Precision 304 Stainless Steel Capillary Tube ASTM A269 Seamless Stainless Steel Tubing
304 stainless steel capillary tube is a precision small-diameter tube manufactured through cold drawing or cold rolling processes. It is widely used in medical devices, instrumentation, electronic components, and automatic control systems where high precision, cleanliness, and corrosion resistance are required.
Capillary tubes typically feature outer diameters ranging from 0.3mm to 8.0mm with wall thicknesses as thin as 0.1mm. The 304 austenitic stainless steel grade provides excellent corrosion resistance, good mechanical properties, and outstanding formability.
| Specification | Details |
|---|---|
| Product Name | 304 Stainless Steel Capillary Tube |
| Material Grade | 304 / SUS304 (UNS S30400, 1.4301) |
| Outer Diameter (OD) | 0.3mm – 8.0mm |
| Wall Thickness (WT) | 0.1mm – 1.5mm |
| Length | Cut to size (100mm – 6000mm) |
| Manufacturing Process | Cold drawn / Cold rolled |
| Surface Finish | Pickled, annealed, polished, bright annealed (BA) |
- High dimensional accuracy – Tight tolerances up to ±0.02mm on OD and ID
- Smooth inner/outer surface – Low friction, minimal flow resistance
- Excellent corrosion resistance – 18% chromium provides reliable protection
- Good ductility – Easy to bend, flare, and swage
- Clean, burr-free ends – Ready for assembly
- Full traceability – MTR provided with heat number
| Element | 304 Standard | Typical Value |
|---|---|---|
| C | ≤0.08 | 0.05-0.07 |
| Si | ≤0.75 | 0.45-0.55 |
| Mn | ≤2.00 | 1.20-1.50 |
| P | ≤0.045 | ≤0.035 |
| S | ≤0.030 | ≤0.020 |
| Cr | 18.00-20.00 | 18.20-18.80 |
| Ni | 8.00-10.50 | 8.20-8.80 |
*Source: ASTM A269 / A213*
| Property | Value |
|---|---|
| Tensile Strength | ≥520 MPa |
| Yield Strength (0.2%) | ≥205 MPa |
| Elongation | ≥35% |
| Hardness (HRB) | ≤90 |
| Density | 7.93 g/cm³ |
| Melting Point | 1398 – 1420℃ |
| OD (mm) | Wall Thickness (mm) | ID (mm) | Typical Use |
|---|---|---|---|
| 0.50 | 0.10 | 0.30 | Hypodermic needle |
| 0.80 | 0.15 | 0.50 | Medical cannula |
| 1.00 | 0.20 | 0.60 | Sensor probe |
| 1.60 | 0.30 | 1.00 | Instrument tube |
| 2.00 | 0.30 | 1.40 | Hydraulic line |
| 2.50 | 0.40 | 1.70 | Gas sampling line |
| 3.00 | 0.50 | 2.00 | Capillary column |
| 4.00 | 0.50 | 3.00 | Cooling coil |
| 5.00 | 0.60 | 3.80 | Instrumentation |
| 6.00 | 0.80 | 4.40 | Control line |
Custom sizes available upon request. Minimum OD 0.3mm, minimum WT 0.1mm.
- Medical Devices – Hypodermic needles, cannulas, surgical instruments, biopsy needles, dental tools
- Instrumentation – Pressure gauges, temperature sensors, flow meters, analytical instruments
- Electronics – Fine wire guides, probe pins, sensor housings, semiconductor components
- Automation – Pneumatic tubing, hydraulic pilot lines, solenoid valve tubes
- Aerospace – Instrument lines, fuel delivery lines, control system tubing
- Laboratory – Capillary columns for chromatography, sample loops, chemical sampling
- General Precision – Watch components, miniature shafts, fine tubes for precision mechanisms
| Advantage | Description |
|---|---|
| Precision Manufacturing | Advanced cold drawing equipment ensures consistent OD/ID tolerances |
| No Internal Burrs | Special deburring process guarantees a clean, smooth internal surface |
| Cut to Length | Custom lengths from 100mm to 6000mm – no waste |
| Flexible Packaging | Plastic caps, foam protection, vacuum sealing, or wooden reels |
| Full Certification | Mill Test Report (MTR) with each shipment |
| Fast Lead Time | Stock sizes ready in 3-7 days |
| Competitive Pricing | Direct factory pricing |
304 stainless steel capillary tubes comply with the following standards:
| Standard | Description |
|---|---|
| ASTM A269 | Seamless and welded tubing for general service |
| ASTM A632 | Seamless tubing for small diameter |
| GB/T 3090 | Stainless steel small diameter seamless tubes (Chinese standard) |
| ISO 9626 | Stainless steel needle tubing for medical devices |
Third-party inspection available (SGS, BV, TÜV) upon request.
| Packaging Method | Protection |
|---|---|
| Plastic end caps | Prevents internal contamination |
| Foam interlayers | Protects surface finish |
| Vacuum sealing | For ultra-clean applications |
| Wooden reels/spools | For long lengths, easy dispensing |
| Export cartons | Standard export packaging |
Delivery: Stock items: 3-7 days; Custom sizes: 15-30 days.
Q: What is the minimum OD available for 304 capillary tubes?
A: Our minimum outer diameter is 0.3mm with a wall thickness down to 0.1mm.
Q: What is the standard length?
A: Standard length is 3000mm or 6000mm. We also offer cut-to-size service from 100mm to 6000mm.
Q: Can you supply capillary tubes with a polished ID surface?
A: Yes. We can provide a bright annealed (BA) finish or an electropolished (EP) inner surface upon request.
Q: Do you provide custom deburring?
A: Yes. We offer precision end finishing – straight cut, square cut, or chamfered – no burrs on ID/OD.
Q: Are these tubes suitable for medical needle applications?
A: Yes. Our capillary tubes meet ISO 9626 requirements for hypodermic needle tubing.
Q: How can I get a quote?
A: Please provide OD, wall thickness, length, and quantity. We will reply within 24 hours.
Ready to order 304 stainless steel capillary tube or need a custom size? Send your inquiry with specifications, and we will respond with a competitive quote within 24 hours.
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