Investigation into Possible AC Corrosion from a Cathodic Protection Groundbed
Bibliographic record
Abstract
Abstract This case study involves an investigation into corrosion anomalies on a 4 km long NPS 6 liquid pipeline that interconnects two facilities in an urban setting. An in-line inspection (ILI) in 2017 identified 70 external corrosion anomalies, with two of them exceeding 55% wall loss. An additional five corrosion anomalies had been previously repaired. Recent annual cathodic protection (CP) surveys, and a close-interval potential survey conducted in 2015, all indicate good cathodic protection levels along the line. AC voltages as high as 6 V were measured along the pipeline and were initially thought to be related to a 0.6 km parallel with a high voltage powerline. AC coupons were installed and AC current densities of up to 1400 A/m2 and DC current densities of 2100 A/m2 were recorded in this area, indicating a severe AC corrosion risk. Waveforms indicated that most of the AC voltage was 120 Hz frequency, and that very little of the AC voltage was related to the fundamental 60 Hz powerline frequency. This paper discusses the testing performed to confirm the source of the elevated AC current densities and quantify the associated corrosion risk. The mitigation strategy employed to address this risk is provided.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".