The primary difference between ASME SA 106 Grade B and ASME SA 106 Grade C is their strength and chemical composition. Specifically, Grade C has higher carbon and manganese content, making it stronger but slightly less ductile and harder to weld than Grade B.
Both fall under the same specification for Seamless Carbon Steel Pipe for High-Temperature Service.
Comparing landed prices for Grade B and Grade C? Submit your requirements now to receive the latest comparative price quotes for both within 15 minutes.
Mechanical Properties (Strength)
Grade C is the "stronger" version of the SA 106 family. Because it has more carbon, it can handle higher internal pressures.
| Property | SA 106 Grade B | SA 106 Grade C | Difference |
| Tensile Strength (Min) | 60,000 psi (415 MPa) | 70,000 psi (485 MPa) | Grade C is ~16% stronger |
| Yield Strength (Min) | 35,000 psi (240 MPa) | 40,000 psi (275 MPa) | Grade C is ~14% stronger |
| Elongation (Ductility) | Higher | Lower | Grade B is more flexible |
Chemical Composition
To achieve the higher strength in Grade C, the "recipe" of the steel is adjusted by increasing carbon and manganese.
| Element | SA 106 Grade B | SA 106 Grade C |
| Carbon (C) Max | 0.30% | 0.35% |
| Manganese (Mn) | 0.29% – 1.06% | 0.29% – 1.06% |
| Silicon (Si) Min | 0.10% | 0.10% |
Note: While the range for Manganese is the same, Grade C typically sits at the higher end of the range to support the increased tensile strength.
Weldability
SA 106 Grade B: Excellent weldability. It is the industry standard for refineries and power plants because it is very "forgiving" during field welding.
SA 106 Grade C: Good weldability, but because of the higher carbon content (Carbon Equivalent), it is slightly more susceptible to cracking if not welded properly. It may require more careful preheating or specific welding procedures in critical high-pressure systems.
Availability and Cost
SA 106 Grade B: This is the most common carbon steel pipe in the world. It is stocked by almost every steel supplier and is the most cost-effective option.
SA 106 Grade C: Much less common. It is usually a "project-specific" item. While it isn't necessarily much more expensive to manufacture, the lack of ready stock can make it more expensive and harder to find for small orders.
Application
SA 106 Grade B: Used for standard high-temperature applications in power plants, refineries, and chemical facilities (e.g., steam lines, process piping).
SA 106 Grade C: Used in specific high-pressure boiler components or specialized refinery systems where the engineer needs extra strength to keep the pipe wall thickness from becoming excessively heavy.
| Feature | SA 106 Grade B | SA 106 Grade C |
| Weldability | Excellent. Lower carbon equivalent makes it the preferred choice for refineries and power plants. | Good. Higher carbon content requires stricter control of preheating and interpass temperatures. |
| Market Availability | Very High. The most widely stocked seamless carbon steel pipe grade globally. | Moderate. Usually custom-ordered for specific high-pressure projects; less common in local stocks. |
| Best Use Cases | General high-temp/high-pressure piping, refinery process lines, steam systems. | Extremely high-pressure systems, boiler headers, or applications requiring thinner walls. |
| Relative Cost | Baseline price; offers the best cost-performance ratio. | Generally more expensive due to lower production volume and higher strength requirements. |
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FAQ
What is SA106 Grade B material equivalent to?
SA106 Grade B is equivalent to the following materials in terms of chemical composition and mechanical properties:
Chinese standard: Equivalent to 20# steel (GB/T 699 or GB/T 8163)
American standard: Essentially equivalent to ASTM A53 Grade B and API 5L Grade B (L245)
European standard: Corresponds to EN 10216-2 P265GH (seamless pipe)
What is ASTM SA106 used for?
SA106 is primarily utilized in fluid transport piping systems operating under high-temperature and high-pressure conditions. It is widely applied across various industrial sectors-including power generation, petroleum refining, chemical processing, and boiler manufacturing-serving in applications such as power plant main steam lines, refinery cracking units, and high-temperature heat exchanger pipelines.
