What does SMLS stand for?
"SMLS" stands for Seamless,often written as "SMLS pipe" or "seamless steel pipe".SMLS pipe meaning that the product was manufactured without any welded seams, making it stronger and more reliable for high-pressure or critical applications.
Seamless pipes / tubes are created by shaping a solid billet of metal (e.g., carbon steel , stainless steel) into a hollow tube using processes like hot rolling or extrusion, resulting in a uniform, continuous structure.
SMLS specifically refers to products that are manufactured without a visible seam or weld line in their cross-section.
mild steel SMLS Steel Pipe Chart
The dimensions of seamless line pipe include nominal diameter, outer diameter, wall thickness, length and other aspects. As a seamless pipe suppliers, Youfa Steel Pipe can also customize according to your project. Whether it is a large structural pipe or a small structural, you can meet the size needs of your pipe.
| DN | NB(inch) | ASME | SCH10 | SCH20 | SCH30 | STD | SCH40 | SCH60 | XS | SCH80 | SCH100 | SCH120 | SCH140 | SCH160 | XXS |
| (mm) | (mm) | (mm) | WT | WT | WT | WT | WT | WT | WT | WT | WT | WT | WT | WT | WT |
| 15 | 1/2" | 21.3 | 2.11 | - | 2.41 | 2.77 | 2.77 | - | 3.73 | 3.73 | - | - | - | 4.78 | 7.47 |
| 20 | 3/4" | 26.7 | 2.11 | - | 2.41 | 2.87 | 2.87 | - | 3.91 | 3.91 | - | - | - | 5.56 | 7.82 |
| 25 | 1" | 33.4 | 2.77 | - | 2.9 | 3.38 | 3.38 | - | 4.55 | 4.55 | - | - | - | 6.35 | 9.09 |
| 32 | 1.1/4" | 42.2 | 2.77 | - | 2.97 | 3.56 | 3.56 | - | 4.85 | 4.85 | - | - | - | 6.35 | 9.7 |
| 40 | 1.1/2" | 48.3 | 2.77 | - | 3.18 | 3.68 | 3.68 | - | 5.08 | 5.08 | - | - | - | 7.14 | 10.15 |
| 50 | 2" | 60.3 | 2.77 | - | 3.18 | 3.91 | 3.91 | - | 5.54 | 5.54 | - | - | - | 8.74 | 11.07 |
| 65 | 2.1/2" | 73 | 3.05 | - | 4.78 | 5.16 | 5.16 | - | 7.01 | 7.01 | - | - | - | 9.53 | 14.02 |
| 80 | 3" | 88.9 | 3.05 | - | 4.78 | 5.49 | 5.49 | - | 7.62 | 7.62 | - | - | - | 11.13 | 15.25 |
| 90 | 3.1/2" | 101.6 | 3.05 | - | 4.78 | 5.74 | 5.74 | - | 8.08 | 8.08 | - | - | - | - | - |
| 100 | 4" | 114.3 | 3.05 | - | 4.78 | 6.02 | 6.02 | - | 8.56 | 8.56 | - | 11.13 | - | 13.49 | 17.12 |
| 125 | 5" | 141.3 | 3.4 | - | - | 6.55 | 6.55 | - | 9.53 | 9.53 | - | 12.7 | - | 15.88 | 19.05 |
| 150 | 6" | 168.3 | 3.4 | - | - | 7.11 | 7.11 | - | 10.97 | 10.97 | - | 14.27 | - | 18.26 | 21.95 |
| 200 | 8" | 219.1 | 3.76 | 6.35 | 7.04 | 8.18 | 8.18 | 10.31 | 12.7 | 12.7 | 15.09 | 18.26 | 20.62 | 23.01 | 22.23 |
| 250 | 10" | 273 | 4.19 | 6.35 | 7.8 | 9.27 | 9.27 | 12.7 | 12.7 | 15.09 | 18.26 | 21.44 | 25.4 | 28.58 | 25.4 |
| 300 | 12" | 323.8 | 4.57 | 6.35 | 8.38 | 9.53 | 10.31 | 14.27 | 12.7 | 17.48 | 21.44 | 25.4 | 28.58 | 33.32 | 25.4 |
| 350 | 14" | 355.6 | 6.35 | 7.92 | 9.53 | 9.53 | 11.13 | 15.09 | 12.7 | 19.05 | 23.83 | 27.79 | 31.75 | 35.71 | - |
| 400 | 16" | 406.4 | 6.35 | 7.92 | 9.53 | 9.53 | 12.7 | 16.66 | 12.7 | 21.44 | 26.19 | 30.96 | 36.53 | 40.19 | - |
| 450 | 18" | 457.2 | 6.35 | 7.92 | 11.13 | 9.53 | 14.27 | 19.05 | 12.7 | 23.83 | 39.36 | 34.93 | 39.67 | 45.24 | - |
| 500 | 20" | 508 | 6.35 | 9.53 | 12.7 | 9.53 | 15.09 | 20.62 | 12.7 | 26.19 | 32.54 | 38.1 | 44.45 | 50.01 | - |
| 550 | 22" | 558.8 | 6.35 | 9.53 | 12.7 | 9.53 | - | 22.23 | 12.7 | 28.58 | 34.93 | 41.28 | 47.63 | 53.98 | - |
| 600 | 24" | 609.6 | 6.35 | 9.53 | 14.27 | 9.53 | 17.48 | 24.61 | 12.7 | 30.96 | 38.89 | 46.02 | 52.37 | 59.54 | - |
Common wall thickness specifications can be divided into the following three types:
Thin-walled mild steel seamless pipe: usually 1 mm to 4 mm.
Medium thickness smls steel pipe: usually 5 mm to 10 mm.
Thick wall seamless steel pipe: usually 12 mm to 30 mm, 30 mm and above.
Key Characteristics of SMLS pipes and tubes
Strength and Durability: Cs seamless pipe eliminates potential weak points at weld seams, making them ideal for high-pressure applications or structural loads requiring consistent integrity.
Smooth Interior / Exterior: The absence of a seam allows for easier flow of fluids (in pipes) or cleaner aesthetics (in tubing used for architecture or machinery).
Contrast with Welded Products:
Welded Tubing/Pipe: Manufactured by rolling a flat metal sheet into a tube and welding the seam. While often more cost-effective, they may have slightly lower pressure ratings or require additional inspection for critical uses.
Applications: Common in industries like oil and gas, automotive, aerospace, and construction (e.g., structural supports, mechanical components).
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