SA 387 Gr. 22 Cl. 2 is a chromium-molybdenum alloy steel plate, specified by ASTM/ASME standards, designed for high-temperature service in boilers, pressure vessels, and heat exchangers, offering superior strength, weldability, and resistance to creep and oxidation, with Class 2 indicating higher tensile strength than Class 1. Its composition includes about 2.25% chromium and 1% molybdenum, requiring normalization and tempering for optimal performance in demanding industrial environments like petrochemical and power generation.
Key Applications and Industries Relying on SA 387 Grade 22 Class 2
Pressure Vessel Industry
Core Applications: Reactors, heat exchangers, pressure vessel shells and high-temperature medium storage vessels.
Target Sectors: Chemical, petrochemical and oil refining industries.
Adaptability Reasons: Withstands 593°C continuous service, resists creep deformation under long-term high temperature and pressure, ensuring pressure-bearing equipment safety.
Boiler and Heat Exchanger Industry
Core Applications: Boiler drums, steam headers, heat exchanger tubesheets and related components.
Target Sectors: Thermal power, industrial boiler and process heating industries.
Adaptability Reasons: Balances thermal conductivity, oxidation and thermal fatigue resistance for stable service in cyclic high-temperature environments.
Power Generation Industry
Core Applications: Steam headers, turbine casings, steam pipelines and high-temperature auxiliaries.
Target Sectors: Conventional thermal power, combined cycle power plants and advanced energy facilities.
Adaptability Reasons: Resists high-pressure steam thermal stress, maintaining stable mechanical properties for long-term reliable operation.
Oil and Gas Industry
Core Applications: Reformer furnaces, hydroprocessing reactors, high-temperature pipelines and offshore/onshore process equipment.
Target Sectors: Onshore oil refining, offshore oil & gas development and natural gas processing.
Adaptability Reasons: Resists hydrogen attack and high-temperature corrosion, adapting to harsh offshore and hydrogenation conditions.
Chemical Processing Industry
Core Applications: Catalytic reactors, process vessels and chemical medium transport pipelines.
Target Sectors: Fine chemical, organic chemical and industrial synthesis industries.
Adaptability Reasons: Resists organic/inorganic media corrosion, maintaining integrity under high-temperature reactions.
Comparing SA 387 Grade 22 Class 2 with Other Alloy Steel
SA 387 Grade 22 Class 2 is a 2.25Cr-1Mo pressure vessel steel known for its excellent high-temperature creep strength and good weldability. Compared with SA 387 Grade 11 Class 2 (1.25Cr-0.5Mo), it provides higher creep and rupture strength due to its higher chromium and molybdenum content, making it more suitable for long-term service at elevated temperatures, though it may require stricter preheat and post-weld heat treatment. When compared to SA 387 Grade 5 (0.5Mo), Grade 22 Class 2 offers superior high-temperature performance, while compared to Grade 9 (9Cr-1Mo), it has better fabricability and lower embrittlement risk. Relative to carbon steels such as SA 516 Grade 70, it exhibits much stronger creep and oxidation resistance at high temperatures, and compared to stainless steels, it has lower cost and higher thermal conductivity but less corrosion resistance. Overall, SA 387 Grade 22 Class 2 is a balanced Cr-Mo alloy steel that effectively meets the demands of many high-temperature, high-pressure pressure vessel applications.
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.
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 |
Mechanical Properties of SA 387 GR.22 CL.2 Plate
| Tensile Strength | Yield Strength | Elongationin 50mm (%) | Reduction of area in % |
| 75-100 ksi, 515-690 MPa | 45 Ksi, 310 MPa | 18 | 45 |
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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 are the common applications of SA 387 Gr. 22 Cl. 2?
It is widely used in refinery equipment, petrochemical reactors, boilers, heat exchangers, and other pressure vessels operating at high temperatures and pressures.
Is SA 387 Gr. 22 Cl. 2 suitable for welding?
Yes, it is readily weldable using common welding processes such as SMAW, GMAW, FCAW, and SAW. Proper preheating and post-weld heat treatment (PWHT) are recommended to prevent cracking.
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 PWHT is required after welding SA 387 Gr. 22 Cl. 2?
A post-weld heat treatment of around 620–680°C for a sufficient duration is commonly applied to relieve residual stresses and improve toughness and creep properties.
What is SA 387 Grade 22 Class 2?
SA 387 Grade 22 Class 2 is a chromium-molybdenum alloy steel plate specified in ASTM A387/A387M, primarily used for pressure vessel and boiler applications requiring good creep strength and heat resistance.
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.
What are the mechanical properties of SA 387 Gr. 22 Cl. 2?
Typical properties include a minimum tensile strength of 415–585 MPa, a minimum yield strength of 205 MPa, and an elongation of 22% minimum. Class 2 requires additional impact testing at lower temperatures compared to Class 1.
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 maximum thickness for SA 387 Gr. 22 Cl. 2 plates?
The standard allows for various thicknesses, but common maximums are around 150 mm or more, depending on the manufacturer's capability and heat treatment requirements.
How does SA 387 Gr. 22 Cl. 2 differ from SA 387 Gr. 11 Cl. 2?
SA 387 Gr. 22 Cl. 2 is a 2.25Cr-1Mo steel, while SA 387 Gr. 11 Cl. 2 is a 1.25Cr-0.5Mo steel. The higher chromium and molybdenum content in Gr. 22 provides significantly better high-temperature strength, creep resistance, and oxidation resistance, especially in long-term service above 500°C. This makes Gr. 22 more suitable for refinery heaters, reformers, and high-temperature reactors, whereas Gr. 11 is often used in less severe temperature conditions. Additionally, Gr. 22 typically requires higher preheat and PWHT during welding due to its higher hardenability.