A huge part of corrosion failures and even of catastrophes takes origin from a trivial mistake in either choice or connection of different materials, as well as from an inaccurate evaluation of the compatibility between materials an environment. The example shown in the present paper summarizes several wrong solutions due to the lack of knowledge of the basic rules of corrosion control. By chance, either the consequences of such mistakes were so precocious that it was possible to find a remedy during the construction, or they were happily so venial as to be tolerated. This paper is third in a series devoted to enhancing the need of a professional corrosion control design for infrastructures.

In many instances paints interlayers delamination is attributed either to environmental or to application reasons. The composition as well as the structure, including morphology are always given for granted. Extended interlayer delamination was observed on two huge structures (>50000m2 each) causing more than $10 M damages. Overcoating time, UV exposure, Solvent retention and other possible environmental possible causes were considered. However, a careful morphological analysis showed that substantial differences existed in terms of the resin to pigment ratio, the surfactants, the quality of pigments and fillers (dimensions, shape, wettability, reactivity, homogeneity of distribution…) with respect to the sample used to certify suitability of the systems to climatic conditions C4 – C5 (ISO12944). The need to avoid any either voluntary or casual modification in both PVC and the kind and size of pigments to be used should be made evident as well as shown in some paragraph of existing Standards.