Hydrochloric acid (HCl) is a versatile chemical used for steel pickling, removing rust/scale; pH control, in water treatment, food processing (fructose, citric acid), and pools; chemical manufacturing, to make PVC, polyurethane, and other compounds; oil & gas, for well acidizing; and in household cleaners, for descaling and sanitizing. It also plays roles in food processing, leather tanning, and laboratory analysis.