Section 151.50-77 - Fluorosilicic acid (30% or less) (hydrofluorosilicic acid)(a) Hydrofluorosilicic acid must be carried in gravity or pressure type cargo tanks independent of the vessel's structure. The tanks must be lined with rubber or other equally suitable material approved by the Commandant (CG-ENG). See § 151.15-3(f)(2) .(b) Notwithstanding the provisions of § 151.50-20(b)(3) , no compressed air may be used to discharge hydrofluorosilicic acid from gravity type cargo tanks unless: (1) The tanks are of cylindrical shape with dished heads, and(2) The air pressure does not exceed: (i) The design pressure of the tank, and(ii) 10 pounds per square inch gauge. The tanks must be fitted with pressure relief devices.(c) During cargo transfer, a water hose must be connected to a water supply and be ready for immediate use. Any leakage or spillage of acid must be immediately washed down. This requirement can be met by facilities provided from shore.CGD 80-001, 46 FR 63279, Dec. 31, 1981, as amended by CGD 82-063b, 48 FR 4781, Feb. 3, 1983; CGD 92-100, 59 FR 17028, Apr. 11, 1994