Technical Basis for Proposed Code Case on Evaluation of Flaws in Butt Fusion Joints in Class 3 High Density Polyethylene Piping
Bibliographic record
Abstract
Abstract There is a need for ASME B&PV Code procedures and acceptance criteria for evaluation of flaws detected by inspection of high density polyethylene (HDPE) piping items in safety Class 3 systems. A Section XI Code Case is proposed to evaluate circumferentially orientated planar flaws in butt fusion joints in PE4710 HDPE pipes with a parent material minimum PENT rating of 2,000 hours. The proposed Code Case contains flaw evaluation procedures and acceptance criteria for both surface and subsurface flaws. Two sets of acceptance criteria that are in terms of the allowable stress intensity factor and the allowable flaw size are provided in the proposed Code Case. The calculation of the allowable stress intensity factor is based on the statistical model documented in the paper PVP2020-21783. The model was developed for predicting the time to failure of a butt fusion joint containing a flaw in an HDPE pipe with a parent material PENT rating of 10,000 hours. This paper provides the technical basis for the application of the statistical model to flaws in butt fusion joints in HDPE pipes with a parent material PENT rating between 2,000 and 10,000 hours. For a piping lifetime of 50 years, simplified engineering equations to calculate the allowable stress intensity factor have been developed, and example calculations of the allowable flaw sizes at the maximum Service Level A & B Code allowable temperature of 60°C (140°F) and the stress level of 500 psi (3.45 MPa) are also provided in this paper.
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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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".