Used 1998 Vilter Shell and Tube 18 ft. Ammonia Heat Exchanger. S/N: H73946-1. Nat'l Bd: 41337. Number of passes: 4. Number of tubes: 121. Tube material: SA-124 carbon steel. Tube dimensions: 1-1/4 in. dia. x 18 ft. Heat transfer surface area: approx. 712 sq. ft. Shell side MAWP @ 400 °F: 300 psig. Shell side MDMT @ 300 psig: -20 °F. Tube side MAWP @ 200 °F: 75 psig. Tube side MDMT @ 75 psig: -20 °F. Heat exchanger is equipped with Hansen pressure relief valves. Inlets: (1) 3-1/2 in. dia. pipe (media), (1) 4 in. dia. pipe (product) with an 8-1/2 in. dia. flange and (8) 3/4 in. dia. attachment holes at a center-to-center distance of 6-1/2 in. Outlets: (1) 2 in. dia. Pipe (media), (1) 4 in. dia. pipe (product) with an 8-1/2 in. dia. flange and (8) 3/4 in. dia. attachment holes at a center-to-center distance of 6-1/2 in. Shell: 20 in. dia. x 18 ft. L. Overall dimensions: 19 ft. L x 28 in. W x 70 in. H. (ACN250)