Seaway 7 has confirmed that it has been informed of an incident involving the folding A-frame on the main crane of Alfa Lift, the semi-submersible offshore installation vessel it has under construction in China
In a statement, Seaway 7 said, “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.”
Alfa Lift was floated out from the drydock at China Merchants Heavy Industry (CMHI) shipyard in Jiangsu, China in March 2021.
The specialist heavy installation vessel, which was designed and is being built to install next-generation XXL foundations for offshore wind turbines, was launched on 28 February 2021.
The Liebherr HLC150000 crane for the new vessel was installed in September 2021. The crane has a characteristic foldable A-frame that can be used to reduce the height of the crane, if required.
With a maximum lifting capacity of 3,000 tonnes at 30 m and 1,000 tonnes at 76 m outreach, the HLC 150000 was designed to have a small footprint. The slew bearing diameter of the HLC 150000 is 14 m, as a result of which the crane requires little space on deck. A special slip ring configuration gives it 360-degree unlimited slewing range.
The foldable A-frame means that, unlike many other crane vessels of this size, Alfa Lift is able to navigate beneath bridges or other obstructions. This feature reduces transit time, for instance if the vessel needs to enter the Baltic via the Storebaltsbroen in Denmark.
The foldable A-frame also provides more flexibility, which in turn leads to both operational and cost-efficiencies, increasing the number of charter days and vessel availability.
The vessel is due to install the foundations for the Dogger Bank offshore windfarm, which will be the world’s largest offshore windfarm when complete.
Alfa Lift will transport and install all of the monopile foundations and transition pieces for each of the first two 1.2-GW phases of the project, between 2022 and 2024.
The foundations will be among the largest ever used for offshore wind and were due to be installed at Dogger Bank A between 2022 and 2023.
OHT, now part of Seaway 7, has previously stated that the vessel, which is of Ulstein design, would arrive in Europe in good time before project mobilisation.
Until the incident, construction had progressed as expected and without significant delays due to the Covid-19 pandemic or other causes.
The Dogger Bank windfarm is being developed by SSE Renewables and Equinor, with first power expected in 2023.
The incident is the second to have hit a heavy-lift crane manufactured by Liebherr for an offshore wind installation vessel. In May 2020, an incident occurred while testing the 5,000-tonne crane on DEME’s newbuild offshore vessel Orion 1.
That crane was undergoing load tests at the time. The ship was due to be delivered to the company later in May 2020 but has not yet been handed over. The crane suffered significant damage.
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