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H. Geiplová, L. Mindoš, J. Mrázek, D. Majtás, P. Macová and P. Pokorný

Abstract

The paper follows the paper describing the condition of wrought iron structure of main railway station [1]. In this paper the investigation of condition of paint system corrosion surface treatment is given and the restoration procedure is described. The withdrawal samples of paint systems were analysed by stratigraphy, FTIR and XRF analysis. Due to identification of Pb pigment presence in primer the water jet technology was chosen which minimalised the danger waste formation.

Open access

P. Pokorný, M. Hrabánek and H. Geiplová

Abstract

This article presents the results of the corrosion survey of the load-bearing structure of the main hall of the Main railway station in Prague. The chemical composition and microscopy view of the metal alloy has been explored, the current state of the anti-corrosion protection system as well as its composition were also evaluated. The corrosion damage of sheets and reinforcements of individual columns of the peron hall is also reported. The corrosion damage of the plates and reinforcements is locally very significant and is related to the drainage of rain water from the damaged roof structure. Renovation is also necessary for the protective coating system. The article concludes a restoration project that fully respects the historical form of the construction of the early twentieth century with minimal compromise.

Open access

K. C. Strachotová, M. Kouřil, K. Kuchťáková and Š. Msallamová

Abstract

Lead in archive environment suffers from severe corrosion attack caused by the organic acids’ vapours usually presented in such an environment. One of possible ways of corrosion protection of lead is its surface treatment by solutions of sodium salts of monocarboxylic acids (general formula CH3(CH2)n-2COONa, noted NaCn, n = 10, 11, 12). The principle of this corrosion protection is a creation of conversion coating on the lead’s surface, which decreases corrosion rate of lead in the atmospheric environment polluted by organic acids’ vapour. Our research aims at the selection of a suitable protection system that would be applicable to conservation of historical lead in archives and museums. This paper evaluates the corrosion behaviour of treated lead based on the values of polarisation resistance and shape of potentiodynamic curves in simulated corrosive environment (0.01 mol l−1 solution of acetic acid). The lead samples with different state of surface (pure, corroded and electrochemically cleaned) were treated with sodium salts of monocarboxylic acids NaCn (n = 10, 11, 12) having concentration of 0.01 and 0.05 mol l−1. In simulated corrosive atmosphere (above 0.001 mol l−1 acetic acid solution vapours), corrosion rate was measured by means of electrical resistance technique. The inhibition efficiency of monocarboxylic acids is dependent on their carbon chain length and their concentration. The greatest inhibiting efficiency in corrosive atmospheres and for all lead samples was observed for the sodium salt of dodecanoic acid having concentration of 0.05 mol l−1. Artificially created corrosion products and salt coatings were analysed by X-ray diffraction analysis and their surface morphology was observed by scanning electron microscopy. A protective salt coatings are mainly composed of metallic soaps in dimer form.

Open access

P. Pokorný and M. Kouřil

Abstract

In this paper, the influence of calcium cations on the corrosion behavior of hot-dip galvanized steel in model concrete pore solutions is evaluated by means of conventional electrochemical methods (measurement of free corosion potencial and polarization resistance), surface analysis methods (optical and confocal microscopy) and XRD phase analysis of precipitated corrosion products. The results of these experiments confirm the conclusions of the current work on a similar topic, i.e. the crystalline calcium based corrosion products Ca[Zn(OH)3]2·2H2O are not able passivate effectively surface of hot-dip galvanized steel in model of concrete pore solutions (pH 12.6; 13.0). If passivation occurs, a mixed Ca[Zn(OH)3]2·2H2O, ZnO and Zn(OH)2 is involved.

Open access

J. Stoulil, M. Kouřil and D. Dobrev

Abstract

The goal of the study was to compare corrosion performance of copper in different bentonite slurries. Copper coil samples were exposed in a slurries of bentonites BaM, Rokle, B75, G2M, Voltex, Sabenil. The test was carried out under anaerobic conditions in glovebox at laboratory temperature for duration of one to four months. Samples were evaluated by means of X-ray diffraction and mass loss. Liquid parts of slurries were analysed by ion chromatography and pH meter. The resistance of copper in all studied bentonites was very high. Corrosion rates were in order of tenths of micrometers per year. No trend between pore solution composition and corrosion rate or composition of corrosion products was observed.

Open access

P. Pokorný, M. Hrabánek, D. Dvorský and L. Turek

Abstract

The corrosion survey of the supporting steel/cast iron structure of the palm greenhouse included not only the characteristics of the used metal materials (microstructure, chemical composition), but also the current state of the system of corrosion protection (thickness and stratigraphy of the applied coating system). From a static point of view, the palm greenhouse design meets the applicable standards if two damaged cast iron columns are repaired. A new top coat with extended corrosion resistance is required on the surface of individual metal profiles.

Open access

T. Lovasi, M. Kouril, T. Jamborova, J. Stoulil and S. Msallamova

Abstract

Electrochemical chloride extraction from a reinforced concrete structure may be accompanied with an electrochemical injection of healing agents if such agents are positively charged and are able to migrate towards the activated reinforcement. Positive charge carried by nanoparticles or cathionic corrosion inhibitors might be the proper choice. Organic substances with a positive charge and their salts are mostly such inhibitors. The essential conditions for successful application of such corrosion inhibitors are their sufficient corrosion inhibition efficiency that was studied and evaluated and their stability of positive charge in chloride containing concrete pore solution.

Open access

L. Poberezhny, A. Hrytsanchuk, G. Hrytsuliak, L. Poberezhna and M. Kosmii

Abstract

In the modern systems of transportation of oil, gas and condensate, in the units of regasification of liquefied natural gas, two-phase flows play an increasingly important role in technological equipment used in the chemical and oil refining industry, power engineering and other industries. All available studies on the formation of gas hydrates were mainly focused on their ability to clog pipes along their entire length. While their ability to cause (initiate) corrosion remains virtually unexplored. Therefore, to increase the efficiency of industrial pipelines it is necessary to study the joint effect of hydration formation and stresses of friction on corrosion of the pipeline. The mathematical model of pipeline corrosion has been further developed by considering the influence of the gas hydrate. The influence of pressure, temperature on the speed of corrosion processes is estimated and it is shown that under the most unfavorable conditions the corrosion rate under the action of gas hydrates can increase several times.

Open access

M. Hagarová, D. Jakubéczyová, G. Baranová and M. Fujda

Abstract

The paper deals with the mechanical properties of steel gas pipeline DN 500 after more than 40 years of operation. Mechanical properties of the pipeline were established by a tensile test at an ambient temperature according to the standard EN ISO 6892-1. The resistance of the pipeline against brittle failure was evaluated by using Charpy impact test according to EN 10045-1. The character of fracture surface after the Charpy test was analysed by using scanning electron microscopy. A high proportion of transcrystalline cleavage was a characteristic feature of fracture surfaces. Mechanical characteristics obtained by static tensile testing were compared with the values obtained from steel manufacturer. Higher elongation was observed in a parallel direction compared to the perpendicular direction to the axis of the pipe. The observed anisotropy of properties was related to the distribution of inclusions in the direction of the deformation of the steel sheets used for the pipeline construction.

Open access

T. Prošek and V. Šefl

Abstract

Main factors affecting the corrosivity of water in water treatment plants and water towers and other storage facilities, observed types of corrosion degradation of stainless steel and the effect of manufacturing and surface treatment on their corrosion resistance are discussed. A list of stainless steel grades currently used in the field of treatment, transport and storage of drinking water is given together with some other suitable ones. Based on literature resources, optimal stainless steel grades are recommended as a function of water composition and treatment method.