A floating hydrocarbon treating plant containing a vessel having a hull and a deck and having tanks located below the deck for storing hydrocarbons, and a plant for treating hydrocarbons located at the deck of the vessel is provided. The plant for treating hydrocarbons includes spaced-apart modules, wherein each module has related plant equipment mounted on a module floor, and the modules rest on closed support girders that extend under the module in a direction perpendicular to the edge of the deck, and wherein the module floor is secured to one of the closed support girders.