Corrosion Performance of N10362 and N06200 Alloys in Formic Acid and Acetic Acid with and without Inorganic Salts

Abstract Acetic acid is widely used in the manufacture of fibers, plastics, agricultural chemicals, pharmaceuticals and other products. Formic acid is used as a preservative for animal feeds and in various chemical processes including ester manufacturer, rubber coagulation and chemical reducing agent. During the process, some reducing or oxidizing contaminants such as chlorides, fluorides, dissolved oxygen, ferric ions and cupric ions could exist in the acids. Materials selection of equipment is complicated. Ti alloy is not suitable for a very reducing environment, Zr alloy is more expensive and susceptible to fluoride attack; welding of Zr alloy could be challenging. Ni-Mo alloy N10665/N10675 and Ni-Cr-Mo alloys such as N10276 have been widely used in many organic chemical processes. In this paper, N10675, several C-type Ni-Cr-Mo alloys, R50400, and R60702 alloy were evaluated in pure and mixed formic and acetic acid with and without impurities such as NaCl and FeCl3. N10362 alloy appears to be the most promising alternative candidate to N10675 at low levels of oxidizing impurities. N06200 is outperformed by N10276. In some cases, N10362 and N06200 alloys are comparable with Zirconium R60702 alloy.