A Flingern's corrosion diagram is the graphical representation of the corrosion resistance of a material of pipes in the flue gas stream under different operating conditions. Typically, areas of high-temperature corrosion for steels of heat exchanger tubes are shown as a function of tube wall temperature and flue gas temperature at certain flow velocities. This form of representation was originally developed for the reproduction of empirical findings under the conditions in the steam generator of waste incineration plants (MVA).
The diagram is used to assess steels that are used for heat exchangers that are installed in the flue gas flow of a boiler with regard to their resistance to corrosion or their expected susceptibility to corrosion. It is assumed that the corrosion resistance of the material to be assessed decreases with increasing smoke gas temperature and with increasing wall surface temperature. These temperature variables are therefore scaled down as boundary conditions in the diagram.
The critical area for corrosion phenomena does not only depend on the boundary conditions of these temperature parameters, but also on the direction and size of the velocity vectors in the flue gas flow. In addition, when deposits are deposited, special conditions may arise that lead to tub-shaped corrosion; they are only incompletely recorded in the usual Flingern diagram. Due to the special dynamics of such corrosion processes, they should not be ignored for the prognosis of the service life and availability of the components. 
The first investigations of this relationship under application conditions were carried out from 1978 to 1980 at the MVA Düsseldorf-Flingern , which is why the corrosion diagram is named after its location in Flingern . In the meantime the diagram has been revised and expanded several times, in particular the flue gas speed is taken into account as an additional criterion.  Since the subject of high-temperature corrosion is also important in biomass heating power stations, for example , the Flingern's corrosion diagram is attracting increasing attention.
- Wolfgang Spiegel et al.: Dynamic chlorine-induced high-temperature corrosion of evaporator and superheater components due to special coating developments: Frequent findings in waste and biomass-fired steam generators . Augsburg 2005 (PDF; 1.6 MB).
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