Gas Terminal Guidance in response to large unit designs

Technical challenges in this sector are being driven by a combination of design and operational issues. These include the increase in the size of terminal hulls, shallow water load effects, frequent partial filling, offloading operations and critical interfaces between the hull and topside structure and between the hull and position mooring system.

Offshore Floating Liquefied Gas Terminals (FLGT) concepts have introduced the possibility of hull structures up to 450 meters in length and 90 meters in breadth, which would make them the largest ship-shaped units yet built. With the hull structure so large, designs with two cargo tanks abreast are being proposed to minimize the internal load effects, particularly from sloshing in the partially-filled tanks during loading and discharge operations. Two other important considerations within the structural analysis include offloading operations and hull and topside interface.

The criteria from ABS addresses liquefied gas terminals with ship-shaped or barge-shaped hull forms, having single center cargo tanks or two cargo tanks abreast arranged along the centerline of the terminal’s hull. This new release of criteria is based on the design and analyses experience gained by the society from classing membrane tank LNG carriers, liquefied LNG and LPG gas carriers with independent tanks and FPSOs.