Used Cust-O-Fab U Tube Shell & Tube Heat Exchanger. Approximate 3090 Square Feet. Carbon steel shell rated 1715 psi at 610 degrees F. (295) 1" diameter x 20' long SA-213-T11 Chromium-molybdenum steel tubes rated 2184 psi at 750 degrees F. Serial# 97-202. National Board# 4666. Built 1997.