A Study of Potential Corrosivity of Borehole Waters in Eket, Nigeria by Saturation Index Measurement

Abstract

A study of water chemistry in some boreholes in Eket, Nigeria, was conducted to determine the calcium carbonate saturation index, in order to establish the corrosion tendency of the waters towards metal substrates in piping systems, boilers, heat exchangers and submersible pumps. Calcium carbonate saturation index using Langelier system was determined to be more negative     (- 4.16 to – 5.2) below the optimum range of – 0.5 to + 0.5 for water that is in equilibrium with calcium carbonate. The water saturation pH (pHs) determined for the waters sampled in the area had values that ranged from 8.82 to 9.55, with a mean value of 9.09. The values were far above the pH values of the waters from all the locations sampled, which ranged from 4.12 to 5.34, with a mean pH of 4.48. The water chemistry was of same characteristic for all the studied locations, indicating that the waters were drawn from same regional aquifer, have same corrosive tendency and the possibility of metal substrates to be attacked by water used for both industrial and domestic purposes in the study area. The more negative the calcium carbonate saturation index, the greater the possibility of the water in its corrosive action especially in oxygenated waters. Therefore, the waters in Eket are likely to exhibit remarkable corrosive tendency against metal substrates. The implication of this finding is that in the study area, there has to be a strategic corrosion control program in piping systems and industrial equipment such as heat exchangers, boilers, domestic water heaters and submersible pumps in tackling corrosion challenges.