Bas Tex single pass shell and tube heat exchanger, U-design, 50 cubic feet capacity. Carbon steel shell rated at 100 PSI at 350 degrees Fahrenheit, stainless steel tube measures 1-1/2" diameter x 15'8" long rated for 65 PSI at 500 degrees Fahrenheit. New in 1984, National Board Number 4918; Serial number 4543-84-8.