Effect of Adjacent Tube Expansion on the Residual Contact Pressure of Tube-to-Tubesheet Joints
Bibliographic record
Abstract
The tubular heat exchangers of nuclear, oil and gas industries often experience shutdowns due to failures of the tube-to-tubesheet joints. They are the very weak link between the heat transfer process thermos-fluids and separation boundary. The complex elasto-plastic behavior of the expanded joint and the lack of a proper design procedure of the expansion process are the two main factors contributing to the low quality and low performance of this kind of assembly. The inadequacy of a proper evaluation of the residual contact pressure achieved by the expansion process make the joint vulnerable and prone to leakage failure. Among the multiple parameters that effect the residual contact pressure is the adjacent tube-to-tubesheet expansion. It is proposed to study the elasto-plastic behavior of tube-tube to tubesheet joints during the expansion process using numerical FEM. The numerical FE model will be validated analytically prior to study the influence of adjacent expansion. Particular emphasis will be put on the effect of adjacent tube expansion and the expansion order sequence on the residual contact pressure. The effect of ligament size and the adjacent tube expansion sequence are also investigated. Such a study would provide general guidelines on how to control the expansion process and help the design engineer to predict accurately the residual stresses that are the major source of stress corrosion cracking and leakage failure.
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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 | 0.002 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".