Offshore Crane Succesfully Delivered by Liebherr
At the beginning of September, Liebherr delivered the second heavy lift offshore crane type MTC 78000 straight from its manufacturing plant in Rostock. The MTC 78000 is one of the biggest offshore slewing cranes worldwide. With a maximum dynamic torque of 78,000 mT, the MTC 78000 is the most powerful machine within the extensive range of cranes and material handling machines. Four units of the new heavy lift crane have already been ordered to date.
Despite its size, the MTC 78000 has been designed as a slewing crane and is supported by traditional large diameter antifriction bearings. With a weight of 70 t, the swing ring has a diameter of approximately 9 m. The manufacturing of such large mechanical parts can only be accomplished through complicated custom processes as conventional gear cutting machines are only available for large diameter antifriction bearings up to a diameter of 5 m. Therefore, Liebherr has acquired correspondingly sized machines and equipment specifically for the mechanical machining of these flanges.
The onsite erection and assembly of the large size crane on the heavy load vessel OSA Sampson presented Liebherr engineers with special challenges – for example, the planning of the individual hoists so that the maximum permitted ground pressure of the pier was not exceeded. As the assembly starting date depended on the arrival of the heavy load vessel and the required lifting equipment needed to be ready on short notice, Liebherr exclusively used their own cranes for the assembly. Two large LHM 600 mobile harbour cranes were used in tandem operation for the heavy duty lifts. Both cranes with their maximum load capacity of 208 t each enabled parts weighing up to 400 t to be mounted in tandem operation. Due to precise project planning, the specially trained team of 50 mechanics was able to assemble the MTC 78000 in only 23 days.
The heavy lifting test of the large crane was carried out in the open sea with a 1,760 t test weight – corresponding to 110 % of the nominal load capacity. The test loads consisted of two water filled pontoons which were lifted out of the water and turned around. After the successful test, the client could be delivered with the heavy load vessel OSA Sampson. The OSA Sampson is one of the largest heavy load vessels worldwide and is being used for platform reconditioning, pipe laying and to set up offshore wind power plants.