Practical application of impression creep data to power plant

S.J. Brett, Juhani Rantala, Stefan Holmström

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

18 Citations (Scopus)

Abstract

The measured "minimum" creep rate in the impression creep (IC) test is currently obtained from a "stabilized" deflection rate, and the time to "stabilization" is somewhat arbitrarily chosen at durations up to 500 h, regardless of the applied load. Nevertheless, IC tests have been successfully utilized for aged ½CrMoV and P91 steam line components by conducting tests at the same load so that the deflection rates can directly be compared and used for ranking. By this experience, the IC test is an excellent tool for material ranking and lifing of service exposed material. However, further development in the IC data assessment procedures and the translation between IC and uniaxial test is still needed for determination of the lower stress range material creep properties from the IC test. It is suggested that the deflection rate should be correlated to a Monkman-Grant type relation with the calculated deflection rate at specified "strain/deflection" against the corresponding uniaxial strain rate at the same specified strain. The modified MG relationship should correct the increasing error expected at IC test conducted at decreasing loads. To be able to do this the strain rate as a function of time (or strain) should be available for primary creep of the uniaxial test. The corrective impact of the modified MG has to be verified by further analysis and testing.
Original languageEnglish
Title of host publicationBaltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts
EditorsPertti Auerkari, Juha Veivo
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages82
ISBN (Electronic)978-951-38-8030-9
ISBN (Print)978-951-38-8029-3
Publication statusPublished - 2013
MoE publication typeNot Eligible
EventBALTICA IX - International Conference on Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
Duration: 11 Jun 201313 Jun 2013

Publication series

SeriesVTT Technology
Number107
ISSN2242-1211

Conference

ConferenceBALTICA IX - International Conference on Life Management and Maintenance for Power Plants
CountryFinland
CityHelsinki-Stockholm
Period11/06/1313/06/13

Fingerprint

Power plants
Creep
Strain rate
Steam piping systems
Stabilization
Testing

Cite this

Brett, S. J., Rantala, J., & Holmström, S. (2013). Practical application of impression creep data to power plant. In P. Auerkari, & J. Veivo (Eds.), Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts (pp. 82). Espoo: VTT Technical Research Centre of Finland. VTT Technology, No. 107
Brett, S.J. ; Rantala, Juhani ; Holmström, Stefan. / Practical application of impression creep data to power plant. Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. editor / Pertti Auerkari ; Juha Veivo. Espoo : VTT Technical Research Centre of Finland, 2013. pp. 82 (VTT Technology; No. 107).
@inbook{85b84c86e4dd446bb6fbfa70e7dd2128,
title = "Practical application of impression creep data to power plant",
abstract = "The measured {"}minimum{"} creep rate in the impression creep (IC) test is currently obtained from a {"}stabilized{"} deflection rate, and the time to {"}stabilization{"} is somewhat arbitrarily chosen at durations up to 500 h, regardless of the applied load. Nevertheless, IC tests have been successfully utilized for aged ½CrMoV and P91 steam line components by conducting tests at the same load so that the deflection rates can directly be compared and used for ranking. By this experience, the IC test is an excellent tool for material ranking and lifing of service exposed material. However, further development in the IC data assessment procedures and the translation between IC and uniaxial test is still needed for determination of the lower stress range material creep properties from the IC test. It is suggested that the deflection rate should be correlated to a Monkman-Grant type relation with the calculated deflection rate at specified {"}strain/deflection{"} against the corresponding uniaxial strain rate at the same specified strain. The modified MG relationship should correct the increasing error expected at IC test conducted at decreasing loads. To be able to do this the strain rate as a function of time (or strain) should be available for primary creep of the uniaxial test. The corrective impact of the modified MG has to be verified by further analysis and testing.",
author = "S.J. Brett and Juhani Rantala and Stefan Holmstr{\"o}m",
year = "2013",
language = "English",
isbn = "978-951-38-8029-3",
series = "VTT Technology",
publisher = "VTT Technical Research Centre of Finland",
number = "107",
pages = "82",
editor = "Pertti Auerkari and Juha Veivo",
booktitle = "Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts",
address = "Finland",

}

Brett, SJ, Rantala, J & Holmström, S 2013, Practical application of impression creep data to power plant. in P Auerkari & J Veivo (eds), Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. VTT Technical Research Centre of Finland, Espoo, VTT Technology, no. 107, pp. 82, BALTICA IX - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 11/06/13.

Practical application of impression creep data to power plant. / Brett, S.J.; Rantala, Juhani; Holmström, Stefan.

Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. ed. / Pertti Auerkari; Juha Veivo. Espoo : VTT Technical Research Centre of Finland, 2013. p. 82 (VTT Technology; No. 107).

Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

TY - CHAP

T1 - Practical application of impression creep data to power plant

AU - Brett, S.J.

AU - Rantala, Juhani

AU - Holmström, Stefan

PY - 2013

Y1 - 2013

N2 - The measured "minimum" creep rate in the impression creep (IC) test is currently obtained from a "stabilized" deflection rate, and the time to "stabilization" is somewhat arbitrarily chosen at durations up to 500 h, regardless of the applied load. Nevertheless, IC tests have been successfully utilized for aged ½CrMoV and P91 steam line components by conducting tests at the same load so that the deflection rates can directly be compared and used for ranking. By this experience, the IC test is an excellent tool for material ranking and lifing of service exposed material. However, further development in the IC data assessment procedures and the translation between IC and uniaxial test is still needed for determination of the lower stress range material creep properties from the IC test. It is suggested that the deflection rate should be correlated to a Monkman-Grant type relation with the calculated deflection rate at specified "strain/deflection" against the corresponding uniaxial strain rate at the same specified strain. The modified MG relationship should correct the increasing error expected at IC test conducted at decreasing loads. To be able to do this the strain rate as a function of time (or strain) should be available for primary creep of the uniaxial test. The corrective impact of the modified MG has to be verified by further analysis and testing.

AB - The measured "minimum" creep rate in the impression creep (IC) test is currently obtained from a "stabilized" deflection rate, and the time to "stabilization" is somewhat arbitrarily chosen at durations up to 500 h, regardless of the applied load. Nevertheless, IC tests have been successfully utilized for aged ½CrMoV and P91 steam line components by conducting tests at the same load so that the deflection rates can directly be compared and used for ranking. By this experience, the IC test is an excellent tool for material ranking and lifing of service exposed material. However, further development in the IC data assessment procedures and the translation between IC and uniaxial test is still needed for determination of the lower stress range material creep properties from the IC test. It is suggested that the deflection rate should be correlated to a Monkman-Grant type relation with the calculated deflection rate at specified "strain/deflection" against the corresponding uniaxial strain rate at the same specified strain. The modified MG relationship should correct the increasing error expected at IC test conducted at decreasing loads. To be able to do this the strain rate as a function of time (or strain) should be available for primary creep of the uniaxial test. The corrective impact of the modified MG has to be verified by further analysis and testing.

M3 - Conference abstract in proceedings

SN - 978-951-38-8029-3

T3 - VTT Technology

SP - 82

BT - Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts

A2 - Auerkari, Pertti

A2 - Veivo, Juha

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Brett SJ, Rantala J, Holmström S. Practical application of impression creep data to power plant. In Auerkari P, Veivo J, editors, Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. Espoo: VTT Technical Research Centre of Finland. 2013. p. 82. (VTT Technology; No. 107).