More than a quarter of the global production of natural gas in 2011 – or nearly 331 billion cubic meters – was liquefied and shipped throughout the world in ocean-going tankers. In preparation for transport, the gas is cleaned, liquefied at minus 162 degrees Celsius, and then loaded onto tankers that carry liquid cargo. This process reduces 600 cubic meters of gas to one cubic meter of LNG (liquefied natural gas). Thus far, these tankers have only been able to travel when either empty or full, because they would otherwise be put at risk by the sloshing of the liquefied gas, which in severe cases might even cause them to capsize. Working together with BASF, the South Korean company Samsung Heavy Industries has therefore developed a new anti-sloshing solution made of the BASF foam Basotect®. This solution can substantially improve the safety of liquefied gas transports while at the same time offering economic and environmental benefits to shipping companies and their customers – as confirmed by studies from two universities.A foam for minus 162 degrees Celsius
Basotect, an open-cell foam made from melamine resin, has very high acoustic and good heat-insulation properties and is both flame-retardant (DIN 4102, B1) and resistant to many chemicals. Due to its favorable set of properties, this BASF foam is used for sound absorption in buildings and heat insulation purposes in automotive and rail engineering as well as in solar thermal and air-conditioning systems. Basotect’s new application in LNG tankers capitalizes on an advantage that had thus far not attracted much attention, namely, the retention of the material’s flexural properties under cryogenic conditions, i.e. down to temperatures of below minus 200degrees Celsius.The blanket uses buoys to float
LNG tankers contain three to five tanks and each tank can hold around 40,000 cubic meters of liquefied gas. These steel tanks must remain cooled to minus 162 degrees Celsius at all times. In addition to this special challenge, all ships that carry liquids must address the problem of sloshing, which even mild seas can cause. As a consequence, LNG tankers can only travel when full (loaded over 80 percent) or empty (loaded under 10 percent). It has thus far not been possible for LNG tankers to have flexible load levels.
The anti-sloshing concept developed by BASF and Samsung consists of a blanket made of Basotect cubes. Each cube, with sides of one meter, is made of two blocks of Basotect. A buoyant entity, or type of buoy, is placed between the two blocks so that the Basotect cube does not submerge more than 80 percent even after becoming fully soaked with liquefied gas. The individual cubes are stitched into Vectran® textile covers and secured to one another with Vectran belts. Vectran, which is made from polyarylate fiber, is produced by the Japanese company Kuraray, and is also suitable for use under cryogenic conditions. In addition, Vectran is extremely durable and abrasion-resistant.
