Deterioration of buried metal pipes due to corrosive soil environment is a major issue worlwide. Although failures of buried pipe due to corrosive soil is an old problem, yet such failures are still uncontrollable even with the application of advanced corrosion protection technologies. Therefore, understanding factors causing corrosion of buried pipes is necessary. This article reviews factors causing corrosion of buried pipes in soils. Factors include moisture content, soil resistivity, pH, dissolved oxygen, temperature and microbial activity. Moreover, we discuss the influence of manufacturing method and the comparison of corrosion behaviour of cast iron, ductile and mild steel pipes. We found that corrosion rate of pipes increases with moisture contents up to the critical moisture value. Although pH affects corrosion, there is no relationship between corrosion and pH and the corrosion rates of buried pipes are inversely proportional to soil resistivity. Soils containing more organic matter show high resistivity. Dissolved oxygen in soil develops differential cell which accelerates corrosion of metallic pipe. Different types of bacteria present in soil develop biofilms on metallic pipes, which deteriorates pipes with time.

Factors influencing corrosion of metal pipes in soils

The effect of nanosized NbC precipitates on electrochemical corrosion behavior of high-strength low-alloy steel in 3.5%NaCl solution

In this paper, we will study the effect of soil engineering properties’ relationship on metal degradation of two series of brass alloys (brass devices). These two types of brass are an α-brass and α + β one. This work aims to specifying the best alloys which are recommended to be used in Azrou soil medium. This research paper was applied by using electrochemical impedance spectroscopy methods, polarization curves, scanning electron microscopy (SEM), and X-ray spectrometry microanalysis measurements. It was found that EC5 is the most resistant alloy between the three α-brasses and EC6 which is the most resistant alloy among the four α + β brasses in this soil type. The different alloy surfaces were examined by SEM, whereas the chemical composition was determined by EDAX analysis. Moreover, we have studied the role and effects of synergy on various additional elements which exist in different brasses and they are responsible for increasing the corrosion resistance.

α -Brass and ( α + β ) Brass Degradation Processes in Azrou Soil Medium Used in Plumbing Devices

Corrosion of underground pipelines in clay soil with varied soil layer thicknesses and aerations

External corrosion assessments of pipeline systems encompass two critical factors: time and space (location). Field measurement databases, laboratory testing, and theoretical prediction studies have been reported, based on continuous monitoring, survey and on-site characterization techniques, and controlled and simulated laboratory-scale environment studies. Theoretical models have identified several critical factors in assessing external corrosion for buried structures at different scales. This work presents a review of critical parameters for characterizing, modeling, and assessing the corrosion process in buried pipelines. A multiscale approach is used to integrate factors identified from field measurements, laboratory testing, and data-driven and computer-based models. Furthermore, we elucidate the importance of macro parameters and the influence of their spatial distribution on the initiation and propagation of local corrosion mechanisms with their corresponding local (micro scale) conditions. This work also reviews the critical parameters and approaches used for deterministic, semi-empirical, probabilistic, and data-driven modeling, defining the scope of global versus local factors for external corrosion at the soil/steel pipeline interface.

Global and local parameters for characterizing and modeling external corrosion in underground coated steel pipelines: A review of critical factors

Effect of soil particle size on the corrosion behavior of natural gas pipeline

Short-term electrochemical corrosion behavior of pipeline steel in saline sandy environments

Understanding the effect of soil particle size on corrosion behavior of natural gas pipeline via modelling and corrosion micromorphology

The EIS behavior, corrosiveness, and seepage structure of sand of varied water content were studied by means of electrochemical impedance spectroscopy under the three-electrode system. The...

Electrochemical impedance spectroscopy of sand of varied particle size and water content using the three-electrode system

The electrochemical behavior of X70 pipeline steel in a 1.5 wt% NaCl sandy soil environment with two typical particle size distributions (PSD), continuous gradation (CG), and gap gradation (GG) was investigated using electrochemical measurements, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that, as the burial time increased, the corrosion rate of X70 pipeline steel increased in the initial corrosion stage, decreased at an intermediate stage, and then increased in the final stage in these two typical soil PSD environments. However, compared with the soil PSD pertaining to the CG environment, the corrosion rate of steel increased significantly in the GG environment, as evinced by the severe corrosion spots observed on the steel surface, attributed to the fact that, in the soil PSD for the GG environment, both the extent of liquid dispersion, and the number of galvanic cells increased, accelerating the cathodic step, i.e., oxygen-reduction reaction in the three-phase boundary (TPB) zone, and anodic step, i.e., the metal dissolution stage, of the X70 pipeline steel corrosion process, respectively. Both the anodic and cathodic processes were activation controlled. Thus, the corrosion of X70 pipeline steel was considerably dependent on the soil PSD in sandy soil environments.

Pengju Han

Papers

Effect of soil particle size on the corrosion behavior of natural gas pipeline

Short-term electrochemical corrosion behavior of pipeline steel in saline sandy environments

Understanding the effect of soil particle size on corrosion behavior of natural gas pipeline via modelling and corrosion micromorphology

Electrochemical impedance spectroscopy of sand of varied particle size and water content using the three-electrode system

Role of typical soil particle‐size distributions on the long‐term corrosion behavior of pipeline steel