A DOME shaped LNG tank steel roof on Curtis Island has been raised almost 40 metres using little more than air.
The significant milestone was made on Curtis Island on Tuesday for the Santos GLNG project's LNG plant, being built by downstream principal contractor Bechtel.
Vice president GLNG Downstream Rod Duke said electric fans were used to lift the 850 tonne roof, using about the same pressure it took to blow bubbles through a straw in a glass of water.
"This is a huge achievement from the 2000 strong workforce on our site at Curtis Island to reach this milestone," Mr Duke said.
"We can now start to build the inner nickel steel tank that will hold the LNG at minus 162 degrees centigrade."
Once in place, the steel roof will be covered by two concrete layers and weigh a total of 7725 tonnes.
It took about two hours to raise the roof, which has a diameter of 79m.
Queensland Curtis LNG also reached another major milestone with the installation of a roof on the project's second tank.
Elevation of the 900-tonne steel dome marks the safe completion of the second engineering feat of this kind for the QCLNG project, after the roof was raised on the adjacent tank in February.
The dome rose 38 metres as fans under the structure increased air pressure only enough to inflate a party balloon.
The three-hour lift was monitored by a team of engineers to ensure a safe and even rise.
At the end of the operation welders attached the 79 metre-wide roof to a steel ring embedded in the concrete tank walls.
The roof will now be covered with concrete. The interior of the tank will be insulated and lined with nickel steel to keep the gas liquefied at minus 162 degrees Celsius.
Four pumps will be installed to transfer LNG to a jetty, where the gas will be loaded on to a specially built vessel for transport to Asia-Pacific markets from 2014.
QCLNG project director Mitch Ingram said the LNG plant was at an advanced stage of construction.
"We continue to meet key targets, with first gas expected to be delivered to the LNG plant around the end of the year to enable the start of commissioning," Mr Ingram said.
"Our project is more than half complete and we are well on the way to producing first LNG in 2014."
Bechtel Australia, the construction contractor for the QCLNG plant, began building the first tank 19 months ago.
Progress elsewhere on the LNG plant continues, with all 62 Train 1 modules and three Train 2 modules delivered and installed. The remaining 15 modules are scheduled to arrive this year.
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