SA 204 Grade B is a molybdenum alloy steel plate designed for welded boilers and pressure vessels, offering higher strength than Grade A, with key properties including good weldability and suitability for moderate temperatures, often used in oil, gas, and petrochemical industries. It's a "killed" steel, meaning it's fully deoxidized, and its composition includes carbon, manganese, silicon, phosphorus, and sulfur, providing enhanced resistance to corrosive environments.
Chemical composition
| Main chemical elements composition | ||||||
| Thickness(mm) | C | Si | Mn | P | S | Mo |
| T≤25 | 0.20 | 0.15-0.40 | 0.90 | 0.035 | 0.035 | 0.45-0.60 |
| 25 | 0.23 | |||||
| 50 | 0.25 | |||||
| T>100 | 0.27 | |||||
Mechanical Properties
|
Mechanical Properties |
||||||
|
Grade |
Thickness |
Yield |
Tensile Strength |
Elongation |
Charpy V Notch Impact Test |
|
|
Degree |
Min Value |
|||||
|
SA204Gr.B |
mm |
Min Mpa |
Mpa |
Min % |
- |
J |
|
5≤t≤50 |
275 |
485-620 |
21% |
- |
||
|
50≤t≤100 |
275 |
485-620 |
17% |
|
||
Key Applications:
Pressure Vessels:
Reactors, separators, storage tanks (spherical & cylindrical), and gas tanks for oil, gas, and chemical processing.
Boilers:
Industrial boilers, drums, and high-pressure components in power generation.
Pipelines:
Networks for transporting oil, gas, coal, and LNG.
Heat Exchangers:
Components requiring resistance to corrosive media at elevated temperatures.
Other Industrial Uses:
Fabrication for maritime (ship hulls, submarines), automotive, aerospace, and general metal fabrication.
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 is SA 204 Grade B?
SA 204 Grade B is a pressure vessel steel plate specified under the ASME SA 204 standard. It is a molybdenum-alloyed steel designed for use in welded pressure vessels and boiler components that operate at elevated temperatures.
How does SA 204 Grade B compare with carbon steel plates like SA 516?
SA 204 Grade B is an alloy steel with molybdenum, which gives it better high-temperature strength and creep resistance than standard carbon steels such as SA 516. SA 516 is more commonly used for lower to moderate temperature pressure vessels, while SA 204 Grade B is preferred when service temperatures are higher and sustained strength under heat is required.
What is the purpose of adding molybdenum to SA 204 Grade B?
Molybdenum is added to enhance the steel's strength and creep resistance at higher temperatures. It also improves hardenability and provides better resistance to thermal fatigue, making the material suitable for service under sustained heat and pressure.
What are the key mechanical properties of SA 204 Grade B?
SA 204 Grade B offers high tensile and yield strength, good toughness, and excellent creep resistance at elevated temperatures. It also has good weldability, allowing for the fabrication of large and complex pressure vessels.
What industries commonly use SA 204 Grade B?
SA 204 Grade B is widely used in the oil and gas, petrochemical, power generation, and chemical processing industries. It is also used in general industrial applications requiring pressure vessels and heat-resistant components.
Is SA 204 Grade B equivalent to any ASTM grades?
SA 204 Grade B is the ASME designation for molybdenum-alloy pressure vessel plates. It is similar in chemical composition and intended use to certain ASTM grades with molybdenum content, but direct one-to-one equivalents may vary by thickness range, heat treatment requirements, and specific mechanical property limits. Buyers and fabricators should always refer to the latest ASME and ASTM standards for precise comparisons.
What is the difference between SA 204 Grade B and SA 387 Grade B?
SA 204 Grade B is a molybdenum-alloyed pressure vessel steel primarily intended for elevated-temperature service in boilers and pressure vessels. SA 387 Grade B is a chromium-molybdenum (Cr-Mo) alloy steel with enhanced creep and oxidation resistance at higher temperatures, making it more suitable for severe high-temperature and high-pressure applications compared to SA 204 Grade B.
What types of equipment are typically made from SA 204 Grade B?
Common applications include pressure vessels, boilers, heat exchangers, storage tanks, and process equipment that operate at moderate to high temperatures. It is often used in components that handle steam, hydrocarbons, and various process fluids.
Is SA 204 Grade B suitable for welding?
Yes, SA 204 Grade B has good weldability. Proper welding procedures, including appropriate preheating and interpass temperatures, are recommended to ensure sound welds and maintain the material's mechanical properties.
What standards cover SA 204 Grade B?
SA 204 Grade B is covered by the ASME SA 204 standard, which specifies requirements for molybdenum-alloy steel plates for pressure vessels. It is commonly used in conjunction with the ASME Boiler and Pressure Vessel Code.