Bosch Rexroth has engineered a disruptive innovation for electrically actuating valves in the subsea process industry. Called the SVA R2 Subsea Valve Actuator, it can replace conventional hydraulic cylinders without taking up additional space. It has an integrated electric controller that offers precise motion control and due to condition monitoring and a safety spring, it satisfies Safety Integrity Level (SIL) 3 in accordance with IEC 61508 and IEC 61511.
The actuator minimises energy consumption and is geared toward delicate ecosystems, while installation and operating costs are reduced. When the SVA R2 is used in subsea factories at a depth of up to 4000 metres, hydraulic pipes or power units are no longer required. The power supply, which is already installed for sensors is adequate to ensure the reliable operation of the actuators. These functions, the operating life and actuator safety have been successfully tested in accordance with international standards.
Previously, process system operators relied mainly on hydraulic cylinders to open and close subsea valves with a quarter turn and a defined force. With offshore installations like oil and gas production, these cylinders are supplied by a central hydraulic power unit with hydraulic pipes several kilometres long. This uses a great deal of energy to compensate for the cumulated losses and cannot control the movement with precision.
Plant engineers and operators relied on hydraulic cylinders because they are the only components to offer field-proven safety systems with a mechanical spring in a compact design. Conventional electric actuators do not have a safety function like this due to the size and weight requirements. Other designs to ensure safety using subsea batteries cannot guarantee the reliable closing of valves over the required operating life of up to 25 years.
For the agile development of the SVA R2, the Bosch Rexroth team worked closely with suppliers and operators of offshore installations and international universities. The new module comprises a pressure-compensated container incorporating an electric drive, a motion control system and a safety device, which can replace the previously used hydraulic cylinders on a 1:1 basis. It requires only one cable for the power supply and communication. The SVA R2 is designed to actuate valves reliably with the power supply that is commonly used for subsea sensors. Switching to compact and safe electric actuators means that the hydraulic pipes several kilometres long and the associated power units and controllers are no longer required.
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