PLEM Control

Offspring International offers a range of PipeLine End Manifold (PLEM) control systems as part of its integrated CALM buoy and conventional buoy mooring and offloading systems. Available under an exclusive agreement with valve actuator manufacturer, Paladon Systems, the PLEM valve control systems can be operated from the surface or subsea, and autonomously with the innovative Autonomous Shutdown Valve (ASV).

Optimised PLEM Control

Offshore loading and unloading Single Point Mooring (SPM) and Conventional Buoy Mooring (CBM) systems feature a PLEM containing single and multiple valves to control flow to and from the terminal. Smooth operation of the valves is critical to maximising tanker movements and trouble-free scheduling.

Offspring International offers several PLEM control systems for SPM and CBM loading and offloading:

SPM – PLEM Control

The PLEM is connected to the SPM CALM buoy via flexible submarine hose(s), typically in either a “Chinese lantern” or “Lazy S” configuration, enabling oil to be transferred to and from the tanker via a floating hose. OIL offers the following PLEM control options:

Manually controlled valve – operated by diver. Ideal for shallow water where calm Sea States are the norm. These valves are normally left permanently open and only closed for a hose change out or in the event of an emergency.

Remote double-acting valve operation from the SPM buoy. The PLEM valve is controlled using a double-acting hydraulically operated actuator, powered open and closed by Hydraulic Power Unit (HPU) mounted on the CALM buoy and connected by a control umbilical.

Remote single-acting valve operation from the SPM buoy. The PLEM valve is controlled using a single-acting, hydraulically operated actuator, powered open by a HPU mounted on the CALM buoy and connected by umbilical. The valve is held open by hydraulic pressure and fails safe via the actuator’s spring when the hydraulic pressure to the actuator is lost.

Autonomous Shutdown Valve

With increasing demands for more efficient tanker scheduling and greater loading / offloading availability, Offspring International offers Paladon Systems’ patented Autonomous Shutdown Valve (ASV). Fully autonomous and self-contained, the ASV offers terminal operators fail-safe offloading operations, greater system availability, and emergency shutdown capability.

Suitable for CALM buoy and conventional buoy mooring systems, the ASV removes the restrictions on offloading operations typically imposed by manual valve operation that can require expensive diver interventions and are only possible during fair weather.

The ASV also replaces the extended chain of components needed with a hydraulically operated valve actuator, powered open by a CALM buoy mounted HPU; effectively removing reliance on a surface control umbilical. It also eliminates the need for frequent maintenance visits to the buoy for  checking and recharging of HPU system pressure.

CBM – PLEM Control

For CBM offloading operations, OIL offers a diver operated valve PLEM control option, as well as the Autonomous Shutdown Valve and its associated benefits.

For more information on Offspring’s range of PLEM Control systems download the PLEM Control Brochure or contact Offspring International


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