For wetted parts, stainless steel SS316 is the most common material. Depending on the aggressivity of the mixed media, 904, duplex stainless steel or titanium are often applied. The surface roughness of wetted parts varies from cold/hot rolled steel, pickling, sand or glass blasting up to Ra0.2 to 0.8 grinded or polished depending of cleanability requirements. Normally, carbon steel and cast iron are applied for non-wetted parts, but in special conditions stainless steel can be applied.
For the most aggressive conditions, wetted parts are protected against corrosion or wear by a rubber or other polymer lining.