Role of Axial Stress in Pipeline Integrity Management
Bibliographic record
Abstract
Abstract In pipeline integrity management, axial stress solely can be a detrimental condition, and it may play an important role in assessment of other threats. Current practice for the assessment of integrity features such as external metal loss, deformation and stress corrosion cracking (SCC) are based on methods validated by burst testing that primarily consider hoop stress to be the maximum principal stress which governs. Observations during recent integrity management practice, however, indicate that axial stress plays an important role in pipeline failures when interacting with integrity features under certain circumstances, and should be carefully considered in integrity engineering assessment. Multiple real-life case studies are described to illustrate the importance of proper consideration of axial stress in integrity management, including: 1) axial compressive stress induced global buckling, 2) yielding of small radius fitting under axial stress, 3) ductile overloading due to axial tensile stress interacting with circumferentially oriented corrosion feature, 4) axial tensile stress and its relationship with formation of circumferential stress corrosion cracking. The details of the case studies, results and findings are summarized in this paper. Determining axial stress for integrity assessment can be critical, depending on site-specific conditions and nature of the loading. In this paper, a multi-level method for calculating axial stress based on finite element analysis (FEA) using various elements and techniques, combined with bending strain measured by in-line inspection (ILI) is described. In addition, a simplified approach for interacting threat analysis with continuum FEA and a simplified assessment based on empirical equations are proposed and discussed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".