The first phase of the operation was an award-winning weighing and load-out of three riser platform modules, weighing 6,223t, 9,239t and 9,766t respectively, and measuring approximately 80m x 20m x 30m, with each module loaded-out consecutively onto a heavy transport vessel (HTV).
An extra crew was brought in to ensure that employees would be guaranteed enough rest during the two-week operation and this also meant the complex manoeuvres could be carried out at a steady pace.
ALE began by installing their skidding equipment underneath the first two modules. The skid tracks were positioned on a foundation of concrete blocks, before skid shoes and push-pull units were put in place. All hydraulics for the push-pull units and skid shoes were connected to power packs at the back of the topside. These were positioned on a small platform, which was skidded along with the topside.
To provide a safe and stable load-out, ALE used a link beam as the best way to control the vertical movement of the HTV. Hinge points to hold the link beam were installed on the quay and on the HTV to connect them during the load-out. ALE’s specialist ALE – Offshore Services division then carried out the weighing using hydraulic jacks and load cells.
The day before the load-out, the first module was skidded towards the quayside. Using the push-pull units, the average skidding speed achieved on land was 12m per hour.
ALE started the load-out operation at low tide and the module was gradually skidded over the link beams onto the HTV. The computerised control of the skidding increased efficiency and provided the most comprehensive overview of the operation for the system’s operator. For increased efficiency and safety, a load-out supervisor was in direct communication with the ballasting control room. This allowed sufficient time for the ballasting and ensured the HTV stayed within the acceptable limits. For the second load-out, the HTV was repositioned and the procedure was repeated.
After the load-out of the first module had been completed, winches pulled the equipment from underneath. On the following day, the skid shoes and push-pull units were removed from the HTV and installed beneath the third module. Once the second load-out was completed, the power packs and their platforms were repositioned to the third module and the remaining hydraulics were connected, ready for when the third load-out began.
Following the first phase of the operation, the client recognised ALE’s communication and management skills with an award for outstanding safety awareness. There were numerous contractors working on the project and the client was impressed by ALE’s communication and time management throughout this phase of the operation. ALE held daily meetings to discuss any safety issues on site, which ensured they could be handled and communicated across all parties consistently, keeping the client updated regularly of the planning procedures. The client also praised how ALE had managed the tight schedule and site deadlines without compromising on their commitment to safety.