Hastelloy 276 and 304
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Hastelloy 276 and 304 stainless steel are used for mechanical seals; both can resist alkaline solutions (32% sodium hydroxide solution). Which material is better?
Hastelloy C276, with the UNS designation N10276 and the domestic designations NS3304 or NS334, is a corrosion-resistant alloy that exhibits exceptional resistance to corrosion. S30408 is what is commonly referred to as 304; it is an stainless steel that offers good resistance to high temperatures and corrosion, and is therefore widely used in various applications.
I did some research, and it seems to be closely related to temperature. The cost of HC is high, but there are certain temperature ranges in which HC may not be the suitable choice. I was wondering if any professionals could provide an answer
Refer to NACE SP0403-2015, “Avoiding Caustic Stress Corrosion Cracking of Refinery Equipment and Piping””
C-276 is more durable than 304 when exposed to high concentrations of sodium hydroxide, but it is much more expensive. When dealing with alkaline solutions, the high cost applies not only to the pump material but also to the seals and cleaning systems. Therefore, the choice should depend on one’s circumstances; if money is no object, using higher-quality materials is a good option. Material of the 316 grade can also work well in such situations
Hastelloy C276 is not expensive, or Q235B can be used for anti-corrosion coating