ASTM A106 seamless pipes are high-strength carbon steel tubes designed primarily for high-temperature service in industries like oil and gas, power generation, and chemical processing. Unlike welded pipes, these are produced without seams, reducing the risk of leaks in demanding environments.
Established under the American Society for Testing and Materials (ASTM) framework, this specification—formally titled "Standard Specification for Seamless Carbon Steel Pipe for High-Temperature Service"—has become a cornerstone for engineers worldwide. Whether transporting superheated steam in power plants, crude oil in refineries, or process gases in chemical facilities, ASTM A106 pipes deliver exceptional performance.
Grades: A, B, and C
ASTM A106 classifies pipes into three grades, differentiated primarily by chemical makeup and mechanical robustness:
- Grade A: Entry-level option with moderate strength, ideal for general high-temperature fluid conveyance. Best used where cold bending is required.
- Grade B: The industry workhorse. Strikes an optimal balance—higher manganese aids deoxidization during melting, improving ductility. Equivalent to API 5L Grade B.
- Grade C: Premium grade for superior strength in harsh, high-stress scenarios. Higher carbon content boosts hardenability but demands preheating for welding.
Chemical & Mechanical Properties
| Element |
Grade A (%) |
Grade B (%) |
Grade C (%) |
| Carbon (C) Max | 0.25 | 0.30 | 0.35 |
| Manganese (Mn) | 0.27-0.93 | 0.29-1.06 | 0.29-1.06 |
| Phosphorus (P) Max | 0.035 | 0.035 | 0.035 |
| Sulfur (S) Max | 0.035 | 0.035 | 0.035 |
| Silicon (Si) Min | 0.10 | 0.10 | 0.10 |
| Property (Min) |
Grade A |
Grade B |
Grade C |
| Tensile Strength (psi) | 48,000 | 60,000 | 70,000 |
| Yield Strength (psi) | 30,000 | 35,000 | 40,000 |
| Elongation in 2" (%) | 30 | 22 | 20 |
Manufacturing Process
ASTM A106 pipes are produced via a seamless hot-rolling method starting with high-quality steel billets. The billet is heated to 1250–1280°C in a rotary furnace, then pierced using a mandrel to form a hollow shell. This shell elongates in a finishing mill, reheats for uniformity, and reduces in a stretch mill to precise diameters. Post-rolling, quenching and tempering refine the microstructure for toughness.
Dimension Tables (1/4" to 42")
ASME B36.10M Standards | Carbon Steel
Small Bore: 1/4" to 5"
| NPS (Inch) |
OD (mm) |
SCH 40 / STD (mm) |
SCH 80 / XS (mm) |
SCH 160 (mm) |
| 1/4" | 13.7 | 2.24 | 3.02 | - |
| 3/8" | 17.1 | 2.31 | 3.20 | - |
| 1/2" | 21.3 | 2.77 | 3.73 | 4.78 |
| 3/4" | 26.7 | 2.87 | 3.91 | 5.56 |
| 1" | 33.4 | 3.38 | 4.55 | 6.35 |
| 1-1/4" | 42.2 | 3.56 | 4.85 | 6.35 |
| 1-1/2" | 48.3 | 3.68 | 5.08 | 7.14 |
| 2" | 60.3 | 3.91 | 5.54 | 8.74 |
| 2-1/2" | 73.0 | 5.16 | 7.01 | 9.53 |
| 3" | 88.9 | 5.49 | 7.62 | 11.13 |
| 3-1/2" | 101.6 | 5.74 | 8.08 | - |
| 4" | 114.3 | 6.02 | 8.56 | 13.49 |
| 5" | 141.3 | 6.55 | 9.53 | 15.88 |
Schedule 20 & 30 (Light Wall)
| NPS (Inch) |
OD (mm) |
SCH 20 (mm / kg/m) |
SCH 30 (mm / kg/m) |
| 6" | 168.3 | 7.11 / 28.24 | 7.92 / 31.28 |
| 8" | 219.1 | 7.04 / 33.31 | 8.84 / 38.72 |
| 10" | 273.0 | 7.80 / 43.70 | 9.27 / 50.62 |
| 12" | 323.9 | 8.38 / 56.60 | 10.16 / 65.54 |
| 14" | 355.6 | 7.92 / 60.30 | 9.53 / 71.50 |
| 16" | 406.4 | 7.92 / 68.50 | 9.53 / 81.90 |
| 20" | 508.0 | 9.53 / 92.30 | 12.70 / 113.20 |
| 24" | 610.0 | 9.53 / 111.00 | 14.27 / 141.50 |
| 36" | 914.4 | 14.27 / 179.00 | 19.05 / 230.60 |
Schedule 40 (STD) & Schedule 60
| NPS (Inch) |
OD (mm) |
SCH 40 / STD (mm / kg/m) |
SCH 60 (mm / kg/m) |
| 6" | 168.3 | 7.11 / 28.24 | 10.31 / 40.22 |
| 8" | 219.1 | 8.18 / 42.52 | 10.31 / 49.15 |
| 10" | 273.0 | 9.27 / 60.27 | 12.70 / 68.50 |
| 12" | 323.9 | 9.53 / 79.70 | 14.27 / 89.40 |
| 14" | 355.6 | 11.13 / 94.55 | 15.09 / 126.71 |
| 16" | 406.4 | 12.70 / 123.25 | 16.66 / 134.00 |
| 20" | 508.0 | 15.09 / 183.75 | 20.62 / 193.70 |
| 24" | 610.0 | 17.48 / 251.60 | 23.80 / 253.20 |
| 36" | 914.4 | 23.83 / 438.00 | 31.75 / 432.10 |
Schedule 80 (XS) & Schedule 100
| NPS (Inch) |
OD (mm) |
SCH 80 / XS (mm / kg/m) |
SCH 100 (mm / kg/m) |
| 6" | 168.3 | 10.97 / 43.70 | 14.27 / 52.14 |
| 8" | 219.1 | 12.70 / 64.55 | 18.26 / 74.47 |
| 10" | 273.0 | 15.09 / 95.92 | 21.44 / 104.30 |
| 12" | 323.9 | 17.48 / 131.30 | 25.40 / 141.50 |
| 16" | 406.4 | 21.44 / 203.53 | 30.96 / 208.50 |
| 20" | 508.0 | 26.19 / 311.17 | 38.10 / 290.50 |
| 24" | 610.0 | 30.96 / 442.08 | 46.02 / 387.00 |
| 36" | 914.4 | 34.93 / 700.00 | 60.33 / 640.70 |
Heavy Wall (SCH 120, 160, XXS)
| NPS (Inch) |
OD (mm) |
SCH 120 (mm/kg) |
SCH 160 (mm/kg) |
XXS (mm/kg) |
| 6" | 168.3 | 14.27 / 54.20 | 18.26 / 67.56 | 21.95 / 79.22 |
| 8" | 219.1 | 18.26 / 90.44 | 23.01 / 111.27 | 22.23 / 107.92 |
| 10" | 273.0 | 21.44 / 133.06 | 28.58 / 172.33 | 25.40 / 155.15 |
| 12" | 323.9 | 25.40 / 186.97 | 33.32 / 238.76 | 25.40 / 186.97 |
| 16" | 406.4 | 30.96 / 286.64 | 40.49 / 365.36 | - |
| 20" | 508.0 | 38.10 / 441.49 | 50.01 / 564.81 | - |
| 24" | 610.0 | 46.02 / 640.03 | 59.54 / 807.78 | - |
Frequently Asked Questions
What is the difference between Grade B and Grade C?
Grade B is the industry standard for general use, offering a balance of strength and weldability. Grade C has a higher carbon content (max 0.35%), providing higher tensile strength for extreme pressure applications, but is slightly harder to weld.
Can ASTM A106 pipe be used for steam applications?
Yes, ASTM A106 pipes are specifically designed for high-temperature service, making them ideal for superheated steam lines, boilers, and heat exchangers.
Do you provide Mill Test Certificates?
Yes, all our pipes come with Mill Test Certificates (MTC) in accordance with EN 10204 3.1.
