A pressure vessel assembly comprising: a plurality of lobes , each of the lobes having at least one vertically arranged interior wall , the plurality of lobes being 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 side and a first wall bottom side , the second interior wall having a second wall top side and a second wall bottom side , the first wall top side is joined to the second wall top side and the first wall bottom side is joined to the second wall bottom side ; a first end wall surface and a second end wall surface of each of the plurality of lobes ; and a plurality of end caps , each of the end caps joined to the end wall surfaces of the lobes ; wherein the first wall top side , the first wall bottom side , the second wall top side and the second wall bottom side each are aligned parallel to a horizontal plane of the pressure vessel assembly and are disposed adjacent a curved wall portion of the lobes ; wherein the plurality of lobes are formed of at least one of high strength aluminum alloys, 4000 series steel, pH stainless steel, and high strength 400 series stainless steel; wherein adjacent lobes are coupled with one or more bonds ; and wherein a process for fabrication of these bonds includes at least one of fusion welding, solid state welding, linear friction welding, brazing, capacitive discharge welding, transient liquid phase bonding, and cold spraying; characterized in that each of the end caps is joined to at least one adjacent end cap ; and each of the lobes comprises a shoulder region located at the first wall top side , the first wall bottom side , the second wall top side and the second wall bottom side , wherein the shoulder region comprises a shoulder wall thickness greater than a wall thickness of the remainder of the lobes . a plurality of lobes , each of the lobes having at least one vertically arranged interior wall , the plurality of lobes being 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 side and a first wall bottom side , the second interior wall having a second wall top side and a second wall bottom side , the first wall top side is joined to the second wall top side and the first wall bottom side is joined to the second wall bottom side ; a first end wall surface and a second end wall surface of each of the plurality of lobes ; and a plurality of end caps , each of the end caps joined to the end wall surfaces of the lobes ; wherein the first wall top side , the first wall bottom side , the second wall top side and the second wall bottom side each are aligned parallel to a horizontal plane of the pressure vessel assembly and are disposed adjacent a curved wall portion of the lobes ; wherein the plurality of lobes are formed of at least one of high strength aluminum alloys, 4000 series steel, pH stainless steel, and high strength 400 series stainless steel; wherein adjacent lobes are coupled with one or more bonds ; and wherein a process for fabrication of these bonds includes at least one of fusion welding, solid state welding, linear friction welding, brazing, capacitive discharge welding, transient liquid phase bonding, and cold spraying; characterized in that each of the end caps is joined to at least one adjacent end cap ; and each of the lobes comprises a shoulder region located at the first wall top side , the first wall bottom side , the second wall top side and the second wall bottom side , wherein the shoulder region comprises a shoulder wall thickness greater than a wall thickness of the remainder of the lobes . <EOS>