We note that the question is from someone located in the Department of Transportation (DoT) but will answer the question from a Department of Defense (DoD) perspective.

As described in the Office of SecDef (Acquisition & Sustainment) Director of Pricing and Contracting Int'l Contracting web page, there is a Defense Federal Acquisition Regulations (DFARS) restriction on "Construction or repair of vessels in foreign shipyards" based on legisltative  restrictions in 10 U.S.C. 7309 and 10 U.S.C. 7310.

Source documents:  https://www.acq.osd.mil/dpap/cpic/ic/docs/domestic_preference_and_competition_requirements.pdf and https://www.acq.osd.mil/dpap/dars/dfars/html/current/225_70.htm#225.7013

However, whether or not these restrictions would apply to purchase of a "foreign made used barge" would depend on:

a) whether a barge is considered a "vessel" (and thus subject to this legislative and DFARS restriction); and,

b) whether the barge would be acquired for DoT use or DoD use since this restriction only applies to "A vessel [acquired] for any of the armed forces."

Finally, the DAU response is provided for information only.  It is ultimately the responsibility of the DOT or DoD Requiring Activity, in consulation with the Contracting Officer responsible for the procurement, to make a final determination whether the legislative restrictions discussed in this answer do (or do not) apply to this specific procurement action.