304/316 Stainless Steel Capillary Tubes – Complete Specification Guide for Engineers & Procurement
Complete Guide to 304/316 Stainless Steel Capillary Tube Specifications
Selecting the right 304 or 316 stainless steel capillary tube requires understanding key specifications including dimensions, tolerances, material properties, surface finishes, and applicable standards. This comprehensive guide covers everything engineers and procurement professionals need to specify capillary tubes correctly.
Dimensional Specifications
Outside Diameter (OD) Range
| Category | OD Range (mm) | Typical Applications |
|---|---|---|
| Micro Capillary | 0.1 – 0.5 | Medical needles, microfluidics |
| Small Capillary | 0.5 – 1.5 | Instrumentation, sensors |
| Medium Capillary | 1.5 – 3.0 | Hydraulic, pneumatic systems |
| Large Capillary | 3.0 – 12.0 | Industrial, structural applications |
Wall Thickness Range
| Category | Wall Thickness (mm) | Pressure Rating |
|---|---|---|
| Ultra-Thin Wall | 0.025 – 0.05 | Low pressure (< 100 psi) |
| Thin Wall | 0.05 – 0.15 | Medium pressure (100-500 psi) |
| Standard Wall | 0.15 – 0.30 | High pressure (500-2000 psi) |
| Thick Wall | 0.30 – 1.0 | Very high pressure (> 2000 psi) |
Dimensional Tolerances
| Parameter | Standard Tolerance | Precision Tolerance |
|---|---|---|
| Outside Diameter | ±0.05mm to ±0.10mm | ±0.01mm to ±0.03mm |
| Wall Thickness | ±10% to ±15% | ±8% to ±10% |
| Roundness | ≤0.05mm | ≤0.01mm |
| Straightness | ≤1.0mm/m | ≤0.5mm/m |
| Surface Roughness (Ra) | ≤0.8μm | ≤0.2μm (electropolished) |
Material Properties Comparison
| Property | 304 Stainless | 316 Stainless |
|---|---|---|
| Tensile Strength | ≥515 MPa | ≥515 MPa |
| Yield Strength | ≥205 MPa | ≥205 MPa |
| Elongation | ≥35% | ≥35% |
| Hardness | ≤92 HRB | ≤95 HRB |
| Density | 8.0 g/cm³ | 8.0 g/cm³ |
| Max Service Temp | 870°C | 870°C |
| Molybdenum | — | 2.0-3.0% |
Surface Finish Options
| Finish | Ra (μm) | Applications |
|---|---|---|
| Pickled | 0.8-1.5 | Industrial, general purpose |
| Bright Annealed | 0.4-0.8 | Instrumentation, food, medical |
| Electropolished | 0.1-0.4 | Medical, pharmaceutical, semiconductor |
| Mechanical Polished | 0.2-0.5 | Decorative, food processing |
Applicable Standards
| Standard | Description |
|---|---|
| ASTM A269/A269M | Seamless and welded austenitic stainless steel tubing for general service |
| ASTM A213/A213M | Seamless ferritic and austenitic alloy-steel boiler, superheater, and heat-exchanger tubes |
| EN 10216-5 | Pressure equipment – Seamless steel tubes – Technical delivery conditions for stainless steel |
| JIS G3463 | Stainless steel tubes for automotive structural purposes |
| ISO 1127 | Steel, stainless steel and titanium tubes – Outside diameters and nominal walls |
How to Specify Your Capillary Tube
- Material Grade: 304 or 316 (or 304L/316L for low carbon)
- Outside Diameter (OD): mm or inches
- Wall Thickness: mm or inches
- Length: Coil or straight length, meters or feet
- Tolerance: Standard or precision
- Surface Finish: Pickled, bright annealed, electropolished
- Standard: ASTM, EN, JIS, or custom specification
- Quantity: Meters, feet, or number of pieces
- Certification: Material test report, EN 10204 3.1
Request a Quote
Contact us with your specifications — material grade, OD, wall, length, surface finish, quantity — and receive a competitive quote within 24 hours. Free samples available for evaluation.
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