Used 166 Square Feet (approx.) Doyle & Roth Vertical Stainless Steel Shell & Tube Heat Exchanger, Shell rated 100 psi @ 350 F, -100 F @ 100 psi, Tubes rated 100 psi @ 350 F, -50 F @ 100 psi. (85) 316L Tubes x 3/4" OD x 10' L. Serial #J-6318-2, National Board #14993. Year Built 1990.