Chem-Tainer TC4594IA 550 gal 45" x 94" Vertical Bulk Storage Tank - Manufactured from linear polyethylene in one piece with seamless construction, this tank series is designed for either indoor or outdoor applications. The flat bottom design provides for easy and cost efficient installation. Tanks come standard with a Vented Manway. Non-Vented and Hinged Manways are also available. Non-vent manways are recommended for applications where chemical fumes should be vented away from the tank area.