Effects of Fatigue Parameters on Fatigue Crack Growth Rate of Pipe Steels and Girth Weld
Bibliographic record
Abstract
Abstract Oil and gas pipeline steels and welds are subjected to a wide variety of cyclic loadings: internal pressure variation, pulsation of gas pressure resulting from the cyclic operation of a reciprocating compressor at a gas compressor station, internal flow-induced vibration resulting from the turbulent flow within the pipe, vortex-induced vibration of a free-spanning section exposed to air (wind) for aboveground pipelines or water for water-crossing pipelines, and cyclic thermal stresses developed by significant changes in temperature due to seasonal changes or changes in operating temperatures. These cyclic loadings are very variable and complex. Considering the fatigue situations, a better understanding of the effects of fatigue test parameters on fatigue behaviors of pipeline steels and welds is required. Hence, in this study, the influences of fatigue test parameters on the Paris law coefficients were studied for pipeline steels and welds. It was analyzed for pipe steels of X65∼X100 and a girth weld of X70. Influences of material strength, crack orientation relative to the pipe axis, and frequency in the range of 1∼30 Hz were insignificant. It was found that the coefficients a1 and b2 of the m-ln(C) relationships linearly relied on the load ratio. The constants (α1, β1, α2, and β2) of these linear relationships between R-ratio and a1 (and b2) were determined for pipe steels.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".