Waterwall damage by fast internal oxidation of boiler tubes

Anu Lokkiluoto, Juha Viuhko, Pertti Auerkari, Sanni Yli-Olli

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

    Abstract

    Recurring waterwall leaks have been observed in a coal-fired boiler where subsequent inspections have shown through-wall internal oxidation, mostly at butt welds of 16Mo3 boiler tubes. In several cases the oxide had retained a thick pit plug even after local penetration of the tube wall. The original initiation site is no longer visible as it was removed by oxidation, but away from the most severe damage the internal oxidation appears to have initiated immediately downstream after a protruding weld root. This location, estimated oxidation rate and oxide appearance suggest that the mechanism is related to locally intensive heating in addition to flow turbulence. In the damage history of the same boiler wall, the first comparable leaks were recorded at shop welds with strongly protruding root shape, presumably inducing particularly strongly turbulent flow, and even then only after long term service. The most recent failures, however, occurred at normal repair welds or even within parent material, and after much shorter time in service. The characteristic features and causative factors of the tube failures are discussed in the paper, based on the available evidence and experience from operation and maintenance.
    Original languageEnglish
    Title of host publicationBaltica X
    Subtitle of host publicationInternational Conference on Life Management and Maintenance for Power Plants
    EditorsPertti Auerkari
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages9
    ISBN (Electronic)978-951-38-8436-9, 978-951-38-8435-2
    Publication statusPublished - 2016
    MoE publication typeA4 Article in a conference publication
    EventBALTICA X - International Conference on Life Management and Maintenance for Power Plants - Cruise, Helsinki-Stockholm, Finland
    Duration: 7 Jun 20169 Jun 2016

    Publication series

    SeriesVTT Technology
    Volume261
    ISSN2242-1211

    Conference

    ConferenceBALTICA X - International Conference on Life Management and Maintenance for Power Plants
    Abbreviated titleBaltica X
    CountryFinland
    CityHelsinki-Stockholm
    Period7/06/169/06/16

    Fingerprint

    oxidation
    damage
    oxide
    parent material
    turbulent flow
    repair
    penetration
    turbulence
    coal
    heating
    boiler
    history
    services
    shop
    inspection
    rate

    Cite this

    Lokkiluoto, A., Viuhko, J., Auerkari, P., & Yli-Olli, S. (2016). Waterwall damage by fast internal oxidation of boiler tubes. In P. Auerkari (Ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants Espoo: VTT Technical Research Centre of Finland. VTT Technology, Vol.. 261
    Lokkiluoto, Anu ; Viuhko, Juha ; Auerkari, Pertti ; Yli-Olli, Sanni. / Waterwall damage by fast internal oxidation of boiler tubes. Baltica X: International Conference on Life Management and Maintenance for Power Plants. editor / Pertti Auerkari. Espoo : VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).
    @inproceedings{99aafff20a104b008207ab9fd3706ffa,
    title = "Waterwall damage by fast internal oxidation of boiler tubes",
    abstract = "Recurring waterwall leaks have been observed in a coal-fired boiler where subsequent inspections have shown through-wall internal oxidation, mostly at butt welds of 16Mo3 boiler tubes. In several cases the oxide had retained a thick pit plug even after local penetration of the tube wall. The original initiation site is no longer visible as it was removed by oxidation, but away from the most severe damage the internal oxidation appears to have initiated immediately downstream after a protruding weld root. This location, estimated oxidation rate and oxide appearance suggest that the mechanism is related to locally intensive heating in addition to flow turbulence. In the damage history of the same boiler wall, the first comparable leaks were recorded at shop welds with strongly protruding root shape, presumably inducing particularly strongly turbulent flow, and even then only after long term service. The most recent failures, however, occurred at normal repair welds or even within parent material, and after much shorter time in service. The characteristic features and causative factors of the tube failures are discussed in the paper, based on the available evidence and experience from operation and maintenance.",
    author = "Anu Lokkiluoto and Juha Viuhko and Pertti Auerkari and Sanni Yli-Olli",
    year = "2016",
    language = "English",
    series = "VTT Technology",
    publisher = "VTT Technical Research Centre of Finland",
    editor = "Pertti Auerkari",
    booktitle = "Baltica X",
    address = "Finland",

    }

    Lokkiluoto, A, Viuhko, J, Auerkari, P & Yli-Olli, S 2016, Waterwall damage by fast internal oxidation of boiler tubes. in P Auerkari (ed.), Baltica X: International Conference on Life Management and Maintenance for Power Plants. VTT Technical Research Centre of Finland, Espoo, VTT Technology, vol. 261, BALTICA X - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 7/06/16.

    Waterwall damage by fast internal oxidation of boiler tubes. / Lokkiluoto, Anu; Viuhko, Juha; Auerkari, Pertti; Yli-Olli, Sanni.

    Baltica X: International Conference on Life Management and Maintenance for Power Plants. ed. / Pertti Auerkari. Espoo : VTT Technical Research Centre of Finland, 2016. (VTT Technology, Vol. 261).

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

    TY - GEN

    T1 - Waterwall damage by fast internal oxidation of boiler tubes

    AU - Lokkiluoto, Anu

    AU - Viuhko, Juha

    AU - Auerkari, Pertti

    AU - Yli-Olli, Sanni

    PY - 2016

    Y1 - 2016

    N2 - Recurring waterwall leaks have been observed in a coal-fired boiler where subsequent inspections have shown through-wall internal oxidation, mostly at butt welds of 16Mo3 boiler tubes. In several cases the oxide had retained a thick pit plug even after local penetration of the tube wall. The original initiation site is no longer visible as it was removed by oxidation, but away from the most severe damage the internal oxidation appears to have initiated immediately downstream after a protruding weld root. This location, estimated oxidation rate and oxide appearance suggest that the mechanism is related to locally intensive heating in addition to flow turbulence. In the damage history of the same boiler wall, the first comparable leaks were recorded at shop welds with strongly protruding root shape, presumably inducing particularly strongly turbulent flow, and even then only after long term service. The most recent failures, however, occurred at normal repair welds or even within parent material, and after much shorter time in service. The characteristic features and causative factors of the tube failures are discussed in the paper, based on the available evidence and experience from operation and maintenance.

    AB - Recurring waterwall leaks have been observed in a coal-fired boiler where subsequent inspections have shown through-wall internal oxidation, mostly at butt welds of 16Mo3 boiler tubes. In several cases the oxide had retained a thick pit plug even after local penetration of the tube wall. The original initiation site is no longer visible as it was removed by oxidation, but away from the most severe damage the internal oxidation appears to have initiated immediately downstream after a protruding weld root. This location, estimated oxidation rate and oxide appearance suggest that the mechanism is related to locally intensive heating in addition to flow turbulence. In the damage history of the same boiler wall, the first comparable leaks were recorded at shop welds with strongly protruding root shape, presumably inducing particularly strongly turbulent flow, and even then only after long term service. The most recent failures, however, occurred at normal repair welds or even within parent material, and after much shorter time in service. The characteristic features and causative factors of the tube failures are discussed in the paper, based on the available evidence and experience from operation and maintenance.

    M3 - Conference article in proceedings

    T3 - VTT Technology

    BT - Baltica X

    A2 - Auerkari, Pertti

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Lokkiluoto A, Viuhko J, Auerkari P, Yli-Olli S. Waterwall damage by fast internal oxidation of boiler tubes. In Auerkari P, editor, Baltica X: International Conference on Life Management and Maintenance for Power Plants. Espoo: VTT Technical Research Centre of Finland. 2016. (VTT Technology, Vol. 261).