DL-EPR measurements on a sensitised Type 304 stainless steel pipe section

Research output: Book/ReportReport

Abstract

lntergranular stress corrosion cracking has been the most frequent failure mode in BWR primary piping. Modern, low carbon stainless steels, improved welding and water chemistry has reduced the amount of IGSCC drastically. Simultaneously the need for investigations on sensitisation has decreased. This could cause a lack of knowledge transfer which could be harmful should the problem arise again. The SAFIR 2014 ENVIS project got permission to use a pipe section from a BWR steam line, suffering from IGSCC, for measurements on the degree of sensitisation. The intentions were twofold: to transfer the knowledge on IGSCC sensitisation measurements from the main investigator (who performed these measurements in the ao·s for BWR primary piping) to the younger generation, and to actually measure the degree of sensitisation as a function of distance from the weld fusion line. Both objectives were achieved, and this report summarises the results. The performed DL-EPR measurements showed that the SS2333 material (Type 304) is slightly sensitised. The highest values were measured at a distance of 6.25 mm from the fusion line. The crack in the pipe was located still further away from the fusion line, between 7 and 12 mm. That the highest DL-EPR value was measured closer to the fusion line than the location of the crack is understandable, since the crack was located in a region where the most severe repair had been performed (based on the appearance of the weld.) The DL-EPR measurements, again, where measured from a region without a crack, and with less severe repair welding. The results show also that intergranular stress corrosion cracking is the result of the three parameters, stress, material and environment. In this case, sensitisation has played a role, but the probably high residual stresses from the repairs during the assembly welding, was likely also been decisive. The third factor, the environment, is involved since the steam environment is oxidising.
Original languageEnglish
PublisherVTT Technical Research Centre of Finland
Number of pages19
Publication statusPublished - 2014
MoE publication typeD4 Published development or research report or study

Publication series

SeriesHelsinki University of Technology: Systems Analysis Laboratory. A: Research Reports
NumberVTT-R-05905-14

Fingerprint

Steel pipe
Paramagnetic resonance
Stainless steel
Fusion reactions
Cracks
Welding
Repair
Stress corrosion cracking
Welds
Pipe
Steam piping systems
Failure modes
Carbon steel
Residual stresses
Steam
Water

Keywords

  • stainless steel
  • sensitisation
  • DL-EPR

Cite this

Autio, J-M., & Ehrnsten, U. (2014). DL-EPR measurements on a sensitised Type 304 stainless steel pipe section. VTT Technical Research Centre of Finland. Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, No. VTT-R-05905-14
Autio, Juha-Matti ; Ehrnsten, Ulla. / DL-EPR measurements on a sensitised Type 304 stainless steel pipe section. VTT Technical Research Centre of Finland, 2014. 19 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05905-14).
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abstract = "lntergranular stress corrosion cracking has been the most frequent failure mode in BWR primary piping. Modern, low carbon stainless steels, improved welding and water chemistry has reduced the amount of IGSCC drastically. Simultaneously the need for investigations on sensitisation has decreased. This could cause a lack of knowledge transfer which could be harmful should the problem arise again. The SAFIR 2014 ENVIS project got permission to use a pipe section from a BWR steam line, suffering from IGSCC, for measurements on the degree of sensitisation. The intentions were twofold: to transfer the knowledge on IGSCC sensitisation measurements from the main investigator (who performed these measurements in the ao·s for BWR primary piping) to the younger generation, and to actually measure the degree of sensitisation as a function of distance from the weld fusion line. Both objectives were achieved, and this report summarises the results. The performed DL-EPR measurements showed that the SS2333 material (Type 304) is slightly sensitised. The highest values were measured at a distance of 6.25 mm from the fusion line. The crack in the pipe was located still further away from the fusion line, between 7 and 12 mm. That the highest DL-EPR value was measured closer to the fusion line than the location of the crack is understandable, since the crack was located in a region where the most severe repair had been performed (based on the appearance of the weld.) The DL-EPR measurements, again, where measured from a region without a crack, and with less severe repair welding. The results show also that intergranular stress corrosion cracking is the result of the three parameters, stress, material and environment. In this case, sensitisation has played a role, but the probably high residual stresses from the repairs during the assembly welding, was likely also been decisive. The third factor, the environment, is involved since the steam environment is oxidising.",
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Autio, J-M & Ehrnsten, U 2014, DL-EPR measurements on a sensitised Type 304 stainless steel pipe section. Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports, no. VTT-R-05905-14, VTT Technical Research Centre of Finland.

DL-EPR measurements on a sensitised Type 304 stainless steel pipe section. / Autio, Juha-Matti; Ehrnsten, Ulla.

VTT Technical Research Centre of Finland, 2014. 19 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05905-14).

Research output: Book/ReportReport

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N2 - lntergranular stress corrosion cracking has been the most frequent failure mode in BWR primary piping. Modern, low carbon stainless steels, improved welding and water chemistry has reduced the amount of IGSCC drastically. Simultaneously the need for investigations on sensitisation has decreased. This could cause a lack of knowledge transfer which could be harmful should the problem arise again. The SAFIR 2014 ENVIS project got permission to use a pipe section from a BWR steam line, suffering from IGSCC, for measurements on the degree of sensitisation. The intentions were twofold: to transfer the knowledge on IGSCC sensitisation measurements from the main investigator (who performed these measurements in the ao·s for BWR primary piping) to the younger generation, and to actually measure the degree of sensitisation as a function of distance from the weld fusion line. Both objectives were achieved, and this report summarises the results. The performed DL-EPR measurements showed that the SS2333 material (Type 304) is slightly sensitised. The highest values were measured at a distance of 6.25 mm from the fusion line. The crack in the pipe was located still further away from the fusion line, between 7 and 12 mm. That the highest DL-EPR value was measured closer to the fusion line than the location of the crack is understandable, since the crack was located in a region where the most severe repair had been performed (based on the appearance of the weld.) The DL-EPR measurements, again, where measured from a region without a crack, and with less severe repair welding. The results show also that intergranular stress corrosion cracking is the result of the three parameters, stress, material and environment. In this case, sensitisation has played a role, but the probably high residual stresses from the repairs during the assembly welding, was likely also been decisive. The third factor, the environment, is involved since the steam environment is oxidising.

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Autio J-M, Ehrnsten U. DL-EPR measurements on a sensitised Type 304 stainless steel pipe section. VTT Technical Research Centre of Finland, 2014. 19 p. (Helsinki University of Technology: Systems Analysis Laboratory. A: Research Reports; No. VTT-R-05905-14).