±
Why can thermal stress be negative?
The app uses Δt = Tmetal − Tsteam. During heat-up, steam normally leads the mean metal temperature, so Δt and bore thermal stress are negative (compression). The governing PDF’s cold-start annexure shows −272.71 MPa. Fatigue uses the full signed stress range; replacing Δt with ABS(Δt) gives the wrong cycle.
The app uses Δt = Tmetal − Tsteam. During heat-up, steam normally leads the mean metal temperature, so Δt and bore thermal stress are negative (compression). The governing PDF’s cold-start annexure shows −272.71 MPa. Fatigue uses the full signed stress range; replacing Δt with ABS(Δt) gives the wrong cycle.
Analysed
—
configured components
Alarm / Watch
—
deterministic status
Life status
—
no unsupported percentage
Advisory mode
—
AI is optional
Component stress status
Equation 6 signed tangential stress = pressure + thermal
Load a dataset and run the analysis.
Governing-document cold-start benchmark
Annexure 2, T92 header/stub geometry. This test is recomputed by the application on every verification run.
| Quantity | Document | Calculated | Check |
|---|
NIMS Grade 91 tube creep-reference validation
Mean material-data regression only. It is not an EN 12952 allowable, a weldment curve, or a commissioned remaining-life result.
Loading benchmark…