C276 Bolting for Valve in NaCl

Q: We are using A4 stainless bolting on Hastelloy C22 valves for a process that involves NaCl processing media. We are experiencing corrosion. Can you suggest a bolt that would help eliminate this. Can you make any suggestions? Also could you share the mechanical properties of any suggestions as well.

A: Given that the valves you are using are Hastelloy C22 and the bolting is A4 stainless steel, we would recommend upgrading the bolting to a more similar alloy to the valve body like Hastelloy C276 bolts. This would eliminate any corrosion concerns due to exposure of the bolting to the NaCl processing media. In terms of mechanical properties, it would depend on the grade of A4 you are talking about but as a rough comparison Hastelloy C276 per ASTM B564 would have a MIN Tensile of 100ksi and a MIN Yield of 41KSI. A4-70 has a min yield of 101 KSI and a yield of 65 KSI.

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