304
General purpose
Common for precision hardware, sleeves, sensor housings and general small-bore tube assemblies.
Product form hub · Capillary tube
Stainless Steel Capillary Tube
Specify stainless steel capillary tube by grade, outside diameter, inside diameter or wall thickness, tolerance, surface condition, length and end preparation. This page gives buyers a practical route from common micro-tube dimensions to a quote-ready specification.
304 / 304L / 316 / 316L
OD / ID / wall controlled
Straight length or coil
Small-bore precision tube · product visual
Common grades304 / 304L / 316 / 316L
Typical reference OD0.3 to 8.0 mm common market range
Typical reference wall0.05 to 1.0 mm common market range
Build the specification
01Choose grade
02Set OD / ID
03Set wall / tolerance
04Choose condition
05Confirm length / ends
06Send RFQ
Product overview
What to define before buying stainless steel capillary tube
Capillary tube is a small-bore stainless tube used when fluid passage, compact geometry or dimensional control matters. Buyers should define the OD, ID or wall thickness, tolerance, tube condition, straightness or coiling, length and end requirement rather than ordering by diameter alone.
Material304 / 304L
General-purpose corrosion resistance for instrumentation, small components and precision fabrication.
Material316 / 316L
Common where chloride exposure, laboratory service or a more demanding corrosion environment is expected.
GeometryOD × ID or OD × wall
Use actual dimensions, for example 1.60 mm OD × 0.20 mm wall.
DeliveryStraight / coil
Specify straight lengths, coil form, cut pieces and any end preparation required for assembly.
M03 · Grade selection
Choose the grade from fluid, environment and fabrication needs
Small tube size does not remove the need for grade selection. Consider corrosion exposure, cleaning media, welding or brazing, temperature and the required downstream forming process.
304L
Low-carbon welding route
Often chosen where joining or welded fabrication is part of the finished component.
316
Higher corrosion resistance
Used where the environment is more demanding or chloride exposure must be considered.
316L
Corrosion + weldability
Common for laboratory, instrumentation and precision fluid-handling components requiring improved corrosion resistance.
M04 · Technical data
Common stainless steel capillary tube size reference
The combinations below are practical market-reference dimensions for small-bore stainless tube. They are not a current-stock promise. Confirm OD, ID, wall, tolerance, grade, length and condition in the RFQ.
| Outside diameter | Reference wall | Calculated inside diameter | Typical grade routes | Typical use note |
|---|---|---|---|---|
| 0.50 mm | 0.10 mm | 0.30 mm | 304 / 316L | Very small fluid path or precision component |
| 0.80 mm | 0.10 mm | 0.60 mm | 304 / 316L | Sensor, needle and micro-fluid hardware |
| 1.00 mm | 0.20 mm | 0.60 mm | 304 / 304L / 316L | Small-bore instrumentation and component tubing |
| 1.20 mm | 0.20 mm | 0.80 mm | 304 / 316L | General precision fluid path |
| 1.50 mm | 0.25 mm | 1.00 mm | 304 / 304L / 316L | Compact tubing assemblies |
| 1.60 mm | 0.20 mm | 1.20 mm | 304 / 316L | Common small instrumentation size |
| 2.00 mm | 0.30 mm | 1.40 mm | 304 / 304L / 316 / 316L | Instrumentation and precision fabrication |
| 2.50 mm | 0.30 mm | 1.90 mm | 304 / 316L | Fluid handling and sensor assemblies |
| 3.00 mm | 0.50 mm | 2.00 mm | 304 / 316 / 316L | General small-bore process tubing |
| 4.00 mm | 0.50 mm | 3.00 mm | 304 / 316L | Instrumentation, sampling and component work |
| 5.00 mm | 0.50 mm | 4.00 mm | 304 / 316L | Larger capillary / small instrumentation tube |
| 6.00 mm | 0.50 mm | 5.00 mm | 304 / 316L | Small-bore transfer and precision assemblies |
Reference calculation: inside diameter = outside diameter − 2 × wall thickness. Exact tolerances can become critical at small dimensions, so quote the required OD, ID or wall tolerance directly when flow, fit or assembly depends on it.
M05 · Dimensions and condition
Define the tube beyond the nominal diameter
At capillary scale, bore condition, wall consistency and end preparation can matter as much as the nominal OD. Put the functional requirements directly into the purchasing specification.
Dimensional definition
- Outside diameter
- Inside diameter or wall thickness
- OD / ID / wall tolerance
- Ovality and straightness when critical
Tube condition
- Annealed / soft condition
- Cold worked / hard condition
- Bright annealed where required
- Straight length or coil
Ends and cleanliness
- Square-cut or specified end cut
- Deburred / burr-controlled ends
- Internal cleanliness requirement
- Protective packing for small-bore openings
M06 · Selection guide
Match the capillary tube specification to the actual function
A visually similar micro-tube can behave very differently if the ID, wall, hardness or surface condition changes. Start from the finished assembly requirement.
Fluid restrictionControl the inside diameter and tolerance because the bore directly affects flow resistance.
Precision fitControl OD, straightness and surface condition where the tube locates inside another component.
Bending / formingConfirm temper, wall and bend radius before selecting a tube only from nominal size.
JoiningWelding, brazing, soldering or mechanical connection may drive grade, end condition and cleanliness requirements.
Worked example
Example of a clear capillary tube specification
Quote-ready example
This is an example of how a buyer can describe the requirement clearly. Replace the values with the actual drawing or application requirement.
ProductStainless steel capillary tube
Grade316L
Dimensions2.00 mm OD × 0.30 mm wall (1.40 mm nominal ID)
ConditionAnnealed, straight length
Length1000 mm cut length
EndsSquare cut, burr controlled
Quality noteConfirm OD / wall tolerance and internal cleanliness before production
M08 · Applications
Where stainless steel capillary tube is commonly used
Instrumentation
Small-bore lines, sensor connections and compact instrument assemblies.
Laboratory equipment
Fluid transfer, sampling and analytical hardware where compact tubing is required.
Precision components
Sleeves, ferrules, probes and small fabricated parts where dimensional fit matters.
Temperature sensors
Protective or transfer tubes used within sensor and probe assemblies.
Dispensing systems
Small fluid paths and controlled delivery components in industrial equipment.
General micro-fabrication
Cut, formed and joined capillary-tube components for compact mechanical assemblies.
Important limitation: do not treat generic capillary tubing as automatically suitable for medical, high-pressure, ultra-clean, vacuum or regulated service. Those applications may require tighter tolerances, cleanliness controls, specific inspection, traceability or a different governing specification.
M10 · Standards
Standards and purchasing references
Use the standard or customer drawing required by the actual project. Small-bore stainless tubing may be purchased under different standards depending on size, service, manufacturing route and inspection requirements.
Seamless and welded austenitic stainless steel tubing for general service. Use the applicable project edition and dimensional requirements.
Seamless and welded austenitic stainless steel tubing in small diameters for general service, commonly relevant when the tube size is very small.
For critical OD, ID, wall, tolerance, cleanliness, ends, straightness or inspection, place the requirement directly on the RFQ or drawing.
M11 · FAQ
Stainless steel capillary tube FAQ
How is stainless steel capillary tube size specified?
Use actual outside diameter plus either inside diameter or wall thickness. Add tolerance, grade, condition, length and end preparation when these affect fit, flow or assembly.
What grades are commonly used?
304, 304L, 316 and 316L are common austenitic routes. 316L is frequently selected where improved corrosion resistance and joining requirements are important.
Is capillary tube supplied straight or in coils?
Both forms are used. Small, thin-wall tube may be supplied in coil, while cut straight lengths are common for precision components and assemblies. Specify the required form in the RFQ.
Why is inside diameter important?
For fluid or gas service, the bore affects flow resistance and fit with internal components. At small dimensions, a small change in ID can have a large functional effect.
Can standard capillary tube be used for medical or high-pressure service?
Do not assume so. Regulated or high-pressure applications can require dedicated specifications, cleanliness, testing, traceability and validation beyond a normal commercial capillary-tube order.
Product details
What buyers usually verify visually
Replace these three visual areas with your own capillary tube product, end-detail and packing images when the first-party media is ready.
Tube geometryOutside diameter, bore, wall and straightness
End & bore detailCut quality, burr control and internal opening
Packing & protectionProtect small-bore ends and precision surfaces during delivery
Capillary tube resources
Continue from technical research to purchase
Material hubStainless Steel
Review the parent material hub and related stainless steel product forms.
Open stainless steel hub → TechnicalTechnical ResourcesUse standards, comparisons and engineering references to clarify the purchase specification.
Open technical resources → SourcingRequest a QuoteMove from a reviewed specification to a purchasing conversation.
Open RFQ page →M13 · Technical reference
Reference basis for this capillary tube guide
This page uses common commercial capillary-tube dimensions together with general stainless small-tube specification logic. Exact dimensions, tolerances, documentation and actual supply availability should be confirmed before order placement.
M14 · RFQ
Request a technical quote
For a faster review, include the grade, OD, ID or wall thickness, tolerance, condition, length, quantity, destination and any end or cleanliness requirement.
- Grade / material designation
- Outside diameter × inside diameter or wall
- Dimensional tolerance
- Straight / coil and length
- Ends, quantity and destination