The collapse of a giant crane on May 2nd on Deme Offshore’s flagship under-construction offshore installation vessel Orion 1, which was at Liebherr’s yard in Rostock, Germany, was caused by a broken crane hook, Liebherr has said.
The vessel is under construction and owned by Cosco (Qidong) Offshore Co Ltd. The vessel was moored at the quayside at the Liebherr construction yard in Rostock, with the crane undergoing several load tests. Deme said that “the crane has suffered significant damage, while damage to the crane and the vessel will be investigated in the upcoming days and weeks”.
The crane, with a 5,000 tonne capacity, collapsed under a 2,600 tonne load.
Germany Construction on the DEME’s vessel Orion started in March 2018. The vessel was successfully launched at the COSCO Qidong shipyard in China, in November 2018. In April 2018, Liebherr started working on the giant new crane.
The high-tech crane was assembled on the 800-tonne pedestal on board as planned. It had a lifting capacity of 5,000 tonnes at more than 35 meters outreach. In theory it could lift nine fully loaded A380 airplanes at once.
The load test for the Offshore heavy lift crane HLC 295000 was planned for a load scenario of 5,500 tonnes. The lift was to be carried out by hoisting a barge. The overload test on 2 May 2020 was the last in a series of tests in the presence of the classification society to gain the final crane and vessel certification, said Liebherr.
On April 25th an initial load test of crane at maximum outreach had already taken place successfully.
The exact reasons for the crane hook failing and setting off the chain reaction that led to the collapse were as yet unclear.
Netherlands based Ropeblock provided the design of the Orion crane’s lifting blocks, including the crane hook.
Liebherr said that “the design and manufacture of the crane hook was purchased from an external supplier. A design or production error of the Liebherr crane can therefore be excluded.”
The crane hook was designed by a renowned supplier conforming with the construction regulations of the classification society and also certified by it.
The materials and production process for the hook were also tested in accordance with the requirements of the relevant construction regulations of the classification society.
Companies belonging to Liebherr-MCCtec GmbH have delivered machines equipped with one or more hooks for decades. No such failure had been recorded for any of the thousands of hooks in operation, said Liebherr.
All parties have agreed that the HLC 295000 should still be completed as soon as possible.
Liebherr has been in contact with specialized salvage companies and is working with them to develop a salvage concept.
Liebherr said, at the moment it is not possible to define the duration of the individual phases of the recovery as a number of factors would affect the salvage work.
Since the crane cannot be salvaged directly on-site the first stage involves appropriate safeguarding of the scene of the accident in order to safely shift the vessel to Berth 25 in Rostock International Port.
In phase two the insecure components such as the jib and A-frame will be recovered, to ensure the controlled and safe dismantling of the crane during phase three.
Liebherr has said that “due to the large dimensions, the salvage work is very complex. Therefore, we are presently unable to make any reliable comments about when the work will begin. According to current information, we expect that the complete salvage work could take until the end of the year.”
The estimated cost of the damage amounts has been in the high double-digit millions of euros.