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Materials and corrosion (2022). doi:10.1002/maco.202213140, Published by Wiley-VCH, Weinheim [u.a.]

This paper examines the influence of oxygen traces on corrosion and hydrogen charging of steel in H 2 S containing environment. It is well known that H 2 S is the driving force for many types of steel failures such as hydrogen induced cracking (HIC), sulfide stress cracking (SSC), and stress-oriented hydrogen induced cracking (SOHIC). Since it is a huge concern for oil and gas industries, standard test methods have been developed and published as NACE technical methods (e.g. NACE TM0284 and NACE TM0177). Though it is recognized that oxygen pollution shall be avoided during H 2 S cracking tests, there is still a lack of experimental data to illustrate the potential impacts of a small oxygen pollution. The aim of the present study was to check if oxygen traces can modify corrosion mechanisms and hydrogen charging of steel in H 2 S medium. Experiments consisted in hydrogen permeation measurements through thin pure iron membrane. They were performed at corrosion potential in order to be in realistic environmental conditions. Corrosion rate was also evaluated through weight loss measurements. Analysis of test solutions was performed in order to identify reaction products between H 2 S and O 2 .

Il presente lavoro riporta uno studio della corrosione ad alta temperatura di diverse leghe, quali AISI 310, AISI 316L e HAYNES® HR-120®, in atmosfera ossidante (aria) e carburizzante (CO/H2/CO2) tramite l'utilizzo di una microbilancia a cristalli (EQCM). Le proprietà dei prodotti di corrosione, formatisi sulla superficie dei materiali bulk, sono stati caratterizzati mediante tecniche convenzionali quali EIS, SEM/EDX, XPS, XRD e RAIR. Gli approcci esplorati convergono nell'indicare che la lega HR-120 risulta essere la meno suscettibile alla degradazione, mentre l'acciaio 316L risulta essere il più reattivo nei due ambienti considerati. Tuttavia, le prove EIS di quest'ultimo hanno indicato che l'ossido termico promosso in aria atmosferica risulta meno poroso e più protettivo.

International audience; Annulus of flexible pipelines represents a specific corrosive environment for the high strength carbon steel wires, mainly due to the low V/S ratio between the volume of electrolyte and the exposed steel surface. This environment induces high super-saturation levels of dissolved iron, together with the establishment of pH values far above thermodynamic equilibrium. Nevertheless, it also induces difficulties to predict actual levels of pH in the annulus, since thermodynamic models do not apply. In order to overcome these difficulties, and to obtain trustful pH values for the design of flexible pipelines, lots of efforts were put both in the experimental and modelling directions. A kinetic model was thus developed a few years ago, taking into account electrochemical and chemical reaction rates which allowed to explain super-saturated pH levels. Specific experiments consisting of continuous in situ pH measurements in confined corrosion cells confirmed the validity of the model in a pressure range 1-10 bar and for short term exposures. In the present paper, the extension of experimental conditions to higher pressures of CO 2 is presented. A good agreement with the model prediction and the short term stabilization of in situ pH was still obtained. Furthermore, longer exposure tests were also performed. It appeared that the evolution of super-saturated pH with time went through a maximum value after a few days, but then decreased slowly to a new equilibrium. This trend was attributed to the slow build-up of an iron carbonate layer, and subsequent decrease of the corrosion rate of the metal. The first version of the kinetic model was well suited to predict the maximum pH reached after a few days, but it did not capture the slow decrease. The model was then modified, in order to take into account the impact of corrosion products precipitation on surface reactions. The new version of the model is now capable to simulate with a good accuracy the complete in-situ pH transient for durations of several weeks until stationary state is reached. It allows not only to predict stabilized super-saturated pH values, but also to quantify the steady-state corrosion rate, which usually stands below a few µm/year. Even with such low corrosion rates, high confinement still induced super-saturation effect, with final pH values at +0.5 pH units above saturated pH.

International audience

In the oil and gas industry, acid gas removal is required for the treatment of natural gas. New applications were also recently pushed forward for CO 2 capture from the flue gas of power plants. For both applications, the most widespread industrial processes use absorption-desorption by an alkanolamine solvent. In such amine units for acid gas removal, corrosion represents an important operational concern. The aim of this paper is to review some of the parameters influencing the corrosivity of amine solvents. In the light of literature data and of new experimental results, the influences of temperature and of acid gas loading are discussed. These two parameters appear to have a strong impact on corrosion rates of carbon steel, with extrapolated corrosion rates of several tens of mm/year for the highest temperature and acid gas loading condition. It is then proposed to discuss about similarities and differences between natural gas processing and CO 2 capture from flue gas. For both applications, alkanolamine processes are used. Still, differences can be found in operating parameters. The most significant gap concerns the lean amine sections. In acid gas treatment, the regeneration of the solvent is often performed down to zero loading. Under these conditions, an extremely low corrosivity of the lean solvent is expected. On the contrary, CO 2 capture from flue gas requires only a partial stripping of the CO 2 in the regeneration section, due to energy efficiency reasons. Then, the lean solvent still contains some acid gas, and subsequently a higher corrosivity.

International audience; Flexible pipelines used in the offshore industry are composed of steel wires enclosed in an annulus formed by inner and outer thermoplastic sheaths. The CO 2 corrosion of the carbon steel wires located in this annulus occurs within restricted volumes of electrolyte. For instance, the typical V/S ratio between the volume of electrolyte and the exposed steel surface is in the order of 0.03 mL.cm-2. In such confined environments, corrosion measurements clearly show that the results classically obtained in bulk conditions (infinite electrolyte volume) do not remain valid. Thus, the corrosion rates measured in the annulus conditions are commonly 2 or 3 orders of magnitude lower than those predicted by classical CO 2 corrosion models. Moreover, measured pH is significantly higher than the saturation pH predicted by thermodynamic models such as CORMED. Recently, large progresses have been made in the understanding of the uniform corrosion processes in the annulus of offshore flexible pipelines. These progresses, related to the design of innovative experimental setups, the achievement of an important testing program and the development of new theoretical models are reported in the present paper.

International audience; Processes using amine solvents for the removal of CO 2 have long been used for the treatment of natural gas. More recently, developments in the field of post-combustion CO 2 capture have gained considerable interest for greenhouse gas mitigation. Even though the nature of the amine is different for both applications, the process flow diagrams are very similar. The raw gas is contacted with the amine solvent in an absorber column, and the CO 2 is absorbed by the solvent. The rich solvent containing the CO 2 then circulates to a regenerator, where the temperature is increased to strip the CO 2. The lean solvent then returns to the absorber for a new cycle. For these processes, corrosion is known to be a major issue. Usually, amines are not corrosive but during operation of amine units, degradation of the solvent may occur due to the reaction with contaminants like oxygen. As a result, corrosive species are formed including other amines and acids products like oxalates, formates and acetates also known as Heat Stable Salts (HSS). Corrosion problems may also depend on other parameters for instance type and concentration of the alkanolamine, temperature of the solvent or CO 2 loading. In order to extend the limits of gas treating processes, but also to develop the new processes for CO 2 capture, a better understanding of corrosion in amine solvents is required. This paper presents the first results of a study where the impact of several parameters will be evaluated by electrochemical methods. The corrosivity of Monoethanolamine (MEA), Diethanolamine (DEA) and methyl-diethanolamine (MDEA) was compared. Other parameters were studied, among which the impact of CO 2 loading and the concentration in HSS. Back-2

Recent case studies reported large scale disbondments of three-layer polyolefin (3-LPE) coatings, which could favour corrosion beneath the coating and lead to possible major damage. Therefore, it is necessary to better investigate the adhesion strength of fusion-bonded epoxy (FBE) primer to steel taking into account the water diffusing through the topcoat within the lifetime of pipeline. A methodology was developed to examine the adhesion of sublayers to steel under wet exposure: peel tests were carried out on pipe rings industrially coated with FBE and adhesive layers only, aged in vapour to simulate the water ingress through the topcoat. This methodology could be included in selection or pre-qualification tests. 1 BACKGROUND Among the two great families of external coatings of pipelines-FBE coatings and 3-LPE-each one has its advantages and disadvantages. In both cases, FBE is applied in direct contact to the freshly grit blasted pipe in order to provide good anchoring to steel.

Objective: The aim of this study was to test age and sex effects on anxiety and depression using the Hospital Anxiety and Depression Scale HADS. Method: Sample 1 consisted of 2037 subjects of the German general population, and sample 2 comprised 2696 cardiologic patients. Results: In the group of the general population we observed a linear increase of depression and (to a lower extent) of anxiety with age. In contrast to that, the patients reached their anxiety and depression maxima in the range of 50 to 60 years, with decreasing mean values for older patients. This effect was observed in both sexes and was proved by an ANOVA interaction between age category and population (P