This year Dutch heavylift specialist Mammoet has demonstrated the versatility of its two Mammoet Sliding Gantry lifting devices, the original MSG 50 and the MSG 50 II, built last year. They are easy to tell apart: the mark II model is in Mammoet yellow, while the first one is red, since it was not originally wholly-owned by Mammoet.
The original MSG 50, the red one, was called into action in May this year at Fort McMurray in Canada, to exchange a reactor vessel at the Syncrude plant. It was used for several lifts to replace the 620t reactor with a new one, and all the while the plant remained in operation. The MSG 50 was set up in simple crane configuration, equipped with a 43m jib on top of a 62m main boom to remove the old reactor and install a new one at a radius of 74.6m. But though it is configured like a crane, it lifts by means of strandjacking rather than using a winch. Some might take the view that this, in itself, makes it an ‘alternative’ lifting machine. But it can also be configured as a series of lifting towers. An example of this versatility was demonstrated by the MSG 50 II on a project at about the same time in Bremen, Germany. The MSG 50 II was used to lower a 2,000t overhead gantry crane into position (main picture). The crane was lowered with a 104m-high engineered gin pole version of the lifting device. Mammoet’s equipment comprised of four MSG lifting strand jacks on top of two lifting beams which were supported by four free-standing towers of containerised mast components. In this configuration, the machine has a lifting capacity of 4,200t and was able to lower the gantry crane into position in one movement.
Since building its second MSG, Mammoet has been acquired by Van Seumeren. There are now no plans to build any more MSG units, since Van Seumeren has its own heavylifting machines that can also be transported in standard sized containers, the Platform Twinring Containerised cranes. The original MSG 50 will remain in the Americas while the MSG 50 II will be based in Europe. Either of them can be dismantled and transported in containers to jobs around the world, as and when they are needed.
Van Seumeren’s biggest ‘lift and shift’ job this year was off the coast of Norway at the Snorre B oil and gas extraction station. The transportation of 10 offshore units was one of the biggest offshore projects of its kind ever completed, according to the Dutch company.
Van Seumeren, contracted to the joint venture of Aker and Kvaerner, had to transport a 4,600t drilling module. The various units, some of which were transported from yards in Scotland, were then joined to make one large platform to be used for oil and gas extraction in Norwegian waters.
The project was significant not only for its size, but also because it was the first time that Van Seumeren used a new jacking system that it has developed. A computer program designed by the company’s innovation department automatically controls the hydraulic pressure and levelling from all jacks. It also puts the engineer in complete control of all jacks from a mouse.
The utility module and the drilling modules were the last units to be installed on the project. The 4,043t utility module was lifted first over two standard North Sea barges onto the 55m-wide dry dock at Aker Stord in Norway. The next stage saw it being jacked up to a height of 5.4m by 12 hydraulic climbing jacks, each with a capacity of 600t, and placed on 160 axle lines of self-propelled modular transporters (SPMTs). The SPMTs were loaded with steel supports and the module was then lifted from the jacks, rotated through 90° and driven across the two barges in the dry dock. The barges had been ballasted throughout the operation using twenty-eight 1,000 tonne/hour hydraulic pumps and the Van Seumeren computer control system.
The drilling module was next to be installed. The 4,625t unit was loaded in from a barge, rotated and transported across the dry dock before being set down on pre-installed hydraulic jacks. A total of 188 axle lines of SPMTs with steel supports were used as the module was driven over a link-span bridge made up of 16 steel ramps, each 12m-long. It was then rotated another 90° before being driven across the site, jacked up and installed parallel to the utility module.
French specialist contractor Entrepose, which has used Mammoet equipment on several recent projects, is planning a major project for next summer. Entrepose will rebuild a blast furnace at Sollac in Dunkirk, again using equipment supplied by Mammoet as well as by its own sister company Montalev Levage. Entrepose will use a 2,400t capacity lifting system, which includes an eight strand lifting unit comprising four 200t and four 600t units and a 1,600t capacity skidding system. The skidding system is based on four 400t capacity skidshoes and a 1,440t capacity SPMT. Parts of the blast furnace will be lowered by the strandjacks onto the SPMTs and put into position (see diagram, above right).
Much of the planning for this job is being taken from the
success of other lifts carried out in France by Entrepose throughout the year. In March it used a Montalev skidding system and 12 air cushions of 40t capacity to move a harbour crane 50m across the dock at the port of Brest in northern France. The skidding system consisted of four skid shoes, each with a 300t capacity and a 34t capacity push-pull unit. The pressure of the air cushions was set to 4 bar. The whole process of equipment installation, ground and skidding beam preparation, lift and then demobilisation of equipment was completed in just one week.
In January, Entrepose installed four boiler blocks at a cogeneration plant in the town of Dole. The 130t boiler blocks were shifted 20m by using four 70t capacity strand lifting units fixed to the top of the boiler structure. These units were made up of seven strand jacks, each with a 17.7mm diameter. They were driven by a monitoring unit and piloted by data based on the load, distance covered and horizontal level of the blocks. The blocks were lifted at a rate of one a day and were fixed to the steel structure as soon as they were in place.
In September, Cranes Today reported on PSC Heavy Lift’s record breaking lift at a fabrication plant in Korea (CT Sept00, p5). PSC jacked up a 12,680t semi-submersible deck, the Deepwater Horizon, a distance of 33m by using 34 of its L600 strand jacks and its Active Loadout System. This mammoth lift beat the record for the heaviest lift that PSC had previously held, which stood at 11,000t.
This year PSC has also been working on the
construction of the approach spans of the Young-Jong suspension bridge in Korea (CT Feb00, p41). This project was finished at the end of July. The 1,375m long Young-Jong bridge, the main road link to the new Inchon airport, consists of eastern and western approach sections linked by a 550m span suspension bridge. PSC’s role included lifting sections into place on both of the approaches, as well as 15 loadouts from the fabrication yard onto barges and to the jobsite. The heaviest bridge sections weighed 6,500t.
PSC was also awarded the contract for tensioning the cables on the suspension bridge, for which it used 80 of its L100 strand jacks, each with a capacity of 105t. These jacks were inverted under the bridge in synchronised groups of four with computer monitored loads to tension the main suspension cable hangar.
To do this, each group of four jacks was connected to the four ends of two hangar cables, two ends of which rose up through the deck and
permanent anchors, passed over the suspension cable and back through their opposed anchors.
With all four jacks working together to pull the cable and to react against the underside
of the hanger, the cables were tensioned to a very tight tolerance. The jack ‘teams’ worked outward from the lowest points of the suspension cables in the centre span section and on each side of the main pylons with pre-determined tolerance levels programmed in before they moved to the next set. The tensioning operation was completed in six weeks after crews had worked on several at a time and jacks had reached operational loads of 100t.
South African rigging company Vanguard completed last year what it heralded as ‘one of the great
engineering feats of modern times’ at the Katse dam in South Africa. Standing at 185m high, the Katse is the highest dam in Africa and has a 60m-thick base wall, a 710m-wide crest and contains more than five million tonnes of concrete. The daunting task that Vanguard was given by Lesotho Highland Consultants was to lower 18 pieces of power generation equipment from an access road in the Lesotho mountains down to the mini hydro chamber at the very bottom of the dam wall. The pieces, the heaviest weighing 7t, had to be lowered through a 3m by 2m opening at the top of the hydro chamber. Vanguard’s engineering division, headed by Luigi Angelozzi, designed an aerial cableway to transport the pieces down. The structure consisted of a lower mast fixed to the generation chamber via a special joint to allow the movement required to install some of the larger components. The top section
consisted of a deflection tower and two anchor points in the mountain side, one for the cableway and one for the 40t winch. The angle of the cableway had to be set at 75° to horizontal, which required very careful control to move the turbine and generator pieces down the mountainside.
Vanguard’s project was made more difficult by political unrest in the area which culminated, one month after completion, in an attempted military coup being put down by the South African army.
