46 U.S.C. § 12120: Liquified gas tankers

Notwithstanding any agreement with the United States Government, the Secretary may issue a certificate of documentation with a coastwise endorsement for a vessel to transport liquified natural gas or liquified petroleum gas to Puerto Rico from other ports in the United States, if the vessel—(1) is a foreign built vessel that was built before October 19, 1996; or (2) was documented under this chapter before that date, even if the vessel is placed under a foreign registry and subsequently redocumented under this chapter for operation under this section.