Chemical

Sulfuric acid plants use concentrated acid at 98% and temperatures up to 200°C. Cast iron or PTFE-lined valves handle dilute acid; concentrated acid requires special alloys. Hydrochloric acid production requires PTFE-lined or Hastelloy C-276 valves. Nitric acid service uses 304L stainless steel for dilute concentrations and titanium for concentrated acid.

Chlor-alkali plants produce NaOH, Cl2, and H2 via electrolysis. Caustic soda (50% NaOH) at 90°C requires nickel or nickel-clad valves — stainless steel suffers caustic embrittlement above 50°C. Dry chlorine gas requires carbon steel valves (with moisture < 0.1%); wet chlorine requires Hastelloy or titanium. Hydrogen service uses carbon steel with appropriate material ratings.

Solvent production (methanol, ethanol, acetone, MEK) involves volatile organic compounds with strict emission limits. Bellows seal globe valves achieve zero fugitive emissions per TA-Luft. For high-purity solvents, electropolished 316L stainless steel valves with sanitary connections prevent product contamination. PTFE packing prevents solvent absorption and swelling.

Ammonia synthesis (Haber-Bosch process) operates at 150-300 bar and 400-500°C with hydrogen/nitrogen mixture. Forged steel valves with special alloy trim handle these extreme conditions. Urea production uses ammonium carbamate which is highly corrosive — requiring 316L UG (urea grade) or titanium-lined valves. Phosphoric acid production uses PTFE-lined valves for slurry service.