Theoretical and Experimental Aspects of the Corrosivity of Simulated Soil Solutions

Abstract

Corrosion of buried steel pipe is a permanent engineering problem and, albeit the counter measures against degradation, when the corrosion process takes place, the damage has costly impact. In order to study the corrosion behavior of pipelines, it is possible to use actual soil extracts or simulated soil solutions. The extract is much related to specific sites and consequently too strict to permit a general understanding. The simulated soil presents, as advantage, its inorganic characteristic and easy preparation. In this paper, we present some theoretical results concerning the chemical equilibria of NS1, NS2, NS3, and NS4 simulated soil solutions. Besides, we have studied the effect of the above four media in corrosion behavior and polarization curves were performed for an API 5L X65 steel. The theoretical findings show that each ionic concentration varies for a 6–12 pH range. The experimental data suggested that the corrosion currents decrease as high is the pH and increase as high is the chloride content. Notwithstanding these facts, for multielectrolyte solutions, a simple correlation with a given ion is not straightforward but the complementary approaches used here give useful insights.

Experimental Investigation on Corrosion Effect on Mechanical Properties of Buried Metal Pipes

“…With the increase of corrosion, hydrogen bubbles showed up in particular in more acidic solution, for example, pH = 3.0, which can be explained by (6). It was also observed that corrosion in different conditions was of different forms.…”

“…Experience and investigation of pipe failures suggest that corrosion of metals, both cast iron and steel, is the most predominant cause of pipe failures [4,5]. Since corrosion is linked to almost all pipe failures, it has become a global problem for all stakeholders, in particular engineers and asset managers of buried metal pipes [6,7]. As such, considerable research has been undertaken in the past few decades on corrosion of metal pipes, more perhaps for cast iron pipes, as represented notably by Doleac et al [8], Dean Jr. and Grab [9], O'Day et al [10], Randall-Smith et al [11], Kirmeyer et al [12], Camarinopoulos et al [13], Sadiq et al [14], Panossian et al [15], and so on.…”

Effects of Cathodic Polarization on the Corrosion Behavior of X60 Pipeline Steel in a Simulated Soil Solution

“…[46,48,49] Polarization at sufficiently cathodic potentials can generate the production of OH À ions and their accumulation on the surface of the steel according to Equation (3) and (4). [15,47] The alkalization causes precipitation of weakly soluble compounds, such as CaCO 3ðsÞ , MgðOHÞ 2ðsÞ etc., [45,50] and MgCO 3ðsÞ [51] according to the following reactions…”

Regularities of Stress-Corrosion Cracking of Pipe Steel 09G2S at Cathodic Polarization in a Model Soil Environment

“…A part of perlite is arranged in the form of bands. To simulate a corrosive environment with a nearneutral pH, to which underground pipeline is exposed to, a neutral NS4 solution of the following chemical composition was used: 0,122 г/л KCl + 0,483 g/l NaHCO3 + 0,181 г/л CaCl2 + 0,131 г/л MgSO4 (рН 8,2) [12,18,[30][31][32][33]. Reagents of analytical grade and a distilled water were used.…”