A 3,000 tonne crane being installed aboard the new offshore wind vessel Alfa Lift was involved in a serious incident last week that may delay the vessel’s planned commissioning date. Details are minimal but it seems to be associated with the crane's folding A-frame.
Offshore wind installation specialist Seaway 7 ordered the semi-submersible heavy lift crane vessel for installing offshore wind tower foundations and transition pieces. The crane, a Liebherr HLC 150000, can handle 3,000 tonnes at a 30 metres radius, or 1,000 tonnes at 76 metres. It was built and tested at the manufacturers maritime plant in Rostock, Germany, then shipped to China, where the vessel is being built by China Merchants Heavy Industry, and where the ‘incident’ took place.
The crane is unusual in that it features a foldable A-frame, which reduces the height of the crane and vessel in order to pass under bridges, such as the Great Belt bridge in Denmark, between the North Sea and the Baltic. The 51,000 tonne vessel has a 148 metre long/10,000 square metre smart deck, which can transport up to 10 XL monopiles or eight jackets at one time. It has accommodation on board for 100 people.
Seaway 7, part of the Subway 7 group, was recently merged with OHT ASA to become 'Seaway 7 ASA'. The company said: “We have been informed of an incident involving the folding A-frame on the main crane of Alfa Lift, currently under construction in China. No personnel have been injured and the unplanned movement of the folding A-frame is currently being investigated. The incident is a matter between the shipyard and crane vendor, and it is too early to indicate if this will have an impact on delivery schedule of the vessel.”
The crane is contracted to install new turbines for the Dogger Bank offshore wind farm next year, with is expected to run through 2024.
A statement from Liebherr added: "We can confirm that during the installation of an offshore crane at a shipyard in Jiangsu (China) an incident with the crane’s A-frame occurred. Investigations into the exact circumstances and causes of the incident are currently underway. We can confirm that no one was injured. A team of Liebherr engineers is on site. Our colleagues are in close contact with all persons involved and are supporting the investigation."