46 CFR §38.20-5

1. (a)Safety relief valves on cargo tanks in barges may be connected to individual or common risers which shall extend to a reasonable height above the deck. An alternate arrangement consisting of a branch vent header system as required by § 38.20-1 may be installed. In any case, the provisions of § 38.20-1 (d) through (j) shall apply.
2. (b)Arrangements providing for venting cargo tanks at sea on unmanned barges will be considered by the Commandant upon presentation of plans.