An improved method for isolating the impacts of flow-altering events in corrosion transport from those due to steady state corrosion in boiler/steam cycle processes. The method includes monitoring, in real time, with a particle counter or particle monitor levels of suspended particles in a fluid flow stream and of automatically collecting insoluble particulates large enough to be captured on a 0.45 micron filter when, and only when, these levels exceed an "event threshold". For use in subsequently characterizing flow-altering events without necessarily weighing the collected particulates for each excursion above this threshold, an average particle count/particle index is obtained and compared with the actual weight of insoluble particulates captured. When excursions are highly infrequent, concentrations of insoluble metal oxides likely to be present in the flow stream and capable of producing above-threshold PC/PIs can be determined and used to identify anomalies when particulates are captured.