Multitube board heat exchanger

The utility model relates to a chemical industry equipment field specifically relates to a multitube board heat exchanger, including casing, first head, second head and many heat exchange tubes. First head is connected respectively in the both ends of casing with the second head, is provided with two at least tube sheets between first head and the casing, and every tube sheet all is provided with the coaxial setting of a plurality of heat exchange tube mounting hole one -to -one of a plurality of heat exchange tube mounting holes, two adjacent tube sheets. The heat exchange tube mounting hole that is close to most the tube sheet of casing in two at least tube sheets is the step hole, and the heat exchange tube mounting hole of keeping away from the tube sheet of casing in two at least tube sheets most is the screw hole, screw hole department be provided with with screw hole complex screw plug. Many heat exchange tubes are installed in the heat exchange tube mounting hole that corresponds and the axial of many