ASTM A387 Grade 22 Class 2 (ASME SA‑387 Gr.22 Cl.2) is a high‑strength 2.25Cr‑1Mo alloy steel plate engineered for welded pressure vessels and boiler components operating under high‑temperature, high‑pressure and sour‑hydrogen service conditions. Compared with Class 1, this grade delivers higher tensile and yield strength and meets more stringent suitability requirements for sour‑gas environments. It is widely used in hydroprocessing units, power‑generation facilities and hydrogen‑rich chemical processes. It is the preferred material for equipment subjected to H₂S corrosion and long‑term creep loading.
GNEE Steel is an experienced exporter of ASME‑compliant pressure‑vessel steel plates, dedicated to supplying premium‑grade products for EPC contractors, pressure‑vessel fabricators and end‑users across global energy markets.
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ASTM A387 Grade 22 Class 2 High Temp Pressure Vessel Steel Plate Specification
| Item | Specification Details |
|---|---|
| Full Product Name | ASTM A387 Grade 22 Class 2 High Temp Pressure Vessel Steel Plate |
| Governing Standard | ASTM A387 / A387M, ASME SA‑387 / SA‑387M |
| Nominal Alloy Composition | 2.25 % Chromium +1.0 % Molybdenum |
| Thickness Supply Range | 8‑150 mm; |
| Width Supply Range | 1650‑4500 mm |
| Length Supply Range | 3100‑18000 mm |
| Surface Treatment | Hot‑rolled black surface; shot‑blasting, pickling & anti‑rust primer available upon request |
ASTM A387 Gr.22 Cl.2 Chrome Moly Steel Plate materials chemical composition
| Element | Heat Analysis | Product Analysis |
|---|---|---|
| C | 0.05‑0.15 | 0.04‑0.15 |
| Mn | 0.30‑0.60 | 0.25‑0.66 |
| Si | ≤0.50 | ≤0.50 |
| P | ≤0.025 | ≤0.025 |
| S | ≤0.025 | ≤0.025 |
| Cr | 2.00‑2.50 | 1.88‑2.62 |
| Mo | 0.90‑1.10 | 0.85‑1.15 |
Note: Grade 2 requires Charpy impact testing in accordance with purchase order specifications; this is critical for hydrogen sulfide-containing media.
ASTM A387 Gr.22 Cl.2 Chrome Moly Steel Plate mechanical property
| Property Index | ASTM A387 Gr.22 Class 2 |
|---|---|
| Tensile Strength, MPa | 515‑690 |
| Min Yield Strength (0.2 % offset), MPa | 310 |
| Min Elongation (50 mm gauge length) | 18 % |
A387 Gr.22 Cl.2 Cr-Mo steel plate thickness chart
|
Thickness |
||
|
25 mm |
8 mm |
20 |
|
12 mm |
5 mm |
40 |
|
10 mm |
4 mm |
32 |
|
15 mm |
8 mm |
50 |
|
16 mm |
6 mm |
|
|
60 mm |
6 mm |
|
ASTM A387 Gr.22 Cl.2 Chrome molybdenum alloy Plate Welding Performance
| Welding Item | Technical Parameters & Requirements |
|---|---|
| ASME P‑Number | P‑No. 5B |
| Preheat Temperature | ≤25 mm: 150 ℃ minimum; ＞25 mm: 200‑260 ℃ |
| Maximum Interpass Temperature | 260 ℃ |
| Matching Welding Consumables | SMAW: AWS E8018‑B3; SAW: F8PZ‑EB3; GTAW: ER90S‑B3 |
| Mandatory PWHT Range | 680‑710 ℃ holding; hold 1 hour per 25 mm plate thickness, minimum hold time 2 h |
| Thermal Cutting Suggestion | Preheat workpiece to ≥150 ℃ before flame/plasma cutting to avoid edge cold cracking |
| Common Risk Reminder | Inadequate PWHT will lead to excessive hardness and raise risk of hydrogen‑induced cracking in sour working conditions |
High‑Temperature Service Performance of A387 Gr.22 Cl.2
A387 Gr.22 Cl.2 combines favourable stress‑rupture properties, oxidation resistance and high‑temperature hydrogen attack resistance for long‑term high‑pressure and high‑temperature service.
- Maximum allowable continuous operating temperature: 545 °C; permissible short‑term peak temperature: 590 °C.
- High‑temperature oxidation stability: oxidation weight gain of merely 0.35 mg/cm² after 1000 hours continuous exposure at 545 °C, outperforming carbon steel and Gr.11 low‑alloy steel by a significant margin.
- Sour‑media compatibility: with hardness controlled ≤220 HB, it satisfies NACE MR0175 requirements for H₂S‑containing environments and passes HIC (Hydrogen‑Induced Cracking) evaluation.
- Hydrogen‑resistant performance: complies with API 941 Nelson‑curve criteria and resists HTHA (High‑Temperature Hydrogen Attack) within hydroprocessing units.
- Microstructural stability: the tempered‑bainite microstructure remains stable under prolonged thermal exposure and reduces susceptibility to high‑temperature embrittlement.
Comparison Table: ASTM A387 Gr.22 vs Gr.11 vs Gr.91
| Parameter | A387 Grade 22 Class 2 | A387 Grade 11 | A387 Grade 91 |
|---|---|---|---|
| Cr‑Mo Alloy System | 2.25Cr‑1Mo | 1.25Cr‑0.5Mo | 9Cr‑1Mo‑V |
| Typical Min Yield Strength, MPa | 310 | 275 | 415 |
| Suggested Max Continuous Temp | 545 ℃ | 510 ℃ | 580‑600 ℃ |
| Sour‑gas(H₂S) adaptability | Excellent (with HIC test) | Limited | Not recommended |
| Creep‑rupture strength | High | Medium | Very high |
| HTHA hydrogen‑attack resistance | Very good | Moderate | Good |
| Typical cost level | Medium‑high | Medium | High |
| Main typical usage | Hydro‑cracker, sour high‑temp vessel | General boiler, non‑sour heat exchanger | Ultra‑high temp power boiler |
Applications of ASTM A387 Gr.22 Cl.2 High Temp Steel Plate
- Petrochemical Hydroprocessing Units: hydrocracking reactors, reformer shells, sour‑gas separation vessels, high‑pressure heat exchangers exposed to hydrogen‑sulfide‑containing media.
- Thermal Power & Waste‑Heat Recovery: high‑pressure boiler drums, main‑steam headers, heavy‑duty waste‑heat‑exchanger shells for coal‑fired and gas‑fired power plants.
- Hydrogen & Chemical Industry: high‑pressure hydrogen‑storage surge vessels, synthesis‑process reactors, high‑temperature separation equipment.
- Oil & Gas Processing: high‑temperature pressure‑bearing shells for crude‑oil processing units, flanges and nozzle sections for high‑pressure piping systems.
Why Choose GNEE?
Custom Fabrication: flame / plasma cutting, CNC bevel milling, plate levelling and blanking, with tight dimensional tolerance held at ±1.0 mm.
Export Documentation Support: supply of EN 10204 3.2 MTC (Material Test Certificate), certificate of origin, commercial invoice and packing list for customs clearance.
Professional Technical Support: reference suggestions for WPS (Welding Procedure Specification), cross‑reference analysis for material grades and drawing review for material‑selection purposes.
For bulk orders exceeding 12 metric tons, GNEE Steel provides free coordination for witnessed mill inspection to help you cut down project‑management costs.
FAQ
What is the maximum long‑term service temperature for ASTM A387 Gr.22 Cl.2?
Stable continuous operation ≤545 ℃; short‑term peak temperature cannot exceed 590 ℃. Overtemperature will accelerate creep failure risk.
Is PWHT compulsory for ASTM A387 Gr.22 Class 2 welding joints?
Yes, Post-Weld Heat Treatment (PWHT) is compulsory for welding joints on ASTM A387 Grade 22 Class 2 (2.25Cr-1Mo low-alloy steel) under major pressure vessel codes like ASME Section VIII Division 1 (Table UCS-56), regardless of thickness, because it falls under P-No. 5A.
What are the key differences between ASTM A387 Gr.22 and Gr.91?
ASTM A387 Grade 22 and Grade 91 are chromium-molybdenum alloy steel plates for elevated temperatures and pressure vessels, but Grade 91 contains significantly more chromium (9% vs 2.25%) and microalloying elements like vanadium and niobium, giving it much higher strength, creep resistance, and temperature limits than Grade 22.
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