"SS316 pipe and ST37 cadmiun coated flange corrosion"

Question:

"We have used SS316 stainless steel pipe with SS37 cadmium coated flanges at the accupling of an equipment. So our customer is suspicious about, as he is called,battery affect. He thinks that thouching of SS316 and ST37CC will cause or accelerate the corrosion of ST37CC and will form rust on the SS316 pipe."

Answer:

In general it is not advisable to electrically couple dissimilar metals in a corrosive aqueous environment. Based on the galvanic series, a cadmium coated metallic material would be expected to be the anode in a dissimilar couple with 316SS, thus preferentially corroding. The extent of the corrosion would depend on the corrosive environment and the anode/cathode area ratios.

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