Lead (Pb) addition to hot-dip galvanizing (HDG) baths affects the physical characteristics of zinc coatings and is also useful to protect kettles. The influence of lead additions on both corrosion rate and morphology as well as on structure of zinc coating is less investigated. In this paper, three different additions, (Pb = 0.4–0.8–1.2 w/w) were chosen for three series of steel substrates, plus references without lead. The three steels chosen as substrates contained silicon (Si) = 0.18, 0.028, 0.225 w/w, respectively. The experimental part included both macro- and micro-electrochemical measurements, weight loss vs. time plots, Glow Discharge Optical Emission Spectroscopy (GDOS) and SEM/EDX microanalysis of both surface and cross-section of samples. Lead concentration is responsible for evident bimetallic coupling in the surrounding of lead inclusion with consequent increased dissolution rate, chunk effect, and rougher surface morphology.

The paper aims to show how the performance of paint coatings is affected by their composition. Samples of two paint coatings, which had delaminated in service, were compared with the same type of paint applied to samples for the purposes of certification. The particle size distribution of the filler materials (inert pigments) affected the flow of resin and wetting of the particles. In both failed samples, large particles sizes had agglomerated creating voids and crevices, resulting in poor wetting by the resin. This poor wetting and inherent lack of bonding had resulted in their premature failure. Both equivalent laboratory samples had a much better particle size distribution, with a lower maximum particle size, resulting in inert pigment being well distributed through the paint layer. The paper concludes that tighter control over the sizes of additives in paint such as inert pigments within Standards is needed to ensure better performance.

A significant aspect of corrosion failures and catastrophes originate from trivial mistakes in either the choice or connection of different materials, as well as from inaccurate evaluation of the compatibility between materials and the environment. The example shown in the present paper summarizes several wrong solutions due to a lack of knowledge of the basic rules of corrosion control. By chance, the consequences of these errors already appeared during construction; therefore, they were not able to cause damage during operation. This paper is the third in a series devoted to enhancing the need for professional corrosion control design for infrastructures.