The use of cured-in-place pipe (CIPP) and Carbon Fiber Reinforced Polymer (CFRP) liners for the rehabilitation of nuclear power plant raw water systems can result in significant cost savings, increased system reliability, and extended piping life. These systems also include the use of internal mechanical seals. The cost advantage for installation of CIPP alone may reach 10:1 for the nuclear power industry versus excavation and replacement of buried carbon steel piping. This paper will present recent examples of these applications, including unique requirements faced in the nuclear industry such as more detailed material and system qualification, licensing, and working within outage and operational restrains, e.g. Limited Condition of Operation (LCOs).
The mass transfer behavior of electroactive solutes from bulk solution to a metal surface under subcooled boiling and pool boiling conditions was investigated using a self designed novel pool-boiling device. This device employed hot oil circulation to heat the specimen until the nucleate boiling take place on the surface of the specimen. The electrochemical method was successfully employed to obtain the mass transfer rate on a boiling surface by measure limiting current density. The effects of subcooled boiling temperature and heat flux on mass transfer on surface were studied. The results show that under subcooled boiling condition the mass transfer coefficient is increasing with the increase of the solution temperature attribute to the increase of diffusion rate. Under pool boiling condition the mass transfer coefficient is increasing with the increase of heat flux when the heat flux is under 90 kW/m2 due to the enhancement of the bubble generated forced convection.
The field experience in H2S + CO2 corrosion which was first reported in 20061 has been significantly increased, some of which has been made available in the literature. Several new cases are included in this paper. This experience has been compiled and extensively analyzed during the last few years, which has allowed some recurrent corrosion effects to be found, and some lessons learned on how to address or mitigate such effects. Six distinct recurrent findings are listed in this paper.
These findings have been analyzed in a very simple approach, which can be summarized as follows:
Under significantly sour conditions and despite a permanent contact with water, the H2S + CO2 carbon steel corrosion rate typically remains low, as long as the following conditions are met:
1. There are sufficient anions and cations at the steel surface to ensure quick FeS precipitation at the steel-water interface,
2. Precipitation kinetics are high enough to ensure the precipitation reaction to be immediate at the interface, hence producing a dense protective corrosion product layer,
3. No detrimental factor is present that would alter this protective layer, neither locally nor on extended parts of the surface.
On the other hand, H2S + CO2 corrosion of carbon steel is possible, as long as water is present, if any of these 3 conditions is not fulfilled.
Though this summary does not provide a detailed mechanistic description of H2S + CO2 corrosion, it provides a very simple way to approach this corrosion threat, while also showing essential tendencies and suggested barriers that future mechanistic description should be able to explain.
Haile, Tesfaalem (Alberta Innovates – Technology Futures) | Wolodko, John (Alberta Innovates – Technology Futures) | Wilkie, Rio (Alberta Innovates – Technology Futures) | Tsaprailis, Haralampos (Alberta Innovates – Technology Futures)
Water plants constructed to process brackish and fresh water sources for in-situ thermal oil sands production have noted failures associated with corrosion. The approach to resolve observed problems may depend on the local or upstream operating conditions, and may involve improved monitoring capabilities, additions of chemicals, and/or material selections. The unpredictable occurrences of serious corrosion issues related to the complex water chemistry make it difficult to choose the appropriate preventative and mitigation measures. This is further complicated by the effects of temperature, pressure, and flow turbulence on the equilibrium concentrations of the different species. Considering that the water chemistries are continually changing, it is beneficial to establish operating windows for the different chemical components and determine the effect of operating parameters such as turbulence and temperature. A better understanding of the singular and interactive effects of dissolved ions and gases in the waters is a necessary precursor for an effective integrity management program.
The current paper details selective findings related to corrosion of brackish water systems used for in-situ thermal operations. The effect of pH, bicarbonate and oxygen were studied using model brackish water and the results show that the corrosion rates were significantly impacted by the pH and oxygen levels, while the reduction of the bicarbonate (alkalinity) content of the brackish waters did not sufficiently reduce the overall corrosion kinetics.
The poor performance of Metal-on-Metal (MoM) bearings has to date been blamed on “adverse loading” conditions. Studies have focused on the effect of cup inclination and microseparation on gravimetric wear rates and highlighted the importance of surgical technique when implanting such devices. Up to four fold increase in the wear rates of MoM bearings subjected to microseparation has been reported during the bedding-in period. The contribution of corrosive processes to overall material degradation during adverse loading has not previously been investigated. In the present study 28 mm HC CoCrMo alloy Total Hip Replacements were tested to 1 Mcycles under standard gait and severe microseparation conditions in an electrochemically instrumented hip simulator. An order of magnitude increase in material lost as a result of oxidation was noted (0.234 to 2.044 mm3/Mcycle) during microseparation. Corrosive degradation may therefore be a much more significant contribution to poor bearing performance under adverse loading than previously considered.
Fernández-Domene, Ramón Manuel (Universitat Politécnica de Valencia) | Leiva-García, Rafael (University of Manchester) | Andrews, Jake (University of Manchester) | Akid, Robert (University of Manchester)
Under some conditions in sweet environments, the precipitation of corrosion products (primarily FeCO3) on the surface of X-65 pipeline steel can decrease the corrosion rate of the metal, this precipitated film acting like a protective scale. However, when these scales are damaged due to effects such as solid-particle erosion or mechanical stress, a galvanic pair can form between the bare steel (anode) and the surrounding undamaged scale (cathode). The aim of this work is to evaluate the magnitude of galvanic coupling that arises when the protective scale is broken and a corrosion cell is established between the defect and the surrounding scale. This study has been conducted in two stages: firstly, the formation of a protective scale on the surface of X-65 samples in CO2 saturated conditions (80 0C and a CO2 pressure of 0.53 bars); secondly, a scaled sample of X-65 steel was coupled with a fresh (non-scaled) X-65 sample in a brine solution saturated with CO2 at 600C. Zero resistance ammeter (ZRA) measurements were then conducted using this galvanic couple. According to the results, there was galvanic coupling between the bare metal and a scaled surface where the magnitude of the galvanic pair was found to be dependent on the anode:cathode ratio.
Pipe wall thickness loss caused by corrosion and erosion is a significant safety concern in industry. In the field and on plant the detrimental effects of corrosion are often evaluated using ultrasonic thickness measurements. Due to difficult field conditions, changes in setup and a range of other factors these measurements are usually only precise to within fractions of a millimetre. However advances in ultrasonic technology as well as the possibility of permanently installing them at reasonable economic cost have seen an increase in precision of several orders of magnitude. This substantial gain in precision allows the evaluation of very small wall loss rates in a matter of hours, which in turn can be used to evaluate and adjust corrosion mitigation strategies. To assess the potential of ultrasonic monitoring, a state of the art permanently installed ultrasonic sensor setup is evaluated in this paper using an electrolytic corrosion cell, which allows us to benchmark the performance of the sensor while controlling conditions inside the cell. The ultrasonic thickness estimates are compared to electrochemical measurements under a range of potentials, currents, pH levels and various electrolytes to investigate the ranges of potential application. The results of the investigation show that below 100 nanometre precision is achievable using the ultrasonic sensor in laboratory conditions.
Less than one year after recompletion, a producing well was shut in due to penetrating wall thickness loss in the API 5CT L80 Type 1 top completion. The short service life included a history of numerous coil tubing jobs, several shut-in periods and only limited production periods. The root cause of a longitudinal local wall thickness loss of approximately 7 mm in 10 months was examined. No indications of wear were detected on the examined tubular and on the basis of the geometries of the longitudinal track and the coil, respectively, the coil itself cannot have induced the penetrating tracks by metal-metal contact. The API 5CT L80-13Cr pup joints were also corroded, indicating a possible effect of oxygenated seawater.A plausible explanation for the failure mode is that the numerous coil tubing operations caused local mechanical damage to protective scale and iron sulfides exposing the bare metal in a track, thereby facilitating localization of corrosion on the inside surface of the tubular. The controlling degradation mechanism is corrosion due to aggressive fluids, including untreated, oxygen-containing seawater used during the interventions. It is essential that the prescribed treatment of seawater with corrosion inhibitor, oxygen scavenger and biocide is followed in all cases and during all interventions.
The effect of Camellia Sinensis (green tea) extract as a ‘green’ inhibitor on mild steel corrosion in 0.5M HCl and 0.8M H2SO4 was studied at ambient temperature. Weight loss/corrosion rate and potential measurement techniques were used for the experimental work. The results were further analyzed using the two-factor ANOVA. Potential measurement was performed using a digital voltmeter and a saturated calomel reference electrode. Results obtained showed effective corrosion-inhibition of the extract on the mild steel test-specimens in the different concentrations of HCl and H2SO4 used. There was increasing inhibition performance with increasing concentration of inhibitor. In 0.5M HCl, 100% green tea gave the optimal performance with weight loss and corrosion rate of 246mg and 0.63 mm/yr respectively. A similar result was observed in 0.8M H2SO4 where 100% green tea gave the best results of 1226 mg weight loss and 3 mm/yr corrosion rate. ANOVA test confirmed the results at 95% confidence and further showed that concentration of green tea extract had greater effect on potential and weight loss measurements. The Gibb’s free adsorption energy signified physisorption in HCl and chemisorption in H2SO4 as the adsorption mechanism of plant extract molecules on the metal surface.
Gindri, Izabelle M. (University of Texas at Dallas) | Burbano, Maria (University of Texas at Dallas) | Siddiqui, Danyal (University of Texas at Dallas) | Russell, Robert (University of Texas Southwestern Medical) | Rodriguez, M. Laura (University of Texas at El Paso) | Rodrigues, Danieli C. (University of Texas at Dallas)
Implant failure can be triggered by metal wear and corrosion in the articular interfaces as well in the modular sections of hip implants, which may induce inflammatory reactions. The goal of this study was to evaluate the surface characteristics related to wear and corrosion of eleven retrieved hip implants due to different clinical causes. Factors that evidenced wear and corrosion such as scratches, pits and discoloration were investigated to obtain information on potential root causes of implant failure. All surfaces showed some degree of wear. The most damaged surface, from a cobalt-chromium modular stem, was further investigated by X-Ray Photoelectron Spectroscopy (XPS) and electrochemical experiments. The surface of this sample showed titanium contamination, which was hypothesized as being released from other implant components due to wear and corrosion.