Solos urbanos de Palmas foram caracterizados fisicamente e quimicamente. As propriedades físicas de resistividade elétrica, granulometria, massa específica e umidade de cinco solos daquela cidade foram analisadas. As propriedades químicas de composição e pH também foram caracterizadas. Dois destes solos tiveram a sua corrosividade para o aço API 5L X70 investigada por ensaio de campo. O ensaio de campo consistiu no enterramento de amostras do aço nos dois solos seguido por retirada após períodos pré-determinados de tempo até 960 dias, ensaio gravimétrico para avaliação das taxas de corrosão em função do tempo de exposição aos solos e observação da superfície. Foram também realizados ensaios em laboratório com extratos aquosos dos cinco solos caracterizados. Os extratos aquosos foram usados como eletrólito nos ensaios eletroquímicos sendo estes ensaios seguidos pela observação da superfície exposta ao eletrólito. Os ensaios eletroquímicos não se mostraram efetivos na classificação da corrosividade dos diferentes solos. Todavia, a observação da superfície das amostras ensaiadas e análise do eletrólito após ensaio mostrou diferenças significativas na corrosividade dos extratos aquosos. A caracterização da corrosividade de solos por ensaio gravimétrico identificou a maior corrosividade do solo arenoso frente ao solo argiloso, o que foi atribuído à maior porosidade do primeiro em comparação ao segundo e foi corroborado pela maior massa específica do solo argiloso em relação ao arenoso. Os resultados deste trabalho indicaram que a porosidade é um dos fatores mais importantes para a corrosividade de solos de resistividade elétrica similar, uma vez que esta influencia diretamente a aeração do solo na região dos materiais enterrados, característica que é preeminente para a corrosividade dos solos. / Urban soils of Palmas were characterized physically and chemically. The physical properties of electrical resistivity, granulometry, specific mass and humidity of five soils of that city were analyzed. The chemical properties of composition and pH were also characterized. Two of these soils had their corrosivity for the API 5L X70 steel investigated by field test. The field test consisted of burial of samples of the steel in the two soils followed by removal after predetermined periods of time up to 960 days, gravimetric test to evaluate the corrosion rates as a function of exposure time to the soil and observation of the surface. Laboratory tests were also carried out with aqueous extracts of the five soils characterized. The aqueous extracts were used as electrolyte in the electrochemical tests and these tests were followed by observation of the surface exposed to the electrolyte. The electrochemical tests were not effective in the classification of the corrosivity of the different soils. However, observation of the surface of the samples tested and analysis of the electrolyte after the test showed significant differences in the corrosivity of the aqueous extracts. The characterization of soil corrosivity by gravimetric test showed a higher corrosivity of the sandy soil to the clayey one, which was attributed to the higher porosity of the first one in comparison to the second and was corroborated by the greater specific mass of the clayey soil than the sandy one. The results of this work indicated that porosity is one of the most important factors for the corrosivity of soils of similar electrical resistivity, since this directly influences the aeration of the soil in the region of the buried materials, characteristic that is preeminent for the corrosivity of the soils.

Antes de transportar os derivados de petróleo por dutos, a sua corrosividade é verificada por meio do ensaio NACE TM-0172 ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). O referido ensaio, por basear-se na avaliação visual, não tem por objetivo a determinação da taxa de corrosão e nem a verificação do tipo de corrosão e, normalmente, os profissionais que o executam não têm conhecimento da influência das variáveis que interferem nos resultados do ensaio. Desta forma, o presente estudo teve como objetivos: verificar a influência de algumas variáveis (velocidade de agitação, geometria do corpo-deprova, temperatura, teor de água, tempo de ensaio e pH) nos resultados obtidos com o ensaio NACE TM-0172 (NACE, 2001), fazer avaliação quantitativa da taxa de corrosão por meio da determinação da perda de massa dos corpos-de-prova expostos ao meio, correlacionar os resultados da avaliação visual com a perda de massa, verificar se o ensaio, que é realizado em condições aeradas, simula adequadamente as condições internas dos dutos. Para condução do estudo, além do próprio ensaio NACE TM-0172 (NACE, 2001), foram realizados outros ensaios simples utilizando o aço-carbono COPANT 1020 na confecção dos corpos-de-prova metálicos. Com base em todos os ensaios realizados, foi possível fazer uma análise crítica do ensaio NACE TM-0172 (NACE, 2001) e justificar a adoção das diferentes condições de ensaio além de apresentar uma explicação para o mecanismo de corrosão do açocarbono na mistura derivado/água. / Before transporting distillate fuels by pipelines, their corrosive properties are verified by the NACE TM-0172 test ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). This test, being based on a visual evaluation, has as its goal, neither the determination of the corrosion rate nor the verification of the corrosion type; the technicians usually do not know the influence of the variables that interfere in the test results. Thus, this study had as its goals: to verify the influence of some variables (stirring speed, coupon geometry, temperature, water content, test duration and pH of the water phase) in the results obtained with the NACE TM-0172 test (NACE, 2001), to make the quantitative evaluation of the corrosion rate by determination of the coupon mass loss exposed to this condition, to correlate the results of the visual evaluation with the mass loss, to verify if the test, which is made in aerated conditions, simulate properly the internal conditions of pipelines. To conduct the study, besides the NACE TM-0172 (NACE, 2001) test itself, other simple tests were made using the carbon steel COPANT 1020 to prepare the metallic coupons. Based on all the tests, it was possible to make a critical analysis of the NACE TM-0172 (NACE, 2001) test and (to) justify the adoption of different test conditions as well as there being the possibility of presenting an explanation for the mechanism of the carbon steel corrosion in the mixture distillate/water.

Antes de transportar os derivados de petróleo por dutos, a sua corrosividade é verificada por meio do ensaio NACE TM-0172 ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). O referido ensaio, por basear-se na avaliação visual, não tem por objetivo a determinação da taxa de corrosão e nem a verificação do tipo de corrosão e, normalmente, os profissionais que o executam não têm conhecimento da influência das variáveis que interferem nos resultados do ensaio. Desta forma, o presente estudo teve como objetivos: verificar a influência de algumas variáveis (velocidade de agitação, geometria do corpo-deprova, temperatura, teor de água, tempo de ensaio e pH) nos resultados obtidos com o ensaio NACE TM-0172 (NACE, 2001), fazer avaliação quantitativa da taxa de corrosão por meio da determinação da perda de massa dos corpos-de-prova expostos ao meio, correlacionar os resultados da avaliação visual com a perda de massa, verificar se o ensaio, que é realizado em condições aeradas, simula adequadamente as condições internas dos dutos. Para condução do estudo, além do próprio ensaio NACE TM-0172 (NACE, 2001), foram realizados outros ensaios simples utilizando o aço-carbono COPANT 1020 na confecção dos corpos-de-prova metálicos. Com base em todos os ensaios realizados, foi possível fazer uma análise crítica do ensaio NACE TM-0172 (NACE, 2001) e justificar a adoção das diferentes condições de ensaio além de apresentar uma explicação para o mecanismo de corrosão do açocarbono na mistura derivado/água. / Before transporting distillate fuels by pipelines, their corrosive properties are verified by the NACE TM-0172 test ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). This test, being based on a visual evaluation, has as its goal, neither the determination of the corrosion rate nor the verification of the corrosion type; the technicians usually do not know the influence of the variables that interfere in the test results. Thus, this study had as its goals: to verify the influence of some variables (stirring speed, coupon geometry, temperature, water content, test duration and pH of the water phase) in the results obtained with the NACE TM-0172 test (NACE, 2001), to make the quantitative evaluation of the corrosion rate by determination of the coupon mass loss exposed to this condition, to correlate the results of the visual evaluation with the mass loss, to verify if the test, which is made in aerated conditions, simulate properly the internal conditions of pipelines. To conduct the study, besides the NACE TM-0172 (NACE, 2001) test itself, other simple tests were made using the carbon steel COPANT 1020 to prepare the metallic coupons. Based on all the tests, it was possible to make a critical analysis of the NACE TM-0172 (NACE, 2001) test and (to) justify the adoption of different test conditions as well as there being the possibility of presenting an explanation for the mechanism of the carbon steel corrosion in the mixture distillate/water.

Research Doctorate - Doctor of Philosophy (PhD) / This work reports the deposition onto high voltage insulators and correlation to atmospheric corrosivity measurement. This work includes corrosion studies at 15 sites in New Zealand (1,816 tests) for in excess of 12 months, and co-operative research in South Africa. In addition, to confirm the relevance and transportability of this proposed model, a review of the published international data on deposition rates on insulators was conducted. It was noted that the deposition rate of airborne pollutants onto a surface is dependent upon the true surface area facing the wind and the aerodynamic properties of the surface. Such is the effect that surfaces with minimal exposure to the wind such as horizontal plates, have been shown to be poor collectors of deposits while vertical plates are more efficient, followed by high voltage glass insulators, the ISO9223 salt candle, and the largest collector is the Direct Dust Deposit Gauge. This study found that the ISO9223 wet salt candle and the average annual deposition rate on the High Voltage Glass insulator bottom surface (unenergized) provided relatively similar deposition results. The deposition onto insulator surfaces may be a more relevant method as it replicates deposition on large surfaces. This Equivalent Salt Dry Deposition (ESDD) method for HV insulators is an all inclusive measure of the airborne pollutants deposition rate and converts the total deposited material into a single value equivalent to that of salt, even though the deposit may consist of sulphur, marine salts, nitrates, and other conductive pollutants. The measured deposition rate on the sheltered insulator bottoms at 85 sites around the world predicted 87% of the ISO corrosivity categories (based on zinc corrosion) for these sites. Results from equatorial Asia appear to be non-compliant and warrant further investigation. The ESDD values are now being quoted from around the world, by electrical engineers who use the recently revised CIGRE methodology, to determine the probability of arc-over (shorting to earth) of high voltage cables due to pollution build-up on insulators. The implications from this research are significant, with the cost of atmospheric corrosivity studies becoming prohibitively expensive, this method converts technically valid surface deposition results from the electrical engineers from around the world (provided at no cost), to valid empirical corrosivity rates from often remote locations.

The aim of the study was to characterise the environment in the Sydney region in respect of atmospheric corrosivity, timber decay risk factors and the corrosion of nails in timber in covered conditions. The study reviewed contemporary research in this field, particularly in Australia, developing an understanding of the durability failure mechanisms for timber and nails in timber. The study looked at the effects of climatic aspects, pollutants, corrosion on timber decay risk factors. The study found that the levels of risk in terms of timber degradation, corrosion and nail corrosion were greatest adjacent to the coast and at marine sites. / Doctor of Philosophy (PhD)

No description available.

A Mechanically Stabilized Earth (MSE) wall is a vertical grade separation that uses earth reinforcement extending laterally from the wall to take advantage of earth pressure to reduce the required design strength of the wall. MSE wall systems are often prefabricated to reduce construction time, thus improving constructability when compared with conventionally cast-in-place reinforced wall systems. However, there is a lack of knowledge for predicting the service-life of MSE retaining wall systems when recycled backfill materials such as Recycled Asphalt Pavement (RAP) and Crushed Concrete (CC) are used instead of Conventional Fill Material (CFM). The specific knowledge missing is how these recycled materials, when used as backfill in MSE wall systems, affects the corrosion rate of the reinforcing strips. This work addresses this knowledge gap by providing recommendations for MSE wall systems backfilled with CC or RAP, and provides a guide to predict the service-life based on corrosion rate test data obtained from embedding steel and galvanized-steel earth reinforcing strips embedded in MSE wall systems backfilled with CC, RAP, and CFM. Experimental data from samples emulating MSE wall systems with steel and galvanized-steel reinforcing strips embedded in CC and RAP were compared to samples with strips embedded in CFM. The results of the testing provide data and methodologies that may, depending on the environmental exposure conditions, justify the use of RAP and CC for the construction of MSE walls. If these backfill materials are obtained from the construction site, this could provide a significant cost savings during construction.