ASTM A387 Grade 22 Class 1
ASTM A387 Grade 22 Class 1 | Pressure Vessel and Boiler Chromium-Molybdenum Alloy Steel Plate
ASTM A387 Grade 22 Class 1 chromium-molybdenum alloy steel plate for welded pressure vessels and boilers, providing elevated temperature strength and resistance to hydrogen attack.
Hot rolling, normalizing, tempering, welding, forming, and post-weld heat treatment
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ASTM A387 Grade 22 Class 1 Introduction
ASTM A387 Grade 22 Class 1 is a chromium-molybdenum alloy steel plate specifically designed for welded pressure vessels and boilers operating at elevated temperatures. This Class 1 grade offers a lower strength level compared to Class 2, favoring higher ductility and improved weldability. The alloy contains approximately 2.25% chromium and 1.0% molybdenum, which appreciably enhance creep strength and resistance to hydrogen attack under high-temperature hydrogen service. Plates are typically supplied in the normalized and tempered condition, ensuring uniform mechanical properties and structural stability. This material is widely adopted in the petrochemical, power generation, and high-temperature processing industries, where long-term service reliability under pressure and temperature is critical.
ASTM A387 Grade 22 Class 1 Chemical Composition
Chemical requirements as specified in ASTM A387/A387M for Grade 22 Class 1. All values are weight percent based on ladle analysis. Residual elements such as nickel, copper, etc., shall conform to the specification limits.
| Chemical Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | 0.05 - 0.15 | Aim for optimum combination of strength and toughness |
| Manganese (Mn) | 0.30 - 0.60 | Promotes deoxidation and hardenability |
| Phosphorus (P) | ≤ 0.025 | Limits for pressure vessel service |
| Sulfur (S) | ≤ 0.025 | Controls inclusion content |
| Silicon (Si) | ≤ 0.50 | Deoxidizer |
| Chromium (Cr) | 2.00 - 2.50 | Provides creep and oxidation resistance |
| Molybdenum (Mo) | 0.90 - 1.10 | Enhances high-temperature strength and hardenability |
ASTM A387 Grade 22 Class 1 Physical and Thermal Properties
These thermal and electrical properties are typical values for 2.25Cr-1Mo steel in the normalized and tempered condition; they are not mandatory specification requirements. Actual values may vary slightly depending on heat treatment and composition. Data provided for design reference.
| Performance Project | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Elastic Modulus (E) | 200 - 210 | GPa | At 20 °C |
| Shear Modulus (G) | 80 - 84 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.27 - 0.30 | - | At 20 °C |
| Thermal Expansion Coefficient (α) | 11.2 | 10⁻⁶/K | 20 - 100 °C, mean coefficient |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20 - 400 °C, mean coefficient |
| Thermal Expansion Coefficient (α) | 13.7 | 10⁻⁶/K | 20 - 600 °C, mean coefficient |
| Thermal Conductivity (λ) | 35 - 40 | W/(m·K) | At 100 °C (approximate) |
| Specific Heat Capacity | 460 | J/(kg·K) | At 20 °C (typical) |
| Electrical Resistivity (ρ_e) | 0.31 | µΩ·m | At 20 °C |
ASTM A387 Grade 22 Class 1 Tensile and Bend Properties
Mechanical properties are determined at ambient temperature using transverse specimens. Tensile tests are mandatory; bend tests apply when specified in the purchase order for plates ≤ 25 mm thick. The values represent the minimum required properties in the normalized and tempered condition.
| Performance Project | Required Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | 415 - 585 | MPa | Room temperature, transverse specimen |
| Yield Strength (ReH) | ≥ 205 | MPa | 0.2% offset, room temperature |
| Elongation (A) | ≥ 18 | % | Gauge length 50 mm, for plate thickness ≤ 50 mm |
| Elongation (A) | ≥ 18 | % | Gauge length 50 mm, for plate thickness 50 < t ≤ 100 mm |
| Elongation (A) | ≥ 18 | % | Gauge length 50 mm, for plate thickness 100 < t ≤ 200 mm |
| Bend Test (if specified)* | 180° bend, d=2T | - | Room temperature, for plate thickness ≤ 25 mm |
ASTM A387 Grade 22 Class 1 Direct Equivalent Material Standards and Grades
| Country/Region | Standard | Designation / Grade | Remarks |
|---|---|---|---|
| USA | ASME SA387/SA387M | Grade 22 Class 1 | Identical chemical and mechanical requirements; ASME adopts ASTM specification directly. |
| Japan | JIS G4109 | SCMV 4-1 | Close match with tensile strength 420–560 MPa, yield ≥205 MPa; commonly used for pressure vessels. |
ASTM A387 Grade 22 Class 1 Application Introduction
ASTM A387 Grade 22 Class 1 plates are employed where high-temperature strength and resistance to hydrogen attack are mandatory. The material can be hot formed, welded, and machined using standard practices, though preheat and post-weld heat treatment are essential to avoid cracking. It is typically chosen for moderate-pressure vessels and boiler components operating up to about 600 °C. Design and fabrication often follow ASME Boiler and Pressure Vessel Code, Section II and Section VIII.
Product Applications: Pressure vessel shells and heads, Boiler drums and steam separators, Heat exchangers and condensers, High-temperature piping systems, Hydrocrackers and reactors, Storage tanks for hot fluids
Processed into products: Ellipsoidal and hemispherical heads, Tube sheets and flanges, Nozzle and manway rings, Shell courses and conical sections, Skirts and support structures, Forged or rolled pipe fittings (with additional qualification)
Application industries: Petrochemical and refinery, Power generation (conventional and nuclear), Boiler and pressure vessel manufacturing, Chemical processing, Hydrogen service and coal gasification
ASTM A387 Grade 22 Class 1 Similar or Alternative Materials for Comparison
| Country/Region | Standard | Designation / Grade | Remarks |
|---|---|---|---|
| Europe | EN 10028-2 | 10CrMo9-10 (+NT) | Higher strength level (ReH ≥280 MPa, Rm 480–630 MPa); corresponds more closely to Class 2. Use with design adjustment. |
| China | GB/T 713 | 12Cr2Mo1R | Yield strength ≥310 MPa typical; stronger than Class 1. Suitable when higher strength is needed with similar Cr-Mo composition. |
| International | ISO 9328-2 | 11CrMo9-10 | Comparable Cr-Mo chemistry, mechanical properties vary; check availability and design code compliance. |
Notes:
Plates can be ordered with supplementary requirements such as Charpy impact testing (S5), ultrasonic examination (S8), or simulated post-weld heat treatment (S3). Welding consumables should match the chemical composition (e.g., AWS E9018-B3). Proper preheat (typically 150–300 °C) and post-weld heat treatment (usually 690–730 °C) are mandatory to maintain toughness. For high-temperature hydrogen service, refer to Nelson curves for safe operating limits.
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