300 mm/sec is a very, very low velocity Are you sure of this ? As pointed out by others, the MOC for tankage, piping etc is strongly affected by the concentration of acid as well as the operating temperature. Certain commercial grade strengths ( such as 93%) at ambient temperatures are commonly stored in carbon steel tanks ( with an extra corrosion allowance and certain features included at nozzles). When the sulfuric acid concentration is decreased, more expensive materials are often required Piping MOC is commonly SS when the velocity exceeds 3-4 ft/second. If temperatures are significantly higher than ambient, a whole new group of materials must be considered There is much information available on the internet about this important commercial chemical What, exactly, are you trying to do ?????/ -MJC