Actuators for subsea gas field duties

Rotork failsafe subsea hydraulic actuators have been ordered for vital safety-related valve duties in offshore gas fields in the Far East.

The Rotork actuators will be mounted on SSIV (Subsea Isolation Valve) and PLEM (Pipeline End Manifold) installations on two pipelines connecting new wellhead platforms to the gas fields’ central processing platform.

Each actuator is fully equipped for ROV (Remotely Operated Vehicle) operations and supplied with a portable torque tool for ROV or diver operation. In addition, a de-clutch mechanism is fitted on the valve spool piece, which, combined with a balancing counterweight on the actuator, facilitates attachment and removal of the actuator without affecting the valve position. This system has been specially developed by Rotork for deep water and other critical valve duties, including projects where the valve has been deployed separately from the actuator or a single actuator is required to operate more than one valve.

Apart from system simplification and cost economies associated with actuator fitting and removal, the declutch mechanism also provides functional and safety features including the ability to fully stroke the actuator independently of the valve, commission the actuator without operating the valve and operate the valve in the event of a hydraulic power failure. The feature is one of many that Rotork has developed during more than twenty years of subsea actuation experience, including installations at depths of over 2,400 metres.

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