Overview of Stage 1b Stress Corrosion Crack Initiation and Growth of Pipeline Steels
Bibliographic record
Abstract
Stress corrosion cracking (SCC) can cause catastrophic failure of buried pipelines for oil and gas transmission. The life cycle of pipeline steels experiencing SCC consists of five stages: incubation stage, stage 1a (crack initiation), stage 1b (early-stage crack growth), stage 2 (sustainable crack growth caused by mechanical driving force), and stage 3 (rapid crack propagation to rupture). Stage 1b encompasses a large portion of the pipeline’s lifespan, which is of great significance to pipeline integrity management aimed at service life extension. However, this stage is less studied so far. This invited paper provides a brief review of the recent progress on stage 1b stress corrosion crack initiation and growth for buried pipeline steels. Emphasis is placed on the effects of loading conditions and their interactions on stage 1b growth of high pH SCC, while some progress of near-neutral pH SCC is included for the purpose of comparison. It first introduces SCC in pipeline steels which is followed by a definition of stage 1b and its significance in terms of the service life of pipeline steels. Then the most recent advancements in understanding early-stage crack growth in stage 1b are reviewed and discussed. In summary, stage 1b growth can be self-induced by existing cracks (the so-called mother-daughter analogy), involving crack initiation in the plastic zone ahead of the surface tip of a surface crack, which is quite different from the stochastic process of coalescence of randomly formed individual cracks. Stage 1b growth extends crack length and increases the stress intensity factor at the depth tip without a physical increase in crack depth, serving as a bridge to stage 2. Further, the need for future research on stage 1b SCC initiation and growth of pipeline steels is 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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.006 |
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".