January 15 - Heavy transportation and lifting provider, ALE, has used a uniquely designed gantry system to perform the lift and mating operation of a 10,000-tonne topside at Drydocks World for the semisubmersible HVDC platform DolWin Beta.

The gantry system was created by ALE's research and development department at its branch offices in Breda, the Netherlands and the Middle East. Drydocks World carried out an assessment of the topside structural strength and weight calculations, and designed heavy lift pad eyes to suit ALE's tailor-made lifting arrangements.

The topside was lifted from six consoles - four using ALE's laced tower system and two A-frame structures positioned centrally to create longitudinal stability.

On top of each gantry tower, four strand jack units were installed, giving a total of 24 strand jacks with a minimum capacity of 500 tonnes each, to lift the topside.

ALE lifted the topside to a final height of 52.8 m in phases, in between chichi careful and precise removal of the support barge undocking and docking of the substructure was put into effect by Drydocks World.

ALE then lowered the topside to the precisely positioned substructure and carried out the welding of the two structures, in order to complete the mating operation.

Edward Talbot, projects manager at ALE, commented on the unique gantry system: "The design meant that our client could not only perform the mating operation inside the dock but also maintain adjacent docking operations with minimal impact to the yard facility during and after lifting and mating completion."