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Picture for Influence of High CO2 Partial Pressure on Top-of-the-Line Corrosion
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Influence of High CO2 Partial Pressure on Top-of-the-Line Corrosion

Product Number: 51324-21220-SG
Author: Maryam Eslami; Bernardo Augusto Farah Santos; David Young; Sondre Gjertsen; Marc Singer
Publication Date: 2024
$40.00
Top-of-the-line corrosion (TLC) is an important type of material degradation that occurs due to the heat exchange between the pipeline and its surroundings, which results in water condensation on the internal surface of the pipe. This type of corrosion is specific to wet gas pipelines with stratified flow regimes. In this research, the effect of high CO2 partial pressure (pCO2) on TLC rate and mechanism was studied. The experiments were conducted in a high-pressure TLC autoclave with pCO2 ranging from 20 to 100 bar, solution temperatures of 30 and 50 °C, and different water condensation conditions (0.001-0.1 ml/m2.s). The experimental conditions covered environments where CO2 was either gaseous or supercritical. The results revealed that uniform and localized TLC rates increase with water condensation rate and solution temperature. However, as long as CO2 remained gaseous, pCO2 showed a negligible influence on both uniform and localized TLC rates. At a high CO2 content, the formation of a protective FeCO3 layer decreased the TLC rate, especially at lower water condensation rates. Nevertheless, the risk of localized corrosion at high and medium water condensation rates remained an issue. In the supercritical CO2 environment (pCO2 of 100 bar and solution temperature of 50 °C), the difference in temperature between the CO2 dense phase and the specimens caused water drop out and corrosion. In this environment, the high pCO2 and low pH of the dropped-out water led to high uniform and localized corrosion rates. However, under this condition, the difference in corrosion rates of specimens with different cooling rates was negligible due to their similar surface temperature.
	Picture for Influence of Pb and Cl in Waste Wood Fuel on Furnace Wall Corrosion of Low Alloyed Steel and Alloy 625
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Influence of Pb and Cl in Waste Wood Fuel on Furnace Wall Corrosion of Low Alloyed Steel and Alloy 625

Product Number: 51324-21033-SG
Author: Annika Talus; Rikard Norling; Alice Moya Núñez
Publication Date: 2024
$40.00
	Picture for Influence of the H2 Impurity on the Fatigue Crack Growth and Fracture in a Dense Phase CO2 Pipeline
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Influence of the H2 Impurity on the Fatigue Crack Growth and Fracture in a Dense Phase CO2 Pipeline

Product Number: 51324-20721-SG
Author: B Bezensek; S Hopkin; J Sonke; F Gui; C Taylor
Publication Date: 2024
$40.00
Transport of dense phase CO2 by pipelines needs to account for possible degradation mechanisms arising due to H2 impurity which can be present in (typically) the 0.75 ~ 1 mol% range depending on the specification used. H2 gas can affect fatigue and fracture properties even at low partial pressures and hence the integrity. In this study a complementary experimental and computational modeling program was undertaken. API 5L X65 grade material samples were used for comparable testing in pure H2 gas at low partial pressure H2 and in dense phase CO2 at 100 barg with H2 impurity added in a 2 mol% and 4 mol% increments (i.e. partial pressures of 2 barg and 4 barg). The test results show effect of the H2 impurity in the dense phase CO2 accelerated fatigue crack growth and reduced fracture toughness. These findings are supported by computational simulation using density functional theory and molecular dynamics. A scoping integrity assessment for a dense phase CO2 pipeline with H2 impurity at 2 mol% shows the measured accelerated fatigue crack growth only affects large pressure cycles (pressure range in excess of 70 bar for OD/WT pipelines of ~30). The fatigue life is significantly shortened compared to the pure CO2 pipeline and this is mainly driven by the reduced fracture toughness at low partial pressure H2. The fatigue damage is proportional to the maximum operating pressure (as it increases the pressure range). For a postulated 50-year design life a safe pipeline design window considering a range of conservative inputs (material properties, integrity operating window, geometry, postulated defect size etc.) a safe operating pressure of 2900 psig (200barg) was found for a new build pipeline using modern materials. For a repurposed vintage material pipeline the safe operating pressure was set at 2200 psig (150 barg). An ECA incorporating the deleterious effect of H2 should be conducted to confirm the above postulate unless the project falls within the limits of the conservative inputs (material properties, integrity operating window, geometry, postulated defect size etc.), from a fracture mechanics perspective, of the four case studies that form the basis of this overall study. Other impurities if exceeded their safe threshold may create water drop out and acid formation. It is imperative that the project specifications err on the side of caution and restrict the impurities to safe limits until further understanding of the complex interaction mechanisms is developed.