"Galvanic corrosion"

Question:

"What is the experience of galvanic corrosion between SS 316Ti and Duplex SS such as 2205 and 2507. Heating coils of Duplex SS are to be welded to SS 316Ti process vessel. In The heating coils steam will be circulated to attain a skin temp of 260C. the junction between SS 316Ti and Duplex SS come in contact with process chemicals whose temp will be around 230C. Whether the HAZ is expected to undergo substantial dissolution. The SS 316Ti heating coils are not giving satisfactory life due to corrosion and erosion."

Answer:

The galvanic couple between 316SS and 2205/2507SS should not be a large one. However, a detailed evaluation of the appropriateness of the couple would involve knowing the geometry and area ratios between the two couples and the conductivity and corrosiveness of the aqueous media. HAZ corrosion of duplex SS is a function of the as-welded austenite/ferrite ratio, which in turn is a function of the duplex chemistry and heat input.

<< return to the previous page ::