What Is ASTM A106?

ASTM A106 is the standard specification for seamless carbon steel pipe intended for high-temperature service. It covers NPS 1/4 through NPS 26 in three grades (A, B, and C) and is arguably the most specified pipe material in refinery and petrochemical process piping.

Grade B is the workhorse. It combines good weldability, adequate strength (minimum yield 240 MPa), and reliable performance at temperatures up to approximately 427°C (800°F).

Property	Grade A	Grade B	Grade C
Min. Yield Strength	205 MPa (30 ksi)	240 MPa (35 ksi)	275 MPa (40 ksi)
Min. Tensile Strength	330 MPa (48 ksi)	415 MPa (60 ksi)	485 MPa (70 ksi)
Carbon (max)	0.25%	0.30%	0.35%
Manganese	0.27-0.93%	0.29-1.06%	0.29-1.06%
Phosphorus (max)	0.035%	0.035%	0.035%
Sulfur (max)	0.035%	0.035%	0.035%
Silicon (min)	0.10%	0.10%	0.10%
Manufacturing	Seamless only	Seamless only	Seamless only
Max. service temp	~427°C	~427°C	~427°C

Key Features

• Seamless only: ASTM A106 does not cover welded pipe. For welded carbon steel, see ASTM A53 (ERW/seamless) or ASTM A671/A672 (EFW).
• Hot-finished or cold-drawn: Both delivery conditions are permitted. Cold-drawn pipes have tighter tolerances and smoother surfaces.
• Heat treatment: Pipes are furnished hot-finished unless cold-drawn, in which case they are heat-treated (normalized or stress-relieved).
• Hydrostatic test: Mandatory per the specification, unless waived by the purchaser.

Applications

ASTM A106 Grade B is specified for:

• High-temperature process piping in refineries and petrochemical plants
• Steam lines and boiler piping (up to 427°C)
• Heat exchanger connections
• Pressure vessels nozzles and connections
• General process piping where seamless carbon steel is required

Pro Tip

ASTM A106 Grade B and API 5L Grade B (PSL1, seamless) overlap in chemistry and mechanical properties. Many mills dual-certify pipes to both specifications, which gives procurement flexibility. Always check if dual certification is acceptable per your project’s material selection criteria.

ASTM A106 vs A53

Both cover carbon steel pipe, but A106 is seamless-only and designed for high-temperature service. ASTM A53 includes both seamless (Type S) and welded (Type E) products and is intended for general mechanical and pressure applications. See the detailed comparison in ASTM A106 vs A53.

Supplementary Requirements

ASTM A106 allows purchasers to specify additional requirements:

• S1: Product analysis (additional chemistry verification)
• S2: Transverse tension test
• S3: Flattening test
• S4: Metallographic examination
• S5: Charpy impact test (for low-temperature applications)
• S6: Grain size requirements

These must be stated on the purchase order. Without them, only the base specification requirements apply.

Read the full guide to pipe types