Seamless steel pipe is produced from solid steel billet without welding seam, mainly divided into hot rolling and cold drawing production routes for different dimensional specifications.

1. Main Production Flow of Hot Rolled Seamless Pipe

Raw round steel billet → cutting sizing → rotary furnace heating → piercing → elongation rolling → sizing / reducing rolling → cooling → straightening → cutting to fixed length → inspection & warehousing. High-temperature piercing turns solid billet into hollow tube blank, followed by multi-pass rolling to reach outer diameter and wall thickness requirements.

2. Production Flow of Cold Drawn Seamless Pipe

Hot rolled tube blank → pickling & phosphating → cold drawing pass by pass → intermediate annealing → finishing drawing → straightening → finished inspection, applied for thin-wall, high-precision small-size seamless tubes.

3. Core Production Equipment

• Rotary hearth heating furnace: uniformly heat round billet to piercing forming temperature;

• Rotary piercing mill: core equipment to punch hollow tube shell from solid steel;

• Continuous tube rolling mill / elongator: reduce wall thickness and improve tube roundness;

• Sizing & reducing mill: precisely control finished pipe outer dimension;

• Straightener: eliminate pipe bending deformation after cooling;

• Auxiliary units: pickling tank, cold drawing bench, heat treatment furnace and NDT inspection machine.

4. Process Control Key Points

Strictly control billet heating temperature to avoid piercing crack; adjust rolling parameters to prevent uneven wall thickness; heat treatment eliminates internal stress to guarantee mechanical property of finished seamless tubes.