Used 4600 Sq Ft. U-Tube Heat Exchanger. Mfg by Energy Exchanger 1988. Carbon steel Shell (SA-516) rated 150 PSI @ 500 deg F; Carbon Steel Tubes (SA-214) rated 550 PSI @ 700 deg F. Carbon Steel Heads (SA-515). Shell - 3'5" dia. x 22'6" L ; (550) Tubes - 3/4" dia. Flanged Nozzles: (1) 16", (1) 12", (1) 6", (1) 3", (1) 1.5". Type AEU. S/N: X-2969-A, NB# 1301.