SA387 Grade 22 Class 1 is a chromium‑molybdenum alloy steel plate covered by the ASME SA387/SA387M standard. It is widely used for pressure vessel and boiler components that operate at elevated temperatures and pressures in industries such as petrochemical processing, refining, power generation, and chemical manufacturing. The steel derives its properties from a carefully balanced composition of chromium and molybdenum, which together provide good high‑temperature strength, creep resistance, and resistance to hydrogen attack and sulfide corrosion. It is usually supplied in the normalized and tempered condition to achieve a fine‑grained microstructure that offers a practical combination of toughness and hardness. The material also demonstrates good weldability when proper preheating and post‑weld heat treatment practices are applied.
Equivalents for ASME SA387 Grade 22 Alloy Steel Plates
| BS | EN | ASTM/ASME | DIN |
| 622-515B | 10 CRMO910 | SA387-22-1 | 10 CRMO910 |
Specifications for ASME SA387 Grade 22 Alloy Steel Plates
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| SA387 Grade 22 | 2.25% | 1.00% |
Tensile Requirements for ASME SA387 Grade 22 Alloy Steel Plates Class 1 Plates
| Designation: | Requirement: | Grade 22 |
| SA387 Grade 22 | Tensile strength, ksi [MPA] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 45 [310] | |
| Elongation in 8 in. [200mm], min % | ... | |
| Elongation in 2 in. [50mm], min, % | 18 | |
| Reduction of area, min % | 45 (measured on round specimen) 40 (measured on flat specimen) |
Chemical Requirements for ASME SA387 Grade 22 Alloy Steel Plates
| Element | Chemical Composition (%) | |
| SA387 Grade 22 | ||
| Carbon: | Heat Analysis: | 0.05 - 0.15 |
| Product Analysis: | 0.04 - 0.15 | |
| Manganese: | Heat Analysis: | 0.30 - 0.60 |
| Product Analysis: | 0.25 - 0.66 | |
| Phosphorus: | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Sulphur (max): | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Silicon: | Heat Analysis: | 0.50 max |
| Product Analysis: | 0.50 max | |
| Chromium: | Heat Analysis: | 2.00 - 2.50 |
| Product Analysis: | 1.88 - 2.62 | |
| Molybdenum: | Heat Analysis: | 0.90 - 1.10 |
| Product Analysis: | 0.85 - 1.15 |
processing
1. Material Preparation and Forming
Cutting: Oxygen-acetylene flame cutting or plasma cutting is used. Due to the material's hardenability, preheating (approx. 100-150°C) is recommended for thick plates to prevent edge cracking.
Forming: Plates can be cold-formed or hot-formed. If cold forming results in significant strain (usually >3% or >5%), a subsequent heat treatment may be required to restore properties.
2. Welding Procedure (Critical Phase)
Welding is the most critical stage due to the risk of hydrogen-induced cracking and reheat cracking.
Preheating: Mandatory preheating is required, typically between 150°C and 250°C, depending on thickness and welding process.
Filler Metals: Use electrodes/wires matching the 2.25Cr-1Mo composition, such as E9018-B3 (SMAW) or ER90S-B3 (GMAW/GTAW). Low-hydrogen consumables are essential.
Interpass Temperature: Must be strictly controlled (typically maintained between 200°C and 300°C).
Dehydrogenation Heat Treatment (DHT): Immediately after welding, the joint is often held at 300-350°C for 2-4 hours to allow hydrogen to escape before the material cools.
3. Heat Treatment
SA 387 Grade 22 Class 1 must be supplied in a heat-treated condition to achieve the required mechanical properties (Tensile Strength: 60-85 ksi / 415-585 MPa):
Normalized & Tempered (N+T): The standard delivery state. The minimum tempering temperature must be 675°C (1250°F).
Post-Weld Heat Treatment (PWHT): After fabrication, the entire component undergoes PWHT. For Grade 22, the typical soaking temperature is 690°C ± 10°C. This reduces residual stress and ensures the hardness of the Heat Affected Zone (HAZ) is within limits (usually <225 HBW).
4. Inspection and Testing
Mechanical Testing: Verification of tensile, yield, and elongation properties.
Non-Destructive Examination (NDE):
Ultrasonic Testing (UT) for internal plate quality.
Magnetic Particle (MT) or Radiographic Testing (RT) for weld integrity.
Special Requirements: For high-pressure hydrogen service (API 934), Step Cooling Tests may be required to evaluate the material's susceptibility to temper embrittlement.
Key Applications
Oil & Gas Refining:
Extensively used in hydrocrackers, reactors, and separators that operate under high-pressure hydrogen and elevated temperatures.
Petrochemical Industry:
Found in storage vessels, piping systems, and heat exchangers that must resist sour gas (containing H2S) and corrosive chemical media.
Power Generation:
Crucial for the construction of industrial boilers, superheaters, and steam headers in both thermal and nuclear power plants, where components are subject to continuous thermal cycling.
Chemical Processing:
Used in high-temperature pipelines, distillation columns, and converters requiring exceptional structural stability.
Principal Advantages
The inclusion of 2.25% Chromium and 1% Molybdenum provides several performance benefits over standard carbon steels:
Exceptional High-Temperature Strength: The molybdenum content ensures high tensile strength and creep resistance at temperatures up to 600°C (1112°F), preventing deformation under long-term thermal stress.
Superior Corrosion & Oxidation Resistance: Higher chromium levels protect against environmental degradation, scaling, and specific hazards like sulfidation and hydrogen-induced cracking in sour service.
High Ductility and Formability (Class 1 Specific): Class 1 is specifically characterized by its improved ductility and lower strength compared to Class 2, making it easier to form, weld, and machine for complex structural designs.
Thermal Stability: Maintains mechanical integrity and dimensional stability even during fluctuating temperature loads, which is essential for preventing surface degradation.
Cost-Effectiveness: While initially more expensive than carbon steel, its extended service life and reduced maintenance requirements provide significant long-term savings in critical industrial applications.
For more details about GNEE's steel products, contact us at beam@gneesteelgroup.com. We look forward to working with you.
Can SA387 Grade 22 Class 1 be machined easily?
It has good machinability with proper tools and parameters. Use high-speed steel or carbide tools, and maintain adequate cutting fluid to reduce heat and tool wear.
What is the modulus of elasticity of SA387 Grade 22 Class 1?
Its modulus of elasticity is approximately 200 GPa (29 × 10⁶ psi) at room temperature, a key parameter for structural analysis and load-bearing capacity design.
What is the Poisson's ratio of SA387 Grade 22 Class 1?
The Poisson's ratio is about 0.3 at room temperature. This value describes the lateral strain response to axial stress, essential for finite element analysis and structural modeling.
Can SA387 Grade 22 Class 1 be used in hydrogen service?
Yes, with proper PWHT, it resists hydrogen embrittlement. It is suitable for hydrogen-containing environments in refineries, provided operating temperature and pressure are controlled.
What is the difference between SA387 Grade 22 and Grade 11?
Grade 22 has higher molybdenum content (0.87-1.13% vs 0.45-0.65% for Grade 11), offering better high-temperature strength and creep resistance for more demanding service conditions.
Is SA387 Grade 22 Class 1 suitable for boiler tubes?
It is mainly used for boiler and pressure vessel plates. For tubes, corresponding grades like SA213 T22 (equivalent to Grade 22) are preferred, as they are designed for tubular applications.
What is the Charpy impact energy requirement for SA387 Grade 22 Class 1?
For Class 1, the minimum Charpy V-notch impact energy is 27 J (20 ft-lb) at 0°C. This ensures sufficient toughness to withstand dynamic loads during operation.
Can SA387 Grade 22 Class 1 be coated with anti-corrosion layers?
Yes, coatings like epoxy, zinc, or chrome can be applied to enhance corrosion resistance in harsh environments. Proper surface preparation before coating ensures adhesion and durability.
What is the creep strength of SA387 Grade 22 Class 1 at 500°C?
At 500°C, its 100,000-hour creep strength is approximately 60 MPa. This indicates its ability to resist permanent deformation under long-term high-temperature loads.
What is the delivery condition of SA387 Grade 22 Class 1 plates?
It is usually delivered in normalized and tempered (N&T) condition. This heat treatment ensures consistent mechanical properties and microstructure for pressure vessel applications.
What are the storage requirements for SA387 Grade 22 Class 1 plates?
Store in a dry, well-ventilated area to prevent rust. Keep plates elevated from the ground, covered with waterproof materials, and avoid contact with corrosive substances.