Metal Coupons Research Articles

Exploration of eco-benign antifoulant in combating seafood-associated biofilms: an in-vitro study on impacts of myrobalan mediated FeNPs against biofilming SS-316 metal coupon

Abstract The biofilm-forming pathogens with acquired antibiotic resistance and associated disease outbreaks are increasing worldwide, especially in the seafood industry. This study hypothesised that the bioengineered iron nanoparticles using the myrobalan (Terminalia chebula) extract (M-FeNPs) and its resin coating have an effective antibiofilm properties. 12 seafood waste-based biofilm-forming strains (SSS) were isolated from SS-316 metal coupon and screened for their antibiotic-resistant profile as per CLSI (2016) standards. M-FeNPs were characterised by UV, FTIR, etc. Over 50 % of SSS were resistant to Ciprofloxacin, Cefalexin and Penicillin-G. The antibiofilm activity of the M-FeNPs showed an excellent inhibition zone (16–24 mm), and the combination of M-FeNPs + Methicillin also showed better activity. in vitro antibiofilm study shows that upon adding M-FeNPs, biofilm formation was reduced from 1.425 g to 0.83 g at the end of the eighth day. The CLSM and SEM images indicated that the M-FeNPs are effective antibiofilm agents against biofilm strains.

Comparing the Efficacy of Select Natural and Synthetic Corrosion Inhibitors on Copper and Iron

Six corrosion inhibitors were evaluated for their effectiveness at preventing corrosion on copper and mild steel in a short-term experiment lasting two weeks. Half of the inhibitors tested were alcohol extracts of natural products (ginger, garlic, and black pepper), and the others were standard chemical reagents including benzotriazole (BTA), cysteine, and 5-amino-1,3,4-thiadiazole-2-thiol (AMT). Metal coupons of both mild steel and copper were immersed in a 0.007M dilute HCl solution with one of the six inhibitors or a combination of two inhibitors. The pH of each solution was monitored to track the corrosion rate and this method proved to be remarkably sensitive and nuanced, allowing for the subtleties of the decay mechanisms to be determined.

Castor oil-based polyurethane adhesives: Effect of cross-linker on the bond strength

Adhesives are important for binding diverse materials, promoting structural integrity and functional versatility in countless daily life applications. An enormous obstacle remains in the development of polyurethane (PU) adhesives exhibiting excellent bonding strength. Designing a chain extender with appropriate molecular structures is critical to improving the bonding strength of polyurethane-based adhesives. In this work, polyurethane-based adhesive was prepared using castor-oil-based polyol and diisocyanate. The bonding strength of the adhesive was improved by adding chain extenders such as N, N-bis(2-hydroxyethyl) thiophene-2,5-dicarboxamide (ETP) and N, N-Bis(2-hydroxyethyl)-terephthalamide (ETAM). The modified adhesive showed high bonding strength after the addition of chain extenders due to the presence of the dicarboxamide group, which served as a center for hydrogen bonding. The bonding strength of PU adhesive increased to 7.22 and 9.68 MPa from 5.0 MPa after the addition of 7.5 wt% of ETP and 5.0 wt% of ETAM, respectively. The bonding strength of the adhesives was tested on both wood (oak) and metal (stainless steel) coupons. The bonding strength of 9.68 MPa on oak wood and 6.73 MPa on stainless steel coupon was observed for the 5.0 wt% of ETAM-based PU adhesive. The bonding failure was observed to be due to wood failure. The reason behind the good bonding is noncovalent bonds which are formed between the functional group of the PU molecular chain and the surface of the substrate. In addition, no major changes in FT-IR after keeping these adhesives in different solvents were observed. Good crosslinking is also confirmed by studying the gelling and swelling data of the adhesives.

Review and interlaboratory comparison of the Oddy test methodology

Since the introduction of the Oddy test in 1973, many museums and cultural institutions have put the method in use, developing their own versions and protocols. Currently the 3-in-1 version, temperature at 60 ºC and 2 g of tested material are set as common practice; however, other variables of the test are not standardized. The purpose of this study is to examine current versions of the Oddy test, to identify differences in the results derived from variations in the procedures, and ultimately raising awareness within the conservation community to work together towards a standardized protocol. In this article, we review the available information on the methodological differences in Oddy test protocols published in the literature related to glassware cleaning, coupon preparation, reaction vessel setup and rating of materials. Based on the review, and to highlight the many variables that could affect the results of the test, seven European cultural institutions working under the H2020 IPERION HS project performed a comparative 3-in-1 Oddy test by blindly evaluating the same ten materials. Each institution used its own test methodology but some guidelines were advised: (1) Detergents as a cleaning procedure for glassware, (2) P600 sandpaper or micromesh pad close to 1500 to prepare metal coupons and (3) 1:100 as water–air ratio. Despite this, differences between institutions’ results were still observed. Some of them are due to the differences in the coupons preparation, either in the sanding pattern or in the edge area. In order to separate the contribution of the experimental setup and the subjectivity of the evaluation in the discrepancies, coupons from all institutions have been rated by a single team of judges with experience in the Oddy Test. Results show that differences in the evaluation criteria play a relevant role in the discrepancies of the results, especially for institutions with less experience in the test. These results highlight the need to further standardize the methodology and criteria for visual assessment. Nevertheless, the Oddy test has been found to be reliable for the identification of materials that produce emissions hazardous for the conservation of cultural assets.

Effects of post-weld heat treatment on the microstructure and properties of the matching SMAW filler metal for weld joints in MarBN steel

AbstractA detailed investigation has been carried out of the matching composition filler metal for welding MarBN steel to explore the influence of welding procedure and post-weld heat treatment (PWHT) on the microstructure and properties of the weld metal and a MarBN steel weld joint. The filler metal was in the form of a shielded metal arc welding (SMAW) electrode. With different interpass temperatures and PWHT procedures applied, the microstructure and mechanical properties, particularly toughness, of the all-weld metal deposits and welded MarBN alloy joints were examined. The differences in microstructure (grain structure, precipitates, etc.) were evaluated to provide a better understanding of how the PWHTs influence the starting conditions of the matching weld metal and welded MarBN steel joints before service. The current work found that for a 30-mm-thick all-weld metal coupon, reasonable impact toughness was achieved after PWHT of 735 °C × 8 h; longer heat treatment durations (16 h and 36 h) did not further increase the toughness. For thicker cast blocks, a PWHT of 735 °C × 16 h was needed for weld toughness comparable to the base metal, hence was considered more appropriate for actual engineering applications. Evenly distributed Laves phase precipitation was observed after 735 °C × 8 h; the precipitates gradually increased in size and area fraction as the duration increased, and appeared to be stable when approaching 36 h. Differences in the precipitation were observed between different weld regions. The weld cap region had a lower density of Laves precipitates compared to the lower weld area. From the current investigation, aspects for further investigation are also identified.

Investigating of the Effect of Air-Formed Surface Films on Copper Corrosion Properties

Canada’s plan for the safe and long-term management of used nuclear fuel involves utilizing an engineered multi-barrier system that will be deposited in a deep geological repository (DGR).1 Developed and proposed by the Nuclear Waste Management Organization (NWMO), the used fuel bundles will be placed in carbon-steel containers that will be coated with a about 3-mm thick corrosion resistant copper (Cu) coating. To date, Cu corrosion studies have been performed on freshly polished metal coupons that have undergone a rigorous cleaning procedure to eliminate air-formed organic and oxide films from the material’s surface. However, prior to emplacement in a DGR, the containers will be fabricated and stored for periods of time where such surface films can deposit and accumulate.2 Furthermore, a standardized surface preparation/finish procedure has yet to be determined. The influence of air-formed surface films on the Cu coating’s atmospheric and aqueous corrosion behaviour is important to understand the likelihood and extent of localized corrosion under anticipated DGR conditions. This work aims to investigate the effect of aging period, surface roughness, and storage environment on the surface film’s chemical composition, morphology, and influence on Cu corrosion properties using a suite of surface analytical and electrochemical methods. The results will assist in the future development of a surface preparation strategy of the Cu coatings prior to used fuel confinement and DGR deposition. Hall, D. S., Behazin, M., Jeffrey Binns, W. & Keech, P. G. An evaluation of corrosion processes affecting copper-coated nuclear waste containers in a deep geological repository. Prog. Mater. Sci. 118, 100766 (2021).Gateman, S. M. et al. Corrosion of One-Step Superhydrophobic Stainless-Steel Thermal Spray Coatings. ACS Appl. Mater. Interfaces 12, 1523–1532 (2020).

Microbial Diversity of the Produced Waters from the Oilfields in the Republic of Tatarstan (Russian Federation): Participation in Biocorrosion

A variety of microorganisms grow in oil reservoirs, where they participate in the biodegradation of oil and lead to changes in oil quality. Today, our knowledge about microbial processes in oil reservoirs is largely limited, and among the urgent tasks for the oil industry, monitoring and controlling microbial activity (including the activity of microbes responsible for biocorrosion) are important. In this work, we aimed to characterize the bacterial community structure of the produced waters from oilfields in the south of the Republic of Tatarstan (Russian Federation) using cultural and molecular methods of analysis. Bacteria from produced water samples from various oil wells were enriched, and 16S rRNA gene amplicon sequencing was used to assess the phylogenetic diversity of the bacterial communities. Thus, analysis of the bacterial communities revealed the presence of various members within the genera Desulfotomaculum, Clostridium, Acetobacterium, Desulfovibrio, Dethiosulfovibrio, Desulfomicrobium, Fusibacter, Dethiosulfatibacter, Thermovirga, Sphaerochaeta, and Desulfoplanes, but in different produced water samples. The role of the bacterial associations in biocorrosion was separately assessed in experiments on monitoring and stimulating biocorrosion. The bacterial community receiving additional nutrition was shown to have a higher corrosion potential, and scanning electron microscopy analysis confirmed changes in the surface of the metal coupons during immersion testing. The practical value of this research lies in identifying the potential contribution of microbial communities to oil pipeline corrosion.

Microelectrode evaluation of in situ oxidant reactivity and pH variability at new ductile iron and copper coupon surfaces.

Thirty-two short term (∼7.5h) abiotic experiments were conducted with new ductile iron and copper coupons exposed to various water qualities, including pH (7 or 9), dissolved inorganic carbon (DIC, 10 or 50mgCL-1) and phosphate (0 or 3mgPL-1) concentrations and 4mgCl2L-1 free chlorine or monochloramine. To quantify oxidant reactivity with the new metal coupons, microelectrodes were used to obtain oxidant (free chlorine or monochloramine and dissolved oxygen (DO)) concentration and pH microprofiles from the bulk water to near the metal coupon surface. From the microprofiles, apparent surface reaction rate constants (k) were determined for each oxidant. An ANOVA analysis evaluated if the five variables (Material, Oxidant, Phosphate, DIC, and pH) significantly affected estimates of k, finding that the Material and Oxidant variables and their interaction were statistically significant (p<0.05), but the effect of variables of Phosphate, DIC, and pH on k values were not significant in this study. In general, both ductile iron and copper coupons showed significant surface reactivity towards free chlorine and monochloramine. For ductile iron, DO consumption was greater than for copper, which showed minimal DO reactivity, and DO was less reactive towards the copper surface than either free chlorine or monochloramine. Furthermore, pH microprofiles provided insight into the complexity that might exist near corroding metal surfaces where the bulk water pH may be substantially different from that measured near metal surfaces which is significant as pH is a controlling variable in terms of scale formation and metal solubility. This study represents an important first step towards using microelectrodes to (1) understand and provide direct measurement of oxidant microprofiles from the bulk water to the metal surface; (2) determine pipe wall reactivity using the directly measured concentrations profiles versus estimated pipe wall reactivity from bulk water measurements, and (3) understand how variables measured by bulk water samples (e.g., pH) may be drastically different from what is occurring at and near the metal surface. Together, these insights will assist in understanding disinfectant residual maintenance, corrosion, and metal release.

Electrochemical Assessment of Mitigation of Desulfovibrio ferrophilus IS5 Corrosion against N80 Carbon Steel and 26Cr3Mo Steel Using a Green Biocide Enhanced by a Nature-Mimicking Biofilm-Dispersing Peptide.

MIC (microbiologically influenced corrosion) is problematic in many industries, especially in the oil and gas industry. In this work, N80 carbon steel for pipelines was tested with 26Cr3Mo chromium pipeline steel for comparison in SRB (sulfate-reducing bacterium) MIC mitigation using a THPS (tetrakis hydroxymethyl phosphonium sulfate)-based commercial biocide (Biotreat 5475 with 75-80% THPS by mass). Peptide A, a nature-mimicking synthetic cyclic peptide (cys-ser-val-pro-tyr-asp-tyr-asn-trp-tyr-ser-asn-trp-cys) with biofilm dispersal ability was used as a biocide enhancer. Metal coupons covered with 3-d old Desulfovibrio ferrophilus IS5 biofilms were immersed in different biocide solutions. After 1-h treatment, 200 ppm Biotreat 5475, 200 ppm Biotreat 5475 + 200 nM (360 ppb) Peptide A, and 400 ppm Biotreat 5475 achieved 0.5-log, 1.7-log and 1.9-log reductions in sessile cell count on N80, and 0.7-log, 1.7-log, and 1.8-log on 26Cr3Mo, respectively. The addition of 200 nM Peptide A cut the THPS biocide dosage by nearly half. Biocide injection tests in electrochemical glass cells after 1 h exhibited 15%, 70%, and 72% corrosion inhibition efficiency (based on corrosion current density) on N80, and 27%, 79%, 75% on 26Cr3Mo, respectively. Linear polarization resistance and electrochemical impedance spectrometry results also indicated antimicrobial efficacies.

Lessons learned from in situ corrosion experiments in the HADES URL

Abstract A wide range of metals have been studied as a candidate container material to be considered in the geological disposal concept of high-level radioactive waste and spent fuel in Belgium. More than 40 years ago, SCK CEN started studies on the corrosion of these metals. The HADES underground research laboratory (URL) played an important role in the corrosion research as it enabled in situ corrosion experiments to be carried out that simulate realistic disposal conditions as closely as possible. These experiments consisted of placing metallic coupons on a steel support tube, heated from the inside, that was installed in Boom Clay, thereby exposing the coupons to various conditions representative of the disposal concept that was considered at that time. Test durations lasted from 6 months to approximately 7.5 years. This paper summarizes the results from the various corrosion studies and discusses their implications in the choice of disposal concept. One of the main outcomes of these experiments was a change of rationale regarding the choice of the container material from carbon steel (corrosion-allowance) to stainless steel (corrosion-resistant). The main arguments for this change were the need to avoid severe pitting corrosion during the aerobic period and to minimize the generation of hydrogen gas during the subsequent anaerobic period.

Effects of Hydrodynamic Environment on the Interaction of Shewanella oneidensis with Low Carbon Steel and the Impacts on Corrosion

Microbiologically influenced corrosion (MIC) impacts various industries such as oil/gas production and transmission, wastewater treatment, power generation, and chemical processing. In such settings, the combined impacts of microbiological activities and fluid flow dynamics could be primary controllers of metal corrosion. We examined the relative influences of fluid flow and the activities of the facultative Fe(III) reducing bacterium, Shewanella oneidensis MR-1, on the corrosion of carbon steel. Rotating cylinder electrode experiments were used to determine the shear stress and velocity at the surface of the metal coupon in a newly constructed flow system. The system was then used to study the impact of increasing fluid velocity and shear stress on the corrosion rate of coupons in O2-limited and O2-nonlimited incubations. Confocal scanning laser microscopy was used to monitor biofilm development on the metal surface at increasing shear stress. We found that the activities of S. oneidensis inhibited corrosion, even under conditions of high shear stress and limited attachment, indicating that the respiratory consumption of O2 by planktonic S. oneidensis protects the metal surface from enhanced corrosion.

Biopolymer and its nanoparticles for surface coating enhancement of epoxy primer on zinc: electrochemical and surface studies

ABSTRACT The purpose of the current work is to develop an eco-friendly formulation which can be successfully utilised to mitigate zinc corrosion in marine environments. Biopolymer amylopectin and its nanoparticles were used to improve the coating characteristics of epoxy primer on zinc. Amylopectin nanoparticles (AMP-Np) were prepared by the microwave-assisted nanoprecipitation method and characterised using XRD, ATR-FTIR, and TEM studies. Inhibition studies were performed to achieve the optimum inhibitor concentration required for corrosion inhibition of zinc in 3.5% NaCl. Detailed surface morphology was studied using scanning electron microscopy and atomic force microscopic techniques. The overall efficiency of the coating after incorporating AMP (0.02 gL−1) was found to be 99.5%. With the addition of AMP-Np (0.005 gL−1), 99.9% coating efficiency was attained by reducing the concentration to 1/4th of AMP. The epoxy-coated metal coupons, along with micro and nano AMP, were dipped in 3.5% NaCl for 15 days to mitigate corrosion of zinc.

Evaluating the effect of glidants on tablet sticking propensity of ketoprofen using powder rheology

Punch sticking has been a leading drawback that has challenged successful tablet manufacturing since its initial conception. Due to the capricious nature of the complication, this can arise during any phase of the development process. Even now, identifying such a problem is a prerequisite during the initial stage of development. The present study evaluated the role of Aerosil®200, talc, and Syloid®244 as glidants in varying amounts ranging from 0.0 percent to 2.0 percent w/w on tablets sticking relatively to five different metal surfaces, with ketoprofen as the model drug. Powder rheology is a predictable technique used to calculate the sticking index. The sticking index of each formulation in comparison to each metal coupon was identified by calculating the kinematic angle of internal friction and the angle of wall friction using the shear cell test and wall friction test, respectively. Interestingly, glidants were found to reduce the sticking propensity of the powder blend in a concentration-dependent manner. In addition, the compression study validated the expected sticking tendency ranking order. According to the research data, the sticking index could effectively be utilized to envisage the possibility of tablet sticking, i.e., by selecting the formulation’s excipient and their percentages or selecting appropriate punched metal surfaces in the tableting process.

Pedal to the Metals: Preserving Automotive Racing History

ABSTRACT The Indianapolis Motor Speedway Museum collections encompass vehicles, memorabilia, art, and archives documenting the history of the Indianapolis Motor Speedway. During a preservation needs assessment conducted by the Conservation Center for Art & Historic Artifacts (CCAHA), Museum staff pointed out tarnish and corrosion on the trophies in the memorabilia collection. This raised a number of questions, foremost being, “What should the museum do to slow down the deterioration of these metal objects?” The two institutions embarked on a collaborative research project aimed at answering this question. Existing literature supplied best practices, but the Museum wanted solutions specific to its needs and priorities. The Museum’s collections manager and CCAHA’s preventive conservation fellow worked together to investigate air quality on a modest budget and timeline. This case study explores the cost-effective and low-maintenance methods that were used to monitor environmental conditions, dust, acid off-gassing, and metal corrosion: dataloggers, sticky dust collectors, A-D Strips, and metal coupons. Evidence-based testing informed, educated, and initiated progress in collections care. The techniques can be adapted by a diverse range of collecting institutions that similarly do not have access to high-tech analytical equipment.

Effect of the Water Condensation Rate with the Presence of Gas Condensate in the Wet Gas Pipeline

Pipelines are a common medium to transfer hydrocarbons, but their integrity is compromised by corrosion issues specifically in top of line corrosion (TLC) due to several influence factors such as water condensation. Water condensation occurs due to a significant variance in temperature outside the pipeline and inside the pipeline as water condenses in the inner pipeline. Hence, this paper aims to study the water condensation rate (WCR) behaviour in the presence of gas condensate in wet gas pipelines. The objectives of the research are to determine the components of the gas condensate by characterizing the gas condensate using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier-Transform Infrared Spectroscopy (FTIR) equipment and later to determine the effect of gas condensate on water condensation rate by conducting 2 different experiments. The condition of TLC was imitated by using a customized TLC testing unit, whereby 2 sets of API 5L X65 carbon steel coupons were used. Meanwhile, the delta temperature of the gas and steel obtained by regulating the temperature setting of the chiller and hot plate respectively enabled the water condensation process to be simulated. Throughout the 7-days of experiments, the gas and steel temperature were daily monitored and the water that only condensed on the surface of the coupons was collected and measured. Subsequently, the WCR was determined. The first objective was achieved as the result from GC-MS showed that there were 67 compounds in the condensate, and 5 functional groups were detected using FTIR, which confirmed that the gas condensate used in this experiment was similar to the gas condensate obtained from the pipelines. The second objective proved that condensate affected the water condensation rate, in which the WCR was reduced by about 73% with the presence of condensate. This WCR reduction is postulated because of the two different liquids (water and hydrocarbon) competing for the same surface area (top metal coupon) to condense.

Additively Manufactured 316L Stainless Steel Subjected to a Duplex Peening-PVD Coating Treatment.

This research studies the individual and combined effects of mechanical shot peening and the deposition of TiAlCuN coating on additively manufactured 316L stainless steel. Shot peening has been found to induce a 40% increase in surface hardness, while the combined effect of shot peening and the coating produced an approximately three-fold increase in surface hardness when compared to the as-printed coupons. Shot peening reduced the surface roughness of printed metal coupons by 50%, showing that shot peening can also serve to improve the surface finish of as-printed 316L stainless steel components. The peening process was found to induce a compressive residual stress of 589 MPa, with a maximum affected depth of approximately 200 μm. Scratch testing of the printed and coated specimens showed complete delamination failure at a normal load of 14 N, when compared to hybrid treated samples which failed at 10 N. On the other hand, from the corrosion tests, it was found that the hybrid treated samples provided the optimal results as opposed to the other variables.

A STUDY ON MICROBE-METAL INTERACTION: ALUMINIUM ALLOY (6061) AND Bacillus cereus IN SIMULATED MARINE ENVIRONMENT

Metals in the marine environment is a lingering with the substantial calamity that poses serious environmental and safety hazards. Electrochemical and chemical interactions cause the gradual decaying of metals’ exteriors and interiors. Marine microorganisms interact with metal and degrade it. Microbial corrosion is a special type of metal corrosion in which microbes act on metals. Microbes use different mechanisms to interact with metal and metalloids present in the environment. Few trace elements are required for their metabolism and absorb these metal ions present in a natural and synthetic environment. Some metal plays an important role in the physiological functions of an organism but if it is in excess may cause toxicity. In the present article, the interaction of Aluminum Alloy (AA) 6061 with Bacillus sp in a 3.5% NaCl (W/V) solution has been reported. The interaction study was performed under static and dynamic conditions for 4 weeks and 2 weeks respectively. Weight loss of the metal coupons was performed regularly. Microbial load in both conditions was checked by doing a viability cell count to ensure metal toxicity. Scanning Electron Microscope observation was done for biofilm formation on metal coupons.

“Impact of γ-radiation on carbon steel anaerobic corrosion and H2 production.”

This article reports investigations on the anoxic corrosion process impacting a carbon steel/ultrapure deaerated water system when it is exposed to gamma radiation (50 Gy h−1), and on the associated molecular hydrogen gas generation. On the one hand, a dynamic semi-open experimental setup allowing to distinguish between the H2 production related to water radiolysis and the one related to anoxic corrosion has been adopted to estimate the corrosion rate associated to three successive temporal phases: pre-irradiation, irradiation and post-irradiation phases. On the other hand, post mortem analyses performed on both liquid and solid samples permitted to (i) quantify the chemical changes occurring in solution due to the formation of water radiolysis products and (ii) observe and characterize the thin corrosion layer composed of magnetite (Fe3O4) at the surface of the metallic coupons. We show that gamma radiation induces a slight diminution of the carbon steel corrosion rate. However, by comparing the mean corrosion rate values obtained for the three studied phases (i.e., before, during and after irradiation), the chemical changes caused by radiolytic species seem to inhibit the formation of a thick magnetite protective layer. Additionally, the corrosion rate observed in post-irradiation phase does not decrease over time, which suggests that irradiation could modify the properties of the corrosion product layer by making it less protective. A structural modification of this oxide film might be caused by the oxidizing water radiolysis products. Such mechanisms may favour continuous active corrosion processes rather than passivation of the metallic surface and thus lead to a reduced lifetime of the component.

Reversible protective and consolidating coatings for the ancient iron joints at the Acropolis monuments

This work presents a corpus of measurement methodologies utilized during a multidisciplinary project, aiming at the protection and conservation of ancient steel joints (clamps and dowels) of the Acropolis monuments, undertaken by the Acropolis Restoration Service (YSMA). The Laboratory of Physical Chemistry of the National Technical University of Athens collaborated with YSMA in designing and evaluating laboratory scale and field experiments, aiming in testing conservation materials. The first phase involved the application of seven coating systems on uncorroded metal coupons. The application characteristics, physicochemical properties (colour, gloss, hydrophobicity), and the protection performance against accelerated corrosion and polymer photo-oxidation were measured. Poligen CE12 and Paraloid B67 +2% nano-alumina were selected as the two most suitable materials for pilot applications on corroded steel joints and outdoor field exposure at the monument site. The assessment of the two coatings reversibility and of the corroded surfaces chemical alteration was undertaken by Raman spectroscopy analyses and orthophotographic documentation. During the 1-year field exposure, the corrosion development was retarded, but some local events of active corrosion could not be prevented. The joint areas coated with Paraloid B67 enhanced with 2% nano-alumina enabled more uniform application on corroded surfaces and exhibited better corrosion protection. In case of Poligen CE12, the nature of corrosion products indicated local acceleration of corrosion reactions.

Impacts of GIC on the New Zealand Gas Pipeline Network

AbstractGeomagnetically induced currents produced during geomagnetic storms present a potential risk to gas pipeline systems by disturbing the cathodic protection (CP) systems used to protect the pipeline from corrosion. In this study we look at CP monitoring data from a number of sites on the gas pipeline network in the North Island of New Zealand. We focus on variations during geomagnetic storms in three aspects of the CP system: (a) the output voltage of the constant current rectifiers, (b) the potential between the pipe and a Cu/CuSO4 reference cell, and (c) the potential between an installed metal coupon and the reference cell. The industry standard for suitable CP is that the latter potential should lie between −0.85 and −1.2 V when the rectifier is momentarily turned off. Three monitoring sites in particular are identified as showing very large variations in rectifier output voltage during geomagnetic storms, suggesting a possible risk to the system at these sites. Additionally, one of the three sites has coupon potentials which appear to rise above the −0.85 V level. Magnetotelluric impedance data are used to assess how effects at the monitoring sites relate to the magnitude and direction of induced electric fields. It clear that the response at any monitoring site is related to effects on the pipeline network as a whole. We also note the risks of disbonding and hydrogen induced cracking, issues we do not believe have been widely recognized in the research community.