Materials Science Forum Vol. 844

Abstract: Nowadays, the cathodic protection is a common way of additional corrosion protection of buried structures. This protection is usually accompanied by cathodic polarisation on the protective potential of-850 mV(CSE). Its function is to prevent undesirable corrosion rates, in case the coating protection fails. Objective was to predict a state in terms of passivity or activity in which a carbon steel is in. And to do so, there is a monitoring of pH values by amphoteric metals, which would track pH changes of cathodically protected material in a soil. For pH detection, Al and Zn, were used. Main aim was to track corrosion rate of these amphoteric metals as a most reliable way to predict pH changes. Cathodic protection led to higher pH values of model soil located closely to surface of protected material. In case of carbon steel, alkalisation led to passive state and in the same time amphoteric metals could exist in active state. The aim of this work was to clarify usage of monitoring the corrosion rate of amphoteric metals for detection of pH values influenced by cathodic polarisation.Graphical abstract: Fig. 1 Kinetic and thermodynamic demonstration of passivation of cathodically protected steel

Abstract: The contribution summarizes some corrosion case studies of the welded steel structures, which happened in Slovakia last years. Features of cracking are illustrated on real cases of breakdowns in the petrochemical industry (SSCC and PTA-SCC of stainless steel), at a cement works (LME of AISI 310 steel due to Ni₃S₂ attack ), at a gas pipeline (LME caused by remelted Cu) and in the water meters & tubes made of stainless steel (MIC).

Abstract: Gas/vapor cloud explosions and fires are responsible for most of the largest property loss events worldwide in the hydrocarbon industry. Motivation for this article is to summarize explosion pressure caused by corrosive gases/vapors in terms of mathematical modeling. Presented explosions based on real scenarios of accidents associated with transport and storage facilities with corrosive flammable chemicals. While explosions of pure flammable chemicals are well described in the literature, the information about explosions of corrosive and toxic flammable substances is rather scarce. This work aims at studying the explosion behavior of pure hydrogen-air, pure ammonia-air, ammonia-hydrogen-air, ammonia-methanol-air, ammonia-ethanol-air mixtures at different initial temperatures and pressures. The results of mathematical modeling of the calculated maximum explosion pressure are described.

Abstract: All industries are interesting in the durability/service life of products, structures, equipment, plants, etc. One factor affecting this is corrosion resistance. There are many methods for received such data. Methods supporting standardized data are long-term atmospheric corrosion tests, mapping of corrosivity, field tests on real structures including the evaluation of long-term exposed materials and coatings. The choice of suitable accelerated test is very important for receiving the reasonable information.

Abstract: Corrosion rate of hot dip zinc coating exposed at atmospheric environment can be predicted according to EN ISO 9223 and EN ISO 9224. Prediction models based on dose response (D/R) functions express the effects of environmental parameters on the corrosion of material. The investigation of corrosion protection of construction exposed longer than 30 years were performed. In this paper the selected results of evaluation of galvanised infrastructures from corrosion failure and durability point of view are presented. The field data are compared to prediction models. The residual thickness of zinc coating was measured on selected profiles of the truss structures. The maintained organic coatings were applied on these constructions and there are presented results after 8 years.

Abstract: The paper describes the impact of multi-pollution of atmosphere on carbon steel construction material in Slovak Republic. Corrosion like one of the most decisive factor determining the lifetime of material increases the risk of failure, which has considerable impact on maintenance costs. The objective of the article is to calculate potential material losses of carbon steel using the dose-response functions derived from the results of outdoor exposure program and by STN EN ISO 9223. The values were calculated and compared from 2003 to 2014. For comparison the impact of air pollution and climate condition maps of the mass loss and maps of the corrosion rate were created using 4-year averages - dates (2003-2006, 2007-2010 and 2011-2014). Actually, map of corrosion losses does not help to protect materials, but it can be useful for prediction of risks by design and analysis.

Abstract: The evaluation of existing bridge structures is the most important process in the global Bridge Management System (BMS) because of providing the basic information about existing bridges required from the viewpoint of decision making process related to the optimal bridge maintenance and rehabilitation strategy. The theoretical approach using conditional probability and the positive effect of the inspection was developed. The new information concerning the actual structure condition is used in this mathematical model. This information is not available in the process of the new structure design [1]. The work is focused on structures subjected to bending [2]. The reinforced concrete beam elements with or without degradation were investigated. The corrosion of reinforcement bars was used as material degradation. The biggest effect of the inspection was obtained for members, which do not degrade. Hereby, the negative effect of degradation on reliability index is also demonstrated.

Abstract: The design of durable structure components requires durability analysis in CAE systems and cloud computations use is favorable for batch processing of multiple same-type calculation routines. To develop CAE durability modules analytical approach to different batch processing systems efficiency estimation is necessary. Such modules are intended for durability analysis of pre-hydrogenated and statically loaded structure components with initial defects. Durability estimate is defined as crack growth time elapsed from initial defect state to structure component fracture. Crack kinetics model had been used to simulate a fracture process, required for safe operation of a structure; crack length curves had been obtained and analyzed. The results were verified with the published experimental data on the subject at hand.The authors’ efficiency criterion was applied for performance analysis of the developed cloud application to find a subset of one modelling parameter in which the application is efficient being constrained in number of computational resources available and in the desirable level of performance.

Abstract: Effective corrosion monitoring can be achieved using mobile potenciostat through the selection of appropriate monitoring methods and special kind of sensor. Stern polarization technique in non-invasive arrangement was used to monitor OCP potential and actual corrosion rate of pipeline with corrosion products in soil mixture. Using global database with range of minimum and maximum corrosion rate limits obtained from terrain measurements we can determine active or passive role of corrosion products and assess risk joint with aggressiveness of soil in location of interest. Finally, values were divided between high active, medium active and passive corrosion. Output is alarm, which can help in decision if reconstruction of underground pipelines where isolation failure in time is sufficient or not. When done properly, corrosion monitoring using non-invasive in-situ technique can serve as an early warning system before the onset of corrosion-related failures.Fig. 1 Non-invasive corrosion monitoring on underground pipelines

Abstract: The rapid growth in the use of corrosive gases transported by pressure vessels and pipelines has brought significant increase of risk to a number of people, both workers and public, whose life could be endangered at any one time by accident involving these chemicals. Due to the complexity of the involved physical phenomena and to the lack of an adequate amount of reliable experimental data, a number of different models and calculation procedures for estimating the consequences following the release of a corrosive gas are presently reported in the literature. The contribution deals with real scenarios of accidents associated with stationary risk facilities with corrosive flammable toxic chemicals. The study presents the results of hazardous zone calculation for the event of various corrosive liquids (Cl₂, NH₃, CCl₂O, C₃H₄O) toxic releases. The goal of this article is to present the results of the approach of modeling using the standard methods and to demonstrate the importance of the next development stage in the area of corrosive materials accident modeling of releases and dispersions in cases of accident.