1. Objective
All electric subsea actuators have been developed to provide solutions for the limitations of the traditional hydraulic actuators, such as demand for top side
hydraulic power unit, need for hydraulic flow lines in umbilical’s. However, when it comes to the high actuation forces like 5’’ or 7’’ gate valves, the all
electric solutions demand a large dimension and weight. However, the power density (force per size) is one of the advantages of hydraulic actuators.
2. Method
Is it possible to create a hybrid solution which combines the advantages of both existing technologies, i.e. to get the best out of electrics and hydraulics?
This work presents a novel approach for actuation of subsea valves which combines the strengths of an electromechanical actuator with a hydrostatic
transmission. The paper will provide a prototype of a hybrid actuator for subsea production based on successful industrial solutions.
3. Results
The main achievements are: 1. Cost-effective modular design (lean production management), 2. Environmental-friendly set up (no leakage of hydraulic
fluid), 3. High power savings (up to a reduction of 75%), 4. High safety level (up to SIL 3), 5. High availability and condition monitoring, 6. Integration of
a mechanical override, 7. Interchangeable electric drives (optional driven by ROV torque tools).
The results are demonstrated by qualification test of a 2’’ gate valve for 3,000 m water depth. Hence, a 5’’ concept design shows the potential to build a
complete actuator in the same space used today by a pure hydraulic cylinder.
4. Novel
The designed Subsea Valve Actuator is more reliable as existing solutions without hydraulic umbilicals and emission of fluid into seawater, by offering a
standard electric interface with integrated condition monitoring and safety. It is an important step to close the technological gap to accomplish the allsubsea
factory, especially to replace existing hydraulic actuators.