Stainless Steel Single Shell Tank-550 Gallon. 304 stainless steel construction. Inside straight wall dimensions: 3 ft. 3 in. dia. x 8 ft. H. Manhole cover diameter: 17-1/2 in. Inlets: (2) 2 in. dia. NPT, (1) 2 in. dia. S-line fittings, (1) 3/4 in. dia. port. Outlets: (4) 1/2 in. dia. NPT, (1) 2 in. dia. port, (1) 2 in. dia. NPT, (1) 2 in. dia. FNPT, (1) 2 in. dia. Q-line fittings, (1) 4 in. dia. Q-line fittings. Overall dimensions: 3 ft. 5 in. dia. x 10 ft. 8-1/2 in. H.