A pressure vessel assembly includes a plurality of lobes, each lobe having at least one vertically arranged interior wall, the lobes positioned in a side by side arrangement such that a first interior wall of a first lobe is positioned adjacent a second interior wall of a second lobe, the first interior wall having a first wall top and bottom side, the second interior wall having a second wall top and bottom side, the first wall top side joined to the second wall top side and the first wall bottom side joined to the second wall bottom side. Also included are first and second end wall surfaces of each of the plurality of lobes. Further included is a plurality of end caps, each of the end caps joined to the end wall surfaces of the lobes, each of the end caps joined to at least one adjacent end cap.