Pressure vessel assembly and method of forming

A pressure vessel assembly comprising:

• a first lobe being circumferentially continuous, and including a first interior wall, a first outer wall, and a first shoulder region joined to and disposed between the first interior wall and the first outer wall, wherein the first shoulder region includes a thickness that is greater than a remainder of the first lobe;
• and
• a second lobe being circumferentially continuous, and including a second interior wall, a second outer wall, and a second shoulder region joined to and disposed between the second interior wall and the second outer wall, wherein second shoulder region includes a thickness that is greater than a remainder of the second lobe, the first interior wall is positioned adjacent to the second interior wall, and the first shoulder region is positioned adjacent to the second shoulder region,
• wherein the first and second shoulder regions each include an outer surface that transitions into respective curved portions of the respective first and second outer walls.