46 CFR § 153.236 - Prohibited materials.
When one of the following paragraphs of this section is referenced in Table 1, the materials listed in that paragraph may not be used in components that contact the cargo liquid or vapor:
(a) Aluminum or aluminum alloys.
(b) Copper or copper alloys.
(c) Zinc, galvanized steel or alloys having more than 10 percent zinc by weight.
(f) Silver or silver alloys.