An apparatus and associated method is disclosed for a riser hanging system. The apparatus includes a first elongated member with a provision for a first external mechanical coupling at a distal location on the first elongated member. A second elongated member is mechanically coupled to the first elongated member at proximal locations on the first elongated member and the second elongated member. A third member is mechanically coupled to a first portion of the first elongated member. The third member includes a fourth member to move through at least a second portion of a length of the second elongated member. Mechanical couplers associated with the second elongated member are provided for a second external mechanical coupling of the riser to the apparatus. The riser may be hoisted using the apparatus for better control during coupling to the wellhead.

A passive heave compensator comprising: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head, a gas phase above the piston head, and at least one oil phase below the piston head separated by a boundary; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and at least one accumulator, the or each accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator, and the or each oil phase being in communication with an oil phase in the main hydraulic cylinder; characterized in that the main hydraulic cylinder further comprises a cylinder sleeve co-axial with the piston head to provide, in co-ordination with the piston head, the boundary between the gas phase and the at least one oil phase in the main hydraulic cylinder. In this way, the variation in the coordination between the shape, longitudinal position, or both of the piston head, which naturally must be smaller in cross-section than the cross-section of the main hydraulic cylinder, and the transverse extent of the cylinder sleeve, provides variation in the cross-sectional area of oil volume in the main hydraulic cylinder, and thus different damping effects along the length of the main hydraulic cylinder, which are available to the user.

A passive heave compensator comprising: a main hydraulic cylinder, including a moveable piston having a piston rod extendible through the main hydraulic cylinder and a piston head, a gas phase above the piston head, and at least one oil phase below the piston head separated by a boundary; an upper connection point associated with the main hydraulic cylinder and a lower connection point associated with the piston rod; and at least one accumulator, the or each accumulator having a moveable separator to divide the accumulator between a gas phase above the separator, and an oil phase below the separator, and the or each oil phase being in communication with an oil phase in the main hydraulic cylinder; characterized in that the main hydraulic cylinder further comprises a cylinder sleeve co-axial with the piston head to provide, in co-ordination with the piston head, the boundary between the gas phase and the at least one oil phase in the main hydraulic cylinder. In this way, the variation in the coordination between the shape, longitudinal position, or both of the piston head, which naturally must be smaller in cross-section than the cross-section of the main hydraulic cylinder, and the transverse extent of the cylinder sleeve, provides variation in the cross-sectional area of oil volume in the main hydraulic cylinder, and thus different damping effects along the length of the main hydraulic cylinder, which are available to the user.

A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic cylinder (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and a selection valve set (850). The selection valve set is adapted to self-configure to a first configuration and to a second configuration when a net load (90) is supported by a first chamber (116, 118) and a second chamber (118, 116) of the hydraulic cylinder, respectively. When the selection valve set is enabled in the first and second configurations, the second and first control valve may fluctuate hydraulic fluid flow to the second and first chamber, respectively, to produce a vibratory response (950) that counters environmental vibrations (960) of the boom. When the selection valve set is not enabled, the first and second counter-balance valves are adapted to provide the hydraulic cylinder with conventional counter-balance valve protection.

The invention is a system for controlling the relative movement of a load P, comprising at least one main damper having a longitudinal action of stroke C and two ends with one end being connected to a frame and the other being connected to the load. A compensation device is included having at least one secondary damper of longitudinal action with two ends with one end being secured to the frame and the other end is connected to the end of the main damper connected to the load The secondary damper is arranged so that, at one point of stroke C, the secondary damper has an action orthogonal in direction to the direction of the movement.

The invention is a system for controlling the relative movement of a load P, comprising at least one main damper having a longitudinal action of stroke C and two ends with one end being connected to a frame and the other being connected to the load. A compensation device is included having at least one secondary damper of longitudinal action with two ends with one end being secured to the frame and the other end is connected to the end of the main damper connected to the load The secondary damper is arranged so that, at one point of stroke C, the secondary damper has an action orthogonal in direction to the direction of the movement.

Heave balance device (1) can balance a lifted or supported load (8). The load can be lifted by a hoisting device (10) or it can be supported. The heave balance device comprises a first frame (2) and a connection unit (22) that can be suspended, e.g. to a hoisting device. Further a moveable carrying unit (32) allows for carrying (suspending or supporting) a load. The device comprises a transmission that couples the connection unit and carrying unit, wherein said transmission is arranged to guide the connection unit and the carrying unit to move along a guideline with respect to each other, the transmission having a spring force balancing arrangement (4) with one or more leverage units, such as one or more pivoting arms (50, 51), and with one or more configurable (gas- or) hydropneumatic springs. A method comprises suspending the load via a (heave) balance device. Further a kit of parts for hoisting devices is provided to allow load decoupling.

Heave balance device (1) can balance a lifted or supported load (8). The load can be lifted by a hoisting device (10) or it can be supported. The heave balance device comprises a first frame (2) and a connection unit (22) that can be suspended, e.g. to a hoisting device. Further a moveable carrying unit (32) allows for carrying (suspending or supporting) a load. The device comprises a transmission that couples the connection unit and carrying unit, wherein said transmission is arranged to guide the connection unit and the carrying unit to move along a guideline with respect to each other, the transmission having a spring force balancing arrangement (4) with one or more leverage units, such as one or more pivoting arms (50, 51), and with one or more configurable (gas- or) hydropneumatic springs. A method comprises suspending the load via a (heave) balance device. Further a kit of parts for hoisting devices is provided to allow load decoupling.

A full-time anti-sway control method of a bridge crane system based on an inverter structure includes steps of: receiving a specified high frequency and a frequency change time, calculating a time setting range according to a plurality of system parameters and a rope length information of the bridge crane system, selecting a time setting value within the time setting range, dividing the frequency change time into a plurality of time intervals according to the time setting value, adjusting an operation frequency command to change between a low frequency and the specified high frequency within the plurality of time intervals to generate a frequency change curve, calculating a frequency correction amount according to the frequency change curve and the rope length information, and superimposing the frequency change curve and the frequency correction amount to generate an anti-sway frequency command to drive the at least one motor.

A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic actuator (110), first and second counter-balance valves (300, 400), first and second independent control valves (700, 800), and first and second blocking valves (350, 450). The actuator includes first and second corresponding chambers. In a first mode, the second counter-balance valve is opened by the first control valve, and the first counter-balance valve is opened by the second control valve. In a second mode, at least one of the counter-balance valves is closed. A meter-out control valve (800, 700) may be operated in a flow control mode, and/or a meter-in control valve (700, 800) may be operated in a pressure control mode. Boom dynamics reduction may occur while the boom is in motion (e.g., about a worksite). By opening the counter-balance valves, sensors at the control valves may be used to characterize external loads. The control valves may respond to the external loads and at least partially cancel unwanted boom dynamics. The system may further detecting faults in actuators with counter-balance valves and prevent any single point fault from causing a boom falling event and/or mitigate such faults.