Reliability and Life Assessment of Coke Drums Through Boat Sample-Based Testing
Bibliographic record
Abstract
Abstract Life assessment of coke drums is vital to prevent circumferential through-wall cracking and to ensure it’s safe and serviceable. Cracking in the shell/skirt-shell junction/welds, permanent distortion, and bulging (due to the ratcheting effect) are common damage mechanisms due to low cycle thermal fatigue. The difficulties in performing an insightful inspection and life assessment are limited by the wall thickness, location heterogeneity due to service conditions, and test methods. In this study, a boat sample-based testing procedure is developed for the life assessment of coke drums. The boat samples are extracted from four different locations named crack, bulge, notch, and benchmark from a 40-year serviced coke drum. The boat samples are machined for sub-size smooth tensile, notched tensile, low-cycle fatigue, and Charpy toughness specimens. Smooth tensile, notched tensile and low-cycle fatigue tests are performed at three test temperatures (room temperature, 250°C, and 480°C). The results of sub-size specimens are calibrated to full-size and compared with the knuckle plate (least temperature in the coke drum). The fracture toughness of boat samples is predicted by the Haggag method using the smooth tensile and metallographic results. The boat samples have gained strength but have a reduction in ductility and toughness compared with knuckle plate material. The boat samples have shown a change in the microstructure and hardness. Carbide precipitation is observed on the grain boundaries and within the ferrite grains. This precipitation might have reduced the ductility and toughness.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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) | 0.000 | 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 teacher head, 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".