I. Full Standard Name

ASTM A106 / ASME SA106 Standard Name: Seamless Carbon Steel Pipe for High-Temperature Service. This standard covers only seamless steel pipes, excluding welded pipes, and is specifically designed for high-temperature, medium-to-high-pressure steam, oil, and gas pipelines.

II. Three Grades (Gr. A / Gr. B / Gr. C)

1. ASTM A106 Grade B (90% market share, equivalent to domestic 20# steel pipe)

- Carbon upper limit ≤0.30%, Mn 0.29~1.06%

- Mechanical properties: Tensile strength ≥415MPa, Yield strength ≥240 MPa

- Operating temperature: Maximum 427°C (800°F)

- Domestic equivalent: GB/T8163 20# fluid pipe, 20G boiler pipe; directly interchangeable with export high-temperature pipelines

- Applications: Power plant steam lines, oil refinery high-temp pipelines, boiler feedwater, petrochemical process piping

2. A106 Grade A (equivalent to 10# steel pipe)

Lower carbon content, reduced strength, improved ductility; suitable only for low-pressure and low-temperature applications; rarely exported.

3. A106 Gr.C

With a carbon limit of 0.35%, it offers higher strength and is used in supercritical boilers and demanding high-temperature, high-pressure applications, resulting in higher costs.

III. A106 Gr.B and Its Correspondence with Chinese 20

1. Piping Scenario (Seamless Pipe)

A106 Gr.B = GB/T8163 20# Seamless Fluid Pipe / GB5310 20G High-Pressure Boiler Tube. For steam and high-temperature fluid export orders, US standard drawings uniformly specify A106 Gr.B.

2. Bars and Plates Are Not Equivalent

The US standard for 20# round bars and steel plates is SAE 1020, not A106; A106 applies only to steel pipes.

IV. Key Differences Between A106 and A53 (Commonly Confused in Foreign Trade)

1. A106: Seamless pipe only; deoxidized and killed steel with high-temperature resistance (427°C), specifically designed for power plant and petrochemical high-temperature pipelines, requiring enhanced flaw detection and hydrostatic testing standards.

2. A53 Gr.B: Weldable pipe + seamless pipe, for low-pressure, normal-temperature water supply and drainage, and general transportation only. Not suitable for high-temperature applications.

V. Key Performance Characteristics (Grade B)

- Excellent bendability, flange forming, and weldability.

- Delivery condition: Hot-rolled/cold-drawn + normalized.

- Inspection requirements: Mandatory hydrostatic test and ultrasonic non-destructive testing; sulfur and phosphorus impurities strictly limited to ≤0.035%.