Measurements of magnetite piles on steam generator tubing with eddy current techniques

Tarja Jäppinen, Kari Lahdenperä

    Research output: Book/ReportReportProfessional

    Abstract

    During in-service inspection the steam generator tubes are generally inspected using single probe eddy current techniques. Magnetite deposit built up on the outer surface of the tubes can be detected with the applied techniques. As deposits grow thicker they tend to split as flakes from the surface of the tubes. These flakes often build magnetite piles between the tubes. Under magnetite piles the conditions are also favourable for corrosion induced defect initiation and growth on the outer surface of the steam generator tubing. This study is a part of the SAFIR2014 project MAKOMON. The experiments were conducted during the years 2012 - 2014 at VTT by using eddy current tube inspection techniques. A small mock-up simulating the horizontal steam generator tubing was used. The goal of the experiment was to develop a technique to size the volume of the detected magnetite piles within the steam generator tubing. The conducted experiments showed that the existence of the magnetic piles can be detected with the applied one and two probe techniques. Additionally the location and extension of the magnetite piles can me mapped with these techniques. The thickness of a solid magnetite layer attached symmetrically to the outer surface of the tubes can be measured more precisely than the thickness of the layer consisting of loose magnetite flakes. The conducted tests showed that if the tube is embedded into unsymmetrical pile, the thickness of the layer of magnetite flakes between the neighbouring tubes cannot be deduced straightforwardly from single measurement, especially when using single probe technique. However, the estimation of the extension of the pile can be mapped.
    Original languageEnglish
    PublisherVTT Technical Research Centre of Finland
    Publication statusPublished - 2015
    MoE publication typeD4 Published development or research report or study

    Publication series

    NameResearch Report
    PublisherVTT
    VolumeVTT-R-00209-15

    Fingerprint

    Magnetite
    Steam generators
    Tubing
    Eddy currents
    Piles
    Deposits
    Inspection
    Experiments
    Corrosion
    Defects

    Keywords

    • magnetite pile
    • magnetite deposit
    • eddy current
    • ET
    • steam generator tubing

    Cite this

    Jäppinen, T., & Lahdenperä, K. (2015). Measurements of magnetite piles on steam generator tubing with eddy current techniques. VTT Technical Research Centre of Finland. VTT Research Report, Vol.. VTT-R-00209-15
    Jäppinen, Tarja ; Lahdenperä, Kari. / Measurements of magnetite piles on steam generator tubing with eddy current techniques. VTT Technical Research Centre of Finland, 2015. (VTT Research Report, Vol. VTT-R-00209-15).
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    abstract = "During in-service inspection the steam generator tubes are generally inspected using single probe eddy current techniques. Magnetite deposit built up on the outer surface of the tubes can be detected with the applied techniques. As deposits grow thicker they tend to split as flakes from the surface of the tubes. These flakes often build magnetite piles between the tubes. Under magnetite piles the conditions are also favourable for corrosion induced defect initiation and growth on the outer surface of the steam generator tubing. This study is a part of the SAFIR2014 project MAKOMON. The experiments were conducted during the years 2012 - 2014 at VTT by using eddy current tube inspection techniques. A small mock-up simulating the horizontal steam generator tubing was used. The goal of the experiment was to develop a technique to size the volume of the detected magnetite piles within the steam generator tubing. The conducted experiments showed that the existence of the magnetic piles can be detected with the applied one and two probe techniques. Additionally the location and extension of the magnetite piles can me mapped with these techniques. The thickness of a solid magnetite layer attached symmetrically to the outer surface of the tubes can be measured more precisely than the thickness of the layer consisting of loose magnetite flakes. The conducted tests showed that if the tube is embedded into unsymmetrical pile, the thickness of the layer of magnetite flakes between the neighbouring tubes cannot be deduced straightforwardly from single measurement, especially when using single probe technique. However, the estimation of the extension of the pile can be mapped.",
    keywords = "magnetite pile, magnetite deposit, eddy current, ET, steam generator tubing",
    author = "Tarja J{\"a}ppinen and Kari Lahdenper{\"a}",
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    language = "English",
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    Jäppinen, T & Lahdenperä, K 2015, Measurements of magnetite piles on steam generator tubing with eddy current techniques. VTT Research Report, vol. VTT-R-00209-15, VTT Technical Research Centre of Finland.

    Measurements of magnetite piles on steam generator tubing with eddy current techniques. / Jäppinen, Tarja; Lahdenperä, Kari.

    VTT Technical Research Centre of Finland, 2015. (VTT Research Report, Vol. VTT-R-00209-15).

    Research output: Book/ReportReportProfessional

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    T1 - Measurements of magnetite piles on steam generator tubing with eddy current techniques

    AU - Jäppinen, Tarja

    AU - Lahdenperä, Kari

    N1 - Project code: 85608

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    N2 - During in-service inspection the steam generator tubes are generally inspected using single probe eddy current techniques. Magnetite deposit built up on the outer surface of the tubes can be detected with the applied techniques. As deposits grow thicker they tend to split as flakes from the surface of the tubes. These flakes often build magnetite piles between the tubes. Under magnetite piles the conditions are also favourable for corrosion induced defect initiation and growth on the outer surface of the steam generator tubing. This study is a part of the SAFIR2014 project MAKOMON. The experiments were conducted during the years 2012 - 2014 at VTT by using eddy current tube inspection techniques. A small mock-up simulating the horizontal steam generator tubing was used. The goal of the experiment was to develop a technique to size the volume of the detected magnetite piles within the steam generator tubing. The conducted experiments showed that the existence of the magnetic piles can be detected with the applied one and two probe techniques. Additionally the location and extension of the magnetite piles can me mapped with these techniques. The thickness of a solid magnetite layer attached symmetrically to the outer surface of the tubes can be measured more precisely than the thickness of the layer consisting of loose magnetite flakes. The conducted tests showed that if the tube is embedded into unsymmetrical pile, the thickness of the layer of magnetite flakes between the neighbouring tubes cannot be deduced straightforwardly from single measurement, especially when using single probe technique. However, the estimation of the extension of the pile can be mapped.

    AB - During in-service inspection the steam generator tubes are generally inspected using single probe eddy current techniques. Magnetite deposit built up on the outer surface of the tubes can be detected with the applied techniques. As deposits grow thicker they tend to split as flakes from the surface of the tubes. These flakes often build magnetite piles between the tubes. Under magnetite piles the conditions are also favourable for corrosion induced defect initiation and growth on the outer surface of the steam generator tubing. This study is a part of the SAFIR2014 project MAKOMON. The experiments were conducted during the years 2012 - 2014 at VTT by using eddy current tube inspection techniques. A small mock-up simulating the horizontal steam generator tubing was used. The goal of the experiment was to develop a technique to size the volume of the detected magnetite piles within the steam generator tubing. The conducted experiments showed that the existence of the magnetic piles can be detected with the applied one and two probe techniques. Additionally the location and extension of the magnetite piles can me mapped with these techniques. The thickness of a solid magnetite layer attached symmetrically to the outer surface of the tubes can be measured more precisely than the thickness of the layer consisting of loose magnetite flakes. The conducted tests showed that if the tube is embedded into unsymmetrical pile, the thickness of the layer of magnetite flakes between the neighbouring tubes cannot be deduced straightforwardly from single measurement, especially when using single probe technique. However, the estimation of the extension of the pile can be mapped.

    KW - magnetite pile

    KW - magnetite deposit

    KW - eddy current

    KW - ET

    KW - steam generator tubing

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    T3 - Research Report

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    PB - VTT Technical Research Centre of Finland

    ER -

    Jäppinen T, Lahdenperä K. Measurements of magnetite piles on steam generator tubing with eddy current techniques. VTT Technical Research Centre of Finland, 2015. (VTT Research Report, Vol. VTT-R-00209-15).