A NEW APPROACH IN EMPIRICAL MODELLING OF CO2 CORROSION WITH THE PRESENCE OF HAc AND H2S

CO2 corrosion is the main threat in upstream oil and gas operations. The requirement to predict the corrosion in design and operational stage is critical. However, the presence of other corrosion species and operational parameters complicate the mechanism of the corrosion. The interaction between those factors affect the accuracy of the corrosion prediction. Although many publications on CO2 corrosion prediction had been published, most of the prediction models rely on specific algorithms to combine individual effect of the interacting species to represent the total corrosion rate. This effort is inefficient and needs a large number of experiments to process all possible corrosion data simultaneously. In order to study CO2 corrosion of carbon steel involving interactive effects of several key parameters, a proven systematic statistical method that can represent the multitude interactive effects is needed. In this research, a combination of response surface methodology (RSM) and mechanistic corrosion theories were used to construct an empirical model that relates the effects of acetic acid (HAc), temperature, and rotation speed on CO2 and CO2/H2S corrosion rate simultaneously. The corrosion experiments are based on both linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) methods. Flow condition is simulated using rotating cylinder electrode (RCE). The RSM regression models for the carbon steel corrosion in CO2 environments involving HAc, temperature and rotation speed as parameters have been successful developed and validated with experimental data and commercial predictive models. In the form of mathematical equations, the effects of independent variables will be easily identified and developed. The combination RSM and mechanistic theory applied in this research is efficient to determine the empirical relationship of the variables tested simultaneously. Furthermore, RSM models can be used to determine scaling temperature, limiting current density and flow dependency characters

A NEW APPROACH IN EMPIRICAL MODELLING OF CO2 CORROSION WITH THE PRESENCE OF HAc AND H2S

CO2 corrosion is the main threat in upstream oil and gas operations. The requirement to predict the corrosion in design and operational stage is critical. However, the presence of other corrosion species and operational parameters complicate the mechanism of the corrosion. The interaction between those factors affect the accuracy of the corrosion prediction. Although many publications on CO2 corrosion prediction had been published, most of the prediction models rely on specific algorithms to combine individual effect of the interacting species to represent the total corrosion rate. This effort is inefficient and needs a large number of experiments to process all possible corrosion data simultaneously. In order to study CO2 corrosion of carbon steel involving interactive effects of several key parameters, a proven systematic statistical method that can represent the multitude interactive effects is needed. In this research, a combination of response surface methodology (RSM) and mechanistic corrosion theories were used to construct an empirical model that relates the effects of acetic acid (HAc), temperature, and rotation speed on CO2 and CO2/H2S corrosion rate simultaneously. The corrosion experiments are based on both linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) methods. Flow condition is simulated using rotating cylinder electrode (RCE). The RSM regression models for the carbon steel corrosion in CO2 environments involving HAc, temperature and rotation speed as parameters have been successful developed and validated with experimental data and commercial predictive models. In the form of mathematical equations, the effects of independent variables will be easily identified and developed. The combination RSM and mechanistic theory applied in this research is efficient to determine the empirical relationship of the variables tested simultaneously. Furthermore, RSM models can be used to determine scaling temperature, limiting current density and flow dependency characters

Application of plants extracts as green corrosion inhibitors for steel in concrete - a review

High requirements in protection of steel reinforcing bar (steel rebar) from corrosion are necessary since there are multi in�teraction of corrosive chemicals which cause early damage of concrete buildings. Corrosion of steel in concrete can destroy the concretes and reduce concrete strength. To protect rebar from corrosion, application of corrosion inhibitor is believed to have higher performance compared to other protection systems. To date, organic inhibitors have promising methods in steel rebar protection as they are environment-friendly, compatible with concrete, cost effective and applicable in any various concrete conditions. Thus, demands in using these in�hibitors tend to increase significantly. This paper reviews the applications of green corrosion inhibitor specifically high�lighted in protecting mechanisms, typical plants extracted, performance in corrosion protection, and classification of green corrosion inhibitors. The corrosion resistances of car�bon steels in concrete protected by green inhibitors are in fo�cus. As summary, it can be confidently notified that green cor�rosion inhibitors for steel in concrete will have a prospect to be used as corrosion prevention in the future with further im�provements

ALUMINUM ALLOY AA2024 COATED WITH ZrO2 USING A SOL-GEL-ASSISTED DIP-COATING TECHNIQUE AND ITS CORROSION PERFORMANCE

Aluminum alloys has been widely used in most of engineering applications, such as marine industries and aerospace, due to its light weight and durability properties. In the aggressive environment, aluminum alloy becomes chemically reactive and losses its corrosion resistance that can significantly limit to its applications. One of the approaches that have been studied in this research is to improve the corrosion resistance of aluminum alloy by adding zirconium oxide (ZrO2) film coating. In the experimental procedure, aluminum alloy was dipcoated into the solution containing zirconium butoxide (as a precursor) in a specific solvent (consisting of acetone, ethanol, and nitric acid). Dipping process was conducted at different dipping-numbers, which are 3, 5, and 7 dipping number. After dip-coating process, the coated aluminum was annealed at 350°C for 3 hours. X-ray diffraction analysis confirmed that the coating film consists of tetragonal ZrO2. Then, increases in dipping number improved the surface quality of the coating layer, where number of cracks and black spots reduced continuously with higher dipping number. This condition gave positive impacts on the corrosion performance of the aluminum, where higher dipping number brings better corrosion protection in NaCl solution

The Roles of H2S Gas in Behavior of Carbon Steel Corrosion in Oil and Gas Environment: A Review

Hydrogen sulfide (H2S) is the most dangerous element which exists in oil and gas reservoir. H2S acidifies water which causes pitting corrosion to carbon steel pipelines. Corrosion reaction will increase fast when it combines with oxygen and carbon dioxide (CO2). Thus, they can significantly reduce service life of transportation pipelines and processing facilities in oil and gas industries. Understanding corrosion mechanism of H2S is crucial to study since many severe deterioration of carbon steels pipelines found in oil and gas industries facilities. To investigate H2S corrosion accurately, it requires studying physical, electrical and chemical properties of the environment. This paper concentrates, especially, on carbon steel corrosion caused by H2S gas. How this gas reacts with carbon steel in oil and gas reservoir is also discussed. This paper also reviews the developments of corrosion prediction software of H2S corrosion. The corrosion mechanism of H2S combined with CO2 gas is also in focused

Modelling the flexural properties of filled epoxy: Effects of volume fraction

The effects of volume fraction on the flexural characteristics of epoxy materials filled with cement, fly ash, and CaCO3 are discussed in this work. At a temperature of 50oC, water was used to soak the filled epoxies. It was discovered that the flexural modulus rose with the volume fraction for all fillers. However, the flexural strength of fly ash and CaCO3-filled epoxies tended to decrease with the increase in volume percent. The flexural strength of cement-filled epoxy somewhat improved with the increment volume fraction. According to those data, cement has a stronger interface than fly ash and CaCO3. In comparison to those in the dry condition, the flexural modulus and strength of all the epoxy systems dramatically decrease for the aged specimen. Epoxy that has been filled appears to lessen the reduction in flexural properties compared to that of neat epoxy. Again, the cement-filled epoxy performs better than fly ash and CaCO3. Halpin-Tsai and Pukánszky models have been successfully applied to model the flexural modulus and strength in the dry condition, respectively, but both models failed to predict those mechanical properties in wet condition

High temperature oxidation in boiler environment of chromized steel

The demand for increasing efficiency has led to the development and construction of higher operating temperature power plant. This condition may lead to more severe thickness losses in boiler tubes due to excessive corrosion process. Hence, the research to improve the corrosion resistance of the current operated material is needed so that it can be applied for higher temperature application. In this research, the effect of chromizing process on the oxidation behaviour of T91 steel was investigated under steam condition. In order to deposit chromium, mixture of chromium (Cr) powder as master alloy, halide salt (NH4Cl) powder as activator and alumina (Al2O3) powder as inert filler were inserted into alumina retort together with the steel sample and heated inside furnace at 1050oC for ten hours under argon gas environment. Furthermore, for the oxidation process, steels were exposed at 700oC at different oxidation time (6h-24h) under steam condition. From FESEM/EDX analysis, it was found that oxidation rate of pack cemented steel was lower than the un-packed steel. These results show that Cr from chromizing process was able to become reservoir for the formation of Cr2O3 in high temperature steam oxidation, and its existence can be used for a longer oxidation time

Enhanced corrosion resistance of reinforced concrete: role of emerging eco-friendly Elaeis guineensis/silver nanoparticles inhibitor

Silver nanoparticles (AgNPs) doped palm oil leaf (Elaeis guineensis/EG) extracts (EG/AgNPs) were prepared as novel, non-toxic, and eco-friendly corrosion inhibitor; which were incorporated in cement composite and examined against reinforcement steel corrosion in natural seawater. Standard corrosion monitoring techniques including linear polarization resistance (LPR), potentiodynamic polarisation, half-cell potential (HCP) and electrical resistivity were used to screen corrosion inhibition potential of EG/AgNPs enabled steel reinforced concrete after exposing them weekly to wet and dry cycles in seawater. Besides, the microstructural, morphological, thermal and elemental properties of such concrete at 365 days of exposure were determined. The microstructures of powder of EG/AgNPs inhibitor, pre- and post-treated concrete (powder and small pieces) as well as the steel reinforcement surface were analysed. Incorporation of 5% green EG/AgNPs inhibitor into the steel reinforced concrete revealed enhanced corrosion resistance, where a protective thin barrier was developed over the steel reinforced surface. This improvement was attributed to the formation of extra calcium silicate hydrate (C-S-H) gel in the concrete and thereby blocked the concrete pores. The maximum inhibition efficiency was recorded to be as much as 94.74%. It is established that these green EG/AgNPs has prospective for optimum corrosion inhibiting treatment to achieve durable concrete structures