Technical Basis for ASME Code Section XI Nonmandatory Appendix C Update

Guzman-Leong, Consuelo E.; Udyawar, Anees

doi:10.1115/pvp2017-65058

Cited by 2 publications

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“…While stress‐intensity factor solutions for circumferential through‐wall cracks in cylindrical shells subjected to tension and bending have been extensively studied in the past, few solutions exist for a shell subjected to torsion, even though both tubular members in offshore structures (eg, jacket structures) and power plant piping may be subjected to torsional loads. A jacket or fixed steel platform is a trusswork tower consisting of tubular members with piles into the seabed, and a topside, used, eg, for oil and gas production.…”

Section: Introductionmentioning

confidence: 99%

Stress intensity factors for circumferential through‐wall cracks in thin‐walled cylindrical shells subjected to tension and torsion

Rege

Pavlou

2019

Fatigue Fract Eng Mat Struct

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In order to assess the structural integrity of tubular members or pipes containing circumferential through‐wall cracks, their stress intensity factor solutions are required. While stress intensity factors for tension and bending are available, few solutions exist for the case of torsion, even though these components may also be subjected to torque. In this paper, the finite element method is used to compute the stress intensity factors for this geometry under tension and torsion. Shell elements are employed to compute the results for thin shells by the means of the displacement extrapolation technique. The computed results indicate that the available analytical solution for torsional loading, which is based on shallow shell theory, is nonconservative for long cracks in thin shells. Shallow shell theory is in general not applicable to long cracks, and the present work is therefore able to provide solutions for a wider range of crack lengths than what is currently available.

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Section: Introductionmentioning

confidence: 99%

Stress intensity factors for circumferential through‐wall cracks in thin‐walled cylindrical shells subjected to tension and torsion

Rege

Pavlou

2019

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

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Load sequence effects and mixed-mode fatigue crack growth in offshore structures

Rege¹

2020

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The total fatigue life of a brace in an offshore jacket structure is conventionally considered in four parts. N 1 is the number of cycles to initiate the first discernible surface cracking as noted by any available method. N 2 is the number of cycles to detect surface cracking by visual examination without the use of crack enhancement or optical aids. N 3 is the number of cycles until the first through wall cracking and N 4 is the total number of cycles to the end of test or final separation of the member. The majority of fatigue tests conducted on tubular connections or on girth welds in brace members obtained only N 3 results, it being common practice to stop testing when a through wall crack was present. In the HSE Guidance the S-N curves for tubular connections and girth welds in braces are therefore based on N 3 data. (In fact it should be noted here that there were very few test results for single sided girth welds available at the time of drafting the HSE guidance; the choice of Class F2 for these joints was therefore based largely on judgement rather than data). In UK waters, flooded member detection (FMD) by ultrasonic inspection with a remotely operated vehicle is used to check whether through cracks are present; however, in practice, fatigue cracks are likely to continue to grow around the brace circumference after breaking through-wall. A review by Sharp (Ref.1) concluded that detailed knowledge of the crack shape development after breakthrough together with a value for the ratio N 4 /N 3 are required. From the structural safety viewpoint, there is clearly a need to quantify the rate of fatigue crack growth after development of a through wall crack, but prior to the point at which final separation becomes a possibility. The present study was designed to examine these factors for circumferential welds in tubular members, and hence allow the efficacy of the FMD strategy to be assessed. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy. HSE BOOKS

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Technical Basis for ASME Code Section XI Nonmandatory Appendix C Update

Cited by 2 publications

References 0 publications

Stress intensity factors for circumferential through‐wall cracks in thin‐walled cylindrical shells subjected to tension and torsion

Stress intensity factors for circumferential through‐wall cracks in thin‐walled cylindrical shells subjected to tension and torsion

Load sequence effects and mixed-mode fatigue crack growth in offshore structures

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