Engineering service provider Penglai Jutal recently lifted a 470-tonne steel framework as part of the assembly of an offshore oil platform on the coast of Penglai in China. The company chose two Terex CC 6800 and two Terex CC 2500-1 crawler cranes that operated in a perfectly synchronized quartet to perform the meticulously planned, high-precision lifting task.
For the two Terex CC 6800 and two Terex CC 2500-1, hoisting the 470-tonne (518 US t) load was a straightforward procedure, but this was only one part of the job. The key challenge was the need to accurately butt joint the huge 75 x 22 meter steel pipe framework of the platform’s central supporting structure on top of a previously positioned section prior to welding. “We work to tolerance margins of under a centimeter, and the pipes of these frames are 75 meters (246 ft) long,” explains the chief project engineer of Penglai Jutal. “In our field, everything is meticulously planned and calculated, and working with cranes that provide the degree of accuracy and reliability is crucial.”
High-precision operation and synchronization
Following a test run, at 12.30 p.m. the four cranes simultaneously lifted the framework to clear the ground to a height of 8 meters (26.25 ft) and then steadily crawled forward 10 meters (33 ft). To maintain the right angle of approach, the cranes hoisted their respective sides of the load to different heights. Sharing the heaviest part of the load, and configured with a superlift mast, a 114-meter (374 ft) main boom elevated 81 degrees at 21-meter (67.25 ft) radius, and 360 tonnes (397 US t) of total counterweight and central ballast, the two CC 6800s lifted their end of the framework up to 57 meters (187 ft).
On the opposite side, set-up with a 74 meter (243 ft) main boom elevated 83 degrees at 14 meter (46 ft) radius, and a total counterweight and central ballast of 180 tonnes (198 US t), the two CC 2500-1s lifted their share of the load to a height of 41 meters (134.5 ft).
Once all four cranes had the frame hoisted to the required height, they then slowly proceeded to travel together under load for 75 meters (246 ft) until arriving face to face with the previously secured section of the frame structure.
From this point forward, it was a question of finely tuning and coordinating the cranes’ hydraulic movements to join both sections together on a precisely calculated incline. “The advantage with Terex crawler cranes is that they are incredibly smooth and accurate to operate,” notes the company’s chief project engineer. “Their IC-1 touch screen control system is an indispensable feature that helps our operators stay perfectly synchronized. By keeping track of the exact under hook weight during the entire process, the data provided by their load moment indicators (LMIs) is also a benefit in keeping the cranes precisely coordinated.”
Individually guided by the Penglai Jutal team’s technicians via interphone, the company’s four crane operators proceeded to adjust their respective loads centimeter by centimeter, bringing the two sections together to form a butt joint at exactly the required position and angle.
By 3 p.m. the entire assembly process was completed, and the framework seamlessly secured in position by jacks ready for welding.
About the Terex® CC 6800
The 1,250-tonne Terex CC6800 lattice boom crawler crane, featuring a maximum load moment of 13,952 mt, is designed for industrial operations worldwide. Its components, which have been dimensioned for a maximum transportation width of 3 to 3.5 m and feature low transportation weights ranging from 15 to 50 tonnes, allow for worldwide, cost-effective transportation. The unit’s strengths can be seen at their very best when building petrochemical plants and power plant facilities or erecting large wind turbines. A simple assembly process allows for short setup times, a main boom variable offset for SW and SWSL configurations, and both a Quadro drive and hydraulically-assisted boom section pinning are standard features for the CC6800. In addition, the variable Superlift attachment, with an adjustable radius of 15–24 m, enhances the crane’s stability and maneuverability at construction sites while also enabling it to work when space is tight. The crane is also equipped with redundant drive units, resulting in increased reliability at the site: if one of the two drive units fails, the other one takes its place. Finally, if the power supplied by both motors is not required, it is possible to save a considerable amount of fuel by simply using only one of them.
About the Terex® CC 2500-1
The Terex® CC 2500-1 is the most powerful lattice boom crawler crane in its class. It has a maximum lifting capacity of 500 tonnes. Maximum load moment amounts to 6140 metre tonnes, and the maximum load radius is 146 metres with SSL/LSL 126 m + 36 m LF. The CC 2500-1 stands out by virtue of its enormous load capacity and great flexibility, especially in Superlift configuration. Variable Superlift radius and variable offset for SW and SWSL boom combinations allow operation in an extended range of applications. Main boom length is up to 126 metres, dependent on the model selected. Weight has been optimised for transport, at a maximum of 39 tonnes per section. The user-friendly IC-1 touchscreen crane control system is designed for simple and safe operation, for example it can calculate load capacities for intermediate main boom positions.
About Penglai Jutal Offshore Engineering Heavy Industries Co. Ltd. (pJOE)
China-based pJOE is a well-known engineering service provider that specializes in the power transportation and shipbuilding industries. With its unparalleled steel fabrication facilities and high-quality equipment for tapping into new sources of energy, seawater desalination, mining, and offshore oil and gas transportation, pJOE has earned an outstanding reputation on the global market. The company, which employs more than 2,100 people, is headquartered in Penglai, in the province of Shandong.
For more information, please visit www.pjoe.com.
Terex Corporation is a diversified global manufacturer of a broad range of equipment that is focused on delivering reliable, customer-driven solutions for many applications, including the construction, infrastructure, quarrying, mining, shipping, transportation, refining, energy, utility and manufacturing industries. Terex reports in five business segments: Aerial Work Platforms; Construction; Cranes; Material Handling & Port Solutions; and Materials Processing. Terex offers financial products and services to assist in the acquisition of equipment through Terex Financial Services. More information can be found at www.terex.com.
Source: Terex News Release