Indicators for Coke Drum Replacement Due to Bulge-Induced Damage
Bibliographic record
Abstract
Abstract Replacement of coke drums is a major project that requires a significant investment and at least 3 or 4 years of planning. One of the leading causes of drum replacement has been the cost associated with repairs and unexpected shutdowns due to bulge-induced damage. An assessment of the total area of bulge-induced damage in 10 coke drums from two refineries (Sites A and B) that are conducting replacement projects is shown as an example of parameters that can be identified and tracked over the life span of the vessel. The Local Plastic Strain Indicator, abbreviated as LPSI, is used as a methodology to quantify and track the evolution of bulged areas and surface damage found during laser mapping and remote visual inspections. LPSI identifies and ranks bulges prone to local failures using plastic strain calibrated against bulges that developed internal or external bulge-induced damage. The LPSI is the ratio of the plastic strain found at the point being analyzed to the calibrated strain limit found at points where through-wall cracks occurred due to bulging, in a percentage form. Using LPSI to find the surface area of the drum cylinder that is bulged is a novel concept. Results show how total bulged area and the area with elephant skin surface damage increases over time, reaching the point where repairs are required to stop bulge growth and maintain safe operations. Eventually the accumulated bulging, surface damage, and amount of repairs required reach the point where the cost and potential for unexpected shutdowns leads to vessel replacement. Examples are provided to assist refiners in understanding how to assess their own drums.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.005 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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".