What are the manufacturing processes for mechanical steel pipes?

There are many types of manufacturing and processing processes for mechanical pipes & tubes. Different processes can be selected according to different materials, uses and precision requirements. The following are common mechanical steel pipe manufacturing processes and their characteristics:

1. Hot rolling process

Process: Heat the steel billet to a high temperature (usually over 1000°C) and roll it into a pipe through a rolling mill.

Features:
High production efficiency, suitable for mass production.
Low dimensional accuracy and surface finish.

Suitable for manufacturing ordinary steel pipes.

Application: building structures, conveying pipelines, etc.

2. Cold rolling/Cold drawing process

Process: Process at room temperature through a rolling mill or drawing machine to gradually reduce the diameter and wall thickness of the pipe.

Features:
High dimensional accuracy and good surface finish.
Thin-walled and small-diameter steel pipes can be produced.
Strong work hardening effect, annealing treatment is required.

Application: high-precision mechanical steel pipes, hydraulic cylinder pipes, etc.

3. Seamless pipe manufacturing process

Perforation method:
The solid steel billet is made into a hollow tube billet through a perforator. Applicable to medium and thick wall steel pipes.

Extrusion method:
The steel billet is extruded into a pipe through an extruder at high temperature. Applicable to difficult-to-process materials such as high alloy steel and stainless steel.

Features:
Seamless structure, high strength. Suitable for high pressure and high precision occasions.

Application: petroleum, chemical industry, aerospace and other fields.

4. Welding process

High frequency welding (ERW pipe):
The edge of the steel strip is heated by high frequency current to fuse and weld.

High production efficiency and low cost.

Spiral welding (SSAW):
The steel strip is spirally curled and welded, suitable for large diameter steel pipes.

Straight seam welding (ERW/LSAW): 
Straight seam welding of steel strips or steel plates, suitable for small, medium and large diameter steel pipes.

Laser welding:
Using laser beam welding, the weld quality is high, suitable for high precision steel pipes.

Features:
Suitable for medium and low pressure occasions.
The quality of the weld affects the overall performance.

Application: construction, furniture, pipelines, etc.

5. Heat treatment process

Normalizing: Refine the grains, improve strength and toughness.
Quenching and tempering: Improve hardness and strength.
Annealing: Eliminate internal stress and improve processing performance.
Solution treatment: Used for stainless steel pipes to improve corrosion resistance.

Features: Optimize material properties and ensure the stability and durability of steel pipes.

6. Surface treatment process

Polishing: Improve surface finish, suitable for medical devices and food industries.
Pickling: Remove oxide layer and improve corrosion resistance.
Plating: Such as zinc plating and chrome plating, enhance anti-corrosion performance.
Spraying: Such as epoxy resin coating, increase wear resistance and corrosion resistance.

Features: Improve appearance and functionality to meet special needs.

7. Precision machining process

Finishing after cold rolling/cold drawing:

Ensure dimensional accuracy through straightening, cutting and other processes.

Inner hole machining:

Improve the inner wall finish and precision through boring, grinding and other processes.

Features: Ensure high precision and consistency of steel pipes.

8. Inspection and quality control

Dimension inspection:

Use tools such as calipers and micrometers to measure outer diameter, wall thickness, etc.

Surface inspection:

Check surface defects by visual or instrument inspection.

Non-destructive testing:

Such as ultrasonic and radiographic testing to ensure that there are no internal defects.

Pressure testing:

Test the pressure bearing capacity of pipes.

Features: Ensure that products meet standards and meet high precision requirements.

9. Special processes

Laser cutting:

Used for high-precision cutting, suitable for complex shapes.

Electrolytic polishing:

Further improve surface finish, suitable for high-demand occasions.

Coating technology:

Such as PTFE coating, increase wear resistance and corrosion resistance.

Conclusion:

The manufacturing and processing processes of mechanical steel pipes includes hot rolling, cold rolling/cold drawing, seamless pipe manufacturing, welding, heat treatment, surface treatment, precision machining and quality inspection, etc. Each process has its own characteristics and application scenarios. Manufacturers need to choose the appropriate process combination according to specific needs to ensure the high precision, high quality and reliability of the product.

Read more: Cold Drawn Seamless Tube for Mechanical & Hydraulic or What materials are mechanical tubes made of?