Get current pricing for Oem, 18,500 Gal IRBY Stee Vertical 18,500 Gallon Carbon Steel Tank. 12', Dia 20', T/t Mounted On Skirt. Dished Top. Shell Is 1/2. Rated 16 Psi @ 300 F. Shell Thic . Product Category: Process Equipment, Sub Category: Process Tanks/kettles: