ASTM A234 WP12 Pipe Fittings – Technical Specifications
1. Overview
ASTM A234 WP12 is a carbon steel alloy pipe fitting specification for butt-welding fittings used in high-temperature and pressure applications. These fittings are commonly used in power plants, refineries, and petrochemical industries due to their strength, weldability, and creep resistance.
2. Key Features
| Parameter | Details |
|———————-|————|
| **Material** | **Alloy Steel (Cr-Mo)** |
| **Grade** | **WP12 (Class 1 & 2)** |
| **Manufacturing** | Forged or wrought |
| **Standards** | ASTM A234, ASME B16.9, B16.28 |
| **Temperature Range** | **-20°F to 1000°F (-29°C to 538°C)** |
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3. Chemical Composition (%)
| **Element** | **WP12 Class 1** | **WP12 Class 2** |
|————-|——————|——————|
| **Carbon (C)** | 0.05–0.20 | 0.05–0.15 |
| **Manganese (Mn)** | 0.30–0.80 | 0.30–0.61 |
| **Phosphorus (P)** | ≤ 0.03 | ≤ 0.03 |
| **Sulfur (S)** | ≤ 0.03 | ≤ 0.03 |
| **Silicon (Si)** | 0.10–0.50 | 0.10–0.30 |
| **Chromium (Cr)** | 0.80–1.25 | 0.80–1.25 |
| **Molybdenum (Mo)** | 0.44–0.65 | 0.44–0.65 |
4. Mechanical Properties
| **Property** | **WP12 Class 1** | **WP12 Class 2** |
|—————————-|——————|——————|
| **Tensile Strength (MPa/psi)** | 415–585 / 60,000–85,000 | 415–585 / 60,000–85,000 |
| **Yield Strength (MPa/psi)** | 220 min / 32,000 min | 220 min / 32,000 min |
| **Elongation (%)** | 22 min | 22 min |
| **Hardness (HB)** | ≤ 197 | ≤ 197 |
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5. Types of Fittings
✔ **Elbows (45°, 90°, 180°)**
✔ **Tees (Equal & Reducing)**
✔ **Reducers (Concentric & Eccentric)**
✔ **Caps**
✔ **Stub Ends**
6. Manufacturing Process
1. **Forging** – Hot-formed for structural integrity.
2. **Heat Treatment** – Normalized or tempered for enhanced mechanical properties.
3. **Machining** – Precision machining for dimensional accuracy.
4. **Testing** – Hydrostatic, NDT (UT, RT), and mechanical testing.
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7. Applications
– **Power Plants** (Boilers, steam lines)
– **Oil & Gas Refineries** (High-pressure piping)
– **Petrochemical Plants** (Hydrocarbon processing)
– **High-Temperature Service** (Up to **538°C / 1000°F**)
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8. Advantages
✅ **High-Temperature Resistance** – Suitable for steam and thermal applications.
✅ **Good Weldability** – Compatible with common welding techniques (preheat required).
✅ **Corrosion & Creep Resistance** – Chromium-Molybdenum alloy enhances durability.
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9. Comparison with Similar Grades
| **Grade** | **Composition** | **Temp Range** | **Key Use** |
|———–|—————–|—————-|————-|
| **WP11** | 1.25Cr-0.5Mo | Up to 593°C | High-temp piping |
| **WP22** | 2.25Cr-1Mo | Up to 593°C | Refineries |
| **WP5** | 5Cr-0.5Mo | Up to 650°C | Severe service |
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10. Ordering Information
Specify:
– **ASTM A234 WP12 (Class 1 or 2)
– **Type of Fitting (Elbow, Tee, etc.)
– **Size & Schedule (e.g., 6″ Sch 80)
– **Heat Treatment (Normalized/Tempered)
– **Testing Requirements (NDT, Hydro, etc.)
ASTM A234 WP12 fittings are high-performance alloy steel fittings designed for high-temperature and pressure applications. Their Cr-Mo composition ensures durability and creep resistance, making them ideal for power plants and refineries.
