Analytical note: catalytic effects of sulfur and other compounds in the azide-iodine test (original) (raw)
Related papers
The Potential Corrosiveness of Soil Physico- Chemical Properties on Pipelines
Journal of Scientific Research and Reports
Aim: The study was conducted to determine the potential corrosiveness of selected soil physicochemical properties on pipelines. Study Design: Soil samples were randomly collected around five pipeline locations with control from a farmland. Duration of Study: The study lasted for three months. Methodology: Standard methods were adopted in the collection of samples and the determination of the physicochemical properties of the samples. Results: Metallic pipelines undergo more regular corrosion because they are used in environments like soil where they are chemically unstable. Soil physicochemical properties such as soil moisture, texture, pH and temperature, sulphate, chloride, redox potential and resistivity were determined. The pH of the five soil samples was acidic (pH =4.0 – 6.5), The highest moisture content was 22.88% while the lowest was 9.84%. The soil samples the potential of being corrosive to the buried galvanized-steel and cast-iron pipes. Delta Steel Company (DSC) roundab...
Electrochemical Corrosion Behavior of Steel Pipe in Alkaline Soil
This study presents an overview of the corrosion threat to liquid pipelines focusing on the detection of external corrosion. For this steel coupon were buried in three different soil containers for 7 month. Corrosion by soil is a complex phenomenon due to the number of variables involved. In principle, steels should be in the passive state in soils but the presence of water and aggressive chemical species such as chloride ions, sulphates as well as different types of bacteria and stray current can cause localised corrosion. Soils constitute the most complex environment known to metallic corrosion. Corrosion of metals in soil can vary from relatively rapid material loss to negligible effects, depending on soil environment. Soil engineering properties and soil contents are important parameters that influence soil corrosivity and level of corrosion dynamic. The corrosion potential and corrosion rate of buried coupons were studied by EIS technique,
Journal of Research of the National Institute of Standards and Technology, 2010
Between 1911 and 1984, the National Bureau of Standards (NBS) conducted a large number of corrosion studies that included the measurement of corrosion damage to samples exposed to real-world environments. One of these studies was an investigation conducted between 1922 and 1940 into the corrosion of bare steel and wrought iron pipes buried underground at 47 different sites representing different soil types across the Unites States. At the start of this study, very little was known about the corrosion of ferrous alloys underground. The objectives of this study were to determine (i) if coatings would be required to prevent corrosion, and (ii) if soil properties could be used to predict corrosion and determine when coatings would be required. While this study determined very quickly that coatings would be required for some soils, it found that the results were so divergent that even generalities based on this data must be drawn with care. The investigators concluded that so many diverse factors influence corrosion rates underground that planning of proper tests and interpretation of the results were matters of considerable difficulty and that quantitative interpretations or extrapolations could be done “only in approximate fashion” and attempted only in the “restricted area” of the tests until more complete information is available. Following the passage of the Pipeline Safety Improvement Act in 2002 and at the urging of the pipeline industry, the Office of Pipeline Safety of the U.S. Department of Transportation approached the National Institute of Standards and Technology (NBS became NIST in 1988) and requested that the data from this study be reexamined to determine if the informa- tion handling and analysis capabilities of modern computers and software could enable the extraction of more meaningful information from these data. This report is a summary of the resulting investigations. The data from the original NBS studies were analyzed using a variety of commer- cially available software packages for statistical analysis. The emphasis was on identifying trends in the data that could be later exploited in the development of an empirical model for predicting the range of expected corrosion behavior for any given set of soil chemistry and conditions. A large number of issues were identified with this corrosion dataset, but given the limited knowledge of corrosion and statis- tical analysis at the time the study was conducted, these shortcomings are not surprising and many of these were recog- nized by the investigators before the study was concluded. However, it is important to keep in mind that complete soil data is provided for less than half of the sites in this study. In agreement with the initial study, it was concluded that any differ- ences in the corrosion behavior of the alloys could not be resolved due to the scat- ter in the results from the environmental factors and no significant difference could be determined between alloys. Linear regression and curve fitting of the corrosion damage measurements against the meas- ured soil composition and properties found some weak trends. These trends improved with multiple regression, and empirical equations representing the performance of the samples in the tests were developed with uncertainty estimates. The uncertain- ties in these empirical models for the corrosion data were large, and extrapolation beyond the parameter space or exposure times of these experiments will create addi- tional uncertainties. It is concluded that equations for the esti- mation of corrosion damage distributions and rates can be developed from these data, but these models will always have relative- ly large uncertainties that will limit their utility. These uncertainties result from the scatter in the measurements due to annual, seasonal, and sample position dependent variations at the burial sites. The data indi- cate that more complete datasets with soil property measurements reflecting the prop- erties of the soil and ground water directly in contact with the sample from statistically designed experiments would greatly reduce this scatter and enable more representative predictions.
External Corrosion of Ductile Iron Pipes Due To Contaminated Soils
2019
An experimental study is conducted to determine the interaction/exchange between metals in contaminated soils and those in metallic water pipes. Experimentation was carried out on two-100 mm diameter (ductile iron pipe) DIP sections, buried in soil and subjected to artificial rainwater (ARW) representing three years' rainfall. The backfill soil was contaminated with controlled concentrations of heavy metals; they were Copper (Cu), Zinc (Zn), Chromium (Cr) and Lead (Pb). These were then allowed to seep through the soil to the pipe external surfaces. The results indicated that there was iron enrichment from the rainwater experiments compared to the controls whose source could only be the pipe sections; the remaining fittings were not metallic. The iron released from the pipe was then determined in the drainage. There was an increasing wash out of iron content with progressive increases in contaminant loading in each following experiment after which it decreased with time because o...