Expanding Our Rental Fleet
Safelink will be building two new passive heave compensation units this autumn – of the type Poseidon X-4500 450/600. These will be state of the art passive heave compensators. In addition to the two units we will make a customized delta plate for additional flexibility. The two units can be arranged in parallel giving a total lifting capacity of SWL 1200 metric tonnes.
Lifting from a supply boat or barge up to a platform or other rig. Typically, a shock absorber is used to reduce dynamic force to increase the lifting capacity of the crane or to reduce dynamic load on sensitive payloads. Shock absorber and compensator characteristics are usually quite different, however the Poseidon X can be adjusted to have shock absorber properties due to the adjustable damping and stiffness system.
Towing of subsea templates beneath the moon pool can cause high dynamic loads. A compensator can reduce DAF and increase the weather window. Conventional towing can also benefit from a soft compensation device. The Poseidon X has a decent sized piston rod which can handle some side loads, however if extreme side loads are expected, then a Titan design is recommended.
Splash zone crossing
Lifting through the splash zone is often problematic, especially with spool systems, mud mats, manifolds and suction anchors. The weather window can be increased significantly by using a compensator. It is important that the compensator stiffness and damping is set up properly. The Poseidon X has a separate splash zone mode, which allows optimum settings for the splash zone crossing even when completely different settings are required later in the lifting operation. It also features a buoyancy compensation system which reduces the stroke length requirement.
Resonance in the lifting system can occur for special combinations of payload mass/added mass and wire lengths/diameters. Resonance can cause large payload movements and large dynamic forces. This problem can be eliminated by using a soft compensator. The Poseidon X is very soft and has compensation for water pressure and temperature, which ensures that the piston rod always is in the correct equilibrium position. This effectively means that the payload is protected all the way down to the sea floor.
Landing speed reduction
It is often important that the landing velocity of lifted objects are low to minimize risk of damage and to be able to install the object correctly. Poseidon X is excellent for this task and can achieve very low landing speeds for virtually all sea states.
Lifting of suction anchors and other equipment from the sea floor may cause large forces due to vessel motion and suction forces. Poseidon X is suited to compensate for the vessel motion, functioning as a constant tension device. The unit is then set in retrieval mode which has damping and stiffness which is optimal for retrieval purposes. The retrieval mode can be activated by an ROV or be pre-set.