Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components

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

Abstract

This paper presents a failure assessment diagram (FAD) and crack size based comparison of the ASME BVPC Section XI Nonmandatory Appendix C and Nonmandatory Appendix H and the British Standard BS 7910:2013 Option 1 assessment methods. The Section XI appendix C evaluates the acceptability of a flaw by determining the expected failure mechanism and by comparing the flaw size with allowable flaw size limits or by comparing the applied stress to the allowable stress. The Section XI appendix H and BS7910 employ a FAD based approach that simultaneously considers brittle fracture, ductile crack extension prior to reaching the limit load and exceedance of the limit load due to the gross plasticity in the cross section. The assessment is performed by calculating the assessment point coordinates and evaluating whether the point is located on the safe side of the FAD line. The three methods are compared for simplified austenitic and ferritic pipes under internal pressure and bending loads with postulated axial and circumferential internal surface flaws. The methods are applied to generate limiting flaw size diagrams for each component under the specified loads. Additionally, the limiting flaw size results are presented in the FAD plots. To maintain comparability between the results, identical input data are used with each analysis approach but using the method-specific formulae.The performed comparison shows that most often the limiting state is governed by the 75 % flaw depth rule in Section XI article IWB-3640. The largest differences between the methods are observed for cracks with a high length to depth ratio. The difference to the tabulated allowable planar flaws in Article IWB-3514 is typically high. When increasing the applied load to values approaching the limit load, differences in the limiting flaw sizes between the methods are observed, mostly due to the different limit load models and different assumptions on the utilization of the post-yield capacity. Besides the presented flaw size comparison, the paper presents a quick tool suitable for ranking different piping segments based on failure potential and for quick scoping evaluations of indications found in inspections. The case specific scoping tool is a map of yearly flaw size lines providing the information on which flaw sizes would grow to the final limiting size in a specified timeframe.
Original languageEnglish
Title of host publicationASME 2018 Pressure Vessels and Piping Conference
PublisherAmerican Society of Mechanical Engineers ASME
Number of pages10
Volume3B
ISBN (Print)978-0-7918-5163-0
DOIs
Publication statusPublished - 2018
MoE publication typeNot Eligible
EventASME 2018 Pressure Vessels and Piping Conference, PVP2018 - Hotel Hilton, Prague, Czech Republic
Duration: 15 Jul 201820 Jul 2018
Conference number: 52

Conference

ConferenceASME 2018 Pressure Vessels and Piping Conference, PVP2018
Abbreviated titlePVP2018
CountryCzech Republic
CityPrague
Period15/07/1820/07/18

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Defects
Load limits
Cracks
Brittle fracture
Plasticity
Inspection
Pipe

Cite this

Kuutti, J., & Oinonen, A. (2018). Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components. In ASME 2018 Pressure Vessels and Piping Conference (Vol. 3B). [PVP2018-84276] American Society of Mechanical Engineers ASME. https://doi.org/10.1115/PVP2018-84276
Kuutti, Juha ; Oinonen, Ahti. / Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components. ASME 2018 Pressure Vessels and Piping Conference. Vol. 3B American Society of Mechanical Engineers ASME, 2018.
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abstract = "This paper presents a failure assessment diagram (FAD) and crack size based comparison of the ASME BVPC Section XI Nonmandatory Appendix C and Nonmandatory Appendix H and the British Standard BS 7910:2013 Option 1 assessment methods. The Section XI appendix C evaluates the acceptability of a flaw by determining the expected failure mechanism and by comparing the flaw size with allowable flaw size limits or by comparing the applied stress to the allowable stress. The Section XI appendix H and BS7910 employ a FAD based approach that simultaneously considers brittle fracture, ductile crack extension prior to reaching the limit load and exceedance of the limit load due to the gross plasticity in the cross section. The assessment is performed by calculating the assessment point coordinates and evaluating whether the point is located on the safe side of the FAD line. The three methods are compared for simplified austenitic and ferritic pipes under internal pressure and bending loads with postulated axial and circumferential internal surface flaws. The methods are applied to generate limiting flaw size diagrams for each component under the specified loads. Additionally, the limiting flaw size results are presented in the FAD plots. To maintain comparability between the results, identical input data are used with each analysis approach but using the method-specific formulae.The performed comparison shows that most often the limiting state is governed by the 75 {\%} flaw depth rule in Section XI article IWB-3640. The largest differences between the methods are observed for cracks with a high length to depth ratio. The difference to the tabulated allowable planar flaws in Article IWB-3514 is typically high. When increasing the applied load to values approaching the limit load, differences in the limiting flaw sizes between the methods are observed, mostly due to the different limit load models and different assumptions on the utilization of the post-yield capacity. Besides the presented flaw size comparison, the paper presents a quick tool suitable for ranking different piping segments based on failure potential and for quick scoping evaluations of indications found in inspections. The case specific scoping tool is a map of yearly flaw size lines providing the information on which flaw sizes would grow to the final limiting size in a specified timeframe.",
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Kuutti, J & Oinonen, A 2018, Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components. in ASME 2018 Pressure Vessels and Piping Conference. vol. 3B, PVP2018-84276, American Society of Mechanical Engineers ASME, ASME 2018 Pressure Vessels and Piping Conference, PVP2018, Prague, Czech Republic, 15/07/18. https://doi.org/10.1115/PVP2018-84276

Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components. / Kuutti, Juha; Oinonen, Ahti.

ASME 2018 Pressure Vessels and Piping Conference. Vol. 3B American Society of Mechanical Engineers ASME, 2018. PVP2018-84276.

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

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Kuutti J, Oinonen A. Comparison of ASME XI and BS7910 Allowable Surface Flaw Size Evaluation Procedures in Piping Components. In ASME 2018 Pressure Vessels and Piping Conference. Vol. 3B. American Society of Mechanical Engineers ASME. 2018. PVP2018-84276 https://doi.org/10.1115/PVP2018-84276