Difference between ASTM A106 Gr. B & ASTM A106 Gr. C Pipes

ASTM A106 is a specification for seamless carbon steel pipe intended for high-temperature service. It covers various grades of carbon steel pipes, including Grade B and Grade C. Here are the key differences between ASTM A106 Grade B and Grade C pipes:

1. Chemical Composition: The chemical composition requirements for Grades B and C are slightly different. ASTM A106 Grade B Seamless Pipes require a minimum carbon content of 0.30%, manganese content of 0.29-1.06%, and maximum sulfur and phosphorus content of 0.035%. On the other hand, ASTM A106 Grade C pipes require a minimum carbon content of 0.35%, manganese content of 0.29-1.06%, and maximum sulfur and phosphorus content of 0.035%.
2. Mechanical Properties: Both Grade B and Grade C pipes have different minimum tensile strength and yield strength requirements. ASTM A106 Grade C Seamless Pipes have a minimum tensile strength of 60,000 psi (415 MPa) and minimum yield strength of 35,000 psi (240 MPa). In comparison, ASTM A106 Grade C pipes have a minimum tensile strength of 70,000 psi (485 MPa) and minimum yield strength of 40,000 psi (275 MPa). Therefore, Grade C pipes have higher mechanical strength properties than Grade B pipes.
3. Impact Test Requirements: Grade B pipes are not required to undergo impact testing, whereas Grade C pipes must be subjected to impact testing. The impact test is conducted to evaluate the ability of the pipe material to withstand a sudden load or impact at low temperatures.
4. Usage/Application: ASTM A106 Grade B pipes are widely used for general high-temperature service applications, including process piping, refineries, power plants, and boilers. ASTM A106 Grade C pipes, with their higher mechanical strength, are typically used in similar applications where higher strength and toughness are required, or in cases where the design conditions necessitate the use of Grade C pipes.

It's important to note that the specific requirements and properties of pipes should always be verified by referring to the latest edition of the ASTM A106 specification or consulting with the manufacturer or a qualified engineer.

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