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The purpose of this study was to carry out an analysis of the corrosion failure on a chrome-moly pipeline transporting highly concentrated sulfuric acid in a demineralization section at a petrochemical plant, along with the feasibility of using inhibitors to minimize the corrosive effects of sulfuric acid.

X-ray fluorescence spectroscopy, high-resolution optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and accelerated corrosion experiments (ACE) were performed.

Erosion-corrosion failure was confirmed by the significant reduction in thickness of the internal surface of the material exposed to sulfuric acid, as well as the formation of an oxide scale/layer. ACE accurately predicted high material loss from exposure to sulfuric acid. Moreover, adding ascorbic acid as a corrosion inhibitor (even at low concentrations) was found to reduce the oxidation by more than 50% in the presence of sulfuric acid.

The main idea/purpose of this work relies on the analysis of recurrent real-life corrosion-attributed failures that are common in industry but are not properly addressed for a variety of reasons, poor management and lack of corrosion preventive strategies being the main ones. This study once again highlights readily available solutions/implementations that are capable of not only addressing technically the issue investigated but also, and as important, economically. By using microscopic imaging, reliable well-tested and widely used characterization methods, all combined with basic experiments and tests, the nature of the repetitive failure investigated was clearly demonstrated as well as readily available alternatives to minimize it in the short term. Nevertheless, implementing material selection techniques appropriately as effective corrosion prevention/control and cost-saving strategies must be enforced in any process.

This paper aims to investigate the reason for natural gas leakage from transmission pipelines between Linyi and Shouguang in China during sealing tests, explore the failure mechanism and provide a reference for taking reasonable measures to prevent such accidents.

Failure analysis for the steel pipe has been addressed with different methods, such as microstructure analysis, inclusion analysis, corrosion product analysis, macro- and micro-morphology analyses and bacterially catalyzed experiments.

Several bulges were observed, especially at the bottom of the steel pipe sample, with the distribution and positioning not related to the weld. The inner surface of the steel pipe was severely corroded, and the oxide scale was flaking in many places. The greatest corrosion area was identified at the bottom of the steel pipe near the gas leakage point. Severe pitting and perforation corrosion in the pipeline were observed, and the main corrosion reaction products were Fe3O4, FeO and FeS. The grain orientation distribution near the crack (coarse grains <101> and fine grains <111> at the microcrack tip) indicates that fine grains may be beneficial in hindering crack propagation.

The principal mechanism for the corrosion failure is supposed to be due to the interaction of chloride ions with the sulfate-reducing microorganisms present and the stress corrosion cracking by chloride and sulfide formed by the sulfate-reducing microorganisms.

The purpose of this paper is to identify the corrosion failure mechanism of a Cu tube in a hydraulic installation and recommend corrective actions to improve the reliability of the entire unit.

Failure investigation process includes mainly stereo-, light optical microscopy and scanning electron microscopy as the main analytical tools for material characterization and root-cause analysis.

The investigation findings, obtained by corroded surface analysis and metallographic evaluation in transverse sections, suggest strongly that the failure was caused by the operation of Type I pitting corrosion mechanism initiated from the inner side and propagated towards the outer tube surface, assisted by the flowing medium composition.

This paper deals with an applied failure analysis/case history, summarizes the stages involved in the mechanism of pitting corrosion Type I, taken place in cold water systems together with the main parameters and corrosive species that enhance corrosion rates, shortening pipeline operation life.

This paper seeks to determine the causes and mechanism of failure of stainless steel piping in a sulphur recovery unit of a gas‐processing plant and to recommend suitable measures to avoid recurrences.

The integrity of the material of construction was verified using various laboratory and analytical techniques. Standard metallographic techniques were used to prepare representative samples obtained from failed stainless steel piping for metallurgical evaluation. Microstructural characterization was carried out in an inverted metallurgical microscope equipped with an imaging facility. Elemental analysis and hardness were used to confirm the identification of the material. Corrosion product/deposits were analyzed using wet chemistry supported by X‐ray diffraction analysis. Microbes were enumerated through standard methods.

The piping failed due to severe pitting corrosion, which resulted in the formation of holes. Microbial‐induced corrosion (MIC) and under‐deposit corrosion were chief contributing factors that caused the failure in stainless steel piping. In addition, the HAZ near welds at some places was found to be sensitized causing accelerated pitting corrosion at these sites.

The expected service life of stainless steel piping could not be realized as the piping failed due to the combined effect of MIC and under‐deposit corrosion. Periodic monitoring of sulphate‐reducing bacteria and sulphur‐oxidizing bacteria coupled with implementation of an effective biocide treatment programme in process fluid was recommended, together with the introduction of a procedure for frequent cleaning of the pipe walls to minimize under‐deposit attack.

The paper – a technical case study of process industry – provides an account of failure investigation. It identifies the causes and mechanism of failure and suggests suitable preventive and corrective measures. This is useful industrial experience that provides valuable information for process and plant corrosion engineers involved in the operation of this type of equipment.

The purpose of this paper is to study the cause of severe corrosion of the galvanized lightning rods in a 220 kV transformer substation, and to seek the effective corrosion inhibition measures for the hollow lightning rods.

The corrosion morphology and rust component of lightning rod was analyzed, and the corrosion process of lightning rod was researched by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), ion chromatography and electrochemical tests.

The results indicated that the outer surface of hollow lightning rod was corroded slightly; however, its inner surface suffered severe corrosion because of a long time high-humidity environment inside the tube caused by the rainwater permeation. A rust layer consisted of Fe₃O₄ and a little FeOOH was accumulated on the inner surface of the hollow lightning rod. Moreover, Fe₃O₄ rust layer worked as a large cathode area which could promote the corrosion of metal substrate further. A self-accelerating corrosion process was formed on the inner surface, making the corrosion failure of lightning rod occurred and aggravated gradually.

The corrosion of inner surface of hollow lightning rod cannot be detected easily. More attention should be paid to the corrosion inhibition of lightning rod. The key of corrosion inhibition for the hollow lightning rod was to avoid the rainwater accumulation inside tube. The research results can provide guidelines on the corrosion inhibition measures selection of lightning rod in transformer substation.

The acceleration of corrosion of rebars in concrete are due to several reasons such as carbonation, chloride attack, influence of microorganisms, etc. The aim of this investigation mainly focused on how the microorganism was involved in the corrosion process and thereby affect a mechanical property of mortar and accelerate the corrosion of steel in mortar. ordinary portland cement (OPC) and portland pozzolona cement (PPC) was used for making mortar specimens. Sodium citrate was used as an inhibitor for the corrosion of steel in mortar.

Compressive strength measurements were conducted for mortar at different ages in the presence of microorganisms to understand the mechanical property of mortar. Potential‐time behavior studies were carried out to determine the status of rebars inside the mortar. Weight loss measurements were adopted to quantify the corrosion level due to microorganisms. The microbial count in the water samples at the initial and final exposure period was also examined.

All these studies showed that additions of sodium citrate level of greater than 1 percent by weight of OPC and PPC severely affected both the mechanical and the corrosion resistance properties of OPC and PPC. Microbiological examination reveals that bacteria consume citrates for their survival and thereby increasing the permeability of mortar specimens.

Generally, citrates are considered as being good corrosion inhibitor for steel in concrete. However, results from the present study indicated that sodium citrate concentrations only of less than 1 percent by weight of OPC and PPC are suitable for use in concretes that are exposed to heterotrophic bacterial environments.

The purpose of this paper is to investigate the corrosion behavior of X65 steel in the CO₂-saturated oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behavior of gathering and transportation pipeline steel. The weight loss tests were carried out in a 3 L autoclave, and effects of water cut and temperature on the CO₂ corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature was 60°C, and the CO₂ partial pressure was 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using x-ray diffraction.

The results showed that due to the wetting and adsorption of crude oil, the corrosion morphology of X65 steel changed under different water cuts. When the water cut of crude oil was 40-50 per cent, uniform corrosion occurred on the steel surface, accompanied by local pitting. While the water cut was 70-80 per cent, the resulting corrosion product scales were thick, loose and partial shedding caused platform corrosion. When the water cut was 90 per cent, the damaged area of platform corrosion was enlarged. Crude oil can hinder the corrosion scales from being dissolved by the corrosive medium, and change dimension and accumulation pattern of the crystal grain, thickness and structure of the corrosion scales. Under the corrosion inhibition effect of crude oil, the temperature sensitive point of X65 steel corrosion process moved to low temperature, appeared at about 50°C, lower corrosion rate interval was broadened and the corrosion resistance of X65 steel was enhanced.

The results can be helpful in selecting the applicable corrosion inhibitors and targeted anti-corrosion measures for CO₂-saturated oil/water corrosive environment.

This paper aims to investigate the high-temperature mechanical properties of HS110S steel and its corrosion behaviors in harsh downhole environment.

In this work, mechanical property measurements were carried out from 25°C to 350°C and the scanning electron microscopy was used to observe the fracture morphology. The weight-loss measurements and surface characterization were used to evaluate the corrosion resistance of HS110S steel in harsh downhole environment.

Results show that the yield strength and tensile strength of HS110S steel at 350 °C are 779 and 861 MPa, respectively. Compared with room temperature, the reduction rate values are both less than 20%. At the high-temperature corrosion environment (350 °C), the static and dynamic corrosion rates are 0.9668 and 1.9236 mm/a, respectively. The generated corrosion products are mainly composed of FeSx, FeCO₃ and Fe₃O₄. Therefore, the HS110S steel applied under such conditions needs to take suitable protective measures.

In general, the HS110 steel has widely used in conventional development conditions (e.g. low H₂S or high CO₂ environments). However, to the best of the authors’ knowledge, no studies have reported on its application at more than 250°C. Therefore, this work can be a reference to the application of HS110S steel in high-temperature corrosion conditions.

This study aims to report the development and experimental evaluation of three innovative corrosion-resistant modified epoxy coatings, namely, nanocomposite/toughened, self-healing and hybrid epoxy coatings, for application on steel substrates.

The corrosion resistance of these coatings was evaluated in a highly corrosive environment of salt fog spray for 2,500 h of exposure. Electrochemical impedance spectroscopy (EIS) measurements in sustained exposure to NaCl in a saturated Ca(OH)2 solution, rust creepage measurements at the location of scribe formed in the coatings and adhesion strength test were used to assess the performance of the innovative coatings. Commercially available marine-grade protective epoxy coatings were used as the reference coatings.

The test results showed that the modified epoxy coatings exhibited excellent corrosion resistance when exposed to an aggressive environment for extended periods. The EIS measurements, rust creepage measurements, pull-off strength and visual appearance of the aged modified–epoxy–coated specimens confirmed the enhanced corrosion resistance of the modified epoxy coatings.

Among the three types of modified coatings, the hybrid epoxy coating stands out to be the best performer.

Important reserves of oil and gas, which are left to be discovered and produced, are mainly concentrated in challenging locations and under severe conditions such as high pressure (HP)/high temperature (HT). The presence of aggressive environments including H₂S, CO₂ and chlorides plus HP/HT causes a series of corrosion problems, which cost the oil industry billions of dollars a year. Thus, there is an increasing challenge for tubes (i.e. oil country tubular goods, for short, OCTG) used in producing oil and gas. The purpose of this study is to summarize different kinds of corrosion problems and their mitigation, to more efficiently protect OCTG from corrosion.

To effectively select proper mitigation methods, the mechanism of corrosion must be understood, which can be classified into four categories: sweet corrosion, sour corrosion, galvanic corrosion and microbiologically induced corrosion. Also, the effects of environmental and material factors on the corrosion rate are presented. Subsequently, current technology of mitigating these corrosion problems has been discussed, including the development of materials, application of chemical inhibitors and application of protective layers.

It is stressed that limits exist for each individual mitigation method; therefore, a careful balance between economic life of OCTG and safety in operation is required.

The main purpose of this essay is to give a brief review and detailed introduction and analysis about those technologies.