Corrosion of a Vertical Shell and Tube Heat Exchanger
Bibliographic record
Abstract
Abstract Inspection revealed severe corrosion of heat exchanger tubes after a short period of service, approximately 2.5 years. A pattern was discovered in comparing metal loss between tubes that were blocked from hot process vapor flow (found to be clogged tubes by polymeric materials), versus the tubes with the most severe wall loss where hot process vapor continued to flow. An investigation was conducted to understand the severe corrosion and its mechanisms. Compared to the internal process side, corrosion was found dominantly on the external cooling water side (shell side of the bundle), with severe wall loss mostly located just underneath the top tube sheet. The severe wall loss of the tubes just beneath the top tube sheet on the cooling water side was due to concentrated corrosive compounds, e.g. sodium chloride, on the tube surface within the empty space, positioned above the cooling water outlet line. For the rest of the tubes, corrosion in the cooling water side was in the form of pits and was the result of tuberculation under deposits. Polymeric materials most likely deposited on the top tube sheet during one single event, with some of the tubes were totally or partially clogged. Deposits of polymers on the top tube sheet were determined to be the major contributor that led to the severe corrosion, with the severe corrosion occurring on the un-clogged tubes where the hot process vapor continued to flow. To mitigate the corrosion, improve operation reliability, and increase the service life of this heat exchanger, it was recommended that the empty space close to the top tube sheet be eliminated by modifying the water exit so that the upper space would always remain completely flooded, and the metallurgy of the tubes be upgraded to a more corrosion resistant duplex stainless steel type alloy.
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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 | 0.000 | 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 | 0.001 |
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".