LPG, LNG, cryogenic gas couplings – general information
Couplings and fittings for liquefied gas hoses and loading/unloading installations: LPG (propane-butane), LNG (natural gas), cryogenic gases (low temperature when liquefied) such as carbon dioxide, nitrogen, argon, oxygen. Basically, the couplings can be divided into two groups: LPG couplings, which are made of carbon steel and brass, for application at temperatures close to ambient and the other group – LNG and cryogenic gases couplings working at very low temperatures down to -196°C (liquid-nitrogen temperature at atmospheric pressure). Therefore the cryogenic couplings are made of stainless steel and brass with high fracture toughness . The couplings for liquid gases often have tapered threads and code features i.e. appropriate slots and pins on the coupler and on the adapter of the coupling. It prevents connecting the coupler of the particular medium e.g. oxygen with the adapter of another medium e.g. nitrogen. There are also the cryogenic couplings compliant with EIGA (European Industrial Gases Association) in this group.