Most process plants, power plants and water treatment plants have one or more sulfuric acid storage tanks. Concentrated sulfuric acid can be stored in carbon steel tanks at ambient temperatures without a lining. Sulfuric Acid becomes more corrosive as it is diluted by water. Some concentrated sulfuric acid storage tanks are lined with a baked phenolic coating to maintain acid purity. It is recommended that some corrosion allowance be designed with each vessel.