1. Manufacturing Process
Seamless Pipe
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Made from a solid round billet of steel.
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The billet is heated and then pierced through the center to create a hollow tube.
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There is no welding seam on the pipe body.
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Example process: Hot rolling → piercing → elongation → sizing → finishing.
Seam (Welded) Pipe
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Made by rolling a flat steel plate or coil into a cylindrical shape, then welding the edges together.
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The welded joint (seam) runs along the length of the pipe.
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Types include ERW (Electric Resistance Welded), LSAW (Longitudinal Submerged Arc Welded), and SSAW (Spiral Submerged Arc Welded) pipes.
2. Structure and Appearance
| Feature | Seamless Pipe | Seam (Welded) Pipe |
|---|---|---|
| Seam | None | Visible weld seam |
| Surface | Smooth and uniform | May have a slight weld bead |
| Dimensional accuracy | Slightly less precise (especially for small sizes) | More precise due to controlled forming |
3. Strength and Performance
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Seamless pipe has higher pressure resistance, better uniformity, and no weak points (since there’s no weld seam).
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Welded pipe may be slightly weaker along the weld line, but modern welding techniques have greatly improved their strength.
4. Applications
Seamless Pipe
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High-pressure and high-temperature applications
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Oil & gas industry, boilers, power generation, automotive, hydraulic systems
Seam (Welded) Pipe
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Low to medium pressure applications
- Structural, water and gas transportation, construction, and general engineering
5. Cost
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Seamless pipe: More expensive due to complex manufacturing and material waste.
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Welded pipe: More cost-effective and widely available.
