QGC AND Bechtel wrapped up integrity testing of one of its liquefied natural gas (LNG) storage tanks earlier this year, capturing a series of unique photographs of the activity.

During the testing, which took place in January this year, the 140,000 cubic metre tank was filled with seawater – which is more dense than LNG – and drained safely over 10 days.

The images show workers in inflatable boats using high-pressure hoses and rainwater to clean the 250-metre circumference as the water receded.

QGC said it believed the photographs were the first to show in detail the hydrotesting of an LNG tank with seawater, which has taken place a dozen or more times around the world since the 1990s.

QGC managing director Mitch Ingram said in April the test represented an important step towards production of first LNG in the final quarter of 2014.

“This work represents the latest in a series of milestones reached safely as we transition from construction to commissioning and operation of our LNG plant,” Mr Ingram said.

“The second LNG tank will be tested in the next few months as part of the quality and assurance work being undertaken across the site on Curtis Island according to stringent regulations.”

The tanks, comprising an inner steel tank enclosed within an outer concrete tank, have been designed and constructed using the most advanced techniques and materials.

The concrete mix has been tested in liquid nitrogen to ensure it can withstand the temperature at which gas becomes a liquid and which LNG is stored at minus 162 degrees Celsius.

In February last year a steel roof was raised on the 48 metre-high LNG tank – the first time such a roof had been lifted in Queensland.