To investigate the flow-accelerated corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 21/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH ...
To investigate the flow-accelerated corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 21/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH $8.0\~10.0$ in an oxygen-free aqueous solution re-circulated in an Erosion-Corrosion Test Loop at $130^{\circ}\;{\ldots}$ for 500 hours. The weight loss of the carbon steel specimens appeared to be positively dependent on the flow velocity. That of the carbon and low-alloy steel specimens also showed to be distinguishably dependent on the pH. At pH levels of $8.0\~9.5$ it decreased, but increased from 9.5 to 10.0. Utility water chemistry personnel should carefully consider this kind of pH dependency to control the water system pH to mitigate FAC of the piping system material. The weight loss of the specimens located further from the orifice in the distance range of $6.8\~27.2$ mm was shown to be greater, except for 21/4Cr-1Mo, which showed no orifice distance dependency. Low alloy steel specimens exhibited a factor of two times better resistance to FAC than that of the carbon steel. Based on this kind of FAC dependency of the carbon and low-alloy steels on the orifice distance and material, we conclude that it is necessary to alternate the composition of the secondary piping system material of NPPs, using low-alloy steels, such as 21/4Cr-1Mo, particularly when the system piping has to be replaced.
To investigate the flow-accelerated corrosion (FAC) dependency of carbon steel (A106 Gr. B) and low-alloy steels (1Cr-1/2Mo, 21/4Cr-1Mo) on pH, orifice distance, and material, experiments were carried out. These experiments were performed using a flow velocity of 4 m/sec (partly 9 m/sec) at pH $8.0\~10.0$ in an oxygen-free aqueous solution re-circulated in an Erosion-Corrosion Test Loop at $130^{\circ}\;{\ldots}$ for 500 hours. The weight loss of the carbon steel specimens appeared to be positively dependent on the flow velocity. That of the carbon and low-alloy steel specimens also showed to be distinguishably dependent on the pH. At pH levels of $8.0\~9.5$ it decreased, but increased from 9.5 to 10.0. Utility water chemistry personnel should carefully consider this kind of pH dependency to control the water system pH to mitigate FAC of the piping system material. The weight loss of the specimens located further from the orifice in the distance range of $6.8\~27.2$ mm was shown to be greater, except for 21/4Cr-1Mo, which showed no orifice distance dependency. Low alloy steel specimens exhibited a factor of two times better resistance to FAC than that of the carbon steel. Based on this kind of FAC dependency of the carbon and low-alloy steels on the orifice distance and material, we conclude that it is necessary to alternate the composition of the secondary piping system material of NPPs, using low-alloy steels, such as 21/4Cr-1Mo, particularly when the system piping has to be replaced.
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제안 방법
). Dissolved iron concentrations sampled after 500 hours were analyzed by using an ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscope, IRIS-DUO).
In this study, to confirm whether FAC would decrease even in a pH range of over 9.5, and to confirm the effects of flow velocity, orifice distance, and material, we investigated the dependencies of FAC in single-phase, carbon steel (A 106 Grade B) and low-alloy steels (ICr-iMo and 2zCr-IMo). The pH was maintained within a range from 8.
To investigate the dependency of the FAC of carbon steel and low-alloy steels [Pll (ICr-iMo) and P22 (2iCr-IMo)] on pH levels, orifice distances, and materials, experiments were carried out using flow velocities of 4 m/sec and 9 m/sec in a pH range of 8.0-10.0 in a dissolved oxygenfree aqueous solution re-circulated in an Erosion-Corrosion Test Loop at 130℃ for 500 hours. The fbllowing observations were made:
To obtain reasonable weight loss data within at least 500 hours, the experiment was carried out in a DO-free aqueous solution at 130℃, thus providing a maximum FAC rate for carbon steel and low-alloy steels.
We observed and analyzed the surface characteristics and chemical features of the specimens before and after 500 hours, using SEM, XPS, and XRD; in addition, ICP-AES was used to measure the concentration of iron in a given solution.
대상 데이터
3. Test specimens were made of carbon steel (A 106 Grade B) and low-alloy steels [A3 3 6 PlH(lCr- Mo) and A335 P22 (2eCr-lMo)], and their chemical compositions are shown in Table 1.
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