Design on the arrangement program of LNG unloading pipeline crossing seawall

It is a technical challenge how the LNG unloading pipelines crosses breakwaters or seawalls while vehicle traffic requirements are satisfied. Moreover, the conventional pipeline crossing program (e.g. pipe jacking and underground laying) is not applicable to the LNG pipelines due to their low-temperature characteristics. In this paper, a seawall crossing program of "box culvert on crown" was proposed for LNG unloading pipelines in reference to the engineering practices of connecting docks and tanks through undersea and underground culverts in the US and Japan. Under this program, a reinforced concrete box culvert is set up on either side of the seawall so as to guarantee the LNG unloading pipelines to run through the seawall smoothly at the same elevation, and 4% ramps are prepared on both sides of the box culvert so as to meet the requirements of level crossing traffic. Field application shows that this program ensures the normal operation and maintenance of process pipelines in LNG receiving terminals, with no effect on the traffic conditions at the crown and the stability of the levee. The designed damp-proof water level of the seawalls was recalculated. Furthermore, the damp-proof capacity of the seawall is not affected. This program of "box culvert on crown" provides a reference for LNG receiving terminals with similar problems in the seawall crossing design of pipelines.