Standard dimensions of the tank and positioning of the NPT openings for simple and easy retrofit installation;Coating is UL-approved;Sandblasted and coated with polyurethane, UV-resistant paints;Light color paint finish such that condensation is less likely to occur within the tank;All tanks are factory pressure tested prior to shipping;UL 142 certification available on 275 & 330 US gal (including a 3" diameter emergency vent opening);Made from ASTM A-1011 steel;NPT female threaded openings;Pressure tested at 5 to 7 PSIG;Innovative double protection resists pressure up to 25 PSIG, ensuring high safety and protection against leakage caused by corrosion;For use at atmospheric pressure only