, the abutment of the pin frustro-conical surfaces is with the wedges 522 and 524 of the socket 518, with the wedges supported by their actuator screws 523 and 525, which are in turn supported by the socket 518. In the event of excessive loading producing movement in a made up connection in the pin axial direction, an outside plate 131 of the leg end 36 will abut the interior transverse face of the pin socket side plate 116. This behavior is common to all of the embodiments of the present invention. For the fourth pin assembly embodiment 400, the abutment of the outside plates 131 of the leg end 36 against the pin socket side plates 116 is the only means other than friction of resisting loads in the pin axial direction.
After the completion of pin extension, the ball valves 57 or 166 are closed and, since pressure is bled off the cylinder extend line, the passive rod locks of the cylinder 60 are engaged to lock the cylinder rod 62. Finally, the threaded keeper pin 125 on the socket 118 is extended into the locking pin socket 113 of the pin 101 by applying torque to its hex head, and then the keeper pin is locked by jam nut 126. Thus, the pin 101 is prevented from disengaging by the keeper pin 125, the cylinder rod lock, and the hydraulic lock due to the isolation of the pin cavity by the ball valves 57 and 166 and O-ring 52.
Reversing the installation procedure can retract the pin 101. This keeper pinning operation for the keeper pin 125 can be performed at or near the surface by a diver or possibly by a ROV following completion of assembly of the platform 10. It should be noted that the connections of the pins 101 of the legs 43 to the damper plate 90 are made in the air, so that use of a diver is not required for installation of the keeper pins 125 for those pin connections.
Note that the pin 101 can also still be caused to extend in event of failure or inadequate output of its hydraulic cylinder 60. This alternate means of extension can be affected by pumping into the pin cavity through one of the ball valves 57 or 166 with the other ball valve closed. Because the cross-sectional area of the pin is so large, only moderate pressures are necessary in order to produce very substantial forces. The procedure can be reversed to cause pin retraction in the event that the pin is submerged and hence subject to external hydrostatic pressure. In such a case, the water in the pin cavity can be ejected by pumping or by displacing the water with nitrogen and then partially venting the nitrogen pressure in a controlled manner.
The insertion of the pins 101 into sockets 118 can be reversed at any time during the process or after completion of the insertion. This permits reversing the platform assembly operation partially or fully.
The operation of the second pin and socket embodiment 200 is very similar to that of the first embodiment 100, with the only differences being related to the stabbing and abutment of frustro-conical shoulders. For the second pin assembly embodiment 200, the reduced diameter of the entry cylindrical surface 205 of pin 201 relative to the mouth of the frustro-conical tapered bore 220 of the socket 218 eases initial stabbing of the pin. The undercut external cylindrical surface 216 of pin 201 minimizes contact area between the pin and socket during stabbing so that, in the event of major misalignment, only the cylindrical surface 205 of the pin will contact the straight bore 219 of the socket. The connection becomes fully tight when the frustro-conical shoulder 211 of the pin 201 fully abuts the frustro-conical tapered bore 220 of the socket 218. At that time, the pin can then be immobilized by use of the rod locks, the isolation of the pin cavity, and the keeper pin 125.
The advantage of connection 200 relative to embodiment 100 is that the most highly loaded portion of the joint is tightened, rather than the relatively lightly loaded outer tip of the pin. The largest load transfer between the pin 201 and the socket 218 is in bearing between the frustro-conical tapered bore 220 of the socket and the frustro-conical shoulder 211 of the pin. The amount of load transfer in bearing between the entry cylindrical surface 205 of the pin 201 and the straight bore 219 of the socket 218 is much lower than the load transfer between the frustro-conical surfaces 211 and 220 at the entry end of the connection.
While there is necessarily sliding clearance provided between the pin 201 and the pin mounting bore 136, this second pin connection embodiment 200 is still fairly tightly connected in comparison with the first embodiment 100. This reduction in the clearances in the most highly loaded region of the connection renders the second pin assembly embodiment 200 more resistant to load reversals than the first pin assembly embodiment 100. Additionally, compared to the first pin assembly embodiment 100, this second pin assembly embodiment 200 is easier to stab and is better able to make two sides of the connection coaxial due to its relatively shorter beam length for the pin 201 between the pin mounting bore 136 and the engaged frustro-conical surfaces.
The third embodiment 300 of the pin assembly again works in a manner very similar to that of the first and second embodiments, with the only differences being in the stabbing and abutment of frustro-conical shoulders. The frustro-conical portion 311 of the pin 301, which enters the socket 318, has a constant taper that can be fully abutted against the corresponding frustro-conical surface 319 of the socket 318. Stabbing is easy and self-aligning. The joint is fully tightened when the two frustro-conical faces 311 and 319 abut, at which point the pin position can be locked using closure of the ball valves 57 and 166, the cylinder rod locks, and the insertion of the keeper pin 125. This third embodiment 300 is able to fully tighten in the socket of the connection, so that it is very fatigue resistant. However, the third pin assembly embodiment 300 is more difficult to machine properly than the other embodiments disclosed herein.
The fourth pin assembly embodiment 400 is structurally the simplest and easiest embodiment to machine, but it is only satisfactory for applications with very minimal dynamic loads, since it cannot be tightened by abutting frustro-conical shoulders. The pin 401 and the bore 419 of the socket 418 are straight right circular cylindrical surfaces. A relatively larger gap between these cylindrical surfaces than for the other pin assembly embodiments shown herein is necessary in order to enable stabbing and sliding to obtain full connection. Initial stabbing is somewhat eased by the entry chamfer on the outer tip of the pin 401. The locking of the pin 401 is done in the same manner as for the other embodiments.
The fifth pin assembly embodiment 500 functions in a different manner than the other pin assembly embodiments in that it relies upon separate, externally actuated wedging to fully tighten the connection after the pin 501 is fully extended into the socket 518. The pin 501 is fully extended into the bore 519 of the socket 518 before the connection is tightened. Both the frustro-conical surfaces 503 and 504 of the pin 501 are inside the bore 519 of the socket 518 when the pin 501 is fully extended. The extension operation for the pin 501 into the socket 518 using the cylinder 60, the ball valves 57 or 166, and the lubrication is identical to that used for the other embodiments.
Once the pin 501 is fully extended, the wedges are tightened using the screws 523 and 525 as screw jacks. The first wedges 522, on the outer side of the socket 518 and for engaging the outer conical surface 504 at the outer end of the pin 501, are moved in the pin axial direction toward the leg end 36 by rotating their first wedge actuator screws 523 to produce wedge translation due to interaction of the actuator screw threads and the first wedge threads. This axial translation of the wedges 522 causes their frustro-conical interior faces bear against the outer conical surface 504 of the pin 501, while their outer cylindrical faces bear against the cylindrical bore 519 of the socket. The transverse shoulders of the second flanges of the first wedge actuator screws bear against the interior side of the reaction plate 521 of the socket in reaction to the thrust applied by the threads of the screws to the first wedges 522 as they tighten against the outer conical surface 504 of the pin 501.
The second wedges 524 are similarly moved axially by rotating their second wedge actuator screws 525 so that their frustro-conical interior faces bear against the intermediate conical transition 503 of the pin 501 and the outer cylindrical faces of the second wedges bear against the cylindrical bore 519 of the socket 518. For connections that are underwater or which are awash, these screw rotations to actuate the wedges can be performed by divers or by a suitably equipped remote operated vehicle (ROV) to engage the hex heads of the first and second wedge actuator screws 523 and 525, respectively. The wedges 522 and 524 of this fifth pin assembly embodiment 500 are able to firmly grip the pin 501 even when it is eccentrically positioned in the socket 518. All radial gaps can be eliminated with this connection, so that tendencies to structural fatigue due to load amplification with loose connections are minimized. Connection release is accomplished by reversing the engagement procedure described above.
The sixth pin assembly embodiment 600, except for differences in stabbing and abutment of frustro-conical shoulders, operates in a manner similar to that of the first four embodiments 100, 200, 300, and 400. In the case of this sixth embodiment, the initial entry of the pin 601 into the frustro-conical bore 620 on the entrance side of the socket 618 is simplified due to the relatively large diametrical difference between the cylindrical surfaces 605 of the pin 601 and 619 of the socket 618.
When the pin 601 is fully inserted into the socket 618, the intermediate frustro-conical transition 603 of the pin fully abuts the socket entrance frustro-conical bore 620, while the outer end frustro-conical section 604 of the pin abuts or nearly abuts the socket exit frustro-conical bore 621. The tolerances on the machining are selected so that contact of comating surfaces 603 and 620 is ensured. Thus the most highly loaded portion of the connection is tight and without rattle or play. A minimal gap or no gap exists in the less heavily loaded region between the outer end frustro-conical section 604 of the pin 601 and the exit frustro-conical bore 621 of the socket 618. While there is still some looseness in the connection 600 due to the necessary sliding clearance between the pin 601 and the pin mounting bore 136, this looseness is minimal. Accordingly, tendencies to structural fatigue due to load amplification with loose connections are expected to be minimal for this sixth pin assembly embodiment 600.
The making of the connection can be completed and the connection 600 locked after pin insertion is completed in the same manner as for the other pin assembly embodiments. Connection release is accomplished by reversing the engagement procedure described above.
Operation of the Alternative Lubrication and Cylinder Control Source Hydraulic Circuits
Referring to
If higher pressure is applied to line 704, the shuttle will shift and block the flow passage 708 from serving as a leak route while permitting flow from line 704 to pass to exit line 719 and thence to the pin lubricant injection ports 115. If higher pressure is applied to line 708, then line 704 will be blocked and lubricant will flow from line 708 to line 710. Accordingly, if one line is blocked or leaky, the other line can still be used to lubricate the pin.
Referring to
When it is desired to use the other pump circuit with pump 840 to operate the cylinder 60, the pilot pressure of the other circuit with pump 801 is released because that pump is idle and its control valve 803 is returned to its venting center position. In the same manner as for the circuit with pump 801, the shuttle valve 868 of the pump circuit with pump 840 selects the higher of the two line pressures from the inlet lines 860, 861 of that circuit to pilot the control valves 820 and 880 to their second position. The pilot pressure from valve 868 permits valves 820 and 880 to overcome their spring bias and shift so that the flow lines 860 and 861 are in communication with the cylinder 60. Again, the cylinder can be operated by the circuit with pump 840 even if the circuit with pump 801 is leaky.
Load Paths and Stresses in the Connections
Because the pins typically will be in a marine environment for a period of many years, it is necessary to make the pins serviceable and inspectable. Thus, the pins should have a large diameter and be hollow so that there is reasonable access for inspection and service personnel. The construction of the pins and the leg ends with their internal diaphragms is a consequence of the need to transfer the loads from the leg end to the pin and thence to the socket in the most efficient manner.
During extension of the pins into their sockets, the legs are ballasted or supported so that misalignment loads to be overcome by the pins are small. By far the largest loadings on the pin connections occur in service when the deck is elevated above the water surface and the platform is exposed to wave loadings. Due to the large diameter of the pins and their relatively short length between load reaction points, the pins experience only limited bending stresses in the direction of their longitudinal axes.
The transfer of load in the pin connection system is described herein for the first embodiment 100 of the pin system, but the load transfer means is substantially the same for all the embodiments in the present invention. The loads from the leg are transferred to the pin by direct bearing between the pin mounting bore 136 and the outer cylindrical surface of the pin 102, with the loads highest due to relative rigidity in the sections where the pin middle 107 and interior end 108 diaphragms are substantially in respective alignment with the leg end outside longitudinal plate 131 and the inboard longitudinal diaphragm 137. Similarly, the loads from the pin are transferred to the socket 118 by direct bearing between the mutual contact surfaces of the pin and socket, with the loads highest due to relative rigidity in the sections where the pin middle 107 and outer end 106 diaphragms are substantially in respective alignment with the socket side plates 116 and 117.
In
Referring to
Likewise, the direct bearing loads transferred from the pin 101 to the socket 118 are highest in the interface between pin right circular cylindrical surface 102 and straight bore 119 of socket 118 in the immediate vicinity of the overlap between intermediate transverse diaphragm 107 and the inside side plate 116 of the socket (Load C). The transfer of loading in direct bearing between the engaged outer tip of the pin 101 at conical transition section 111 and the comating conical bore transition 127 of the socket 118 (Load D) is relatively higher where the outer transverse diaphragm 106 of the pin is aligned with the outer side plate 117 of the socket, but again, this pin tip loading is substantially less than the Load C transferred in the vicinity of the middle diaphragm 107 of the pin. Vectorially, Load C and Load D act in opposed directions.
As a first-order approximation, it may be assumed that all load transfer between the leg end 36 and pin 101 and between the socket 118 and pin 101 is discretized into the planes where the plates and diaphragms of these members overlap. Since the pin 101 is static once engaged, the sums of forces and moments on the pin are both zero. For this reason, a first order approximation is that: (Load A)−(Load B)=(Load C)−(Load D)=Shear Transferred internally in Diaphragm 107.
With the approximation above, the Load B transferred to the pin 101 from the interior of the leg end 36 is transferred to the middle diaphragm 107 by shear and bending in the tubular wall of the pin between those two diaphragms, but these stresses are relatively quite low. Likewise, the Load D transferred from the outer side plate of the socket 118 to the outer transverse diaphragm 106 of the pin 101 is also relatively low and is similarly transferred within the pin by shear and bending in its tubular portion between outer diaphragm 106 and middle diaphragm 107. The net force (Load A−Load B) on the leg side of the transverse midplane of middle diaphragm 107 of pin 101 is opposed by the equal and opposite net force (Load C−Load D) on the socket side of the transverse midplane of middle diaphragm 107. Vectorially, these two net loads act in opposite directions. The internal transfer of these net loads from the interior end of diaphragm 107 to the exterior end of diaphragm 107 is by direct shear in the transverse midplane of the diaphragm, again with the shear stresses being quite low.
The hoop bending stresses induced in the annular middle diaphragm 107 of the pin from the opposed net loads on the pin are appreciably higher than the middle diaphragm shear stresses, but are still acceptable. If necessary, the inner diameter of the middle diaphragm 107 of the pin can be flanged in order to reduce its bending stresses.
By providing stiff diaphragms 106, 107, and 108 in the interior of the engaged pin 101 that are substantially coplanar with and interacting with planar stiff members 131 and 137 in the leg end 36 and the side plates 116 and 117 in socket 118 to transfer loads, a very efficient pin structure is obtained. Thus, stiffness and strength both are concentrated for more efficient load transfer and use of material. At the same time this reliance upon stiffening diaphragms provides sufficient space in the interior of the pins of the present invention so that personnel can enter the pins to inspect and service the pins.
The inclined leg floating production platform 10 of the present invention offers a number of substantial improvements over the existing technology used for deepwater petroleum production platforms. One primary advantage for the inclined leg floating production platform is its relatively low cost of construction and installation. This low cost arises largely from the availability of the pinned connections disclosed herein, since the pinned construction can take place low to the ground rather than high in the air.
The critical features of the pins for assembly of the platform 10 include selectable and reversible pin insertion and the ability of the pinned connections to permit rotation about their axes. Other than requiring machining of the pin outer diameters and socket bores, the fabrication for the platform uses conventional shipyard construction methods. Roll-formed and press-broken plate construction is generally very inexpensive in a shipyard, and the use of cast or forged components for the pins leads to considerable economies. These and other advantages will be obvious to those skilled in the art. Additionally, the ability to rapidly interchange a drilling deck for a production deck while reusing the balance of the platform offers excellent economies due to time saving and construction cost savings. All of these advantages are a consequence of the ability to assembly the platform 10 by means of any of the different pin assembly embodiments of the present invention.
The ability to minimize or eliminate operational gaps between mated load carrying components is critical in the marine environment in order to avoid fatigue failure of the connections due to dynamic load amplification of impacts in loose joints. The pin connections of the present invention greatly minimize any tendencies of the connections to structural fatigue because of the low stresses resulting from their large sizes, which in turn result from the need for personnel access inside the pins. Additionally, for all embodiments except for pin assembly embodiment 400, loose joints are minimized or substantially eliminated. The minimization of looseness in these joints and the attendant “working” of these connections under varying loads helps to minimize fretting and galling on the mating surfaces of the connections.
The utilization of transverse diaphragms interior to the pin and their alignment with corresponding planar diaphragms and plates in the legs and sockets results in a very efficient design with relatively low weight and stresses for the size of the pins. These pin connections can be serviced in the field by access either through the manway passage 109 in the pin or by a through-leg tunnel entering the pin cavity. Likewise, the pin mechanisms can be inspected from the interior of the pin, so both thorough visual and ultrasonic inspection are possible in the field.
It should be appreciated by those skilled in the art that the conceptions and the specific embodiments disclosed herein might be readily utilized as a basis for modifying or redesigning the structures for carrying out the same purposes as the invention. As will readily be understood by those skilled in the art, a variety of substitutions or alterations in the invention could be made without departing from the spirit of the present invention. For instance, the routing or the number of hydraulic and grease injection hoses could be changed, along with their penetration points into the leg structure. Similarly, the control valve circuitry for permitting two independent controls for the hydraulic cylinder assembly 60 can be configured in a variety of ways to obtain substantially the same results as the approach shown herein.
Likewise, the geometry of the leg end cross-sections and framing and its proportions could be altered. Different seals could be used on the pins of the field mateable pin assemblies, and the cylinders could be of either the passive self-locking type or with a separately set locking means. Multiple cylinders could be used on individual pins. Screw jacks could be used in place of hydraulic cylinders to extend and retract the pins. For the case of the fifth embodiment 500 of the pin assembly, the pin could be made a straight right circular cylinder and the outer reaction surface for the wedges made frustro-conical. In such a case, the wedges would still tighten to grip the pin in substantially the same manner. None of these changes would depart from the spirit of the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
The present application, pursuant to 35 U.S.C. 111(b), claims the benefit of the earlier filing date of provisional application Ser. No. 60/650,196 filed Feb. 4, 2005, and entitled “Selectably Operable Field Mateable Pin Assembly” and provisional application Ser. No. 60/660,404 filed Mar. 10, 2005, and entitled “Selectably Operable Field Mateable Pin Assembly”
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|---|---|---|---|
| 3720066 | Vilain | Mar 1973 | A |
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| 4455108 | Lausberg | Jun 1984 | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20060177272 A1 | Aug 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60650196 | Feb 2005 | US | |
| 60660404 | Mar 2005 | US |
