Thin-walled seamless carbon steel pipe

What is a thin-walled seamless carbon steel pipe?

Thin-walled seamless carbon steel pipe refers to a carbon steel pipe produced by a seamless process (such as cold rolling, cold drawing or hot extrusion), with a small ratio of wall thickness to pipe diameter (usually wall thickness/outer diameter < 0.05). Since there is no weld, its structure is uniform and suitable for scenes with high requirements for precision, lightness and surface quality.

Main features of thin-walled seamless carbon steel pipe:

Seamless structure: no weld, avoid stress concentration, and improve fatigue resistance.

High precision: cold rolling/cold drawing process can control the outer diameter tolerance (within ±0.1mm).

Lightweight: thin wall thickness (usually 0.5~5mm), light weight, saving material cost.
Smooth surface: smooth inner wall, small fluid resistance, suitable for precision instruments or clean systems.

Good processing performance: easy to bend, cut, weld, suitable for complex structure processing.
General pressure resistance: suitable for low pressure scenes (usually ≤10MPa).

Production process:

Thin-wall seamless carbon steel pipes are mainly produced by cold processing, and the core processes include cold rolling and cold drawing. The specific process is as follows:

Cold rolling method (high precision, large batch):

1. Billet preparation: Select high-quality hot-rolled seamless carbon steel pipes as mother pipes.
2. Pickling: Remove surface oxide scale (immersion in hydrochloric acid or sulfuric acid).
3. Phosphating/lubrication: Apply phosphate layer to reduce rolling friction.

4. Cold rolling forming:
Use multi-roll cold rolling mill (such as LG type rolling mill) to reduce wall extension.
Control rolling force to ensure dimensional accuracy (such as Φ20mm±0.05mm).

5. Annealing: Eliminate work hardening (optional, depending on material requirements).
6. Straightening & cutting: Ensure straightness and cut to size.

Cold drawing method (small batch, high surface quality):

1. Billet preparation: hot-rolled pipe or cold-rolled pipe.
2. Pickling & lubrication: Same as cold rolling process.

3. Cold drawing:
Through die or mandrel stretching to reduce diameter and wall (can be drawn multiple times).
Applicable to ultra-thin wall tubes (such as wall thickness 0.5~1mm).

4. Heat treatment: annealing to restore plasticity (if deep processing is required).

Thin-walled seamless carbon steel pipe vs. thick-walled seamless carbon steel pipe:

1) Thin-walled seamless carbon steel pipe

Wall thickness range: 0.5~5mm;
Pressure bearing capacity: low pressure (≤10MPa);

Weight: lightweight
Cost: low (material saving)
Typical process: cold rolling/cold drawing

2) Thick-walled seamless carbon steel pipe:

Wall thickness range: 5~50mm+;
Pressure bearing capacity: high pressure (≥30MPa);

Weight: heavier
Cost: higher
Typical process: hot rolling/hot extrusion

Typical application areas of thin-walled seamless steel pipes:

Precision machinery: hydraulic system thin tubes, bearing sleeves.
Automotive industry: fuel pipes, brake pipes, exhaust pipes (parts).
Home appliances and electronics: air conditioning condenser tubes, printer rollers.
Medical equipment: stainless steel composite thin-walled tubes (such as CT machine brackets).

Decoration engineering: handrails, display racks, lamp frames.

Notes on thin-walled tube selection:
1. Thin-walled tubes are preferred: when the demand is lightweight, precision processing, and low pressure (such as furniture, electronic equipment).
2. Avoid overpressure: thin-walled tubes have limited pressure bearing (≤10MPa), and thick-walled tubes can reach more than 30MPa, and the working pressure needs to be strictly calculated.

3. Surface treatment: If used in a humid environment, galvanizing or plastic coating is recommended for rust prevention.

Thin-walled seamless carbon steel pipes are an ideal choice for light industry, automobiles, and home appliances due to their high precision, easy processing, and economy. The use of thin-walled seamless carbon steel pipes requires strict evaluation of working conditions to strike a balance between lightweight, high-precision requirements and mechanical properties. For key pressure-bearing parts, it is recommended to give priority to thick-walled tubes or stainless steel materials.

Read more: Thick Wall Steel Pipe or Schedule 80 carbon steel pipe