SA387 Grade 22 Class 2 is a high-strength, chromium-molybdenum alloy steel plate, specified by ASTM A387/ASME SA-387, primarily used for manufacturing elevated-temperature pressure vessels, boilers, and heat exchangers in industries like oil, gas, and petrochemicals, offering superior weldability, corrosion resistance, and mechanical strength compared to Class 1, thanks to its higher chromium and molybdenum content, supplied normalized and tempered for demanding service.
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 2 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 Composition of SA387 GR.22 CL.2 Plate
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 - 0.15 | 0.25 - 0.66 | 0.035 | 0.035 | 0.5 max | 1.88 - 2.62 | 0.85 - 1.15 |
Manufacturing Process
Melting
The steel is melted in an electric arc furnace and refined to achieve the required chemical composition and cleanliness.
Secondary Refining
Vacuum degassing and ladle refining are applied to reduce impurities and improve homogeneity.
Casting
The molten steel is cast into slabs or ingots under controlled conditions to avoid segregation.
Heating and Hot Rolling
Slabs are heated and hot rolled to the desired thickness, with careful temperature control to ensure good microstructure.
Heat Treatment
Plates are normalized and tempered to enhance strength, toughness, and creep resistance.
Inspection and Testing
Ultrasonic testing, mechanical testing, and chemical analysis are performed to ensure compliance with ASTM standards.
Testing of the plates of SA 387 Grade 22 Class 2
Various testing is essentially given greater importance by the producers in order to make sure that the supplied plates are free of errors. The testing is done by the expert by effectively making use of available latest and modern tools. The tests done are positive material identification test, hardness test, intergranular corrosion test, flattening/flaring test, macro/micro test, chemical analysis, pitting resistance test and mechanical test.
Key Applications
Pressure Vessels
Used in chemical, petrochemical, and refinery pressure vessels operating at elevated temperatures.
Boilers and Heat Exchangers
Ideal for boiler drums, headers, and heat exchanger components requiring high-temperature strength and oxidation resistance.
Power Generation
Applied in steam headers, turbine casings, and other high-temperature power plant components.
Oil and Gas Industry
Used in reformers, hydroprocessing reactors, and high-temperature piping systems.
Chemical Processing
Suitable for reactors and process equipment handling high-temperature and corrosive media.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
What standards are equivalent to SA 387 Gr. 22 Cl. 2?
It is equivalent to ASTM A387 Grade 22 Class 2. In some international standards, it is comparable to 2.25Cr-1Mo steel grades used for pressure vessels.
What preheating temperature is recommended for welding SA 387 Gr. 22 Cl. 2?
Preheat temperatures typically range from 200–300°C, depending on plate thickness and welding procedure. Thicker plates may require higher preheat to reduce hydrogen-induced cracking.
What is the creep strength of SA 387 Gr. 22 Cl. 2?
It has good creep resistance at elevated temperatures, commonly used in applications up to around 593°C (1100°F), making it suitable for high-temperature pressure vessels.
What is the difference between SA 387 Gr. 22 Class 1 and Class 2?
The main difference is in impact toughness requirements. Class 2 requires Charpy V-notch impact testing at a lower temperature (usually 0°F or -18°C), ensuring better toughness for more demanding applications.
What is the typical chemical composition of SA 387 Gr. 22 Cl. 2?
It generally contains around 2.00% chromium, 1.00% molybdenum, along with controlled amounts of carbon, manganese, silicon, phosphorus, and sulfur. The exact composition must comply with the limits specified in ASTM A387/A387M.
How does SA 387 Gr. 22 Cl. 2 compare to SA 387 Gr. 5 Cl. 2 in terms of alloy content and performance?
SA 387 Gr. 22 Cl. 2 has a higher chromium and molybdenum content (2.25Cr-1Mo) compared to SA 387 Gr. 5 Cl. 2 (0.5Cr-0.5Mo). This higher alloy content gives Gr. 22 superior high-temperature strength, creep resistance, and oxidation resistance, allowing it to be used in more severe service conditions. Gr. 5 is typically used in lower-temperature pressure vessel applications, while Gr. 22 is widely used in refineries, petrochemical plants, and power generation facilities for components operating at temperatures up to 593°C.
What are the strength differences between SA 387 Gr. 22 Cl. 2 and SA 387 Gr. 22 Cl. 1?
While the tensile and yield strength requirements for Cl. 1 and Cl. 2 are nearly identical, Cl. 2 has more stringent impact toughness requirements. This means that Cl. 2 plates must undergo additional testing to ensure they maintain toughness at lower temperatures, which is critical for thick-walled structures and applications where safety is paramount. The improved toughness of Cl. 2 also provides better resistance to fatigue and thermal shock, making it the preferred choice for critical pressure equipment.
What is the difference in welding requirements between SA 387 Gr. 22 Cl. 2 and SA 387 Gr. 11 Cl. 2?
Both grades require preheating and post-weld heat treatment (PWHT) to prevent hydrogen-induced cracking and ensure good toughness. However, SA 387 Gr. 22 Cl. 2 typically requires higher preheat temperatures (200–300°C) and a more controlled PWHT due to its higher chromium and molybdenum content, which increases its hardenability. Welding consumables for Gr. 22 must also be matched to its alloy content to maintain strength and creep resistance in the weld zone. Gr. 11, with its lower alloy content, generally requires lower preheat and less stringent PWHT.