Project Overview

Pipeline Actuation Control assisted a high profile Australian oil & gas operator to tie in a new 10” production riser and a new 8” water injection riser to the existing Submerged Turret Production (STP) system of a Floating Production Storage and Offloading vessel (FPSO).  

PAC secured the project by providing a solution that “squeezed” class 1500 valves into spare slots in the turret that had previously been designed to accommodate only class 900 valves.  The higher pressure means larger valves with higher torques which in turn means larger actuators so the geometry was prohibitive for even the compact actuation solutions that are typically employed in a turret.

The subsea flow lines on this facility are tied back to the STP buoy around which the FPSO weathervanes during normal operation.  The STP buoy may also be disconnected from the FPSO and lowered though the surrounding hull to 50m below the surface to enable the FPSO to be sailed away for maintenance or during cyclonic conditions. The interlocking and swivelling nature of the STP arrangement is the reason for such tight geometrical constraints.

The operator had very strict engineering safety margins to ensure with absolute certainty that the valves will move to the required position under any routine or emergency conditions.  Drawing upon both PAC’s experience and that of our suppliers and by employing a little lateral  thinking around actuator configuration and orientation, PAC provided a solution that comprehensively met the end user’s geometrical constraints as well as the design specifications for materials, pressure, temperature, flow, control function and safety integrity level (SIL).



Actuator selection, control system design, supply, assembly & testing of riser emergency shutdown valves, hydraulic operated valves and emergency shutdown valves.


ASTM A182 F51 duplex stainless steel, metal to metal seats with tungsten carbide overlay, environmental seals & IP68 rated Exd control components for submerged service, compact flanges for riser connections, coating to NORSOK specifications

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