Homero Castaneda

Bayesian Modeling of External Corrosion in Underground Pipelines Based on the Integration of Markov Chain Monte Carlo Techniques and Clustered Inspection Data

In this study, a model is developed to assess external corrosion in buried pipelines based on the uni- fication of Bayesian inferential structure derived from Markov chain Monte Carlo techniques using clustered inspection data. This proposed stochastic model com- bines clustering algorithms that can ascertain the simi- larity of corrosion defects and Monte Carlo simulation that can give an accurate probability density function es- timation of the corrosion rate. The metal loss rate is cho- sen as the indicator of corrosion damage propagation, obeying a generalized extreme value (GEV) distribution. Bayesian theory was employed to update the probability distribution of metal loss rate as well as the GEV param- eters in order to account for the model uncertainty. The proposed model was validated with direct and indirect inspection data extracted from a 110-km buried pipeline system.

Corrosion inhibition of mild steel by an imidazolium ionic liquid compound: the effect of pH and surface pre-corrosion

The corrosion inhibition performance of 1-decyl-3-methylimidazolium chloride (DMICL) on mild steel was investigated in a carbon dioxide-saturated NaCl solution at pH 3.8 and 6.8. Electrochemical and surface analysis techniques were used to characterize the corrosion process in blank and inhibiting solutions. Open circuit potential, polarization curves and impedance spectroscopy were recorded to analyze the inhibition behavior of DMICL for specimens with a well-polished surface and a pre-corroded surface. Scanning electron microscopy images showed that the specimen surfaces were well protected from uniform corrosion in the inhibition solution. The energy dispersive spectroscopy and X-ray photoelectron spectroscopy data indicated the presence of specific elements following a dissolution mechanism under different pH conditions. The electrochemical fitting data facilitated calculations of inhibition efficiency and accounted for the interfacial changes.

Analysis of Soft Coating Corrosion Performance on Carbon Steel Using Electrochemical Impedance Spectroscopy

Electrochemical impedance spectroscopy (EIS) was used to characterize the performance of rust preventives (soft coatings) formed on the surface of metal in different electrolytes. ASTM B117, the accelerated salt spray corrosion test, was also used to characterize the films with a 5 wt% sodium chloride (NaCl) solution. The results obtained by both methods were compared and used to explain the degradation occurring at the film/steel substrate interface. EIS was used to quantify and characterize transport mechanisms and correlate the magnitudes obtained by the films damage evolution due to three electrolytes {3 wt% NaCl, 5 wt% NaCl, and 1.15 wt% ammonium borate [(NH4)3BO3]}. ASTM B117 and EIS were used to determine the performance of six different rust-preventive samples based on the damage evolution. The experimental and analytical results indicate good correlation between each method.

Coating studies of buried pipe in soil by novel approach of electrochemical impedance spectroscopy at wide frequency domain

Abstract The coating performance of buried pipe in clayey soil has been studied by electrochemical impedance spectroscopy (EIS). The results of EIS at 300 days have been analysed by electric equivalent circuit (EEC) models. The new parameters ensemble average phase (EAP) and ensemble average impedance (EAI) were introduced, obtained directly from Bode plots at a wide frequency domain in EIS data. These two parameters proved to be effective and convenient when evaluating the performance evolution of the coatings used in buried pipe in clayey soil, for both intact and defective coatings. The results indicated that the EAI parameter has a good agreement with the fitting results by EEC models and that the changes in EAP over time illustrated the three damage evolution stages of coated pipe in soil. It is concluded that EAP and EAI can be used for fast evaluation of coatings used in practical buried pipeline in soil.

Proposed model for quantification of dissolution—and evolution of a steel-CO2 solution interface by the transmission line approach

The corrosion mechanisms occurring at the homogeneous porous layer was determined assuming that the pores had a cylindrical geometry, and that the initial interface of a carbon steel-CO2 solution behaved as a transmission line (TL). TL modeling quantitatively assessed the impedance distribution and the mesoporous layer formation and evolution at the interface, while describing the physical characteristics of the mesoporous FeCO3 layer at the base and wall within the initial pore. The TL helped to characterize four stages during the interfacial evolution: active, active-porous layer, mixed layer, and the reactive stages. Using TLs helped to quantify the dissolution process and distinguish the mechanisms with good agreement between calculated magnitudes and experimental data.

Reliability-based temporal and spatial maintenance strategy for integrity management of corroded underground pipelines

Abstract In this work, a novel stochastic model framework for predicting the external corrosion growth in buried pipeline structures has been developed, and a reliability-based temporal and spatial maintenance strategy is presented. The spatial correlation of soil properties is modelled via hidden Markov random field. The temporal correlation of the corrosion rate is characterised by the geometric Brownian bridge process. A Bayesian inferential framework is employed to estimate the model parameters of the corrosion growth model using in-line inspection data. The proposed corrosion growth model was validated with actual inspection data. In the reliability analysis, the impact of device detectability is considered and hence the estimated failure probability is more realistic. The proposed maintenance strategy is directly based on the time-specific and location-specific failure probability. The application of the proposed model and maintenance strategy is illustrated through a real-life pipeline system. The results indicate that the proposed maintenance strategy is an adaptive and dynamic scheme that is able to improve the efficiency of inspections.

Influence of Zinc Content and Chloride Concentration on the Corrosion Protection Performance of Zinc-Rich Epoxy Coatings Containing Carbon Nanotubes on Carbon Steel in Simulated Concrete Pore Environments

The influence of zinc content on the mechanisms of corrosion protection of zinc-rich epoxy primers containing carbon nanotubes (CNT-ZRPs) on carbon steel under exposure to simulated concrete pore s...

Dissolution and Inhibition Mechanism of 1018 Steel in Simulated Cooling Water by Adding Phosphononoacetic Acid Compound under Two Flow Conditions

It was monitored the dissolution process of 1018 steel in simulated cooling water during the transient and steady state conditions with time. Dissolution and growth of corrosion product layers were following using a linear flow cell and flow magnetic-induced cell. By using Electrochemical Impedance Spectroscopy, it was analyzed the dissolution and inhibition process. The growth of a layer when adding hydroxyphosphonoacetic acid, inhibits metal dissolution and it presents two different influences at the interface for impedance response. They showed that new layer forms in a simple array depending on the flow regimen and the hydroxypphosphonoacetic group added to the surface. After stabilization time of 5 hours in absence of inhibitor, continuous growth and dissolution of a layer changed the electrical characteristics for the scaling and corrosion product due to flow regimen. Electrical passive elements described qualitatively the characteristics of the layer formation due to inhibitor addition.

Oxidation behaviour of Fe–40 at.-% Al intermetallics with Li or Cu additions at high temperature

ABSTRACT Fe–40 at.-% Al intermetallics with the addition of Li (1 and 3 at.-%) and Cu (3 and 5 at.-%) were produced using standard casting techniques. The oxidation behaviour was obtained using thermogravimetric analyses in an atmosphere of 99.99% oxygen at 800, 900, 1000, and 1100°C. The oxidation product layers on the top and cross-sectional views were characterised using SEM and energy-dispersive X-ray spectroscopy mapping. The different alumina phases can produce a double layer with different mechanical and chemical properties. The results showed that the addition of 1% Li assisted the activation of the oxide production at 1000 and 1100°C, while the rest of the third element additions slightly modified the oxidation resistance.

Application of Electrochemical Techniques on Study of Effect of Nano-ZnO in Conductive Polyaniline Containing Zinc-Rich Primer

Effect of zinc oxide nanoparticles on anticorrosion performance has been studied in conductive polyaniline containing zinc-rich primer in 3.5 wt% NaCl solution, using Electrochemical Impedance Spectroscopy (EIS) and localized electrochemical Scanning Vibrating Electrode Technique (SVET). The results showed that the addition of nano-zinc oxide particles in conductive polyaniline containing zinc-rich primer made the reaction of zinc more stable and slower, further increasing the effective cathodic protection period. EIS and SVET results confirmed that three performance evolution stages were obtained for zinc-rich primer being immersed in 3.5 wt% sodium chloride solution.