Heaters are designed to be placed in vessels, tanks or pressure vessels and come into direct contact with the fluid. By using electrical resistors with external protective sleeves, the heat exchange becomes very efficient, allowing compact dimensions of specific equipment. These products are designed according to the design data provided by the customer, taking into account the desired application and the physical, chemical and thermodynamic characteristics of the fluid to be heated, the working temperature, the installation area and the maximum dimensions of the compartment in which the heater will be installed.