Raising of Ichthys LNG tank roof (Video)

April 20, 2015

In January, the first roof has been fitted to the US$34 billion Ichthys LNG Project cryogenic tanks in the Northern Territory.

The feat was achieved through an ‘air raising’ – a common construction method for large diameter tanks, Laing O’Rourke said.

“Initially the suspended deck is lifted in, followed by the roof petals,” says field engineering manager, Riccardo Menon, “and each is lifted into position on a temporary central and peripheral ring of supports.”

Once a circumferential seal and balancing cables are fitted, air is gently pumped into the tank to raise the roof into place, where it is secured. Thanks to the massive area of the roof, only 2.28kPa (0.3 psi), or 1/100th the pressure of a car tyre, is needed to lift the huge weight.

The 1100 tonne structure was constructed on the tank floor and then raised into place over a four hour period using two powerful fans.

The enormous roof framework and sheeting for each tank are being pre-assembled offshore in sections and shipped to site, before being assembled within each tank.

The milestone was delivered by Laing O’Rourke’s Top End crews alongside partners Kawasaki Heavy Industries.

The four tanks are between 58 and 91 metres across and up to 56 metres high.