Rail tanker couplings
Rail tanker couplings – general information
Liquid, gaseous and bulk products transported by rail are unloaded from rail cars (tank cars) through flexible hoses or loading arms installed on the facilities of a loading terminal (filling and emptying equipment). The tank cars are fitted with valves and simple threaded or flanged connections, which often require adjustments (e.g. mounting a dry disconnect coupling adapters) for unloading in accordance with current safety and environmental standards.
Loading/unloading fluid
The loading and unloading of liquid products can be carried out using top loading or bottom loading method. For bottom unloading, the tank cars are equipped with a bottom outlet valve and side valves located in the lower part on the sides of the tank car. The valves are fitted with male thread pipe stubs (typically M130x6, M130x9, M140x10, 5.1/2″ (DIN) or other rail standard) or flanged pipe stubs.
The flanged pipe stubs located at the top of the tank car, under the manhole, are intended for unloading the product from the top. A product hose assembly, e.g. DN100 or DN80, through which the substance to be pumped (liquid phase) will flow, is connected to the product pipe stubs directly or via a dry disconnect coupling. Vapour containment, that is, the transfer of vapours from the tank being filled to the tank being emptied (vapour recovery) is performed using the second line – a vapour recovery hose assembly and coupling on the tanker (gaseous phase). The transfer of liquid substances is carried out by gravity, pumps or pushing the liquid substance out of the tank with gas, such as nitrogen.
Bulk material loading/unloading
Dry bulk cargo is transported by rail in special tanker cars. Loading is performed from the top, through a filling manhole. The tankers are equipped with pipe stubs fitted with PERROT or similar lever couplings when unloading is carried out through flexible hoses. The product (cement, ash, lime) is unloaded using compressed air to push it out of the tank.