Hydrogen Embrittlement in Titanium and Superferritic Stainless Steel Steam Surface Condenser Tubing
Bibliographic record
Abstract
Abstract Embrittlement or hydriding of titanium and superferritic stainless steel steam surface condenser tubing can occur when solubility limits of nascent hydrogen are exceeded. The results of such an excursion can, in the case of titanium, induce the formation of brittle hydrides or, in the case of superferritic stainless steels, which typically do not form stable hydrides, result in reduced ductility and subsequent fracture attack. In either case, both corrosion events can ultimately lead to a loss of structural integrity of the material. Additional contributing factors may include elevated temperature, pH extremes and other parameter anomalies. However, since the typical powerplant steam surface condenser tube/tubesheet interface is continually passivated by circulating water, (CIRH20) and the operating temperatures remain relatively low, the solubility limit of hydrogen is rarely threatened. Indeed, the mere existence of hydrogen embrittlement in a surface condenser environment has been infrequent reportedly occurring only several times over the past 40+ years of powerplant condenser tube service. Conversely, industries such as the chemical process industry (CPI), which can expose the heat exchanger to elevated temperatures, pH extremes and high levels of hydrogen charging without the benefit of passivation have reported hydrogen embrittlement damage. Notwithstanding the infrequency of this form of corrosion in powerplant condenser service, recently identified activity has surfaced that warrants further investigation of this phenomenon related to both stainless steel and titanium tubing. As a result of these recent events, the paper will identify and research multiple case studies associated with hydrogen embrittlement. An in-depth investigation of each will provide a practical benchmark for future lessons learned operating experience. Since there appears to be a common denominator to most if not all of the reported hydrogen damage, the paper will attempt to clear the air in terms of apparent confusion surrounding merely the innocuous hydrogen charging of certain materials vs. actual embrittlement damage.
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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 | 0.000 | 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) | 0.001 | 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".