Stainless steel is durable, corrosion resistant, easy to clean and generally has a long life. Both materials have their purpose and fill a niche. Carbon steel is much more likely to rust and require repairs compared to stainless, but the upfront expense of stainless steel is higher than C/S. Some products are suitable for one material, but not the other. When a smooth, sanitary interior is an important factor, stainless is the best choice (food, beverage, pharmaceutical). Ultimately, guidance and selection of material is the responsibility of the process engineer or a metallurgist.