Seamless Stainless Steel Square Tubing High Pressure High Temperature Grade
Seamless stainless steel square tubing is a hollow structural section with four equal sides and no welded seam along its length. It is manufactured by extruding a solid billet of stainless steel into a hollow tube, then forming it into a square shape.
The absence of a weld seam provides superior strength, uniform wall thickness, and excellent performance under high pressure and extreme temperatures. Our seamless square tubing is ideal for critical applications where reliability is paramount.
| Parameter | Details |
|---|---|
| Standard | ASTM A312, A269, A213, EN 10216, JIS G3459 |
| Grades | 304, 304L, 316, 316L, 321, 310S |
| Size (Width x Width) | 10 mm x 10 mm – 150 mm x 150 mm |
| Wall Thickness | 1.0 mm – 10.0 mm |
| Length | 3000 mm, 4000 mm, 6000 mm (custom cut available) |
| Process | Cold drawn or cold rolled seamless |
| Surface Finish | Mill finish, Pickled, Annealed, Polished |
| Element | Grade 304 | Grade 304L | Grade 316 | Grade 316L |
|---|---|---|---|---|
| Carbon (C) | ≤ 0.08 | ≤ 0.03 | ≤ 0.08 | ≤ 0.03 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 |
| Chromium (Cr) | 18.0 – 20.0 | 18.0 – 20.0 | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 8.0 – 10.5 | 8.0 – 12.0 | 10.0 – 14.0 | 10.0 – 14.0 |
| Molybdenum (Mo) | — | — | 2.0 – 3.0 | 2.0 – 3.0 |
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 304 | ≥ 515 | ≥ 205 | ≥ 35 |
| 304L | ≥ 485 | ≥ 170 | ≥ 35 |
| 316 | ≥ 515 | ≥ 205 | ≥ 35 |
| 316L | ≥ 485 | ≥ 170 | ≥ 35 |
Note: The values above are for reference only. Please refer to the mill test certificate for actual data.
- No welded seam – eliminates weak points
- Uniform wall thickness throughout
- Superior pressure and temperature resistance
- Excellent corrosion resistance
- Higher strength than welded tubing
- Smooth internal surface for fluid flow
| Feature | Seamless Tube | Welded Tube |
|---|---|---|
| Manufacturing | Extruded from solid billet | Formed from strip and welded |
| Weld Seam | None | Present |
| Pressure Rating | Higher | Lower |
| Wall Thickness Consistency | Very consistent | Consistent |
| Strength | Superior | Good |
| Corrosion Resistance at Seam | Uniform | Potential weak point |
| Cost | Higher | Lower |
| Lead Time | Longer | Shorter |
| Best For | High pressure, high temperature, critical applications | Structural, architectural, general purpose |
Seamless stainless steel square tubing is used in demanding applications where reliability is critical:
- Instrumentation tubing
- Hydraulic lines
- Downhole equipment
- Refinery components
- High pressure processing lines
- Heat exchanger tubing
- Reactor components
- Corrosive fluid handling
- Boiler tubing
- Nuclear power components
- Steam lines
- Heat recovery systems
- Aircraft hydraulic systems
- Structural components
- Fuel lines
- Missile guidance systems
- Sanitary processing lines
- High purity fluid transfer
- Clean steam lines
- Biopharmaceutical equipment
| Grade | Best For |
|---|---|
| 304 | General high pressure applications, food processing |
| 304L | Welded structures in high pressure systems |
| 316 | Marine, chemical, and chloride environments |
| 316L | Welded structures in corrosive environments |
| 321 | High temperature applications (up to 900°C) |
| 310S | Very high temperature applications (up to 1150°C) |
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