DECOMMISSIONING Ӏ CASE STUDIES
health and safety was to remove
the masts and to land them both on the ship so that any possible future works will still have the original equipment in one place.” The masts were estimated to
weigh between 900kg and 1000kg; they were approximately 12m tall and measured 270mm in diameter. Pipework was estimated to weigh 700kg, but during the lift the crane was reporting near 900kg for the front mast and near 1,000kg for the rear mast. A local rental company provided
a 35-tonne capacity Terex AC 35 L all terrain crane and led on the lift plan and selection of below the hook equipment; a 22-metre Skyjack SJ66T telescopic boom was also used to fit one-tonne capacity, one-metre-long slings to the masts.
Despite the length of the masts,
centre of gravity wasn’t a concern because the masts were landed on the boat, then re-slung to create a horizontal lift. “The existing mast tensioners
were kept attached to the masts and tied to each mast during the lift,” explained Edwards. A safe working area was created for the one-day duration of the work.
TANDEM TEAMWORK A decommissioning assignment that involved a tandem lift was recently undertaken in Germany by Frankfurt-based crane service provider Auto-Service Safar. It decided to use its Tadano AC
5.220-1 all terrain crane to handle a boiler that had been removed from service at the old industrial park in Griesheim, near Frankfurt, and to do it together with Neuwied-based Hack Schwerlast which brought its very own Tadano AC 5.220-1 to help. According to Safar the only way to lift the boiler, which weighed 120 tonnes and had a length of 11.60 metres and a diameter of
40 CRANES TODAY
3.50 metres, was via a tandem lift and it says Hack Schwerlast was a solid partner in the endeavour. The plan was for both cranes to lift the boiler to a height that would make it possible to move a lowbed trailer underneath it so that the load could then be lowered onto it. After that, the boiler would be transported to its destination in Turkey. “To do this we started by optimally positioning both cranes after measuring the required radius of 13 metres and then rigging the load,” reports Safar’s heavy load and crane manager Detlef Precht, who also operated the Tadano AC 5.220-1. Together with the corresponding slinging gear the boiler came in at a gross weight of 122 tonnes, which was split evenly by having each crane handle 61 tonnes. Set up with a counterweight of 71 tonnes and a boom length of 21.56 metres the two cranes lifted the boiler to a height of one metre in synchronisation. After this a team from transport specialist Max Goll moved a 12-axle semi-trailer with a four- axle tractor underneath the boiler and the two Tadano cranes lowered their load onto the semi-trailer. “Thanks to preparation and
perfect teamwork when carrying out the tandem lift, everything went exactly as planned,” reports Precht. He listed the prerequisites for a successful tandem lift. “The things that are absolutely crucial for us as crane operators are having a direct line of sight, being able to communicate smoothly with each other at every phase of the lift, and having experienced signal people that we can rely on one hundred percent.” Abuzer Colak, managing director
of client Colak, summarised the lift: “They carried out the job with professionalism and without issues within the scheduled time-frame."
PRECISE OPERATION German heavy lift contractor Autokrane Schares used its new Enerpac JS-250 jack-up system to assist in the challenging removal of a bridge.
The Marggraff bridge over the
Britzer Verbindungs canal in Berlin was built in 1965. It consists of three bridge sections built adjacent to each other. Autokrane Schares was responsible for removing the first 60m long bridge section weighing 1500 tonnes. Overhead power lines and lack of space at the busy road intersection were severe constraints and meant that an Enerpac jack-up system was the preferred lifting solution. The close proximity of a busy highway meant that precise operation of the JS-250 was critical. To position the JS-250 jack-up
tower bases on the narrow canal towpath a section of bridge deck was removed at each end of the bridge and the jack-up bases lowered onto the path, followed by the header beams. Once those were in position additional jack-up tower barrels were added from a pontoon. Synchronous lifting of the bridge section was achieved using two interconnected split flow pumps. The bridge deck was removed
in three stages, each 60m long and weighing between 450 and 630 tonnes, over a two-week period. For each stage the JS-250 raised the bridge deck three metres clear of the bridge abutments. Two pontoons were positioned underneath, and the bridge deck lowered onto steel frames resting on support structures. The bridge was then floated to the side and lowered on to SPMTs for transportation by road to a nearby site for dismantling. “Space restrictions at the site made this a very challenging project,” said Max Boere, team leader SPMT, Autokrane
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