Get current pricing for St Mary Iron Works, 540 Gal St. Mary Iro 540 Gallon Horizontal 304l-ss Tank. Internal Rated 15 Psi @ 300 Deg F. (dished Heads. 42 Dia X 6', 6 T/t (7', 9 Oal). Thickness: 0.187 . Product Category: Process Equipment, Sub Category: Pressure Vessels: