Comparative laboratory testing of molten salt attack of superheater tube materials

Maria Oksa, Martti Mäkipää

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    Abstract

    In some practical superheater corrosion failure cases one finds that the corrosion environment has actually been a low-melting salt film spreading on the tube surface. In this study a modified crucible test method is introduced that simulates this corrosion condition. Metallic specimens exposed in air atmosphere as half-immersed into a molten alkali chloride - alkali sulphate salt mixture of eutectic composition in 520-530°C. Materials evaluation is based on the post-experiment examination of the specimens and their cross-sections. Low-alloy steels and various austenitic steels and nickel alloys were tested using this method. For low-alloy steels and austenitic stainless steels the characteristic corrosion attack mode was intergranular attack and growth of oxide scales. More corrosion resistant steels and alloys suffered from pitting attack. Corrosion morphologies observed had a close resemblance to practical corrosion morphologies in cases involving alkali sulphate - alkali chloride melt attack.
    Original languageEnglish
    Title of host publication10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages523-538
    ISBN (Electronic)951-38-5724-7
    ISBN (Print)951-38-5721-2
    Publication statusPublished - 2001
    MoE publication typeA4 Article in a conference publication
    Event10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI - Helsinki, Finland
    Duration: 21 Aug 200124 Aug 2001

    Publication series

    SeriesVTT Symposium
    Number215
    ISSN0357-9387

    Conference

    Conference10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI
    Abbreviated title10th ISCPPI
    CountryFinland
    CityHelsinki
    Period21/08/0124/08/01

    Fingerprint

    Superheater tubes
    Molten materials
    Salts
    Corrosion
    Testing
    High strength steel
    Superheaters
    Austenitic steel
    Crucibles
    Nickel alloys
    Alloy steel
    Austenitic stainless steel
    Pitting
    Eutectics
    Melting
    Oxides
    Steel

    Cite this

    Oksa, M., & Mäkipää, M. (2001). Comparative laboratory testing of molten salt attack of superheater tube materials. In 10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2 (pp. 523-538). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 215
    Oksa, Maria ; Mäkipää, Martti. / Comparative laboratory testing of molten salt attack of superheater tube materials. 10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2. Espoo : VTT Technical Research Centre of Finland, 2001. pp. 523-538 (VTT Symposium; No. 215).
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    title = "Comparative laboratory testing of molten salt attack of superheater tube materials",
    abstract = "In some practical superheater corrosion failure cases one finds that the corrosion environment has actually been a low-melting salt film spreading on the tube surface. In this study a modified crucible test method is introduced that simulates this corrosion condition. Metallic specimens exposed in air atmosphere as half-immersed into a molten alkali chloride - alkali sulphate salt mixture of eutectic composition in 520-530°C. Materials evaluation is based on the post-experiment examination of the specimens and their cross-sections. Low-alloy steels and various austenitic steels and nickel alloys were tested using this method. For low-alloy steels and austenitic stainless steels the characteristic corrosion attack mode was intergranular attack and growth of oxide scales. More corrosion resistant steels and alloys suffered from pitting attack. Corrosion morphologies observed had a close resemblance to practical corrosion morphologies in cases involving alkali sulphate - alkali chloride melt attack.",
    author = "Maria Oksa and Martti M{\"a}kip{\"a}{\"a}",
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    Oksa, M & Mäkipää, M 2001, Comparative laboratory testing of molten salt attack of superheater tube materials. in 10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2. VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 215, pp. 523-538, 10th International Symposium On corrosion in the Pulp and Paper Industry, ISCPPI , Helsinki, Finland, 21/08/01.

    Comparative laboratory testing of molten salt attack of superheater tube materials. / Oksa, Maria; Mäkipää, Martti.

    10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2. Espoo : VTT Technical Research Centre of Finland, 2001. p. 523-538 (VTT Symposium; No. 215).

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

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    N2 - In some practical superheater corrosion failure cases one finds that the corrosion environment has actually been a low-melting salt film spreading on the tube surface. In this study a modified crucible test method is introduced that simulates this corrosion condition. Metallic specimens exposed in air atmosphere as half-immersed into a molten alkali chloride - alkali sulphate salt mixture of eutectic composition in 520-530°C. Materials evaluation is based on the post-experiment examination of the specimens and their cross-sections. Low-alloy steels and various austenitic steels and nickel alloys were tested using this method. For low-alloy steels and austenitic stainless steels the characteristic corrosion attack mode was intergranular attack and growth of oxide scales. More corrosion resistant steels and alloys suffered from pitting attack. Corrosion morphologies observed had a close resemblance to practical corrosion morphologies in cases involving alkali sulphate - alkali chloride melt attack.

    AB - In some practical superheater corrosion failure cases one finds that the corrosion environment has actually been a low-melting salt film spreading on the tube surface. In this study a modified crucible test method is introduced that simulates this corrosion condition. Metallic specimens exposed in air atmosphere as half-immersed into a molten alkali chloride - alkali sulphate salt mixture of eutectic composition in 520-530°C. Materials evaluation is based on the post-experiment examination of the specimens and their cross-sections. Low-alloy steels and various austenitic steels and nickel alloys were tested using this method. For low-alloy steels and austenitic stainless steels the characteristic corrosion attack mode was intergranular attack and growth of oxide scales. More corrosion resistant steels and alloys suffered from pitting attack. Corrosion morphologies observed had a close resemblance to practical corrosion morphologies in cases involving alkali sulphate - alkali chloride melt attack.

    M3 - Conference article in proceedings

    SN - 951-38-5721-2

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    BT - 10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2

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    Oksa M, Mäkipää M. Comparative laboratory testing of molten salt attack of superheater tube materials. In 10th International Symposium on Corrosion in the Pulp and Paper Industry- ISCPPI. Vol. 2. Espoo: VTT Technical Research Centre of Finland. 2001. p. 523-538. (VTT Symposium; No. 215).