Corrosion testing of high-nickel alloy composite tube materials in simulated recovery boiler lower furnace conditions

Martti Mäkipää, Maria Oksa, Pekka Pohjanne

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

    Abstract

    High-nickel alloys like Alloy 825 and Alloy 625 have been found very promising as substitutes for 304L austenitic stainless steel composite tubing commonly used in recovery boiler lower furnace water-wall panels. High-nickel alloys may be applied as outer layers of composite tubing or as weld overlays. As compared to austenitic stainlesss steels they possess higher yield strength at elevated temperatures and their thermal expansion coefficient is as closer to that of carbon steel. These properties make them, as compared to type 304L austenitic stainless steel, less prone to thermal fatigue or stress corrosion cracking. However, because of the high-nickel content, their sulphidation resistance has been questioned. This paper reports about recent results of comparative laboratory testing of sulphidation and stress corrosion cracking susceptibility of some candidate high-nickel alloys. Laboratory testing performed under simulated lower furnace environments at exposure temperatures of 360oC and higher indicate that corrosion and stress corrosion cracking resistance of high-nickel alloys of type 625 is superior to austenitic stainless steel of type 304L under normal lower furnace operation conditions. Corrosion resistance of Alloy 825 as compared to austenitic stainless steel of type 304 L varies depending on the detailed environmental conditions. Testing programme will be continued and extended to higher temperatures and more aggressive chemical conditions.
    Original languageEnglish
    Title of host publication10th International Symposium on Corrosion in the Pulp and Paper Industry, ISCPPI. Vol. 1
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages73-88
    ISBN (Electronic)951-38-5724-7
    ISBN (Print)951-38-5720-4
    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
    Number214
    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

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  • Cite this

    Mäkipää, M., Oksa, M., & Pohjanne, P. (2001). Corrosion testing of high-nickel alloy composite tube materials in simulated recovery boiler lower furnace conditions. In 10th International Symposium on Corrosion in the Pulp and Paper Industry, ISCPPI. Vol. 1 (pp. 73-88). VTT Technical Research Centre of Finland. VTT Symposium, No. 214