Abstract: The heat exchanger according to the invention consists of two flat or slightly incurved parallel surfaces formed in two sheets of metal (2) and (3). The longitudinal edge pieces (8) and (9) and transverse edge pieces (12) and (13) have rounded edges. The entire exterior surface is coated with enamel. These exchangers may be used in groups of several parallel units arranged inside a tubular body, or they may be disposed in a radiating pattern inside a cylindrical tank in a chemical reactor, forming a complex exchanger. This invention is of interest to manufacturers of industrial heat exchangers, particularly exchangers designed for the chemcial, pharmaceutical or agricultural/food industries.