---
kind: "section"
citation: "46 C.F.R. § 151.50-23"
title: "46"
number: "151.50-23"
heading: "Phosphoric acid."
url: "https://uscodex.org/cfr/46/151.50-23"
---

# §151.50-23. Phosphoric acid.

- (a) The term phosphoric acid as used in this subpart shall include, in addition to phosphoric acid, aqueous solutions of phosphoric acid, and super phosphoric acid.
- (b) Phosphoric acid may be carried in either gravity or pressure type cargo tanks. The tanks shall be rubber-lined, or lined or clad with other suitable material acceptable to the Commandant, or shall be fabricated of a phosphoric acid resistant stainless steel. See [§ 151.15-3(f)(2)](/cfr/46/151.15-3.md?p=f-2).
- (c) The vessel's shell plating shall not be used as any part of the boundaries of gravity type cargo tanks.
- (d) Cargo piping, including valves, fittings, and flanges where exposed to the acid, shall be rubber-lined, or lined, coated or clad with other corrosion-resistant material, or shall be fabricated of a phosphoric acid resistant stainless steel. Vent piping, including flanges and fittings, shall be similarly protected at least to the height of the frangible disk if such is installed.
- (e) Phosphoric acid adulterated by other chemicals, inhibitors, oils, solvents, etc., shall not be transported in bulk cargo tanks except upon authorization by the Commandant (CG-ENG).
- (f) The requirements of [§ 151.50-20](/cfr/46/151.50-20.md) are also applicable to the shipment of phosphoric acid.

## Notes

### Amendments

[CGFR 70-10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 82-063b, 48 FR 4781, Feb. 3, 1983; USCG-2014-0688, 79 FR 58284, Sept. 29, 2014]

### Authority

Authority: 33 U.S.C. 1903; 46 U.S.C. 3703; Department of Homeland Security Delegation No. 0170.1.

### Source

Source: CGFR 70-10, 35 FR 3714, Feb. 25, 1970, unless otherwise noted.

### Amendments

[CGFR 70-10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 82-063b, 48 FR 4781, Feb. 3, 1983; USCG-2014-0688, 79 FR 58284, Sept. 29, 2014]