Protection effectiveness of commercially available vapor corrosion inhibitors powders with different particle size was evaluated. Conventional powder size of and nano-particle powder inhibiting effectiveness was compared using the vapor-inhibiting ability (VIA) NACE TM 208.

This study investigates the influence of thermal cycle as a result of repeated welding heat input on the mechanical and microstructural properties of the SA516 Gr 65 steel plates weldment in as-welded condition. The test specimens used were having an identical joint design, welded with submerged arc welding (SAW) process. Three different heat inputs of 0.96kJ/mm (low heat input), 1.5kJ/mm (medium heat input) and 3.58 kJ/mm (high heat input) were used for welding three individual specimens. All weld longitudinal tensile testing, Charpy V-notch impact test and weld metal & heat affected zone (HAZ) microstructural testing were done. The work shows that low heat input (LHI) produced welds with highest yield, tensile strength and toughness in the weld metal whereas high heat input (HHI) resulted in decrease in yield, tensile strength and toughness in the weld metal. Increased level of acicular ferrite and a fine grain structure in weldment were achieved with LHI, while the HHI produced coarse grain structure in the weldment and in the HAZ.

During drilling operations the drillstring might be subjected to downhole conditions leading to pitting corrosion. State-of-the-art directional drilling technologies are very demanding in terms of material requirements including corrosion resistance. Manganese-stabilized fully austenitic stainless steels in strain-hardened condition own a beneficial combination of high strength high ductility and high toughness by keeping their own non-magnetic character. Therefore CrMn-stainless steels have been extensively used in drilling equipment. Once in contact with high chloride bearing drilling fluids at elevated temperatures however their passivity is compromised leading to pit nucleation and propagation. In consequence the pitting corrosion resistance of these materials becomes a significant limiting factor for their selection as well as for assessing the service life of drillstring components. To date extensive research work has been conducted to characterize the pitting susceptibility of CrMn-stainless steels under static conditions. Little attention however has been paid to the effect of shear stresses introduced by the flow of the drilling fluid on the pitting resistance and damage morphology produced on these materials when exposed to brines at elevated temperatures. To address this electrochemical examinations were conducted using the rotating cylinder electrode (RCE). The present paper discusses the results from potentiodynamic polarization tests and their relation to the hydrodynamic conditions produced in the RCE at different temperatures.

Drop evaporation test at three different temperatures were conducted with duplex stainless steel for the study of the influence of temperature strain and welding energy on its stress corrosion cracking (SCC) suitability. Three welding conditions were performed: regular condition according to N133 standard other with low welding energy with the objective of causing high ferrite content in the fusion zone and other with high welding energy in order to induce the precipitation of deleterious phases in the heat affected zone. The specimens were assayed with three different tensile stresses with a bending device and assayed for 500 hours and dripped with synthetic sea water solution with a flow rate of 10 ± 1 drops per minute. All specimens tested with a temperature of 110ºC showed a fracture in the region adjacent to the drip below the salt deposit and away from the weld with the presence of multiple nucleation and branched crack propagation. The fracture surface showed topography similar to cleavage with small regions of decohesion. The test specimens tested at 90ºC only showed localized corrosion preferential of the ferrite it occurred also in the region adjacent to the drip. The results showed that the crevice condition introduced by the salt layer offered more severe conditions than the welding conditions. The same tests were made with the dropping aiming adjacent region at temperatures of 70ºC and 90ºC to induce the crack in critical regions like fusion zone or heat affected zone but there was no evidence of SCC indicating that the critical temperature is higher than 90ºC even with non-standard welding conditions.

Feedwaters for industrial cooling water systems contain a variety of metal cations (such as calcium magnesium barium etc.) and anions (such as carbonate sulfate phosphate etc.) which overall constitute scaling ions. Their combination (depending on the particular water chemistry and solubility products) creates precipitates and deposits. These mineral salts cause enormous operational problems upon their deposition onto critical equipment surfaces (eg. membranes heat exchanger tubing tower fill etc.). Calcium carbonate and calcium phosphates are the most frequently encountered deposits. Other deposits although less common are equally troublesome. These include amorphous (colloidal) silica. Prevention of scale formation is greatly preferred by industrial water users to the more costly laborious (and potentially hazardous) chemical and mechanical cleaning (for example HF is required for the dissolution of silica deposits) of the adhered scale after a scaling event.This paper focuses on amorphous/colloidal silica fouling and its control by additive-driven inhibition. The use of several designed treatment additives will be described with emphasis on the structural elements of inhibitors used. These efforts address the question “what are the chemical moieties that contribute to silica inhibition and why”? Almost all silica inhibitors are polymers (either charged or uncharged). Certain silica scale inhibitors described can maintain up to ~ 400 ppm soluble silica in solution. Attention will also be paid to the designed chemical approaches that should be used to combat silica scale for example the use of inhibitor blends in search for potential synergistic effects. A detailed analysis will be given on the entire chemical treatment process starting from proper selection of the treatment program to proper application to effective monitoring and maintenance of system performance. Finally the general scope of silica chemistry fundamentals will be presented.

The Alloy UNS(1) N07718 is among the most used alloys in the oil and gas industry. Due to the presence of the alloying elements niobium, aluminum and titanium, this alloy is precipitation hardenable by the formation of the phases Gamma’ and Gamma’’. Although presenting excellent strength properties and good resistance in sour gas applications, this material is known to be susceptible to hydrogen embrittlement and most field failures are related to this limiting property. 

The use of Alloy 718 (UNS N07718) for oil & gas applications is regulated by the API(2) 6ACRA1  standard and it is available in three different grades, the 120K, with minimum 120 ksi yield strength, the 140K, with minimum 140 ksi yield strength, and the 150K, with minimum 150 ksi yield strength. Previous studies showed that, due to the different hardening heat treatment parameters, each of the available grades presents a different precipitation behavior in terms of distribution and amount of precipitates, and the obtained microstructure is directly related to the resistance of the material to hydrogen embrittlement. 

The composite protective coating is the most widespread technology among various methods used in corrosion protection for the marine industry. Carbon-based materials are the most promising as anticorrosion pigments due to its mechanical strength chemical inertness non-cytotoxicity and very strong absorption of UV and visible light. In present study graphene oxide (GO) and multiwalled carbon nanotubes (MWCNT) were investigated as addictive and also they were modified by nitrogen-doping. The samples of stainless steel (316L) coated by epoxy resin with carbon-based pigments were exposed to UV irradiation (340nm) for 1000h and corrosion behavior in 3.5 wt% sodium chloride (NaCl) solution was investigated before and after UV degradation. Experimental results showed that corrosion current significantly decreased in presence of carbon-based materials especially nitrogen-doped ones in the composite coating. The degradation of the epoxy coating after UV exposure was retarded by the presence of the GO MWCNT and the nitrogen-doped pigments suggested that carbon-based nanomaterials may enhance the lifetime of composite coating. Finally a protection mechanism was built to explain the carbon-based nanomaterials improved corrosion resistance and effect of nitrogen-doping on the corrosion behavior.KEY WORDS: UV radiation composite coating corrosion graphene oxide multiwalled carbon nanotubes nitrogen doping

Stress corrosion cracking behavior measured by slow-strain rate tests with accelerated anodic & cathodic reactions. Results indicated the UNSM treatment has a significant effect on the corrosion condition. No effect appeared in the hydrogen embrittlement.

Many hangars, shelters and silos used for storage of military weapons systems are several decades old and have started to show signs of aging and corrosion assisted damage of support structures. Case study.

In the oil and gas production industry carbon steel tubing and piping are susceptible to erosion-corrosion damage due to the erosive and corrosive nature of the flow. The combined effect of solid particle erosion and corrosion can increase the metal degradation rate while simultaneously decreasing the efficiency of corrosion protection systems including iron-carbonate scale formation and chemical inhibition. These combined effects can lead to higher corrosion rates surface pitting and material failure. Thus prediction of chemical inhibitor effectiveness when solid particles are being produced particularly important. Modeling this behavior is critical when the wells are deep or off-shore because coupon testing is impractical and replacement costs are high. Considerable research has been devoted to investigate the effect of sand erosion on the efficiency of corrosion inhibitors in sweet production/CO2 environments in presence of sand particles. However sand particles are not the only particles that occur during oil and gas production. Calcium carbonate (CaCO3) particles can also be produced during oil and gas production because the majority of oil and gas production in the world is from carbonate reservoirs where calcium carbonate (CaCO3) particles can enter into the flow of produced gas and oil. Currently little is known about the erosive effects of CaCO3 particles on the performance of corrosion inhibitors in CO2 environments. This paper describes experimental and modeling studies directed at understanding the influence of CaCO3 particles on the effectiveness of imidazoline-based inhibitor in reducing CO2 corrosion of carbon steel material. The performance of the inhibitor with CaCO3 particles is compared with the inhibitor performance for a flow containing sand particles. A phenomenological model based on Frumkin-type isotherm is presented as a technique for predicting inhibitor effectiveness for these flow conditions. Erosion-corrosion experiments were performed using flow loop set up with a direct impingement configuration in an iron carbonate forming environment. Electrochemical linear polarization resistance and weight loss methods were utilized to experimentally characterize erosion-corrosion rates for both types of solid particles.