Abstract: A mooring unit and method of retrofitting a mooring unit are provided. Certain existing combination mooring units, of the type having two wire rope drums and two wildcats, are experiencing increased winch drive train component stress levels during operation when used in water deeper than they were designed for. Existing units are modified by providing left and right twin drum traction winch assemblies and additional winches. The existing wire rope drums are discarded, or reused with the additional winches. The additional winches are preferably mounted below the mooring unit. The twin drum traction winch assemblies, which deliver a constant winch pull force, are vertically mounted within the support flanges where the removed wire rope drums were previously mounted, without any modification to the support flanges.

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: Force transducers are integrated in an elastomeric flex bearing to provide signals for determining the tension and torque upon a tension member coupled to the bearing and for computation of the azimuth and elevation of the tension member. Preferably the force transducers are mounted to or embedded in an outer metal load ring of the flex bearing and are bonded with the outer metal load ring to the elastomer of the flex bearing. The force transducer, for example, include a diaphragm bonded to the elastomer, and the diaphragm has a diameter in excess of the spacing between the outer metal load ring and the nearest laminated metal reinforcement of the bearing. In one embodiment, metal foil strain gages are bonded to the surface of the diaphragm opposite from the elastomer. In another embodiment, the diaphragm transmits pressure to hydraulic fluid between the diaphragm and the outer metal support ring.

Abstract: Vertical movement of a floating marine platform is reduced by tendons extending from the platform to anchors on the seabed. A final tension adjustment to equalize the load on all of the tendons is made by a respective tension adjustment mechanism incorporated into the top connector of each tendon. The tension adjustment mechanism includes a split load ring assembly having an upper ring and a lower ring. The upper ring and the lower ring abut each other at respective complementary surfaces. Each surface has a series of serrated ramps. A rotation of one ring with respect to the other causes the upper ring to climb over the lower ring to thereby increase the tension in the tendon. Rotation of the upper ring with respect to the lower ring, for example, is achieved by a motor driven gear ring.

Abstract: A flexible joint is provided for facilitating bending of tubular segments. The flexible joint includes an outer cylindrical housing and at least one inner tubular member disposed within the outer cylindrical housing. The outer cylindrical housing has a first end which has an inwardly projecting bevel-shaped portion. The inner tubular member has a first end which has an outwardly projecting bevel-shaped portion. An elastomeric pad is bonded between an inner surface of the outer cylindrical housing and an outer surface of the inner tubular member at their respective first ends. The elastomeric pad has a bevel-shaped section which is adjacent to the inwardly projecting bevel-shaped portion of the first end of the outer cylindrical housing and the outwardly projecting bevel-shaped portion of the first end of the inner tubular member.

Abstract: A method of retrofitting an offshore platform fendering system includes the steps of installing a jib crane on a platform leg above the existing fendering system, detaching the upper and lower load cells from the leg, and removing the existing fendering system using the jib crane in concert with a support vessel crane. The upper load cell of the existing fendering system is detached to leave a protruding cylindrical stub. Using the jib crane and vessel crane, a new unitary fendering system is then positioned next to the leg. The upper load cell is coupled to the stub and the lower load cell is clamped to the leg. The new fendering system is installed as a unitary piece, that is, an elongated bumper with the upper and lower load cells already attached.

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: A continuous bend flexible/rigid riser system is provided for coupling a subsea location to an offshore platform or vessel. The riser system comprises a first rigid pipe section coupled at its upper end to the platform. A plurality of intermediate pipe sections are mutually coupled end to end, and are coupled in series with the first rigid pipe section by means of a plurality of flexible couplings. The lower end of the last in the series of intermediate pipe sections is coupled to the subsea location. The flexible/rigid riser system reduces bending stresses transmitted along the riser by allowing angular displacement of the pipe sections with respect to one another.

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 non-metallic pipeline cleaning pig for cleaning a variable diameter pipeline comprises an elongated cylindrical body, front and back cups coupled to the body, and a plurality of generally circular wiping discs coupled to the body between the cups. The wiping discs are disposed in pairs spaced apart from one another. Each disc has plurality of circumferentially spaced fingers respectively separated by a plurality of circumferentially spaced slots. Each finger has a peripheral surface of a given arc length. The number and configuration of the fingers and slots is chosen so that the sum of the arc lengths is approximately equal to the internal circumference of the smallest diameter pipe section encountered.An abrasive may be applied to the fingers to enhance the cleaning action. In addition, cleaning solvent may be jetted from behind the pig to the internal surface of the pipeline in front of the pig.

Abstract: To overcome problems with the pistons of an energy cell rotating and becoming misaligned with one another in response to the forces exerted on the energy cell by a riser tensioner system, a two-piece elastomeric spring is disposed about each piston to create an elastomeric strut. Each piece of the spring is composed of a plurality of elastomeric layers separated by relatively inelastic spacers. These springs facilitate the longitudinally flexing of the elastomeric strut while substantially preventing rotation and misalignment in the radial direction.

Abstract: A method and apparatus for erecting a vertical mast 10 on a drill platform 15 with minimal reliance on existing cranes. An elevator guide section 20 is first constructed on the platform 15. The elevator guide section 20 has one open side for receiving the mast top section 40, mast bottom section 70, and one or more mast intermediate sections 58A-D, all of which, have approximately the same horizontal cross section. A pair of mast elevators 28A-B are slidably coupled to the elevator guide section 20. By means of the existing platform crane, the top section 40, which has a prestrung crown block 45 and travelling block 46, is placed within the elevator guide section 20 and on the elevators 28A-B. Lifting power is transmitted to the elevators 28A-B by the existing drawworks 52 via the travelling block 46. Through a series of vertical movements of the elevators 28A-B, the top section 40 is raised and one more intermediate sections 58A-D are stacked thereunder.

Abstract: A sucker rod coupling 10 having a high ultimate tensile strength, resistance to corrosion, and resistance to surface cracking arising out of a method of making the sucker rod coupling 10, which employs a five-step process of forming a coupling 10. First, a hollow cylindrical core 12 from a heat treatable steel is formed. Second, a thin coating 18 of metallic alloy is applied to the outer surface of the core 12. Third, the core 12 is heat treated. Fourth, threads 20 are partially cut in the inner surface of the core 12. Fifth, the threads 20 are cold worked to transform the partially cut threads 20 into finished threads 20 and to place the thread roots 22 in compression.

Abstract: A sucker rod coupling 10 having a high ultimate tensile strength, resistance to corrosion, and resistance to surface cracking arising out of a method of making the sucker rod coupling 10, which employs a five-step process of forming a coupling 10. First, a hollow cylindrical core 12 from a heat treatable steel is formed. Second, a thin coating 18 of metallic alloy is applied to the outer surface of the core 12. Third, the core 12 is heat treated. Fourth, threads 20 are partially cut in the inner surface of the core 12. Fifth, the threads 20 are cold worked to transform the partially cut threads 20 into finished threads 20 and to place the thread roots 22 in compression.

Abstract: A well drilling apparatus includes a monitoring system for monitoring the exact elevation of the traveling block. The monitoring system detects the elevation of the traveling block by means of periodically transmitted signals which are reflected back to the monitoring system by the traveling block. The apparatus further includes a control system preferably including an industrial control digital computer which is responsive to the elevation of the traveling block and controls the drawworks of the apparatus to prevent the traveling block from crashing into the crown block or working floor. In one embodiment of the apparatus the velocity of travel of the traveling block and the load being supported by the traveling block are also monitored in order to further restrict raising and lowering of the traveling block to be maintained within predetermined safe limits of operation.

Abstract: This invention provides for a loading arm for use with material handling systems and includes a support structure and an arm pivotally attached to the support structure for swivel movement in both the horizontal and vertical plane relative to the support structure.

Abstract: A system for sensing, computing, and displaying the length and the speed of chain or cable payout or reel in. The system employs only a single sensor which measures cable drum movement. The calculation function is accomplished by a microprocessor or minicomputer which is programmed with the basic dimensions of the cable and cable drum and with the required calculation formulae. A display gives continuous readout to the operator of the cable payout and speed values from a predetermined cable reference point. The system is directly employable in drum payout and recovery systems regardless of their application. The cable references may be of steel, rope or even chain and the system may be incorporated in helicopter or aircraft cable systems, mine hoists or elevator systems wherever a precise control or readout of cable payout is required.