Three contracts for LNG tanks projects

Paul Boughton
ESAB, the supplier of welding consumables, has added three major new projects to its portfolio of LNG tanks.

The company’s nickel-alloy based OK 92.55 electrode has been chosen for construction of a new LNG storage tank at the Jiangsu extension and another at the Jovo LNG extension project in Eastern China. ESAB’s OK 92.55 electrodes have also been chosen by Toyo Kanetsu Indonesia for a new tank at the Donggi LNG project in Indonesia.

Liquefied Natural Gas (LNG) is the fastest-growing primary fossil fuel market in the world today, with approximately four times the annual consumption being discovered in new reserves every year.

However, because most of the new reserves are located a long way from the main consumption areas, there is a strong demand for the transportation and storage of large quantities of liquefied gas.

Natural gas is liquefied by cooling to -163˚C, a process which reduces the volume of the gas by a factor of 600. Once liquefied, the gas must be kept at this low temperature for storage and transportation.

LNG storage tanks comprise a reinforced concrete outer barrier surrounding a high quality 9 per cent nickel steel inner skin, the space between the inner and outer layers being heavily insulated to maintain the low temperature.

To withstand the pressure of the liquefied gas, the inner container must be strong enough to withstand the pressure of the liquefied gas. It is therefore relatively thick and requires a lot of high quality welding, all of which is done on site, plate by plate.

All welds must be capable of maintaining fracture-resistance at the extremely low temperatures experienced inside and LNG tank. They are therefore made using expensive Ni-base alloy electrodes. Construction of LNG tanks is therefore high in value and technical complexity, an area where ESAB excels.

ESAB’s has enabled the company to develop highly effective welding methods combining NiCr-based alloy electrodes with submerged-arc welding (SAW) to produce highly impact resistant welds. ESAB’s OK 92.55 electrode is specifically designed for welding 9 per cent Ni steels for cryogenic applications down to -196˚C.

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