Custom tilt-up by ALE

ALE installed an 800 tonne riser access tower using an innovative tilt-up design for an offshore installation.

The UK-based transport and heavy lift specialist was contracted to install the riser access tower (RAT) on the K15-FA-1 gas field, off the Netherlands coast. It was built in sections that were assembled by ALE using mobile cranes.

Following assembly, the RAT was loaded out using ALE's SPMT trailers onto a cargo barge. After sea fastening the barge, it was towed to the installation point in the K15-FA-1 gas field.

The barge is equipped with a heavy duty grillage for the skidding system. The grillage also contains the main rotation point of the upending frame and the connections for the upending strand jacks and cylinders.

ALE design engineers created the bespoke upending frame that is used to support and guide the RAT during skidding, upending and lowering. The skidding was carried out using a hydraulic compensated and self propelled skidding system. After upending, the RAT was lowered on the sea bed with two strand jacks.

Full control during the positioning, the self penetration, suction and final positioning was managed by the ALE team using the expertise of suction pile foundation specialist SPT.

"Projects such as this demonstrate the expertise and innovation that ALE can offer our customers; we strive to find new and increasingly efficient solutions rather than constricting ourselves and our clients by following the norm," said Kees Kompier, ALE executive director.