The threshold hydrogen content of a material regarding hydrogen embrittlement plays an increasingly important role in corrosion research. This value indicates the hydrogen content to which the material can be used without failure. However, when determining the threshold hydrogen content, different test methods, different analysis methods and different interpretations of the results come together. This paper is intended to provide a guideline for the determination of the critical hydrogen concentration of high strength steel wire samples.

The generation of active disinfectants by electrochemical processes (ECA)gains market share due to the lack of need for transportation and storage of dangerous goods as well as the ease of operation. Usually the process involves the use of specific electrodes for electrolysis of water to produce active chlorine species sometimes supported by addition of chlorides to the process water. Thus the influence on the corrosion behavior can vary widely.The work comprises investigation of the passive and repassivation behavior of stainless steels typical for the beverage industry in contact with industrially available disinfectant fluids. Measurements were conducted in electrochemical cells according to ASTM G 150 and with artificial crevices. Results from exposure experiments are shown as well. Specimens made from new sheets as well as from sheets exposed to laboratory cleaning cycles with the disinfectant fluids were investigated. Additionally welded specimens were evaluated to reflect the representative behavior of real installations. The combination of the influence of oxidant and chloride concentration were examined in detail.

In oil and gas industry, during the transportation of wet gas with a stratified flow regime, the temperature difference between the fluid inside the pipelines and the surrounding environment leads to condensation of water on the upper internal surface and causes metal degradation. This phenomenon is known as Top-of-the-Line Corrosion or TLC.

The condensing phases can consist of not only water but also condensable hydrocarbons.

External post-tensioned tendons are used in segmental precast box girder bridge construction to hold segments together and prevent service cracking. The tendons consist of multiple 7-wire prestressing strands contained within a high-density Polyethylene (HDPE) duct located within the inner opening of the box girders. They run continuously through deviator blocks, which helps form the profile of the tendon.

Top-of-the-line corrosion (TLC) is an important type of material degradation that occurs due to the heat exchange between the pipeline and its surroundings, which results in water condensation on the internal surface of the pipe. This type of corrosion is specific to wet gas pipelines with stratified flow regimes. In this research, the effect of high CO2 partial pressure (pCO2) on TLC rate and mechanism was studied. The experiments were conducted in a high-pressure TLC autoclave with pCO2 ranging from 20 to 100 bar, solution temperatures of 30 and 50 °C, and different water condensation conditions (0.001-0.1 ml/m2.s). The experimental conditions covered environments where CO2 was either gaseous or supercritical. The results revealed that uniform and localized TLC rates increase with water condensation rate and solution temperature. However, as long as CO2 remained gaseous, pCO2 showed a negligible influence on both uniform and localized TLC rates. At a high CO2 content, the formation of a protective FeCO3 layer decreased the TLC rate, especially at lower water condensation rates. Nevertheless, the risk of localized corrosion at high and medium water condensation rates remained an issue. In the supercritical CO2 environment (pCO2 of 100 bar and solution temperature of 50 °C), the difference in temperature between the CO2 dense phase and the specimens caused water drop out and corrosion. In this environment, the high pCO2 and low pH of the dropped-out water led to high uniform and localized corrosion rates. However, under this condition, the difference in corrosion rates of specimens with different cooling rates was negligible due to their similar surface temperature.

Corrosion inhibitors are used for carbon steel pipelines in the oil and gas industry. Based on current
understanding, the inhibitor molecules mitigate corrosion through adsorption to the internal surface of
the pipeline, forming a barrier film that impedes electrochemical corrosion reactions at the metal
surface. Micellization is a key factor of the surfactant distributions.

CO2 captured from different sources for carbon capture and storage (CCS) will contain impurities. Although it is technologically possible to treat CO2 to near 100% purity in the gas conditioning process, it is preferable to have fewer rigid specifications to reduce both operational and capital costs. From a corrosion point of view, SOx, NOx, H2S, and O2 are considered to be the most aggressive impurities.

Macro and microbiological growth can have significant impacts on safe and efficient operations in oil & gas applications especially in water injection and underground storage systems. Operators must provide protection against both chemical and microbial corrosion to protect assets from degradation and failure. High density polyethylene (HDPE) coatings have been shown to provide long-term corrosion protection for salt brackish and brine piping. However HDPE is susceptible to biodegradation. This study explores the development and testing of a novel HDPE coating containing a unique blend of antimicrobial powder additive engineered to protect against common bacteria and fungi in brine water. Experiments were conducted to evaluate the biological and material performance of the coatings. Results from microbiological testing showed that coatings enhanced with the material additive resisted and deactivated over 70% of bacteria present in the brine water and over 90% of the harmful fungi which causes fouling in pipelines. Testing results indicated that the additive has no significant impact on the mechanical properties or corrosion resistance of the HDPE lining. These results are significant because the additive protects against harmful microbes while maintaining properties of the HDPE system. This technology provides transformative change in prevention methods for on-shore brine pipeline applications.

Primary water stress corrosion cracking (PWSCC) of Ni-base Alloy 600 (Ni-16Cr-8Fe in wt%) has been a major concern in the primary sides of pressurized water reactors (PWRs). In response to the cracking problems in Alloy 600 another solid-solution strengthened Ni-base Alloy 690 (Ni–30Cr–10Fe in wt%) has become the common replacement material for use in PWR service. Alloy 600 and Alloy 690 have an identical crystal structure and similar mechanical properties; however there are noticeable differences in the corrosion resistance and cracking behavior between them owing to their different Cr contents. It is necessary therefore to reveal the root causes of the different cracking behaviors of Alloy 600 and Alloy 690 in PWR primary water to ensure safe service and good performance.PWSCC testing of Alloy 600 and Alloy 690 was conducted using 1/2T compact tension (CT) specimens at 325 ℃. The simulated PWR water was prepared prior to the test in a storage tank. The test conditions were 1200 ppm B (weight) as H3BO3 and 2 ppm Li (weight) as LiOH in pure water a dissolved oxygen content below 5 ppb a hydrogen content of 30 cc/kg H2O and an internal pressure of 15.9 MPa. The crack growth rates (CGRs) were measured depending on the stress intensity factor at a crack tip. Before the CGR test the CT specimens were pre-cracked by fatigue at lengths of 2 mm in air. A surface oxidation test using plate specimens was conducted in the same test conditions as those of the CGR test for a period of 3600 hours. After the tests cracking properties and surface oxidation layers were precisely characterized using SEM high-resolution TEM STEM/EDS and STEM/EELS.The average CGR of Alloy 600 was measured as 7.6 x 10-9 mm/s when the stress intensity factor at a crack tip was maintained at 30 MPa·m1/2 whereas Alloy 690 did not crack under the present conditions. This means that the resistance to PWSCC of Alloy 690 is much higher than that of Alloy 600. From a microscopic examination on crack propagation it was found that the predominant failure mode of Alloy 600 was intergranular (IG) SCC which indicates that the grain boundaries are preferential paths for cracking. On the other hand PWSCC of Alloy 690 was reported to show a mixed mode consisting of IG and transgranular (TG) cracking which indicates that the grain boundaries are not always active for cracking in the case of Alloy 690. It was revealed from a microscopic investigation on the surface that oxygen diffused into the grain boundaries of Alloy 600 from the external primary water resulting in IG oxidation. As a result of IG oxidation Cr oxides formed in the oxidized grain boundaries leaving Ni depletion. The most important finding in Alloy 690 was that the internal oxidation into the bulk grains was promoted resulting in the formation of relatively thick internal oxidation layer whereas the IG oxidation was significantly suppressed owing to the continuous innermost Cr2O3 layer which formed around a grain boundary. The innermost Cr2O3 layer was formed through inward diffusion of oxygen from the surface and grain boundary diffusion of Cr resulting in Cr depletion along the grain boundary. From the present results it is believed that the different IG oxidation behaviors of Alloy 600 and Alloy 690 appear to lead to the different cracking resistance capabilities and cracking behaviors in these alloys.

To evaluate through fracture toughness tests the susceptibility of SDSS to HISC and to determine the effect of the cathodic protection potential and the stress intensity factor rate (K-rate).

Due to its attractive combination of strength corrosion resistance and cost 25% Cr Duplex Stainless Steel Pipe is used extensively in subsea production systems. Pipes are made by different production methods. The various production methods affect the microstructure and the mechanical properties of the final product. Components used subsea are externally exposed to cathodic protection. Experiences have shown that 25Cr duplex stainless steel is vulnerable to hydrogen induced stress cracking (HISC). The assumption is that the resulting microstructure affects the resistance. This is reflected in the DNVGL-RP-F112 design guideline which uses austenite spacing to determine a design factor. In this paper the HISC susceptibility of 25Cr duplex stainless-steel pipes produced through hot extrusion with- and without subsequent cold drawing forging and centrifugal casting have been examined. Two different test methods have been used; i) Stepwise (slow) load increase and ii) Slow Strain Rate Testing. Samples pre-charged with hydrogen and samples without hydrogen were included in the test program. Pre-charged samples were also polarised cathodically during testing under stress.The microstructure was characterised including measurements of austenite spacing. After testing the samples were examined in optical microscope for secondary cracks. In addition the fracture surfaces were examined in scanning electron microscope for characterisation of fracture morphology. Reduction in area were calculated for all samples. Finally hydrogen content in selected samples were measured with a melt extraction technique.The tests revealed that 25Cr duplex stainless steel from the different production methods included in the test showed various degree of HISC and that the effect was dependant on the production method and resulting microstructure. Hot extruded material with no cold deformation showed the highest HISC resistance while centrifugal cast material seemed to be more exposed to HISC than the other methods. The fracture surfaces of all hydrogen charged test materials showed features indicating a reduction in ductility due to HISC as well as both ductile and brittle fracture characteristics across the surfaces. The fracture surfaces for the reference specimens showed ductile fracture characteristics. The hydrogen content in the charged samples were in the range 50-80 wppm.The ranking of production methods was as follows: hot extruded pipes > hot extruded pipes with subsequent cold drawing > forged pipes >centrifugal cast pipes.The two test methods – stepwise load increase and SSRT – gave consistent test results.

Benchtop activity tests serve an essential role in the evaluation of new treatment components and programs in cooling water applications. Limited research has been previously conducted into the underlying processes which determine whether new materials pass or fail these initial activity tests. Markedly similar performance behavior for threshold inhibitors and dispersants has been observed in benchtop tests utilizing a variety of scaling ions. The predominant mechanism involves extensive formation of microparticles and subsequent primary/secondary agglomeration processes. Scanning electron microscopy, particle size distribution and micro­ electrophoresis techniques have characterized the particulates formed in benchtop activity tests and provided additional support for the proposed mechanism.