46 U.S.C. § 3704: Coastwise trade vessels

A segregated ballast tank, a crude oil washing system, or an inert gas system, required by this chapter or a regulation prescribed under this chapter, on a vessel entitled to engage in the coastwise trade under chapter 551 of this title shall be installed in the United States (except the trust territories). A vessel failing to comply with this section may not engage in the coastwise trade.