Protective gase

Industrial gases Hz, N2, O2, Ar, He, CO2, natural gas Sweetening and CO2 removal from natural gas, removal of hydrocarbons from air, preparation of protective gases Aromatic compounds... 

The production of smaller volumes of hydrogen/nitrogen mixtures used as protective gases for chemical products [1435] and for metal-working processes [1436] by decomposition of ammonia over iron- or nickel-based catalysts at 800 - 900 °C may be an economic alternative where production or purchase of pure hydrogen is too expensive [1437], [1443], Energy-related applications of ammonia are proposed in [1429],... 

Fluxless re-melting involves the use of sulphur containing protective gases, which contribirte to global warming (SFg) or are poisonous (SO2). This issue is discussed in 4.2.7.1. 

Helium and argon are utilized as protection gases in the bright annealing of special steels and other alloys. The noble gas atmosphere prevents the metallic surface from oxidation at the high temperature of the process. 

However, still today, when more sophisticated materials and more productive and less expensive techniques are at the users disposal, MMA welding remains a favoured process to weld pipes. Its easy use, capacity to reach positions of difficult accessibility, the simplicity of the necessary generators (or the fact of being able to use motor generators network power is not always available on installation sites), the fact that protective gases (difficult to find in certain countries, in particular third world countries), necessary in welding with solid or cored wires, are not required, all these and others are the reasons for this choice. 

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