Used 350 Sq. Ft. Horizontal Missouri Boiler & Tank Company Stainless Steel Shell & Tube Heat Exchanger. Steel shell rated 285 psi @ 475 F on the shell, and Stainless steel tubes rated 125 psi @ 475 F. Serial # H5240, National Board #3138, Built 1971. Previous Use: Nitric Acid - Tail Gas Preheater