An Enerpac precision heavy lifting system was used to spectacular effect, when it delicately positioned the entire bridge onto a multifunctional ship being built for the New Zealand navy by the Australian company Tenix.
The SyncHoist system, a high precision hydraulic load manoeuvring system for cranes, was used with a single floating crane to position the 600-ton superstructure to within an accuracy of one millimeter.
Enerpac’s internationally proven SyncHoist system is one of a family of PLC-controlled synchronised ifting systems used above and below loads to hoist and position bridges, buildings, draglines, pipelines, oil platforms, rolling stock, heavy machinery and cargoes.
Instead of the usual two floating cranes, only a single one was available earlier this year for placing the superstructure onto the Multi Role Vessel (MRV) under construction for the New Zealand Ministry of Defence at Merwede Shipyard in Holland.
Merwede Shipyards (one of the leading shipyards in the Netherlands and part of the IHC Holland Merwede BV group of companies) sought an alternative and calling on Enerpac’s technologies provided the answer.
The MRV involved in the lift Hardinxveld-Giessendam was part of an order for the Australian company Tenix Defence, which is the prime contractor for delivery of a fleet of seven vessels to the New Zealand Ministry of defence.
The MRV, a new multifunctional transport and patrol vessel for the Royal New Zealand Navy, was constructed at Merwede Shipyard; however, the superstructure and the funnel unit were outsourced to Maatschappij De Maas BV in Rotterdam, which operates from the former RDM premises on Heijplaat. This is also where the superstructure and the funnel unit had to be placed on the ship, which was towed to Maatschappij De Maas after being launched at Merwede Shipyard.
This kind of placement task for heavy ship components to precise geometric tolerances in both the vertical and horizontal planes normally requires two cranes or floating derricks to be used.
The problem was that the sheet steel structure had to be lifted carefully to ensure that all parts of the structure were moved synchronously, when it was hoisted, otherwise unacceptable stresses could arise within the construction.
According to Merwede Shipyard, the weight of the superstructure is no problem for a single crane. It is the volume that makes it awkward. It could be compared to lifting a flexible cardboard box. That is why Merwede Shipyard designed the construction for hoisting using two cranes.
However, in this case, there was only a single floating derrick available, so an alternative solution had to be found for hoisting and positioning the superstructure. Enerpac’s tried and tested hydraulic system SyncHoist provided the solution. The SyncHoist system was developed by Enerpac to improve the accuracy of the placement. SyncHoist system allows the load to be manoeuvred precisely in the vertical and horizontal plane using just a single crane. Furthermore, it can keep the interplay of forces under tight control, so that the risk of sagging and the consequent undesirable stresses can be excluded.
A special hoisting frame was constructed to facilitate positioning of the bridge, using this lifting frame, they were able to keep all the features that we had constructed intact.
A total of eight lifting points were used. Four of these were provided on two heavy-duty beams on the underside of the superstructure, with lifting cables that ran through the construction. The other four cables were attached to the very outside of the superstructure and were there to keep the entire construction properly balanced. The double-acting hydraulic cylinders of the SyncHoist system were integrated into the four outermost cables. Their double action (powered extension and retraction) allows both lifting and lowering corrections in each cable to be controlled extremely precisely.
The four cylinders, each with a capacity of 85 tons, were placed in the right position before the lift, so that a type of pre-tensioning was achieved. During the lift, this pre-tensioning ensured that the entire superstructure could be hoisted synchronously. Then, while lifting and positioning the superstructure, the interplay of forces in the cylinders and the movements were monitored by sensors and a PLC control system, and corrected if necessary to the pre-defined values.
Using the SyncHoist system provided significant advantages for Merwede Shipyard. Due to Enerpac’s hydraulic SyncHoist system, the crane was able to use multiple lifting points to a tolerance of ±1mm. Not only were there cost savings due to the fact that just a single floating crane was used, but Enerpac was also able to guarantee that the superstructure could be positioned without being subject to stresses. Although this did not really play a part since there was relatively little wind, the SyncHoist system is less affected by weather conditions than the application involving two cranes.
Synchoist is designed to permit vertical and horizontal load manoeuvring using one crane, while eliminating the risk of damage from oscillations of wire rope caused by sudden crane stop/starts.
The PLC or manually controlled system, offering 60-110 tons capacity for each of its four lifting points, is the new member of Enerpac’s family of Synchronous Lifting Systems for heavy loads.
Offering accuracies of plus/minus one millimeter over cylinder strokes of up to 1500mm, the SyncHoist differs from standard Synchronous lifting systems in that it generates pull forces, while suspended from a crane above the load, rather than generating push forces from underneath.
Typical SyncHoist functions include high precision load positioning; pre-programmed positioning, tilting and aligning; and counterweighting to determine centres of gravity.
- Positioning of roof sections, concrete elements, steel structures
- Positioning of turbines, transformers, fuel rods
- Precise machinery loading, mill rod changes, bearing changes
- Precise positioning of pipelines and blow-out valves
- Positioning and aligning of ship segments prior to assembly
According to Enerpac, benefits of the system include vastly improved operating and positioning speed and worker safety. It means also that weather conditions play a less critical role. Enerpac’s works with global synchronous lifting technology specialists to introduce advanced concepts to Australia. This includes the synchronous lifting system used to lift a dragline at Curragh coal weighing more than 3000 tonnes.
Intelligent hydraulics such as SyncHoist can turn conventional lifting systems into high accuracy hoisting and load positioning systems. SyncHoist and Synchronous Lifting can produce cost reductions and safety benefits when compared with conventional lifting systems.
Advanced lifting systems featured in Enerpac’s new E325a catalogue include synchronous systems that one person can operate from up to a kilometre away to lift giant weights (including bridges, turbines, draglines and drilling platforms).