Homero Castaneda, Jorge Alamilla, Hongbo Liu, Marco Antonio Antonio Espinosa-Medina and Eliceo Sosa
The purpose of this paper is to develop a real-time methodology to detect damages in coating and metallic structure in buried pipelines by using DC bias added to AC signal under…
Abstract
Purpose
The purpose of this paper is to develop a real-time methodology to detect damages in coating and metallic structure in buried pipelines by using DC bias added to AC signal under field operation conditions, including cathodic protection.
Design/methodology/approach
Impedance measurements were performed on buried pipeline for different field conditions, to develop a methodology to detect and locate damages by impedance distribution along the metallic structure.
Findings
Field condition measurements were conducted as a pilot test on a buried steel pipeline segment with a diameter of 16 inches and length of 20 km. The frequency-based technology shows some differences but overall good behavior between impedance magnitudes vs localization of the interface changes at the soil-coating-steel interface at different frequencies using DC bias added to AC signal under field operation conditions, including cathodic protection.
Research limitations/implications
The methodology is not applicable to highly resistive soil or high degradation coatings.
Practical implications
In this work, we depict a methodology that describes real time monitoring technology for buried metallic structures using AC signal. This monitoring is capable to detect and locate real time damage occurrences on the pipe surface (coating break). Field measurements include different conditions, such as temperature, soil resistivity and soil physical structure and chemical composition.
Social implications
In consideration of the satisfied application in the field of the methodology, it is believed that it can be used for the monitoring of damages in pipes in areas with high consequences and hence pipe integrity can be increased.
Originality/value
This real-time methodology is based on the impedance distribution signal and the differential changes along the pipeline under operating conditions. The results showed good agreement with the proposed methodology, which is able to discriminate some situations inherent of field conditions by using different impedance measurements performed along ±10 km of buried steel pipeline and assuming the reference location as the cathodic protection set up.
Details
Keywords
Luis Manuel Quej-Ake, Antonio Contreras, Hongbo Liu, Jorge L. Alamilla and Eliceo Sosa
The purpose of this paper is to study the corrosion rate for X52, X60, X65, X70 and X80 steel immersed in Mexican oilfield produced water. For the electrochemical characterization…
Abstract
Purpose
The purpose of this paper is to study the corrosion rate for X52, X60, X65, X70 and X80 steel immersed in Mexican oilfield produced water. For the electrochemical characterization of the five steels rotating disk electrodes, 20°C, 30°C and 45°C of experimental temperature and 0, 500, 1,000 and 2,000 rpm of rotation speed were taken into account. The temperature dependence was analyzed using Arrhenius law. Thus, Rct values obtained from EIS data in comparison with the corrosion rate obtained from polarization curves data were taken into account. Hydrodynamic effects were analyzed by Rct and corrosion rate data.
Design/methodology/approach
Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to assess the electrochemical behavior for five pipe steels steel immersed in a natural solution.
Findings
The resistance and corrosion rate taken from electrochemical tests decreased as temperature and hydrodynamic condition also decreased. In addition, the Arrhenius parameter revealed that the natural solution increased the corrosion rate as the activation energy decreased. Typical branches related to reduction-oxidation reaction (dissolution-activation process or corrosion products dissolution) on steel surface were discussed. Optical images analysis shows that corrosion products for X65 steel exposed to oilfield produced water can be attributed to more susceptibility to corrosion damage for this steel grade (Quej-Ake et al., 2018), which is increased with the temperature and rotation speed of the working electrode.
Originality/value
Corrosion process of the five steels exposed to oilfield produced water could be perceptive when Arrhenius analysis is taken into account. This is because oilfield produced water is the most aggressive condition (brine reservoir and sour water) for internal pipelines walls and storage tanks (brine tanks). Thus, stagnant condition was considered as a more extreme corrosive condition because produced water is stored in atmospheric stationary tanks as well as it is transported under laminar condition in zones where oilfield produced water is maintaining in the bottom of the pipe during the production, transporting and storing of the crude oil. In addition, a brief operational process for Reynolds number and the flowrate of the stock tank barrel per day (Q in STBD) using field and Reynolds number data is discussed.