Seamless Tube Manufacturing Process - From Raw Material to Final Product (2025 Complete Guide)

The journey begins with a solid round billet made from:

• Carbon Steel
• Stainless Steel
• Alloy Steel
• Duplex / Super Duplex
• Nickel Alloys

Billets are cut into required lengths (typically 600–1600 mm).

Billets are heated to 1100–1300°C inside a rotary hearth furnace.

Why heat?

• Makes the billet soft
• Allows piercing
• Reduces cracking risk

Heating is precisely controlled using temperature sensors.

The most important step.

The hot billet is passed between rotating conical rollers along with a piercing mandrel.

Result:

• A hollow tube shell is created
• No welding needed
• Smooth continuous inner diameter

This is what makes seamless tubes different from welded tubes.

The hollow shell is rolled depending on required size:

• Plug Mill: Medium-thick tubes
• Mandrel Mill: Long-length, high-precision tubes
• Pilger Mill: Thin-wall, very accurate tubes

During rolling:

• Tube is stretched
• Wall thickness is reduced
• Length increases
• Dimensions become uniform

This step ensures correct OD & wall thickness.

Tube passes through several rollers to:

• Correct outer diameter (OD)
• Improve roundness
• Reduce thickness if needed
• Achieve final dimensions

This ensures tight tolerances.

Heat treatment depends on material:

• Carbon Steel: Normalizing
• Alloy Steel: Quenching & Tempering
• Stainless Steel: Solution Annealing
• Duplex: Annealing

Purpose:

• Improve mechanical properties
• Relieve stress
• Increase corrosion resistance

After heat treatment, tubes may bend slightly.

Straightening machines ensure:

• Perfect alignment
• Better roundness
• Uniformity

Tubes are cut into required lengths:

• 4 meters
• 6 meters
• 12 meters
• Custom lengths

High-quality seamless tubes must undergo strict inspection:

• Ultrasonic Testing (UT)
• Eddy Current Test
• Radiography (RT)
• Hydrostatic Test

• Tensile
• Flattening
• Flaring

• PMI
• Hardness
• ID/OD measurement

Moksh Tubes follows ASTM, ASME, EN, and API standards.

Finishing options include:

• Pickling & passivation (SS)
• Cold drawing (bright finish)
• Polishing
• Coating (carbon steel)

Improves appearance and corrosion resistance.

Final checks include:

• Dimensional check
• Visual inspection
• Thickness measurement
• MTC documentation

Packaging options:

• Bundles
• Wooden boxes
• Crates
• Export wrapping

Finally shipped worldwide.

Seamless tubes are widely used in:

• Boilers
• Heat exchangers
• Superheaters
• Condensers
• Oil & gas pipelines
• Mechanical engineering
• Hydraulic cylinders
• Petrochemical plants

Because they offer zero weld weakness and high pressure resistance.