STEEL TUBES

Steel tube manufacturing processes, from start to finish, plus the common variations you’ll see in industry.

RAW MATERIAL PREPARATION

Steel tubes start as:

• Steel billets (solid)

• Steel slabs or coils (flat steel)

The starting form determines whether the tube will be seamless or welded.

SEAMLESS STEEL TUBE PROCESSES

No weld seam — used for high-pressure, critical applications.

Rotary Piercing (Mannesmann Process)

• Heated billet is pierced to form a hollow shell

• Rolled and elongated to size

• Common for pressure vessels, oil & gas, mechanical tubing

Plug Mill / Mandrel Mill

• Refines wall thickness and diameter

• Mandrel supports the inside during rolling

Cold Drawing (CDS)

• Tube is pulled through a die (and mandrel)

• Improves:

  • Dimensional accuracy

  • Surface finish

  • Mechanical properties

WELDED STEEL TUBE PROCESSES

More economical, high-volume production.

ERW (Electric Resistance Welding)

• Steel strip formed into a tube

• Edges heated electrically and fused

• No filler metal

• Used for structural, automotive, mechanical tubing

HFW (High-Frequency Welding)

• A refined ERW process

• Higher speeds and better weld quality

SAW (Submerged Arc Welding)

• Uses filler metal and flux

• Types:

  • LSAW (Longitudinal)

  • SSAW (Spiral)

• Common in large-diameter pipes (pipelines, piling)

TUBE FORMING & SIZING

After welding or piercing:

• Sizing mills adjust diameter

• Straightening mills correct shape

• Cut-to-length (flying saws)

HEAT TREATMENT

Improves strength and consistency:

• Normalizing

• Annealing

• Quenching & tempering

• Stress relieving (especially welded tubes)

FINISHING PROCESSES

Depending on application:

• Pickling

• Shot blasting

• Galvanizing

• Coating / painting

• Polishing

INSPECTION & TESTING

Critical for quality and compliance:

• Eddy current testing

• Ultrasonic testing

• Hydrostatic testing

• Dimensional & visual inspection

COMMON END FORMS

• Plain end

• Beveled end

• Threaded & coupled

• Grooved

TYPICAL APPLICATIONS BY PROCESS

• Seamless: Oil & gas, pressure vessels, bearings

• ERW/HFW: Structural, automotive, furniture

• SAW: Pipelines, offshore, piling