We present here an original application linking an electrochemical
domain and the computational aspect of electromagnetic fields to make a
corrosion diagnosis of a protected underwater steel structure. After a
defined operating time, it is mandatory to check an underwater steel
structure. This control may happen too early, if the protection has not been
damaged; but it may happen too late, if some particularly bad environmental
conditions have already damaged the structure. Moreover, current examination
techniques require immobilizing the structure for a long time: they may be
complicated to dry (pipe lines or tanks) or to place in dry docks for
vessels. The efficiency of these techniques could be improved. The purpose
of this paper is to replace this checking/examination by a series of close
electrical measurements in the electrolyte which provides a corrosion
diagnosis of the structure. This also allows computing the electric and
magnetic fields caused by this phenomenon everywhere in the electrolyte. The
new method introduced ensures a great time-saving but also an accuracy never
reached before.