Abstract: Systems and methods that permit assembly, disassembly, and relocation of modular structures, such as platforms and towers, without the need for permanent attachment of the modules, such as welding. Aspects of certain embodiments replace permanent attachment means, such as welding, with connectors at the structural interfaces between modules. Certain embodiments of the connectors of the present invention allow for the repeated reuse and relocation of modular structures as needed. Certain embodiments allow for the use of float-over methodologies to coupled topside modules to supporting structures without offshore welding.

Abstract: An elastomeric flex joint is provided with a rotational bearing so that torsional stress is relieved by slip of the rotational bearing. In a first embodiment, the flex joint is designed to resist flexing from a mean position at which there is a substantial bend of axial direction, and the rotational bearing does not normally slip. An adjustment mechanism reduces the loading on the elastomeric flex element and the rotational bearing so that the bearing will slip during an initial orientation or during an adjustment of the joint. In a second embodiment, all small torsional deflections are absorbed by the elastomeric flex element, and large torsional deflections are absorbed by the rotational bearing. This is desirable because the elastomeric flex element has a greater fatigue capacity for small oscillations than the rotational bearing. An elastomeric clutch can be used to precisely control the break-out torque.

Abstract: A riser tensioner system 10 is provided for use on offshore oil drilling platforms to support a riser 12 relative to a floating platform. The riser tensioner system 10 uses either elastomeric pads 32 or helical metal springs 100 as an energy absorbing medium, rather than hydraulic, or pneumatic systems. The elastomeric pads 32 or helical metal springs 100 are maintained in compression within a shock absorber housing 76 by a plunger 70 which is compressed by the weight of the riser 12. If the riser tensioner system 10 is arranged to place the shock absorber 20 in tension, the shock absorber plunger 70 is inverted in the housing 76 to maintain the elastomeric pads 32 or helical metal springs 100 in compression. To achieve varied response characteristics, nested inner and outer elastomeric pads 50, 52 or compression springs 102, 106 are arranged to act together.

Abstract: A compression element having a deflectable elastomeric member is disclosed. The compression element exhibits a decreasing axial spring rate in response to axial movement and compression of the deflectable member. The compression element may be used alone or in combination with other compression elements in riser tensioner systems to maintain a substantially constant upward tensioning force on a riser as it moves axially relative to a floating platform.

Abstract: A riser tensioner system for applying a substantially constant tensioning force to a riser and allowing a floating platform to move within a given range along a longitudinal axis of the riser. The system includes a plurality of tensioner assemblies each of which are coupled to the riser and to the platform. Each of the tensioner assemblies includes an upper member, a lower member, a connecting member coupled to the upper and lower members, and intermediate members coupled to the upper and lower members at a point intermediate the ends of the upper and lower members. At least one of the upper member, the lower member, and the intermediate members are adapted to provide a constant tensioning force. The arrangement of the upper member, lower member, connecting member, and intermediate members further provide a linkage whose centerline in angularly spaced from the longitudinal axis of the riser by a substantially constant amount throughout the range of motion of the linkage.

Abstract: An elastomeric drive line coupling. The coupling includes an input drive shaft having a longitudinal axis and terminating at one end with a housing and an output drive shaft having a longitudinal axis and terminating at one end with a ball. The housing has a partially elliptical interior and the ball has a partially elliptical exterior which is disposed within the housing. A partially elliptical rigid shell is provided between the ball and the housing. Both the ball and the rigid shell are bonded with elastomeric layers forming interleaved nested ellipses within the housing. These ellipses are oriented 90.degree. out of phase from one another. Torsional loads are applied to the output drive shaft by the input drive shaft through compression deformation of the elastomeric layers as the partially elliptical rigid shell attempts to rotate relative to the housing and the ball.

Abstract: A compression element having a deflectable elastomeric member is disclosed. The compression element exhibits a decreasing axial spring rate in response to axial movement and compression of the deflectable member. The compression element may be used alone or in combination with other compression elements in riser tensioner systems to maintain a substantially constant upward tensioning force on a riser as it moves axially relative to a floating platform.

Abstract: A riser tensioner system 10 is provided for use on offshore oil drilling platforms to support a riser 12 relative to a floating platform. The riser tensioner system 10 uses either elastomeric pads 32 or helical metal springs 100 as an energy absorbing medium, rather than hydraulic, or pneumatic systems. The elastomeric pads 32 or helical metal springs 100 are maintained in compression within a shock absorber housing 76 by a plunger 70 which is compressed by the weight of the riser 12. If the riser tensioner system 10 is arranged to place the shock absorber 20 in tension, the shock absorber plunger 70 is inverted in the housing 76 to maintain the elastomeric pads 32 or helical metal springs 100 in compression. To achieve varied response characteristics, nested inner and outer elastomeric pads 50, 52 or compression springs 102, 106 are arranged to act together.

Abstract: An improved conduit seal is provided for the upper connector assembly (10) of a TLP where the upper end of a tether (14) is pivotally secured within the tether conduit (38) of a floating platform (12). The conduit seal includes an annular elastomeric seal (48) and a series of mounting blocks (52) bonded thereto. The tether mounts a CLB housing (24) which has an annular lip (74) with a continuous groove (80). Each of the mounting blocks is provided with a locking pin (84) which can be hydraulically driven into the groove (80) to lock the mounting blocks on the CLB housing, and confine the seal (48) relative to the CLB housing.

Abstract: A number of riser tensioner systems which use passive energy storage devices, such as springs, are disclosed. The geometrical construction of these systems, along with the selection of proper spring rates for the individual springs, produces systems that have a total spring rate which varies in proportion to the stroke of the riser. Thus, the tensioning force exerted by the systems on the riser remains substantially constant throughout the range of motion of the riser.

Abstract: A riser tensioner system 10 includes a pair of supports 14, 16 affixed to an offshore platform in spaced apart relation to one another. A shaft 24 extends between the supports 14, 16 and is pivotally coupled thereto by an elastomeric bearing 26. A central support 22 is pivotally coupled to the shaft 24 at about the midpoint between the supports 14, 16 and fixedly coupled to coil springs 30 or elastomeric springs 100 coaxially arranged about the shaft 24 and extending between the central support 22 and each of the supports 14, 16. The central support 22 is also coupled to a riser 12 so that relative movement between the offshore platform and the riser 12 causes the central support 22 to pivot on the shaft 24 and wind or unwind the coil springs 30 or elastomeric springs 100 for relative upward and downward movement thereof. A pretensioner mechanism 42 increases the force exerted by the springs 30 or elastomeric springs 100 to increase the upward force applied to the riser 12.

Abstract: An improved keyhole latch is provided for securing offshore structures in place. The back flange of the flex joint and latch assembly has a male portion and the load ring of the receptacle has a female portion. By matching the male and female portions, rolling of the load ring and flex joint and latch assembly is minimized and the noncontinuous surface on the load ring is strengthened.

Abstract: There is disclosed a compression loaded torsional coupling device for use in drive shafts to provide a resilient interface between input and output portions of the shaft. Elastomeric cushions between fins extending in alternating fashion from opposed coupling members provide the resiliency. The coupling is produced by a unique process. Elastomer is first inserted into alternating gaps between adjacent fins. This elastomer is then compressed by applying a torque to rotate the coupling members with respect to each other. Elastomer is then placed in the remaining gaps. The torque is then released, permitting the compressive forces to redistribute in the elastomeric material around the circumference of the coupling.

Abstract: A closure for a chain entry aperture in which two or more seal blocks of a suitable elastomeric material are slidable between a position in which the aperture is open, and a position in which the seal blocks cooperate to close the aperture and seal around a chain extending through the aperture. Contact surfaces of the seal blocks are shaped to accommodate the chain passing through the aperture when the seal blocks are in the closed position.