PURPOSE: To prevent of marine pollution due to an oil leakage without setting up a cargo oil pipe, connecting a manifold and a pump house in a tanker, on the upper deck as well as to promote the simplification of cargo oil pipe maintenance and improve in trafficability and operability on the upper deck, aside from the effectively setup of other outfittings.

CONSTITUTION: A cargo oil pipe 5 is composed of a vertical pipe to be connected to a manifold 6, a horizontal pipe to be connected to this vertical pipe, and a longitudinal pipe to be connected to this horizontal pipe, and this cargo oil pipe 5 is set up in the hull or in an cargo oil tank 4 that is a main feature in this tanker's cargo oil piping structure.