HEAVY LIFTING Ӏ SECTOR REPORT
j a structural failure mode, where a part of it breaks, or it has a stability failure mode where it tips over. And that is true regardless of size. “But we design our cranes,
we don’t manufacture them. As with anything in the construction industry the trick is: ‘How do you translate something that appears feasible on paper or on your desktop onto something that someone can actually build?’ There is always the bridge between what is designed and what you can actually deliver. “On a super-heavy lift crane
like the Focus you have to ask 'is there a manufacturer that makes bearings of this size?’, 'is there a
producer who makes wire ropes at this diameter?', and 'do they have a test bed at their facility that enables them to certify pieces of this weight?’. It is about finding that sweet spot between practicality and what you can design.” The trend for many years in all kinds of engineering has been to build prefabricated modules as large as possible before moving them, to minimise assembly on site. Oil platform tops as large as 10,000 tonnes are being moved, from shore to ship to offshore platforms as single units. How much bigger, and heavier, can lifting get? Are we approaching the practical limit?
“I don’t think so," says Kerr. "If
you talk about modules, methods of moving them have moved from cranes towards SPMTs, and land- based cranes are not really used for anything over 3,000 to 3,500 tonnes. In principle we can put as many SPMT trailers underneath [heavier modules] as possible; but then you wonder ‘are the ships that you need to transport them available?' or 'are the fabrication facilities that are needed to build them already out of capacity?’ Cranes are not the only bottleneck. “But then consider offshore
wind, for example: that is perhaps the new frontier of growth in terms of size and weight. Go back f
Enerpac keeps 10,000 tonnes level throughout large-scale ship build
Vancouver-based Seaspan shipyard are building a new Joint Support Ship for the Canadian navy. It will weigh an estimated 10,895 tonnes. They wanted to find a way to keep it level throughout the project. As any large-scale ship build progresses the increasing weight can cause the ground underneath to move. This can put a strain on the ship’s
structure. Previous methods of levelling the ship involved deploying a team of people manually adjusting each lift point. Seaspan instead turned to Enerpac. Effective, safe, and precise movement of such a large and heavy object requires exact control and synchronised movement of all lifting points. To achieve this, they used an Enerpac EVO synchronous lifting pump and 12 high tonnage hydraulic lifting cylinders. The EVO system works using a programmable logic controller, enabling each of the 12z lifting points to be monitored and controlled by a single operator. The cylinders used were Enerpac HCG1506-Series single acting models. Each of these are capable of supporting a load of up to 168 tonnes and can withstand 10% side-load over the full stroke. They were positioned between the footings and the frame assembly supporting the ship. Each point was adjusted by automatic control of the
oil flow to each cylinder, causing the cylinder plungers to advance and retract accordingly. The EVO pump maintained accurate positional control within 0.040 inches (1 mm) between lagging and leading cylinders and included built-in warning and stop alarms.
18 CRANES TODAY
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
