Adsorption/desorption process of 1-(2-aminoethyl)-2-oleyl-2-imidazolinium chloride on carbon steel. To study adsorption of imidazolinium chloride on carbon steel, in-situ atomic force microscopy measurements were performed in air, with and without imidazolinium chloride, in a 1 wt% NaCl solution purged with CO2 at pH 4.
Due to the special structure and chemical properties graphene oxide has a broad application prospect in corrosion protection. Graphene oxide/epoxy composite coatings were prepared to investigate the CO2 corrosion behavior in high chloride environment. SEM XRD and other technologies were used to characterize the physical properties of the graphene oxide/epoxy composite coatings. The corrosion resistance of graphene oxide/epoxy coatings was studied by electrochemical impedance spectroscopy and polarization curve.In order to increase the dispersion of graphene oxide in epoxy 3-triethoxysilyl-1-Propanamine(KH550) was used to modify the graphene oxide. Then graphene oxide/epoxy composite coatings with different mass fraction of modified graphene oxide were prepared by physical dispersion method.Results showed that the addition of modified graphene oxide improved the anti-corrosion properties of the epoxy coating. The corrosion potential(Ecorr) of 0.5%wt graphene oxide/epoxy composite coating (Ecorr =-255mV) was more positive than that of the epoxy coating(Ecorr =-631 mV). Besides although the corrosion resistance of the graphene oxide/epoxy composite coating was weakened after long-term immersion it still can provide a considerable protection for the base metal from CO2 corrosion in high chlorideenvironment.
The measurement of the open circuit potential of the reinforcement is used to identify regions in concrete structures with active process of corrosion. For black steel rebars ASTM C876: 2015 provides the correlation between the numerical value of the potentials measured and the steel rebar condition defining a range with a greater than 90 % probability of occurrence of corrosion or a greater than 90 % probability of not being corroded and between these an corrosion condition uncertain. However the values of potential established for black steel rebar are not applicable to reinforced concrete structure composed of galvanized steel rebars because the zinc and the steel are a galvanic couple and the value of the open circuit potential is a function of the exposed area ratio of the zinc by area of the steel. In order to verify and elaborate a classification similar to that of the black steel rebar for galvanized steel rebar the open circuit potential of galvanic couple of zinc/steel was measured considering various area ratios in simulated pore solutions with and without chloride ion contamination. The obtained potentials were compared to the steel rebar potentials embedded in concrete.
In this paper, a detailed analysis was performed on weld longitudinal cracks (Weld Bond Cracks can be mistaken for Hydrogen Induced (HIC) cracks.) appeared after HIC testing of Electric Resistance Weld pipes (ERW) 8”-16” NPS 0.375”-0.5” WT carbon steel grade X60 which was welded using a 150-hertz induction heating has been studied in relation the development of hydrogen induced cracking. A comprehensive experiment and testing was done to evaluate both mechanical and microstructural properties of the cracks. The result of the study indicates that raw material failure to meet HIC resistance requirements may appear on the ERW welded pipes due to Steel re-oxidation, Low tundish level, and Double calcium treatment during steel making
The precipitation-hardenable Nickel Alloy UNS(1) N07718 is one of the most commonly applied alloy in the oil and gas industry. Enriched with amounts of niobium molybdenum titanium and aluminum this alloy is known as having good corrosion resistance in sour gas applications while presenting excellent strength properties.The austenitic matrix of g phase is strengthened by the intermetallic precipitates g‘ (ordered FCC Ni3Al phase) and g‘‘ (body-centered tetragonal Ni3Nb phase). Co-precipitates can also be observed.Studies have been carried out in order to compare and better understand the hydrogen embrittlement resistance of three different aging conditions of N07718. Different VIM/VAR commercial heats were age hardened under the standard ageing temperature range to produce a minimum 120 ksi yield strength material under a lower temperature that is responsible for optimizing the mechanical properties (to produce a minimum 140 ksi yield strength material) or under a two-step heat treatment that gives to the material improved mechanical properties (minimum 150 ksi yield strength) when compared to the single-step heat treatment.The interaction of hydrogen with the microstructure has been evaluated by means of hydrogen embrittlement susceptibility tests and structural characterization by neutron diffraction and small angle neutron scattering techniques.
Methodology to simulate actual oil and gas field condition in laboratory tests. A sulfide stress cracking test is carried out on 13% Cr stainless steel with various buffer solutions. Then, pH behavior was estimated. A suitable composition of the solution is proposed by using thermodynamic calculations.
Glycol systems are widely used in gas processing plants for the removal of contaminants such as moisture from the gas. Since the majority of the piping and vessels in these plants are fabricated from carbon steel there is a high potential for corrosion. This paper provides a brief overview of some of the major corrosion mechanisms associated with Glycol regeneration unit. In addition a case study from a Try-Ethylene Glycol (TEG) regeneration system is also discussed where localized corrosion was noticed in the Glycol reboiler and surge vessel. Booster Station facility receives gas from Gathering Center for further compression and removes moisture before being exported to the refinery. This is achieved by compression of gas in multiple stages with locally provided compression equipment and processed in glycol dehydration units to remove the moisture. Water vapor removal from the gas stream is achieved by contacting the wet gas counter-currently with lean (dry) TEG in the glycol contactor column. The rich glycol having water content is routed through a pre-heating coil flash tank filters and finally comes in the Glycol reboiler. Due to the high temperature in reboiler the glycol loses its ability to hold water. Separated water is vaporized and leaves through top of the still column. The regenerated glycol flows to the surge tank and from there it is pumped to Glycol absorber. During one of the Plant Maintenance shutdowns Glycol reboiler and surge vessel were opened for internal inspection and appreciable corrosion was noticed in the top sections of the vessels. A study was initiated to find out the probable causes of the deterioration. Corrosion products were collected for XRD analyses. Also chemical analysis of lean & rich Glycol samples taken from various streams was carried out. A corrosion pattern was established along the glycol regeneration circuit which revealed mainly the low pH of Rich Glycol due to possible decomposition reaction of glycol into organic acid. Presence of Iron sulfate and various forms of iron sulfide including Pyrite Greigite and Pyrhotite (also referred to as Black Powder Derivatives) all known to expedite localized corrosion and deterioration of the metals. This paper presents the findings based on the analysis of the corrosion products and glycol samples and discusses the possible corrosion mechanisms. Recommendations are also provided to ensure the integrity and reliability of these vessels for sustainable operation. This case history demonstrates the diverse nature of the causes of Glycol related corrosion in plants and the differing approaches that have to be taken to mitigate corrosion in Glycol regeneration equipment.
The durability design of new structures at Florida DOT is currently performed by environmental classification of structures. Bridge substructure and superstructure environments can be assigned to slightly aggressive moderately aggressive or extremely aggressive according to the FDOT Structures Design Guidelines. Each classification requires prerequisites regarding concrete composition and concrete cover. The disadvantage of this durability design approach is that the achievable service life remains unknown. However full-probabilistic service life models for predicting the service life in case chloride-induced reinforcement corrosion are available. The objective of the paper is a selected benchmark of the durability design of reinforced concrete bridges in Florida by means of probabilistic modeling.