ReddRadar
Agent skill
pressure-vessel
Skill for pressure vessel design and analysis per ASME BPVC
Install this agent skill to your Project
npx add-skill https://github.com/a5c-ai/babysitter/tree/main/library/specializations/domains/science/mechanical-engineering/skills/pressure-vessel
Metadata
Additional technical details for this skill
- phase
- 5
- domain
- science
- category
- structural-analysis
- priority
- medium
- specialization
- mechanical-engineering
- tools libraries
-
[ "COMPRESS", "PVElite", "ANSYS", "ASME BPVC" ]
SKILL.md
Pressure Vessel Design Skill
Purpose
The Pressure Vessel Design skill provides capabilities for designing and analyzing pressure vessels per ASME Boiler and Pressure Vessel Code, ensuring code compliance and safe operation.
Capabilities
- ASME Section VIII Division 1/2 compliance
- Shell and head thickness calculations
- Nozzle reinforcement analysis
- Flange rating and selection
- Hydrostatic test specification
- MDMT (Minimum Design Metal Temperature) determination
- Stress classification and evaluation
- U-stamp documentation support
Usage Guidelines
ASME Section VIII Overview
Division Comparison
| Aspect | Division 1 | Division 2 |
|---|---|---|
| Design basis | Design-by-rule | Design-by-analysis |
| Allowable stress | Lower | Higher |
| Safety factor | 3.5 (UTS) | 2.4 (UTS) |
| Analysis required | Limited | Detailed FEA |
| Typical application | General service | High pressure, critical |
Shell and Head Design
Cylindrical Shell (Division 1)
Internal pressure:
t = (P * R) / (S * E - 0.6 * P)
External pressure:
t = iterative based on L/D_o and D_o/t
Where:
t = required thickness
P = design pressure
R = inside radius
S = allowable stress
E = joint efficiency
Head Types
| Type | Stress Ratio | Application |
|---|---|---|
| Hemispherical | 0.5 | High pressure |
| 2:1 Elliptical | 1.0 | General purpose |
| Torispherical | 1.77 | Low pressure |
| Flat | Variable | Limited pressure |
| Conical | Variable | Transitions |
2:1 Elliptical Head
t = (P * D) / (2 * S * E - 0.2 * P)
Where:
D = inside diameter
S = allowable stress
E = joint efficiency
Nozzle Reinforcement
Area Replacement Method
Required reinforcement area:
A = d * t_r * F
Where:
d = finished nozzle diameter
t_r = required shell thickness
F = correction factor for plane
Available area from:
- Excess shell thickness (A1)
- Excess nozzle thickness (A2)
- Reinforcing pad (A3)
- Weld area (A4, A5)
Criterion: A1 + A2 + A3 + A4 + A5 >= A
Reinforcement Limits
Horizontal limit: d or R + t_n + t
Vertical limit (shell): d or R + t_n + t
Vertical limit (nozzle): 2.5 * t_n or 2.5 * t + t_e
Flange Design
Flange Types
| Type | Rating | Application |
|---|---|---|
| Slip-on | 150-600 lb | General, lower pressure |
| Weld neck | 150-2500 lb | High pressure, critical |
| Socket weld | 150-600 lb | Small bore |
| Blind | 150-2500 lb | Closures |
| Lap joint | 150-600 lb | Corrosive service |
Flange Rating
ASME B16.5 pressure-temperature ratings:
- Class 150, 300, 600, 900, 1500, 2500
Select class where:
P_design <= P_rating at T_design
MDMT Determination
Impact Test Exemption
Impact test required if:
T_design < MDMT
MDMT determination:
1. Base MDMT from UCS-66 curves
2. Adjust for actual stress ratio
3. Consider coincident ratio
4. Apply Table UCS-66.1 reduction
Stress ratio reduction:
MDMT_adjusted = MDMT - temperature credit
Impact Test Requirements
If impact testing required:
- Test temperature <= MDMT - 30 F (typical)
- Minimum energy: 15 ft-lb (full size Charpy)
- Average of 3 specimens
- Single specimen minimum: 10 ft-lb
Hydrostatic Test
Test Pressure
Division 1:
P_test = 1.3 * MAWP * (S_test / S_design)
Division 2:
P_test = 1.43 * MAWP * (S_test / S_design)
Where:
MAWP = Maximum Allowable Working Pressure
S_test = allowable stress at test temperature
S_design = allowable stress at design temperature
Test Procedure
1. Fill vessel completely with water
2. Remove all air pockets
3. Apply test pressure slowly
4. Hold for minimum 10 minutes
5. Reduce to MAWP for inspection
6. Inspect all welds and connections
7. Document results
Stress Classification (Division 2)
Stress Categories
| Category | Symbol | Limit |
|---|---|---|
| General membrane | Pm | S |
| Local membrane | PL | 1.5S |
| Bending | Pb | 1.5S |
| Secondary | Q | 3S |
| Peak | F | Fatigue analysis |
Stress Combinations
Primary stress:
Pm <= S
PL <= 1.5S
PL + Pb <= 1.5S
Primary + Secondary:
PL + Pb + Q <= 3S
Fatigue:
Use peak stress F in fatigue curves
Code Compliance Documentation
U-1 Data Report
Required information:
- Manufacturer identification
- Vessel description and design data
- Material specifications
- Joint efficiencies
- Inspection data
- Test data
- Stamping information
Process Integration
- Related to structural analysis processes for pressure equipment
Input Schema
{
"vessel_type": "pressure|vacuum|combined",
"design_conditions": {
"pressure": "number (psig or barg)",
"temperature": "number (F or C)",
"MDMT": "number (F or C)"
},
"geometry": {
"diameter": "number",
"length": "number",
"head_type": "elliptical|hemispherical|torispherical|flat"
},
"material": {
"shell": "string (SA-XXX)",
"heads": "string",
"nozzles": "string"
},
"code_edition": "string",
"division": "1|2"
}
Output Schema
{
"design_summary": {
"MAWP": "number",
"required_thicknesses": {
"shell": "number",
"heads": "number"
},
"selected_thicknesses": "object"
},
"nozzle_schedule": [
{
"size": "string",
"purpose": "string",
"reinforcement": "object"
}
],
"MDMT_evaluation": {
"MDMT": "number",
"impact_test_required": "boolean"
},
"hydrostatic_test": {
"test_pressure": "number",
"test_procedure": "string"
},
"code_compliance": {
"paragraph_references": "array",
"calculation_summary": "object"
},
"drawings_required": "array"
}
Best Practices
- Always use current code edition
- Verify material availability and certification
- Consider corrosion allowance
- Check MDMT early in design
- Coordinate with authorized inspector
- Document all design decisions
Integration Points
- Connects with Material Selection for appropriate materials
- Feeds into FEA Structural for Division 2 analysis
- Supports Welding Qualification for weld procedures
- Integrates with FAI Inspection for verification
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