Oxygen Reactor External Stress Corrosion Cracking and Repair
Bibliographic record
Abstract
Abstract External stress corrosion cracking (ESCC) was found on two solid 316L stainless steel oxygen reactors that had been in service for 10 years in a pulp and paper mill in eastern Canada. Both reactors had been designed to Section VIII, Division 1 of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code for service under internal pressure and with external circumferential stiffeners for protection against vacuum. ESCC was found beneath wet thermal insulation on the top head and where water had collected on the circumferential stiffeners, but was most severe where water had gained access behind external reinforcing rings for the circumferential stiffeners. Crack depths up to ½ inch (13 mm) deep were encountered in the 316L shell although no cracks went completely through to the process side. Shallow stress corrosion cracking (SCC) was also observed on the process side near the bottom cylinder-to-cone transition. All external and internal cracks were removed by grinding. The National Board Inspection Code (NBIC) was used to evaluate the locations of grinding that went below the minimum values permitted by the ASME Code. Some locations were deemed acceptable to be left as-is, other locations of deeper grinding were built up using type ER309L stainless steel weld metal, and 316L flush patches were installed in locations where extensive grinding below Code minimum had been necessary to remove the cracks. Both reactor shells were restored to a safe condition for the design pressure and new circumferential stiffeners with taller reinforcing rings were installed before the reactors were re-insulated and returned to service.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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) | 0.002 | 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".