ASTM A234 WP22 Pipe Fittings

ASTM A234 WP22 Pipe Fittings – Comprehensive Technical Specification

1. Material Overview
ASTM A234 WP22 specifies chromium-molybdenum alloy steel pipe fittings for high-temperature and high-pressure service. These 2.25Cr-1Mo alloy fittings offer superior:
– Creep resistance
– High-temperature strength
– Oxidation resistance
– Sulfidation resistance

3. Chemical Composition (%)
| Element | Class 1 | Class 3 |
|———|———|———|
| Carbon (C) | 0.05-0.15 | 0.05-0.15 |
| Manganese (Mn) | 0.30-0.60 | 0.30-0.60 |
| Phosphorus (P) | ≤0.03 | ≤0.03 |
| Sulfur (S) | ≤0.03 | ≤0.03 |
| Silicon (Si) | 0.50 max | 0.50 max |
| Chromium (Cr) | 1.90-2.60 | 1.90-2.60 |
| Molybdenum (Mo) | 0.87-1.13 | 0.87-1.13 |

4. Mechanical Properties
| Property | Class 1 | Class 3 |
|———-|———|———|
| Tensile Strength (MPa) | 415-585 | 485-655 |
| Yield Strength (MPa) | 205 min | 275 min |
| Elongation (%) | 20 min | 20 min |
| Hardness (HB) | ≤197 | ≤197 |

5. Temperature Capabilities
– **Continuous Service**: Up to 593°C (1100°F)
– **Maximum Temperature**: 649°C (1200°F) for short-term
– **Minimum Temperature**: -29°C (-20°F) with impact testing

6. Manufacturing Standards
– **Base Standard**: ASTM A234
– **Dimensional Standards**:
– ASME B16.9 (Factory-made butt-welding fittings)
– ASME B16.28 (Wrought steel butt-welding short radius elbows)
– **Testing Requirements**: Hydrostatic, NDT, mechanical testing

7. Available Fitting Types
1. **Elbows** (45°, 90°, 180°; short/long radius)
2. **Tees** (equal and reducing)
3. **Reducers** (concentric and eccentric)
4. **Caps**
5. **Stub Ends**
6. **Crosses**
7. Lap Joint Stub Ends

8. Heat Treatment Requirements
– **Normalizing**: 899-954°C (1650-1750°F)
– **Tempering**: 677-760°C (1250-1400°F)
– **PWHT**: Mandatory after welding (704-760°C / 1300-1400°F)

9. Quality Control
– **Mandatory Tests**:
– Hydrostatic testing at 1.5x design pressure
– Tensile testing
– Hardness testing
– **Optional Tests**:
– Charpy V-notch impact testing
– PMI verification
– Full radiographic examination

10. Welding Considerations
– **Preheat Temperature**: 200-300°C (400-600°F)
– **Interpass Temperature**: ≤300°C (600°F)
– **Recommended Filler Metals**:
– SMAW: E9018-B3
– GTAW/GMAW: ER90S-B3
– **PWHT Requirements**: Mandatory after welding

11. Corrosion Resistance
– **Oxidation Resistance**: Excellent up to 593°C
– **Sulfidation Resistance**: Superior to lower alloy steels
– **Hydrogen Attack Resistance**: Good at moderate temperatures

12. Applications
– **Power Generation**:
– High-pressure steam lines
– Boiler components
– Turbine piping
– **Petrochemical**:
– Hydrocracker units
– Catalytic reformers
– High-temperature reactors
– **Oil & Gas**:
– Refinery process piping
– High-pressure manifolds
– Hot oil systems

13. Comparison with Similar Grades
| Grade | Cr Content | Mo Content | Key Difference |
|——-|———–|———–|—————-|
| WP5 | 4-6% | 0.44-0.65% | Higher chromium |
| WP9 | 8-10% | 0.90-1.10% | Higher alloy content |
| WP11 | 1.00-1.50% | 0.44-0.65% | Lower Cr-Mo content |

14. Purchasing Specifications
When ordering WP22 fittings, specify:
– ASTM A234 WP22 (Class 1 or 3)
– Fitting type and size
– Schedule or wall thickness
– Heat treatment condition
– End preparation
– Testing requirements
– Certification needs (EN 10204 3.1/3.2)

15. Maintenance Considerations
– **Inspection Intervals**:
– Annual for critical service
– Biannual for less severe service
– **Key Inspection Methods**:
– Ultrasonic thickness monitoring
– Dye penetrant inspection
– Replica metallography for creep assessment
– Replacement Criteria:
– 20% wall thinning
– Visible creep damage
– Cracking in HAZ regions

WP22 fittings require careful temperature control during welding and heat treatment to maintain optimal mechanical properties. Always consult applicable ASME codes for specific application requirements.