Used 399 sq ft Atlas shell and tube heat exchanger, hastelloy C22 tubes, tube sheets and bonnets, carbon steel shell with (208) 3/4" diameter x 120" long tubes, rated 100 PSI and full vacuum @ 300 F, shell rated 100 PSI @ 300 F, 10", 6", 4" tubes inlet/outlet, (2) 4" shell inlet/outlet, serial# 8291, national board# 7020, new 1993.