Characterization of the Corrosive Action of Mineral Waters from Thermal Sources: A Case Study at Azores Archipelago, Portugal

Abstract

Abstract:Waters from natural sources of the São Miguel Island in the Azores archipelago have been investigated regarding their corrosive action on metallic materials. The corrosive and encrusting characteristics of the waters have been established in terms of relevant chemical parameters (namely pH, conductivity, total dissolved solids (TDS), and concentrations of bicarbonate, calcium, magnesium, chloride, and sulfate ions) and their temperature by using Langelier, Ryznar, Puckorius and Larson-Skold indexes. The validity of this methodology has been tested by measuring the corrosion rates of various metals exposed to various waters using electrochemical methods. The materials of industrial OPEN ACCESSWater 2015, 7 3516 interest under investigation were carbon and galvanized steel, zinc, 304 and 316L grade stainless steels, brass, and Cr-Ni alloys. The greater aggressiveness of these waters was found for the less noble materials, and they experienced high corrosion rates.

Assessment of Corrosion Properties of Selected Mineral Waters

“…Previous studies [15,39] have indicated the importance of the selection of pipe material in water systems with high corrosiveness, among others, on the basis of water quality parameters, such as pH, alkalinity, and calcium hardness. The presented approach has been proven to be suitable for assessing the corrosive properties of mineral waters, as confirmed by analysis shown in [40,41]. The mentioned research shows the need for the broad characterization of mineral water compositions, including their aggressiveness concerning different materials, using the analyzed indices, which in turn will help to establish criteria for categorizing stability of the water [42,43].…”

Hydraulic and Technological Investigations of a Phenomenon Responsible for Increase of Major Head Losses in Exploited Cast-Iron Water Supply Pipes

“…In relation to the LSI, the Ryznar stability index broadens the range of parameters liable to affect corrosion and water hardness because it considers magnesium content, temperature and dry residue, which indirectly considers typical components of dissolved substances, i.e., chlorides and sulfides. The RSI has a more extended corrosivity range than the LSI: 4 < RSI < 5-strong precipitation of sediment, 5 < RSI < 6-medium precipitation of sediment, 6 < RSI < 7-weak precipitation of sediment or initial corrosion, 7 < RSI < 7.5corrosion, 7.5 < RSI < 9-strong corrosion, RSI > 9-very strong corrosion [56,57,[68][69][70][71]. Basing on the performed determinations of quality parameters of the water transported by the investigated cast-iron pipelines (Table 1), the Langelier saturation index was calculated, which amounted to 0.07, which indicates very low precipitatibility, whereas the Ryznar index amounted to 7.17, which indicates very low corrosive features of the water flowing through the investigated pipelines.…”

The Influence of Water Quality Change on the Corrosion Process in Galvanized Pipes of Fire Protection Installations

“…Water is aggressive when the I value is greater than 1.0. Another indicator that describes the corrosivity of water is the Langelier Saturation Index (LSI) [16]. It is an indicator of the possibility of scale formation in the water.…”

“…The measure of the influence of the actual pH, the concentration of calcium, bicarbonate, TDS, and temperature forms another index called the Ryznar Stability Index (RSI) [16], expressed as: RSI = 2(pH s ) − pH In this equation, a value below 5 indicates water instability, and a CaCO 3 sediment forming capacity, and thus the corrosivity of the water, is lowered. Within 5-7, the depleting CaCO 3 does not form a sediment, the water is corrosive, and sub-sediment corrosion may occur.…”