PLET Supporting Structure

An EPIC client was looking to expand their capabilities during pipeline installation campaigns, by incorporating an overside PLET (Pipeline End Termination) Handling System into one of its pipelay vessels. The system would be utilised for larger PLETs that could not be installed through the existing firing line in the vessel's conventional S-Lay configuration.

Based on the brief received from the client, and sensitive to the vessel layout, MDL designed the PLET Supporting Structure (PSS). The modular system incorporated MDL's proven portable technology for efficiently skidding large loads on the back deck and safely deploying them overboard from the preferred location on the vessel. In line with the client's requirements, the PSS was designed to integrate with an existing hang-off platform is order to prevent clashes between the PLET resting on the PSS and the Mast Crane's boom while in rest state.

The MDL PSS allows secure transport and deployment of PLETs through a range of features pertinent to MDL's technology for offshore lay and retrieval operations. The system can skid the PLET from transportation position to the required installation poisiton, with actuated clamp assemblies fitted with failsafe locks ensuring all elements remain securely in place at all times. When in transit mode, the PLET sits within a structural guide frame, adjustable to varying PLET sizes and secured there with hydraulically actuated locking claw assemblies. For installation, the top level of the system tilts up to a 92º angle while a sheave assembly guides the tugger winch wire rope for controlled lowering of the PLET subsea. All handling of the PSS is fully automated via PLC controls.