FEA of Nozzle N2 and Half Skirt for D21 Lift Knock Out Pot (ASME VIII Div.2)
1. The Engineering Challenge
A high-pressure D21 Lift Knock Out Pot requires comprehensive nozzle and skirt stress evaluation per ASME VIII Div.2 Part 5 across 9 load cases including transport.
- MAWP 16.67 MPa at 100°C
- 9 load cases including 4 transportation
- Nozzle N2 – critical junction
- Half skirt support evaluation
- 7 tonnes operating weight
| Parameter | Value |
| Design Code | ASME VIII Div.2 Class 2, Ed. 2023 |
| Design Temperature | 100 / -20 °C |
| MAWP | 16.67 MPa |
| Design Pressure (Int) | 16.5 MPa |
| Hydrotest Pressure | 23.827 MPa |
| Operating Pressure | 8.6 / 6.2 MPa |
2. FEA Model
Figure 1: Model with GA Drawing
| Metric | Target | Status | Notes |
| Aspect Ratio | < 5.0 | ✓ Pass | Within acceptable limits |
| Jacobian Ratio | < 30 | ✓ Pass | Good element quality |
| Skewness | < 0.95 | ✓ Pass | Acceptable |
| Element Quality | > 0.5 | ✓ Pass | Good |
3. Results Preview
Figure 2: Stress at Skirt-Dishend Junction
Figure 3: Boundary Conditions
Key Takeaways
- All 9 Load Cases PASS: Design, operating, empty, hydrotest, and all 4 transportation load cases satisfy ASME limits.
- Nozzle N2 – Critical Location: Highest utilization of 96.8% at Nozzle N2 under LC-1 (MAWP), confirming tight but safe design.
- Transportation Loads Verified: All 4 transportation LCs (uplift/downward + roll/pitch) pass with max PL of 130.93 MPa vs 262 MPa allowable.
- SCL Method Validated: Stress Categorization Lines at every critical location – membrane + bending stresses well within ASME limits.
Download the Full Technical Case Study
The complete engineering report includes:
- Full 3D CAD and FEA model details
- Complete stress contour plots for all load cases
- Stress linearization diagrams
- Buckling mode shapes
- Sway rod force analysis and turn buckle validation
- Foundation reaction forces
- ASME compliance documentation