Lifter maximises safety during maintenance
27 August 2008
Enerpac Synchronous Lifting system, one of the world’s most advanced heavy lifting systems has been deployed in Australia to maximise safety and precision while monitoring the 2200-ton load’s centre of gravity during the lift on Dredger 16 at Loy Yang Power.
Lifter maximises safety during maintenance
Dredger 16 is longer than the MCG, as high as 55 metres and has a slew ring bearing 15.2 metres in diameter containing 177 balls of 200mm diameter each weighing 32kg. It weighs a total of more than 5.000 tons and can remove 60.000 tons of overburden a day.
The delicate job of carrying out the lift with maximum safety and minimum downtime was carried out with the assistance of a team led by Shift Supervisor Mr David Little of Silcar, who is an asset manager and provider of maintenance services for technically complex assets.
The task involved two-stage lifting and lowering over 250mm, with the Enerpac Synchronous system governing six 630 ton hydraulic cylinders used in pairs at three lift points.
Project Manager Mr Tom Lamin acting for Loy Yang Power, said the lift proceeded smoothly, with the hoisting being undertaken on May 7 and lowering on May 13. The huge task was facilitated by the accuracy and fluency of the synchronous lift operation, and the real-time centre of gravity display.
Hydraulic and Pneumatic Sales Manager Mr Robert Lewis said the job required thorough planning to maximise safety and minimise downtime for a client operating the largest open cut coal mine in the southern hemisphere. Loy Yang operates 24 hours a day mining more than 30 million tonnes a year of the brown coal that provides more than half of the State’s electricity needs.
The Synchronous Lifting system used by Hydraulics and Pneumatic was an eight-point model that can be used with multiple cylinders ranging from 10-1000 tonnes capacity each. Larger models feature up to 64 control points. The hydraulic technology involved is the same type chosen to maximise safety on some of the world’s most precise lifts, ranging from Ariane rocket launch pads and oil drilling platforms in Europe’s North Sea, to splitting coal shovels and building and weighing wharves and infrastructure in Australia.
Enerpac Engineer Ray Paasila said safety was built into the synchronous system – “During lifting in automatic mode, the software meticulously follows each lifting point and each cylinder. The software also constantly monitors which lifting points are in the highest and lowest positions and whether these are still within the set tolerances. If a correction has to be applied, the 2/2 movement valve opens briefly and the relevant (lowest) cylinder receives a short hydraulic impulse, instantly followed by a new reading. This correction process is so fast that the relays that control the valves give the effect of perfect switches.
“The course of the lifting process can be followed on screen (per lifting point). The software also contains an extra control function, by which the system can temporarily be stopped and manually corrected. Emergency stops also built into the system. If something goes wrong, the system will stop automatically and block all points of support.
“In addition to time saving and the exceptionally accurate and virtually stress-free movement of an object, the advantages of Synchronous Lifting include its ability to record and document the entire repositioning process. All the values are stored in the control systems memory for later use. With satisfactory progression of the procedure, this provides both the contractor and the client with a clear guarantee that excessively high stresses have not occurred.”
Enerpac synchronous lifting technology has been used in Australia for integrated solutions involving ultra-precision civil, mechanical, industrial and maintenance engineering tasks, including the splitting of a dragline at Curragh coal for maintenance and during vital stages of the ongoing $A1.2 billion expansion of the Dalrymple Bay Coal Terminal near Mackay, where it was used to lift and weigh 80-tonne sections of wharf.
“In addition to time saving and the exceptionally accurate and virtually stress-free movement of an object, the advantages of Synchronous Lifting include its ability to record and document the entire repositioning process.
“All the values are stored in the control systems memory for later use. With satisfactory progression of the procedure, this provides both the contractor and the client with a clear guarantee that excessively high stresses have not occurred.” Paasila continued.
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