API 5L Grade B and ASTM A106 Grade B are both specifications for seamless steel pipe, but they serve different purposes and industries:

API 5L Grade B:

Purpose: API 5L Grade B is primarily used for transporting oil and gas in transmission lines, distribution networks, and offshore drilling platforms.

Specification: It covers seamless and welded steel line pipe. API 5L specifies the requirements for the manufacture of two product specification levels (PSL 1 and PSL 2) of seamless and welded steel pipes suitable for use in conveying gas, water, and oil.

Steel Grade: A, B, X42, X46, X52, X56, X60, X65, X70, X80 (and higher)

Application: It is specifically designed for transportation systems in the petroleum and natural gas industries.

ASTM A106 Grade B:

Purpose: ASTM A106 Grade B is used for high-temperature service (up to 750°F or 400°C) in industries such as power plants, boilers, petrochemical plants, oil and gas refineries, and ships.

Specification: It covers seamless carbon steel pipe for high-temperature service. A106 specifies seamless carbon steel pipe for high-temperature service.

Steel Grade: A, B, C (most common is Grade B)

Application: It is used where fluids and gases are transported at elevated temperatures and pressures.

Key Differences:

Application Focus: API 5L Grade B is specifically designed for oil and gas transportation, while ASTM A106 Grade B is used for high-temperature service applications.

Steel Grade Range: API 5L Grade B covers a wider range of steel grades suitable for various strengths and applications, including higher strength grades, whereas ASTM A106 Grade B is limited to standard carbon steel grades.

Manufacturing Standards: Both specifications require seamless manufacturing processes, but API 5L Grade B also allows for welded pipes.

In summary, API 5L Grade B and ASTM A106 Grade B are distinct specifications tailored to different industrial uses. API 5L Grade B is ideal for oil and gas transportation, while ASTM A106 Grade B is suited for high-temperature applications in various industries.