A335 Seamless Steel Pipe Product Overview
ASTM A335 Chrome-Molybdenum (Cr-Mo) Seamless Pipes are heat-resistant, creep-strength-enhanced tubing engineered for power plants, refineries, and petrochemical systems operating at 540–620°C (1,000–1,150°F). With grades like P91 (9Cr-1Mo-V) and P22 (2.25Cr-1Mo), these pipes deliver 120–200 MPa yield strength at 600°C, resisting hydrogen attack, sulfidation, and thermal fatigue. Compliant with ASME B16.25 end prep standards, they replace costly stainless steels in superheater coils, catalytic crackers, and high-pressure steam lines.
Key Technical Specifications
1. Dimensional & Manufacturing Properties
- Size Range:
- OD: 6.35 mm (¼”) – 914 mm (36″)
- Wall Thickness: 1.65–150 mm (Schedules 10–XXS)
- Tolerances:
- OD: ±0.75% (≤NPS 24), ±1.0% (>NPS 24)
- Wall Thickness: +20%/-12.5% (ASME B36.10)
- Heat Treatments:
- P91/P92: Normalized (1040–1080°C) + Tempered (730–800°C)
- P11/P22: Annealed (870–900°C) or Stress-Relieved
2. Mechanical & Chemical Performance
Chemical Composition (Key Grades):
| Grade | Cr | Mo | V | Nb | N | W | Creep Temp Limit |
|---|---|---|---|---|---|---|---|
| P5 | 4–6% | 0.45–0.65% | – | – | – | – | 540°C |
| P11 | 1.0–1.5% | 0.44–0.65% | – | – | – | – | 565°C |
| P22 | 1.9–2.6% | 0.87–1.13% | – | – | – | – | 580°C |
| P91 | 8–9.5% | 0.85–1.05% | 0.18–0.25% | 0.06–0.10% | 0.03–0.07% | – | 620°C |
| P92 | 8.5–9.5% | 0.30–0.60% | 0.15–0.25% | 0.04–0.09% | 0.03–0.07% | 1.5–2.0% | 650°C |
Mechanical Properties:
| Grade | Yield (MPa) | Tensile (MPa) | Elongation (%) | Hardness (HB) | Impact (J @ 20°C) |
|---|---|---|---|---|---|
| P11 | ≥205 | ≥415 | ≥20 | ≤163 | ≥18 |
| P22 | ≥310 | ≥515 | ≥18 | ≤201 | ≥20 |
| P91 | ≥585 | ≥760 | ≥14 | ≤250 | ≥40 |
| P92 | ≥620 | ≥820 | ≥12 | ≤265 | ≥45 |
Pressure Ratings:
| OD (mm) | P91 Wall (mm) | Max Pressure @ 600°C (bar) | Design Life |
|---|---|---|---|
| 168.3 | 18.2 | 240 | 100,000 hours |
| 323.9 | 32.5 | 180 | 200,000 hours |
Applications by Industry
| Industry | Use Case | Grade | Key Benefit |
|---|---|---|---|
| Power Generation | Ultra-supercritical boiler tubes | P92 | 650°C creep strength >100 MPa |
| Oil Refining | Fluid catalytic cracker transfer lines | P5 | Sulfidation resistance @ 540°C |
| Petrochemicals | Ethylene furnace radiant coils | P91 | 40% cost savings vs. 347H stainless |
| Nuclear | Reactor coolant system headers | P11 | ASME III Code compliance |
| Hydrogen Plants | Steam methane reformer outlets | P22 | Hydrogen attack resistance |
Global Standard Equivalents
| USA (ASTM) | Europe (EN) | Japan (JIS) | China (GB) |
|---|---|---|---|
| A335 P11 | EN 10216-2 13CrMo4-5 | STPA 23 | GB 9948-2013 |
| A335 P91 | EN 10216-2 X10CrMoVNb9-1 | STPA 26 | GB 5310-2017 |
Certifications & Compliance
- Heat Treatment: AMS 2750 Pyrometry Standards
- Welding: ASME Section IX with PWHT (Post-Weld Heat Treatment)
- Certifications: NACE MR0103 (Sour Service), TÜV Nord, PED 2014/68/EU
Packing And Delivery
