QIDAMT
A reliable seamless pipe for pressure and structure
20# is a high-quality carbon structural steel widely used for seamless pipes. Produced by hot rolling or cold drawing without any weld seam, it delivers a smooth bore, uniform wall and dependable pressure resistance to GB/T 8163 (fluid service) and GB/T 8162 (structural service).
With a balanced composition of carbon, silicon and manganese, 20# pipe offers good strength, excellent machinability and weldability, and stable performance at moderate temperatures — the first-choice material for conveying water, air, oil and gas, for boiler and heat-exchanger tubing, and for machined shafts and cylinders.
Why choose 20# seamless pipe
Chemical composition (wt%) — GB/T 8163 · 8162, Grade 20#
| Element | Carbon (C) | Silicon (Si) | Manganese (Mn) | Sulfur (S) | Phosphorus (P) |
|---|---|---|---|---|---|
| Content | 0.17 – 0.24 | 0.17 – 0.37 | 0.35 – 0.65 | ≤ 0.035 | ≤ 0.035 |
Note: single values are maximum limits. Residual elements Cr ≤ 0.25, Ni ≤ 0.30, Cu ≤ 0.25 per standard. Heat analysis applies to ladle samples.
Mechanical properties — Grade 20# seamless pipe
| Property | Yield Strength ReH | Tensile Strength Rm | Elongation A | Impact (0°C) | Hardness (approx.) |
|---|---|---|---|---|---|
| Value | ≥ 245 MPa | 410 – 550 MPa | ≥ 20% | ≥ 27 J | ~ 137 HBW |
Physical properties
Common sizes & specifications
| Outside Diameter (mm) | Wall Thickness (mm) | Length | Process | End Finish |
|---|---|---|---|---|
| 21.3, 25, 32, 38 | 2.8, 3.0, 3.5 | 6 m / 12 m | Cold drawn | Plain / beveled / threaded |
| 42, 48, 57, 60 | 3.5, 4.0, 5.0 | 6 m / 12 m | Hot rolled / cold drawn | Plain / beveled |
| 76, 89, 108, 114 | 4.0, 4.5, 5.0, 6.0 | 6 m / 12 m | Hot rolled | Plain / beveled |
| 159, 168, 219, 273 | 6, 8, 10, 12 | 6 m / 12 m | Hot rolled | Plain / beveled |
| 325, 377, 426, 480, 530, 630 | 10, 12, 14, 16, 20 | 6 m / custom | Hot rolled / expanded | Beveled |
Non-standard OD × WT combinations, honed tubes and special lengths are available on request.
Where 20# seamless pipe is used
- Transporting water, air, oil, gas and steam
- Boiler tubes and heat exchanger tubing
- Hydraulic cylinders, honed tubes and pistons
- Machined shafts, spindles and mechanical parts
- Steel structures and scaffolding systems
- Automotive and agricultural equipment
Processing services & export packaging
Threading (NPT / BSP)
Honing & skiving for cylinders
Surface treatment (oiling / painting)
Hydrostatic testing
Ultrasonic / eddy-current inspection
Hexagonal or square bundling
End caps & woven wrap for sea freight
Wooden pallet / steel frame export packing
Mill test certificate (MTC) supplied
3rd-party inspection acceptable
Tell us your OD, wall thickness and length — we reply within 24 hours with a competitive quote, stock status and delivery schedule.
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