Site report: Jack-up job for ALE

UK-based heavy lift and specialized transport company ALE helped increase the height and alter the track centre distance of four container cranes at the Port of Antwerp in Belgium. IC reports

Raising the height of ship to shore container cranes is an accepted practice around the world as a way of extending the useful life of these already large port cranes by allowing them to accommodate the ever-larger container ships plying the world’s oceans.

Latest of these were four cranes at the Port of Antwerp in Belgium. They were relocated from the Port of Zeebrugge to the Port of Antwerp. International heavy lift specialist ALE, headquartered in the UK, used its Mega Jack 800 system to jack up the cranes by 4 metres so that new steel leg and frame sections could be added in. The cranes were then transported to and from the jacking location using winches to pull them along the existing rail tracks, a company spokesperson said.

As the maximum allowable ground bearing pressure on site was 6 tonnes per square metre, ALE placed three layers of load spreading mats underneath the Mega Jack 800 jacking system to reduce that ground load to a minimum.

Between the Mega Jack 800 and the beams of the container crane, a 10.5 m high support construction was used consisting of ALE gantry components. The towers of the construction were slightly skewed to allow the loads to be introduced closest to the strong points of the crane. By assembling the Mega Jack 800 in this way, large top beams could be eliminated, ALE said.

First, the Mega Jack 800 received 25 % of the crane’s weight. Afterwards, the client removed bolts, connecting the sill beam and bogies with the upper part of the crane. With all of the bolts removed the whole weight of the crane was transferred to the Mega Jack 800 and the jacking could start.

The crane was jacked-up in 550 mm increments until it reached a height of 4.5 m. As the crane was lifted, ALE needed to stabilise the bogies. The landside bogies were stabilised with ALE’s skidding system, installed to move them inwards. The waterside bogie was stabilised using diagonal bracing. An hydraulic jack was used on this bracing so that the bogie could be precisely positioned underneath the crane as the crane was set down on the modified lower structure.

The landside bogies and sill beam had to be moved 540 mm to the inside of the crane. For this ALE used an SS150 skidding system. On top of the skid beams, a beam with integrated jacks was used. With these jacks, the bogies could be lifted out of the rail tracks. After moving the landside bogies, the client installed the leg extensions. When completed, the crane was lowered again on its bogies.

As the cranes were disconnected from the electrical power during the upgrades, ALE used winches to relocate the cranes to and from the jacking location. The set-up consisted of two winches on both sides of the crane; two on one side for pulling, and the two on the other side for braking and precise positioning of the cranes above the jacking system. The Mega Jack 800 remained on the same position for all four cranes.

All four cranes were upgraded in six weeks, with one upgraded per week. It took one week for the mobilisation and assembly of equipment and another for demobilisation.

This site report was taken from the February 2016 issue of International Cranes and Specialized Transport magazine.