Monster in the sun
A heavy lifting world record has been claimed by Dutch lifting giant Mammoet with its recent lift of two reactors – each with a weight of more than 2,000t – 80km north of Doha in Qatar.
A second-generation gas-to-liquid (GTL) complex is currently under construction in the Ras Laffan industrial city complex. This facility will be supplied with 330,000 ft_/d of lean methane rich gas from the Qatar North gas field, and will produce 34,000 barrels of liquid gas per day.
The Qatar North gas field has proven reserves of over 900 trillion cu ft. The new GTL complex will be the world’s largest and most technologically advanced facility; in addition, it is the first GTL project in the Middle East. Mammoet came to the site to assist in the further expansion of the complex
Mammoet deployed a crew of 25 on the site, as well as a range of equipment including a Mammoet Sliding Gantry (MSG). The climax of the project was the installation of the two reactors.
The company carried out these extremely heavy lifts using the MSG configured with a 75.5m main boom, 15.4m jib, and 2,600t counterweight. Four 900t strand jacks (160 strands) were fitted to the boomhead, and four 600t strand jacks were fitted to the backmast (144 strands).
During both lifts a tailing frame developed by Mammoet was used to guide the base of the reactor while it was moved into position on Mammoet’s skid system. The MSG, working at a radius of 34m, succeeded in shifting the reactors smoothly and slowly to their final destination.
Mammoet’s Cees Segeren, technical advisor engineering, explained: “Using the MSG enabled the client to continue the construction work on the plant without interruption, since this was the only crane capable of positioning both reactors in the middle of the section of the new plant.”
Finally, both reactors were safely positioned at the heart of the process.
First job for PTC 111
In August, Mammoet’s PTC 111 was erected at the Petrobras refinery in Brazil to perform its first real lifting job. Challenges confronting the crane and crew included the restricted space available at the refinery, which made it impossible to erect the entire crane from the ground upwards.
The solution? Part of the PTC was erected ‘in the air’.
A temporary auxiliary structure was con-structed to position the entire boom and backmast horizontally over a piperack. Large mobile cranes then lifted the PTC. The old 654t reactor head of the UFCC unit at the Petrobras refinery was to be replaced by a new head. The rigging, block, spreader, etc., required for the lift added the necessary weight, and the total weight ultimately amounted to 722t.
With this lift Mammoet beat its own record land lift in Brazil (a PTC lift of 465t at Rio Polimeros Project in 2003).
The entire job took four weeks to complete, after which the PTC was dismantled in the air in the reverse erection sequence.
Push-up record in Caspian region
Mammoet recently performed its third successful push-up at an offshore yard in Baku Azerbaijan. The 16,800t topside for the West Azeri oil exploration platform in the Caspian Sea was the heaviest structure ever to be lifted in the Caspian region.
Mammoet used its push-up system to raise the supporting platform to the required height of 13m. The company’s Larissa van Seumeran explains: “The platform was shipped to the Azeri oil field in the Southern Caspian Sea, where a float-over took place. A float-over means that you position the platform on the ‘jacket’ (the platform support that stands in the sea) by means of a pontoon. In order to position the platform at the required height onto the jacket, you need to push up the platform on land.”
A 1,200t load-out frame was also installed as part of this project.
Mammoet has since completed the next phase of the project, the load-out of the platform’s topside. Four 900t capacity strandjacks were used to pull the structure onto a barge, two on each side of the load out frame (installed under the platform to support it).
At the same time Mammoet, installed its 1,000t capacity computerised ballast system on the barge comprising high capacity pumps, piping, and connections to maintain stability.
All the lifting equipment had been transported to the site from Mammoet’s base in the Netherlands in standard containers. The entire structure – including the load-out frame – was then loaded onto a barge ready for the float-over operation in the Southern Caspian Sea.
