Michał Szociński

Although composting is a mature and economically favorable waste treatment technology, the controlled aerobic biodegradation of organic waste generates physicochemical conditions that are highly aggressive toward metallic and cementitious materials. This paper examines the corrosive environment in municipal solid waste composting facilities and its implications for material degradation and structural durability. Appropriate corrosion protection strategies were proposed based on the obtained results. The corrosivity of composting atmospheres arises from both chemical and microbiological processes. Elevated temperatures (40–70°C), persistent high relative humidity (>90%), and the presence of condensates enriched with organic acids, ammonia, carbon dioxide, and reduced sulfur compounds create an environment conducive to accelerated corrosion. Operational factors, including condensation–evaporation cycles and acid-laden runoff, accelerate corrosion kinetics and compromise protective coatings. Given the limited empirical data on composting-specific atmospheric corrosivity, the corrosion rate of steel and zinc was determined under the conditions of a real operating composting plant according to the methodology described in the ISO 12944-2 standard and the appropriate corrosivity categories were defined. Based on this, optimized anti-corrosion systems were developed for new and renovated municipal solid waste composting facilities.

Excessive cathodic polarization of underground stainless steel structures results in hydrogen evolution, increasing the risk of hydrogen embrittlement and the disbonding of protective coatings from the structure’s surface. This study was conducted to determine the critical potential and critical cathodic protection current density at which hydrogen evolution occurs on the surfaces of stainless steel grades 1.4301, 1.4401, 1.4125, and 1.4512, and, for comparison, on carbon steel S235. The tests were carried out in an aqueous solution of synthetic (artificial) soil and in a soil filtrate prepared from a soil sample taken in the vicinity of an existing underground gas pipeline connection with stainless steel fittings. The tests showed that the higher the chromium content in the stainless steel was, the lower (more negative) the hydrogen evolution potential was. In an artificial soil environment, the values of this potential ranged from −1105 mV to −1175 mV vs. copper sulphate electrode (CSE) for steels 1.4301, 1.4401, and 1.4125, which contain more than 16% of chromium. For steel 1.4512, containing 12% of chromium, the hydrogen evolution potential was −1050 mV. For comparison, for S235 carbon steel, the hydrogen evolution potential was −1135 mV. The critical cathodic protection current density ranged from 0.30 A/m² to 0.38 A/m² for all tested stainless steels, whilst for S235 steel, this value was higher, equal to 0.65 A/m². The results obtained indicate that applying the commonly accepted potential criterion for cathodic protection for carbon steels (i.e., polarization to a potential in the range from −0.85 V to −1.1 V vs. CSE) poses no risk of causing excessive cathodic polarization of stainless steel. This is important for the design and operation of cathodic protection systems for complex structures containing galvanically connected carbon steel and stainless steel components.

This study presents dynamic electrochemical impedance spectroscopy (DEIS) as a tool for online impedance monitoring of electrophoretic deposition of a cataphoretic coating. The process was examined via the acquisition of instantaneous impedance spectra during sample polarization from their corrosion potential to the selected potential values corresponding to various stages of the cataphoresis. The conducted experiments allowed calculation of the instantaneous parameters of the process during its duration and distinguishing subtle changes in their evolution, which provided the information about advance of the deposition. Thanks to the application of the DEIS method, it was discovered that the majority of electropaint was deposited at a certain narrow potential span at the beginning of the polarization range. The DEIS approach may be widely applicable in research on the mechanism, kinetics, and optimization of the electrophoretic coating deposition processes.

Stray currents leaking from electrified DC rail systems cause the greatest corrosion risk to underground metal gas pipelines and can lead to pipeline wall perforation in a very short time. Leakage and gas explosion, and other direct and indirect effects, can even disrupt the stability of the energy system. Maintaining the reliability of gas pipelines, therefore, requires protecting them against corrosion caused by stray currents. It is therefore necessary to conduct field studies to identify sections of gas pipelines at risk and where protective installations should be installed. The paper discusses the most important field methods for assessing the risk of stray currents to gas pipelines: the potential of rail traction relative to ground, electric field gradients in the ground associated with stray current flow, correlation of gas pipeline potential and voltage of pipeline vs. the rail, and time-frequency analysis of the pipeline and rail potentials. A typical application case for each method is indicated, and the advantages and disadvantages of each research technique are identified. The criterion for selecting methods for this review was a short measurement duration (tens of minutes), after which it is possible to determine the level of the hazard to the gas pipeline caused by stray currents in the examined location. This is why these methods have an advantage over other research techniques that require long-term monitoring or exposure of probes or sensors. The review will be useful for cathodic protection personnel involved in the operation of gas pipelines and may be helpful in developing new methods for assessing the impact of stray currents.

This paper presents the methodology developed for underwater measurements using electrochemical impedance spectroscopy (EIS) technique, aimed at determining the resistance of an epoxy coating applied in seawater to the legs of an oil production platform. Performing such underwater tests in an offshore environment was technically challenging. The results of measurements obtained on the platform were confronted with comparative results obtained in the laboratory, where the properties of the coating applied in water collected from the Baltic Sea (thickness, hardness, adhesion, and electrical resistance) were examined. This made it possible to conclude about the correctness of the paint coating application by divers on the legs of the platform. The single-layer epoxy coating applied by brush to the platform legs had a resistance above 10 kΩ∙cm² and thus met the assumed minimum resistance of the protective coating cooperating with cathodic protection as the anti-corrosion protection system of the platform legs. The synergy of these two technologies ensures full protection of offshore structures against corrosion. Measurements of the potential of the platform legs confirmed this. Before painting, the potential value at a depth of 0–15 m was 310 ÷ 320 mV versus the zinc reference electrode, while after painting the potential value decreased to 220 ÷ 240 mV, which means that the effect of full cathodic protection was achieved and the platform legs were protected from corrosion. The developed methodology for underwater EIS measurements on the high seas can be applied to any underwater metal structure to assess the quality of protective coatings.

This paper presents the most typical corrosion mechanisms occurring in the petroleum industry. The methods of corrosion monitoring are described for particular corrosion mechanisms. The field and scope of the application of given corrosion-monitoring methods are provided in detail. The main advantages and disadvantages of particular methods are highlighted. Measurement difficulties and obstacles are identified and widely discussed based on actual results. Presented information will allow the corrosion personnel in refineries to extract more reliable data from corrosion-monitoring systems.

The paper presents the results of non‐destructive testing examinations, metallographic tests and risk assessment of degradation related to corrosion of amine regeneration unit in a desulphurisation system. Intensive corrosion resulting from acid gases environment upon water condensation causes perforation of the pipeline. Detailed analysis reveals cracking related to the mechanism of wet H₂S. Hydrogen penetration, resulting from the wet H₂S process, causes a decrease in mechanical properties of steel and an increase in hydrogen content inside steel. Corrosion results mostly from high stream velocity, the presence of acid gases (with high ammonia content), the presence of amine and low stream temperature.

Additive manufacturing technologies are gaining more and more attention, resulting in the development or modification of 3D printing techniques and dedicated materials. On the other hand, economic and ecological aspects force the industry to develop material recycling strategies. In this work, the multiple reprocessing of a commercially available PLA conductive composite with carbon black filler, dedicated to 3D printing, was investigated. The effects of extrusion temperature (190 °C and 200 °C) and reprocessing steps (1–5 steps) on the rheology, morphology, thermal and electrochemical properties of the conductive PLA 3D-printing filament were evaluated. The results showed deterioration of the thermal stability and material strength, as well as the influence of reprocessing on the melting point, which increases after initial melting. The electronic conduction mechanism of the composite depends on the percolation paths and it is also affected by the multiple processing. The reversibility of the [Fe(CN)₆]^3−/4− redox process diminishes with a higher degradation level of the conductive PLA. Importantly, the material fluidity was too high after the multiple reprocessing, which should be considered and suitably corrected during CB–PLA application as a 3D-printed electrode material.