The Electrochemical Behavior of Alloy in Extreme Chloride and Bitrate Environments

Alloy 22 specimens were tested in high temperature (100 to 160 C), high concentration chloride and nitrate environments. Results of this study indicate that increasing nitrate to chloride ratio to 0.5 in these electrolytes increases resistance to localized breakdown and enhances repassivation. In these extreme environments, localized corrosion occurred by pitting even though specimens were tested using artificial crevice formers. Open circuit (E{sub corr}), breakdown and repassivation potentials all increase, and pitting morphology changes as nitrate to chloride ratio increases from 0.05 and 0.15 to 0.5. Results also indicate that increasing the temperature from 100 to 160 C increases E{sub corr} values, while breakdown potentials and repassivation potentials peak at 130 C for the 0.5 nitrate to chloride ratio electrolytes

SCC Initiation in Alloy 600 Heat Affected Zones Exposed to High Temperature Water

Studies have shown that grain boundary chromium carbides improve the stress corrosion cracking (SCC) resistance of nickel based alloys exposed to high temperature, high purity water. However, thermal cycles from welding can significantly alter the microstructure of the base material near the fusion line. In particular, the heat of welding can solutionize grain boundary carbides and produce locally high residual stresses and strains, reducing the SCC resistance of the Alloy 600 type material in the heat affected zone (HAZ). Testing has shown that the SCC growth rate in Alloy 600 heat affected zone samples can be {approx}30x faster than observed in the Alloy 600 base material under identical testing conditions due to fewer intergranular chromium rich carbides and increased plastic strain in the HAZ [1, 2]. Stress corrosion crack initiation tests were conducted on Alloy 600 HAZ samples at 360 C in hydrogenated, deaerated water to determine if these microstructural differences significantly affect the SCC initiation resistance of Alloy 600 heat affected zones compared to the Alloy 600 base material. Alloy 600 to EN82H to Alloy 600 heat-affected-zone (HAZ) specimens where fabricated from an Alloy 600 to Alloy 600 narrow groove weld with EN82H filler metal. The approximate middle third of the specimen gauge region was EN82H such that each specimen had two HAZ regions. Tests were conducted with in-situ monitored smooth tensile specimens under a constant load, and a direct current electric potential drop was used for in-situ detection of SCC. Test results suggest that the SCC initiation resistance of Alloy 600 and its weld metal follows the following order: EN82H > Alloy 600 HAZ > Alloy 600. The high SCC initiation resistance observed to date in Alloy 600 heat affected zones compared to wrought Alloy 600 is unexpected based on the microstructure of HAZ versus wrought material and based on prior SCC growth rate studies. The observed behavior for the HAZ specimens is likely not related to differences in the environment, differences in surface stress/strain between the various specimen regions (weld, HAZ, wrought), differences in surface residual stress, or differences in the microstructure of the various specimen regions (weld, HAZ, wrought). The behavior may be related to differences in the creep behavior of the various weld regions or differences in the surface area of the various materials (weld, HAZ, wrought) exposed to high temperature water

Long Term Corrosion Potential and Corrosion Rate of Creviced Alloy 22 in Chloride Plus Nitrate Brines

Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. In conditions where tight crevices exist in hot chloride containing solutions and at anodic potentials, Alloy 22 may suffer crevice corrosion, a form of localized attack. The occurrence (or not) of crevice corrosion in a given environment (e.g. salt concentration and temperature), is governed by the values of the critical potential (E{sub crit}) for crevice corrosion and the corrosion potential (E{sub corr}) that the alloy may establish in the studied environment. If E{sub corr} is equal or higher than E{sub crit}, crevice corrosion may be expected. In addition, it is generally accepted that as Alloy 22 becomes passive in a certain environment, its E{sub corr} increases and its corrosion rate (CR) decreases. This paper discusses the evolution of E{sub corr} and corrosion rate (CR) of creviced Alloy 22 specimens in six different mixtures of sodium chloride (NaCl) and potassium nitrate (KNO{sub 3}) at 100 C. The effect of immersion time on the value of E{sub crit} was also determined. Two types of specimens were used, polished as-welded (ASW) and as-welded plus solution heat-treated (ASW+SHT). The latter contained the black annealing oxide film on the surface. Results show that, as the immersion time increases, E{sub corr} increased and the CR decreased. Even for highly concentrated brine solutions at 100 C the CR was < 30 nm/year after more than 250 days immersion. Some of the exposed specimens (mainly the SHT specimens) suffered crevice corrosion at the open circuit potential in the naturally aerated brines. Immersion times of over 250 days did not reduce the resistance of Alloy 22 to localized corrosion

Anodic Behavior of Alloy 22 in High Nitrate Brines at Temperatures Higher than 100(degree)C

Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C

Business and Information Technology Alignment Measurement -- a recent Literature Review

Since technology has been involved in the business context, Business and Information Technology Alignment (BITA) has been one of the main concerns of IT and Business executives and directors due to its importance to overall company performance, especially today in the age of digital transformation. Several models and frameworks have been developed for BITA implementation and for measuring their level of success, each one with a different approach to this desired state. The BITA measurement is one of the main decision-making tools in the strategic domain of companies. In general, the classical-internal alignment is the most measured domain and the external environment evolution alignment is the least measured. This literature review aims to characterize and analyze current research on BITA measurement with a comprehensive view of the works published over the last 15 years to identify potential gaps and future areas of research in the field.Comment: 12 pages, Preprint version, BIS 2018 International Workshops, Berlin, Germany, July 18 to 20, 2018, Revised Paper

Long Term Corrosion Potential and Corrosion Rate of Creviced Alloy 22 in Chloride Plus Nitrate Brines LONG TERM CORROSION POTENTIAL AND CORROSION RATE OF CREVICED ALLOY 22 IN CHLORIDE PLUS NITRATE BRINES

ABSTRACT Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. In conditions where tight crevices exist in hot chloride containing solutions and at anodic potentials, Alloy 22 may suffer crevice corrosion, a form of localized attack. The occurrence (or not) of crevice corrosion in a given environment (e.g. salt concentration and temperature), is governed by the values of the critical potential (E crit ) for crevice corrosion and the corrosion potential (E corr ) that the alloy may establish in the studied environment. If E corr is equal or higher than E crit , crevice corrosion may be expected. In addition, it is generally accepted that as Alloy 22 becomes passive in a certain environment, its E corr increases and its corrosion rate (CR) decreases. This paper discusses the evolution of E corr and corrosion rate (CR) of creviced Alloy 22 specimens in six different mixtures of sodium chloride (NaCl) and potassium nitrate (KNO 3 ) at 100°C. The effect of immersion time on the value of E crit was also determined. Two types of specimens were used, polished as-welded (ASW) and as-welded plus solution heat-treated (ASW+SHT). The latter contained the black annealing oxide film on the surface. Results show that, as the immersion time increases, E corr increased and the CR decreased. Even for highly concentrated brine solutions at 100°C the CR was < 30 nm/year after more than 250 days immersion. Some of the exposed specimens (mainly the SHT specimens) suffered crevice corrosion at the open circuit potential in the naturally aerated brines. Immersion times of over 250 days did not reduce the resistance of Alloy 22 to localized corrosion

Design of low-cost sensors for industrial pocesses energy consumption measurement. Application to the gas flow consumed by a boiler

International audienceThe demand for energy is becoming increasingly important, and who says strong demands for energy says rising CO 2 emissions. Everyone agrees that a great part of the energy consumed by industry and households can be saved. The energy savings can take many forms. In addition to the necessity to build equipments more and more energy efficient, it is also necessary to get a clear view of how the energy is used. This obviously involves the implementation of an energy flow measuring system for long lasting optimization solutions. It is precisely in this context that the project CHIC (Low cost industry utilities monitoring systems for energy savings), funded by the French National Research Agency (ANR), emerged. The objective of this project is to develop and test low-cost non-intrusive sensors to monitor and analyze the energy consumption of major flows used in the manufacturing sector (electricity, gas, compressed air). With such sensors, it should be possible to tool up a factory, equipment by equipment, which is not feasible with intrusive sensors. The ultimate goal is the long term consumption monitoring and the detection of the consumption deviations rather than a precise measurement. The measurement accuracy is fixed to 5%. These developments are based on the recent approaches in system identification and parametric estimation. This project, concretely, involves the design of new low-cost sensors in the following areas: current sensors, voltage, power, and gas flow, relying on the international ISO 50001 standard for Energy Management Systems. The work presented in this chapter focuses on the modeling of the gas flow supplied to a boiler in order to implement a soft sensor. This implementation requires the estimation of a mathematical model that expresses the flow rate from the control signal of the solenoid valve and the gas pressure and temperature measurements. Two types of models are studied: LPV (Linear Parameter Varying) model with pressure and temperature as scheduling variables and a non-parametric model based on Gaussian processes