Reaction of Stainless steel pipe And the gas

Hydrogen corrosion phenomena may occur in ammonia synthesis, hydrogen desulfurization hydrogenation and oil refining device. Carbon steel is not suitable for high pressure hydrogen device for above 232 ℃. The hydrogen diffusion into the steel, and in the grain boundary or pearlite zone and reaction of iron carbide and produce methane, the methane (gas) can't spread to the outside steel all together, and white spots and cracks in metal or one of them. In order to prevent to produce methane, cementite must replacement into stable carbide, chromium, vanadium, titanium, or must be added into the steel drill. Data points out, improve the chromium content allows the use of higher temperature and hydrogen partial pressure formed in the steel chrome carbide, and it encounters of hydrogen is stable. In the use of harsh conditions (temperature higher than 593 ℃), the chromium content is more than 12% chromium steel and austenitic stainless steel in all known applications are corrosion resistance.
Most metals and alloys at high temperature molecular nitrogen is unresponsive, but nitrogen atoms can react with many steel. And penetration into steel and the formation of a brittle nitrides surface layer. Iron, aluminum, titanium, chromium and other alloying elements may be involved in these reactions. The main source of nitrogen atoms are ammonia decomposition. Ammonia converter, the system of ammonia plant production of heater and in 371 ℃ ~ 593 ℃, a nitriding furnace under atmospheric pressure ~ 10.5 Kg/was have ammonia decomposition of the operation. In the atmosphere, in the low chrome steel chromium carbide. It may be affected by the corrosion of nitrogen atoms to produce chromium nitride, and release of the carbon and hydrogen to generate methane, as above, then possible to generate white spots and cracks, or one of them. But chrome content more than 12%, the carbides in the steel than chromium nitride is more stable, so the response will not appear in front of, so now the stainless steel used in the high temperature of hot ammonia environment.
Stainless steel in ammonia state depends on temperature, pressure, gas concentration of chromium and nickel content. Field experiment results showed that the ferrite and martensite stainless steel corrosion rate (alteration metal depth or carburized depth) is higher than austenitic stainless steel, the nickel content, the higher the better corrosion resistance. With the increase of content increased corrosion rate.

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