Cyanidic ammonium bisulfide corrosion assessment

It has been shown (F.W.H.Dean, C.M.Fowler, R.Farnell, S.J.Mishael, ‘Hydrogen flux and corrosion rate measurements on hydrogen induced cracking susceptible and resistant A516 steels in various sour environments’, Corrosion 2010, Paper 10179, Conf. series, NACE, Houston, 2010) that ammonium bisulfide generates a very substantial flux when cyanide is present. This is often the case in refinery hydrotreatment, and cataltyic cracker units in refineries. Often the corrosion is sufficient to cause hydrogen damage. Routine inspection with Hydrosteel 6000 using AT-S probes at critical sites is generally recommended, to ensure corrosion is effectively controlled.