The microbiologically influenced corrosion (MIC) is a very dangerous process, which affects the oil industry. The activity and microorganisms' growth at the pipelines steel cause surface modifications, which can induce a more complex corrosion process. The biocide evaluation for the MIC decrease has been normally based upon microbiological tests, and just a few references mention alternating methods which can be used as criteria for their evaluation. In this work, a commercial biocide was tested, using different electrochemical laboratory techniques, to determine its effect upon a biofilm generating bacteria consortium.Using microbiological techniques, the biocide lethal concentration was determined, and a concentration of 200 ppm was used to kill completely the consortium population in both, plancktonic and sessile parts. The electrochemical techniques: Polarisation Resistance (PR) and Electrochemical Impedance Spectroscopy (EIS), allowed describing the corrosion process associated to the microbial consortium and the biocide effect upon it.
During the characterization of sediments formed in pipelines transporting hydrocarbons, the knowledge of the microbiological diversity becomes very interesting, especially when it is related to microbiologically influenced corrosion (MIC). The presence of microorganisms is considered as one of the factors that affect the corrosion processes occurring at the pipeline; therefore, their corrosiveness must be determined. In this way, the identification of new species affecting the MIC processes is still considered relevant. In this work, the effect of Clostridium celerecrescens upon the corrosion of API KL 52 steel was evaluated. This microorganism was isolated and identified from the sediments collected during the inner cleaning procedures of a gas pipeline. The polarization resistance (PR) and electrochemical impedance spectroscopy (EIS) techniques were considered to estimate the microorganism behavior during the corrosion process. The results were complemented with a metal surface analysis, using a scanning electron microscope (SEM). The resistance values induced by the presence of the microorganisms clearly indicated that C. celerecrescens has an effect on the corrosion process occurring at the API XL 52 steel surface.
The high number of leak events that took place in recent years at a 25.4 cm (10") Ø pipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.
The Electrochemical Impedance Technique was used to evaluate the influence of a microbial consortium, isolated from a gas pipeline, upon API XL52 steel corrosion rate. The bacteria growth exhibited two different kinetics behavior, one for the plancktonic and the other for the sessile phase. The sessile bacteria were found to be the main responsible for the corrosion rate increment observed during the experiments and no relationship between the plancktonic microorganisms and the corrosion rate increment was found.The diagrams obtained from the electrochemical impedance measurements, indicated a biofilm formation and that the system changed from activation to diffusion control. Although the system was under diffusion control, an increment on the corrosion rate was detected, and a localized corrosion process was induced. The results were complemented with some surface analysis using Scanning Electron Microscopy.
The objective of this study consisted in investigating the possible causes which give rise to the presence of low wall pipe thicknesses on a 16 00 natural gas transport pipeline, even though during the last 12-year period cathodic protection (CP) potentials were kept in the protection range at which external corrosion should not occur. Results from in-line inspection from a 16 00 natural gas transport pipeline showed 46 indications with more than 80% wall thickness lost due to external corrosion in the second segment of the pipeline. Direct inspection at the indication locations, review of the CP system performance, pipeline maintenance programs and studies, allowed to make an integral diagnostic where it was found out that the main cause of external corrosion was an inappropriate coating application since the pipeline construction, this situation has originated the increase of CP shielding effects through time.
The effect of sulfate reducing bacteria (SRB) upon the cathodic protection of XL 52 steel was determined, in order to identify if the potential value of À0.950 V versus copper/copper sulfate electrode is good enough to protect the metal surface. During the experiments, different operational parameters were monitored: hydrogen sulfide production, iron concentration, electrolyte alkalinity, microorganisms' population, as well as the metal surface damage. At the same time, the corrosion rate was determined using two electrochemical techniques: polarization resistance (PR) and electrochemical impedance spectroscopy (EIS). According to the results, it was observed that the protection potential of À0.950 V versus copper/copper sulfate electrode is not enough to control the microbiologically induced corrosion. This situation is reinforced by the fact that significant iron concentration was found in the electrolyte. The microbiological activity is not affected by the protection potential. On the contrary, the population growth is slightly strengthened. The alkalinity generated by the applied potential did not stop the SRB growth. A type of localized corrosion was developed during the experiments with microorganisms, even when the protection potential was applied to the system.
The Electrochemical Impedance Spectroscopy (EIS), was used to evaluate and compare the behavior of three different corrosion inhibitors: quaternary amine (QA), oleic imidazoline (OI) and amino coco propionic acid (ACP), on the corrosion of mild steel in 3% NaCl solutions, saturated with CO 2 gas, under static conditions. Two pH values: 3.8 and 5.5 were considered. Under the conditions considered in this work, the results indicated film formation at the metal surface, probable due to the formation of iron carbonate. This condition modified the values of the resistance and double layer capacitance of the system. In general terms, the ACP inhibitor exhibited better performance, compared to the QA and OI. During the impedance measurements with OI and ACP, some deviations were observed at high frequencies, indicating probably that the inhibitors adsorption occurs in different way to the QA inhibitor and the amine adsorption is weaker than the other two inhibitors adsorption.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.