Characterization of deposit layers formed on grey cast iron

Abstract

This paper presents the results of diagnostic examinations conducted on the water pipe made of grey cast iron that were operated in conditions for 260 thousand hours. The tube was exposed in a soil. The phase composition of the deposit layers formed on both sides of the tube walls (outside and inside) was examined using optical and confocal microscopy and X-ray diffraction. The obtained XRD test results showed that mainly -FeOOH) and γ-FeOOH is formed on the inside of the pipe wall. In turn, on the outside, in addition to the above-mentioned compounds, also SiO2 is formed. The results of these examinations have shown a higher degradation of pipe on the outer side. The arithmetic mean deviation of the profile from the mean line was 6.23 µm and 8.07 µm for the inner and outer side of the pipe wall, respectively. The work demonstrates the usefulness of material science, especially X-ray structure, topography and surface studies, in characterizing the degradation processes of layers formed on gray cast iron exploited in the water supply industry.