ENGINEERING: Monster Crawler Crane Lifts Sasol Gasifier
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This was the third heavy lift task carried out by the new crane the only one of its kind in Africa since it was commissioned into the fleet in mid 2010. The other two operations were mining related.
“The new crane’s versatile capabilities in tight, congested areas made it ideally suited to the Sasol job,” Johnson Crane Hire’s Grant Parker, who was project manager on this assignment, says. “The crane can reduce superlift radius while it is operational, which not only makes for ease of use, but also saves time. The LR 1750 is able to move while fully assembled and rigged from one location to the next and can handle higher lifts and heavier loads to further radii than any other crane currently available locally.”
The Liebherr LR 1750 750-ton lattice boom crawler crane is equipped with additional driving gears with four drive motors on the crawler tracks which facilitate smoother travel, even in poor underfoot conditions. It features a 245 t machine counterweight and an additional 95 t central ballast counterweight. When used for lifts requiring its maximum capacity, the crane can be fitted with a maximum of 400 tons of super lift counterweight which is mounted on a suspended super-lift tray.
The crane features a massive 133 metre main boom, but when in luffing fly-jib configuration, it has a main boom length of 84 metres, a luffing fly-jib length of 70 metres and is able to reach a height of 150 metres. With tracks 1.5 metre wide and the use of specialised crane mats ground pressures are substantially reduced and the crane can perform single lifts up to a height of 130 metres. It is powered by a Liebherr eight cylinder turbo diesel 400 kW engine and can travel at a maximum speed of 1.65 km per hour.
Gasifier lift operation
A nine-man Johnson Crane Hire project team was involved in the Sasol gasifier lift operation, managed on site by Danie Earle, who is the Johnson specialist on the Liebherr LR1750. Prior to lifting the vessel, which weighed in at just under 140 tons, the company submitted a comprehensive technical rigging study outlining how the operation would be carried out. This study was scrutinised by Grinaker-LTA, The Linde Group and Sastech Technology who supplied the gasifier. Only once all three companies had given their go-ahead, could the project proceed.
The crane crew began by mobilising the crane to move it to the Sasol site, configuring it for the task and conducting load tests. Parker says it took about 40 truckloads of components to complete the complicated configuration.
“We used two heavy lift cranes a 550 ton and a 275 ton to load the gasifier and supplied a multi-axle trailer to move it on site,” he says. “The vessel was offloaded in a horizontal position using the 550 ton crane and the LR 1750 and then maneuvered into an upright position, balancing the weight between the two cranes.
“We had to do some quick thinking during this delicate operation, when we found that the actual weight of the gasifier was less than originally specified to us. This meant we had to remove some ballast from our superlift tray to get the balance back within specification. Once we had attended to this adjustment, we boomed out to a radius of 35 metres over the port into which the gasifier had to be lowered and then slewed and lowered the boom.
“The next task was to do the main lift, which involved lowering the vessel down into the port and holding 50% of its weight while the Grinaker-LTA team secured it to its foundation.”
Johnson Crane Hire was also tasked with installing a 70 ton waste heat boiler at 33 metres in the same plant, which Parker says was an awkward operation owing to jutting nozzles and steelwork. Ultimately, the crane crew had to remove some steel beams before the boiler could be lowered into place.
Safety was a primary priority during the operation, which took place over a live plant. In addition to Sasol’s stringent safety procedures, Johnson Crane Hire conducted daily Toolbox Talks and risk assessments and obtained the entire crew’s buy-in to the lifting plan.
“Although we were given a tight timeframe in which to complete the task, we managed to come in comfortably within the time allotted,” Peter Yaman, general manager of Johnson Crane Hire’s projects and heavy lift division, says. “We were thrilled to have completed a job of this scale and complexity including responding to the weight differential with such a degree of efficiency and success.
“This operation has clearly positioned us as a company fully equipped to offer a total turnkey solution on a diversity of projects within different engineering environments. On the Sasol project we supplied all our own equipment, including an imported 300-ton capacity main lift shackle and a 125-ton tailing shackle, as well as a variety of smaller cranes, to meet the client’s requirements.
“One of our main strengths derives from our network of 13 branches throughout South Africa. Each branch notably our Trichardt branch on the Sasol operation has built up excellent relationships with local suppliers and its personnel draw from an in-depth knowledge of local conditions in their areas of operation.”
Johnson Crane Hire has successfully completed several contracts for Grinaker-LTA over the past 12 months and was the biggest supplier of cranes for Sasol’s maintenance shutdowns in November 2010.
Business News Sector Tags: Engineering|