Used 309 Sq Ft. U-Tube Heat Exchanger. Mfg by Energy Exchanger 1987. Carbon steel Shell (SA-106-B) rated 300 PSI @ 650 deg F; Carbon Steel Tubes (SA-214) rated 150 PSI @ 500 deg F. Carbon Steel Heads (SA-515). Shell - 13.25" dia. x 19'6" L ; (44) Tubes - 3/4" dia. Flanged Nozzles: (2) 6", (2) 3". Type AEU. S/N: X-2920, NB# 1261.