Putting a blanket on is normally associated with keeping warm. In the cryogenic world of LNG, however, the ABAS Blanket maintains the liquefied gas at -162°C and reduces the amount of gas lost as boil-off and also reduces the pressure in the tank, explains RINA in 'The Naval Architect: October 2013.
This is just one of the ways that SHI’s ABAS Blanket can improve the commercial prospects for LNG carrier operators according to Samsung Heavy Industries (SHI). Tank tests have shown that the ABAS blanket also has a dampening effect that slows the motion of the LNG cargo and reduces the impact pressure by around 20% says SHI.
Changes to the links of the system have improved it. Essentially the blankets are one metre cubes of Basotect, a foam developed by German chemicals firm BASF that is lightweight, soft, absorbent and is able to maintain its form at temperatures below -200°C. The Basotect cubes have an aluminium ball inserted for buoyancy and are covered with another hardwearing material, Vectran, which is made from polyarylate fibre and is produced by the Japanese company Kuraray.
Dr. Sangeon Chun, Cryogenic Research & Development Center (System R&D), SHI says the original design of the blanket used metal U-bolts to link the one metre basotect cubes together to form the blanket, but he admitted the bolts could: “hit the primary membrane and damage it”.
As a result the latest ABAS Blankets have dispensed with the U-bolts and the cubes are linked with Vectran belts instead. Furthermore, he says that the system cannot be used with GTT’s NO96 membrane system, as there is also a risk of damage to the blanket.
Source: RINA/The Naval Architect