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Charakterystyka fizyczna i chemiczna osadów korozyjnych w rurach żelaznych eksploatowanych w obecności przepływu wody

Przywara Lucyna, Jaszczurowska Agnieszka

Polish Journal of Materials and Environmental Engineering

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2022

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Vol. 4 (24)

30--40

EN

The presented paper contains issues related to corrosion of water supply lines formed in cast iron and steel. This process can manifest in different ways, including pipe degradation, release of iron by-products, water flow restriction, microbial growth and the reduction of drinking water safety for consumers, which present a significant threat to water supply safety. The aim of the paper was to show changes that emerged in pipes formed in grey cast iron and steel as a result of potable water flow depending on the duration of their use. The corrosion scales from old water pipe lines were analyzed for their structure and composition. The description of the test methodology presents the procedure regarding, analysis of the inner and outer coating with the use of scanning equipment, and chemical analysis of the corrosion sludge. In this study, corrosion products were carefully collected from four old, corroded iron pipes made of different materials – gray cast iron and steel. It can be concluded that scale charac-teristics, including micromorphology, porosity and composition, vary significantly due to different pipe materials and times operating. Characteristics of corrosions scales sampled from different pipe segments show obvious differences, both in physical and chemical aspects. Corrosion scales were found highly amorphous. Diverse results can be observed in the case of the test of inner and outer surface of water supply pipes with the use of scanning equipment. The highest quantity of corrosion pits in the structure were present in the line formed in grey cast iron no. 2, while the deepest pits – over 14 mm – were recorded in steel pipe no. 4. Lines with the most reduced cross-section include steel pipe no. 3, which was characterized by presence of sludge sized over 26 mm. When considering the issue of the chemical composition of the formed corrosion sludge, particular attention must be drawn to the elements that may penetrate into water as a result of its flow, thus causing a considerable deterioration of its quality in chemical and physical terms. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by silicon, aluminum, sulfur, calcium, manganese, magnesium. Consequently, characterization of corrosion scales is indispensable to water quality protection.

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Calcium Carbonate Scale Formation, Prediction and Treatment (Case Study Gumry Oilfield-PDOC)

Saifelnasr A., Bakheit M., Kamal K., Lila A.

International Letters of Chemistry, Physics and Astronomy

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2013

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Vol. 12

47--58

EN

In this study the predictions and probabilities of calcium carbonate scale formation and corrosion occurrence inside Gumry Field Process Facilities (GFPF) and produced water injection process units (PWTP) was carried out. This was done calculating the Langelier Saturation Index (LSI), Ryznar Stability Index (RSI), Puckorius Scaling Index (PSI). The samples results for LSI index and PSI index were compared and found that all samples under threaten of calcium carbonate scale. The samples results for RSI index and found that all samples under formation of heavy calcium carbonate scale. Special excel computer program was designed to calculate the (LSI, RSI, PSI). The scale was cleaned and removed by 10 % diluted hydrochloric acid and commercial scale inhibitor.

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The influence of the scale formation and the die angle on the heat transfer in the drawing out process

Hadała B., Malinowski Z.

Computer Methods in Materials Science

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2007

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Vol. 7, No. 2

218-223

EN

The article describes the influence of the scale formation and the die angle on the heat transfer in the drawing out process. The die angle affects the surface of contact of the ingot with the anvils and it results the heat flux transferred to the air and tools. In order to describe the heat transfer boundary conditions in the zone of material contact with the dies the secondary scale formation as a function of time and a forged steel surface temperature have been taken into account. The scale thickness has been calculated on the basis of the experimental equation defining the growth of the weight of scale while steel cooling in the air. It was assumed that the scale formed during heating of the ingot in the furnace has been completely removed during preliminary operations. It has made it possible to vary the heat transfer coefficient as a function of process time and the scale thickness. The dependence of the heat transfer coefficient on the type of anvil has been determined by taking into account the die angle and the deformation ratio during the drawing out operation. The empirical functions have been established to approximate the ratio of material contact with the anvils. The tape of anvil and the deformation ratio have been taken into account. On the basis of the developed heat transfer boundary conditions, the temperature field of the forged shaft has been calculated. The temperature distributions in the cross section of the shaft have been presented. The temperature calculations have been performed by the finite element method.

PL

W artykule przedstawiono analizę wpływu zgorzeliny i kąta kowadeł na wymianę ciepła w procesie wydłużania swobodnego wlewka. Kąt kowadeł wpływa na powierzchnię styku kutego materiału z kowadłami i w rezultacie zmienia się strumień ciepła odprowadzanego do kowadeł i przejmowanego przez powietrze. W celu ustalenia warunków brzegowych w strefie kontaktu wlewek - kowadło, uwzględniono, wzrost grubości zgorzeliny wtórnej w zależności od czasu i temperatury powierzchni kutej stali. Grubość zgorzeliny wyliczono na na podstawie eksperymentalnych zależności przyrostu masy zgorzeliny podczas chłodzenia w powietrzu po operacji nagrzewania. Założono, że zgorzelina pierwotna, powstała podczas nagrzewania w piecu, została usunięta w czasie wydłużania wstępnego. Pozwoliło to na wykazanie zmienności współczynnika wymiany ciepła w zależności od grubości zgorzeliny i czasu trwania procesu. Wykazano także zależność współczynnika wymiany ciepła od rodzaju zastosowanych kowadeł z uwzględnieniem kąta rozwarcia powierzchni roboczej kowadła i wielkości gniotu stosowanego podczas operacji kucia. Dla każdego z kowadeł została przyjęta funkcja empiryczna umożliwiająca przybliżenie udziału pola powierzchni styku. Na podstawie ustalonych zależności wykonano obliczenia pola temperatury wlewka i przedstawiono przykładowe wyniki rozkładu temperatury w przekroju poprzecznym w strefie styku kowadła z odkształcanym materiałem. Obliczenia zostały dokonane za pomocą metody elementów skończonych.