Identification of the accumulation mechanism of major elements on pipe surface is essential to investigate the development of corrosion scales and co-occurrence of trace inorganic contaminants. In this study, corrosion scale samples were collected from old, corroded iron pipes made of different materials and exposed to different water qualities and operation conditions. Elemental composition of these scales was determined by energy dispersive X-ray spectroscopy (EDS). Cumulative occurrence analysis, Q-style hierarchical cluster analysis (CA), and principal component analysis (PCA) were conducted to ascertain major elements typical for corrosion scales and to estimate the dominant influencing factor to each elemental constituent. The major elements in the examined scales are Fe, C, Zn, Si, Ca, Al, and S in the descending prevalence. Their occurrences are influenced by an interactive effect. Pipe material imposes a significant effect on the accumulation of Fe, Zn, and Ca in corrosion scales; water composition can account for the presence of Si, Al, and S in this study; hydraulic condition is identified as the primary factor influencing the occurrence of C and Ca. Q-style CA and PCA are verified practicable for data interpretation and identification of dominant factors influencing scale characteristics.
Keywords: Cluster analysis; Corrosion scales; Elemental accumulation; Hydraulic condition; Pipe material; Principal component analysis; Water composition.