Quantitative Evaluation of Indirect Inspection Reliability and Pipeline Reliability Based on Statistical Methods
Bibliographic record
Abstract
To support an External Corrosion Direct Assessment (ECDA), Indirect Inspections were performed on a 44 km section of NPS 6 extruded polyethylene coated natural gas pipeline. Based on previous investigations of the pipeline, external corrosion defects were known to have occurred at coating holidays. Such holidays can often be detected using current voltage gradient surveys and close interval surveys. Two successive ACVG surveys over the pipeline were preformed. In addition, Close Interval Survey data were considered in order to complete the Indirect Inspection dataset. Statistical analysis methods were developed and employed against the data generated from these surveys so that the following objectives could be met: 1. Assess the reliability of the Indirect Inspection technique in terms of its ability to locate coating holidays and hence, its ability to locate potential corrosion features; and, 2. Assess, in quantitative terms, the reliability of the pipeline in terms of its potential for failure, and quantitatively establish the impact that the Indirect Inspection and dig program had in improving that reliability. In completing the first objective, duplicate survey results were compared with Direct Examination results. The statistical analysis provided a means of estimating technique reliability, which was conservatively estimated at 96%. Subsequent evaluation of factors affecting technique reliability indicated that the density of indications and consistency of applying the Indirect Inspection technique had a bearing on the overall reliability. The second objective was completed by applying the results of the Indirect Inspection reliability study to a statistical analysis of corrosion incidence data and corrosion size distributions that were derived from the Direct Examination data. Pipeline reliability was quantitatively expressed as a function of year of operation and the reliability of the Indirect Inspection technique. For the case examined, the Indirect Inspection techniques that were applied were found to increase pipeline reliability by approximately an order of magnitude.
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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 | 0.044 | 0.133 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.009 | 0.007 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| 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".