Key words: oil-tanker terminal, tank, oil-loading pipeline, pressure, hydraulic shock, pressure surge, gas hood, safety valve, the protection system, mathematical simulation, method of characteristics.
Protection of oil-loading pipelines of the tanker-terminals against hydraulic pressure surge by using devices called ‘gas hood’ is studied in this paper. The gas hood is a residential dampener tank are usually 5-20 m3 (in the simplest case it is short segment of a pipe closed at one end) partially filled with an inert gas such as nitrogen. This device is intended to protect the oil-loading pipeline against the leaks of oil or oil product to the sea water occurring as result of a hydraulic shock arising in the event of an emergency when valves are fast closed down. The hood has a gas trap for an emergency discharge of the oil into the tank in the event of hydraulic shock. The advantage of these devices to other systems for the same purpose is that they avoid the installation of cumbersome open containers for receiving liquids and pumps for pumping it back into the pipeline. The volume of the gas hood and the initial gas pressure therein to reduce pressure in the oil-loading pipeline to an acceptable value is determined in this article. In particular, it is shown that the combined protection system, consisting from two gas hoods (on the quay and on the coast) has a higher efficiency with a smaller volume tank, installed at the quay.
