4130 Small Diameter Tubing
Small diameter 4130 tubing covers the bottom of the size range, from about 0.250" OD upwards. It is used for linkages, bracing, instrument and fluid lines, and light structural members where strength is needed in a compact section.
Verified Small-OD Range
The verified minimum OD in the standard supply range is 0.25" (6.35mm). At small ODs, the wall-to-OD ratio is higher for a given wall thickness, meaning the tube is proportionally thicker relative to its size. This is actually an advantage for many applications — small 4130 tubes can carry significant loads relative to their light weight.
Dimensional Accuracy at Small OD
CDS dimensional tolerances expressed as a percentage of OD become physically small at fine sizes. Small-OD tube may require specific tolerance class confirmation for fitting compatibility. State OD tolerance requirements explicitly at the enquiry stage.
| Small OD Range | Typical Application |
|---|---|
| 0.250"–0.500" | Instrumentation lines, fine-bore hydraulics |
| 0.500"–0.750" | Lightweight chassis bracing, bicycle stays |
| 0.750"–1.000" | Roll cage diagonals, bicycle main tubes, suspension rods |
| Form | Cold Drawn Seamless (CDS) — standard |
| Documentation | MTC 3.1 required |
Choosing and Handling Small 4130 Tube
Two things change as the diameter drops. First, the wall becomes a large share of the section, so a small change in wall makes a large change in weight, stiffness and bore. Second, the tube is easier to damage: thin small-bore tube kinks if it is bent without support and is easily bowed in transit.
For fluid lines, remember that 4130 is not corrosion resistant and needs internal and external protection; stainless is often the better choice for that duty, as discussed under instrumentation tubing. For structural use, the 0.500" OD page gives a worked table of walls, bores and weights at a typical small size.
Frequently Asked Questions
What is the smallest OD available in 4130 CDS?
The verified minimum OD in the standard supply range is 0.25" (6.35mm). For ODs smaller than this, the product becomes capillary tube — a specialist product with different enquiry requirements.
Can small diameter 4130 tube be bent without a mandrel?
Generous radii can be bent with simple formers if the wall is relatively heavy for the diameter. Thin walls and tight radii need internal support to avoid kinking.
How is small diameter tubing packed for shipment?
Small tube is bundled and supported along its length so it does not bow. For export it is normally boxed or crated. State any packing requirement with your order.
What walls are available in small diameter 4130 tube?
Light walls from about 0.035" are usual. The wall must be small enough relative to the diameter for the tube to be drawn.
Is small diameter 4130 tubing supplied in coils?
No. It is supplied in straight lengths.
Enquire for Small-Diameter 4130 Tubing
Specify OD, wall, condition, and footage for a small-diameter 4130 quotation.
- OD (exact, in inches or mm)
- Wall
- Standard
- Condition
- Footage
- MTC
- Delivery