Steel Corrosion under a Disbonded Coating with a Holiday—Part 1: The Model and Validation
Bibliographic record
Abstract
A model was developed to investigate the corrosion of a coated pipeline surface in a thin, narrow channel crevice formed between the pipe surface and the coating. Such crevices are often found on natural gas pipelines when the coating is high-density polyethylene (HDPE). Imposed cathodic protection current passage through the holiday and oxygen diffusion through both the holiday and the coating were included in the model. The effect of the corrosion product, ferrous hydroxide (Fe[OH]2), on the transport of oxygen and ionic species in the crevice solution was neglected because it is porous. Mass balance for oxygen pressure and Laplace’s equation for the steel potential in the crevice solution were used to derive the model equations. For a crevice solution with uniform pH and uniform resistivity, the model equations were solved using a collocation technique programmed in MATLAB. This new model was validated with published experimental data and model results—good agreement was found.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".