Corrosion Fatigue and Near-Neutral pH Stress Corrosion Cracking of Pipeline Steel in Very Dilute Carbonate/Bicarbonate with and without the Presence of Hydrogen Sulfide Using the Compliance Technique
Bibliographic record
Abstract
Abstract Crack advance has been studied in a X-70 pipeline steel, using the compliance technique. The electrolyte was very dilute brine bubbled with 10% carbon dioxide. Cracking rates were studied at a range of frequencies and R-values. The R-values simulated typical high-pressure gas service, but the frequency used was significantly higher. Similar testing was carried out in the presence of a 1% hydrogen sulfide using the Shell Canada sour gas test facility. The crack advance observed in dilute brine bubbled with 10% carbon dioxide could be explained using the rates of corrosion fatigue and a threshold ΔK of WMPa√m. If we extrapolate the results to much lower frequency then crack advance in the pipelines that is attributed to near-neutral pH stress corrosion cracking could also be explained as corrosion fatigue provided the ΔK at about R=0.65 exceeds this threshold value. Since the extrapolation is over at least two orders of magnitude in frequency this requires further experimental confirmation. The effect of 1% hydrogen sulfide was to dramatically increase the cracking rate at the tested frequencies.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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 | 0.000 |
| 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".