10 mm Tube Fittings: Instrumentation, Stainless Steel & High-Alloy
A 10 mm tube fitting is a metric compression tube fitting. Its ferrules swage onto 10 mm outside-diameter tubing under nut torque, forming a mechanical seal that's leak-tight and holds against both gas and vacuum. Crestflo manufactures these 10 mm instrumentation tube fittings in 316/316L stainless steel and in corrosion-resistant alloys. They come in single- and double-ferrule designs, and every part carries a heat number stamped on it. Dimensional interchange is qualified under ASTM F1387.
These are instrumentation-grade metric compression fittings in stainless steel and corrosion-resistant alloys, not brass plumbing, copper compression, push-to-connect pneumatic, or hydraulic-adapter fittings. They land 10 mm OD analyzer, sample-system, and instrument-line tubing on European-spec skids, imported analyzers, and OEM equipment sold into the US.
Also Specified As: 10 mm Compression Fitting, Metric Double-Ferrule & 10 mm OD Tube Connector
Engineers and buyers know this part by several names. Most often it's called a 10 mm compression fitting, though you'll also hear 10 mm compression tube fitting, 10 mm double-ferrule (twin-ferrule) fitting, 10 mm stainless steel tube fitting, 10 mm 316 fitting, 10 mm instrumentation fitting, 10 mm OD tube fitting, 10 mm metric fitting, and 10 mm tube connector. Some write it out as ten-millimeter tube fitting, others as 10 millimeter tube fitting. The size designation points to the tube OD the fitting accepts: 10 mm, or 0.3937 in nominal. That figure isn't arbitrary. It's set by the same product standards that govern the whole tube-fitting family: ASTM A269/A213 for the tubing itself, ASTM F1387 for fitting performance, and NACE MR0175 / ISO 15156 for sour service applications.
What "10 mm" Means: Metric Tube OD, the 3/8" Difference & Internal Diameter
The "10 mm" refers to the tube's outside diameter, the part the fitting grips and seals. It's not a thread size, and it's not a bore measurement. A compression fitting has to match the tube OD precisely, which is why 10 mm fittings only take 10 mm tube.
- 10 mm equals 0.3937 in as a nominal figure. The closest fractional size, 3/8 in (9.525 mm), comes in about 0.475 mm smaller, and it won't interchange with 10 mm. Ferrules from the two sizes simply won't seal against each other. Go a step further down and 1/4 in (6.35 mm) is smaller yet.
- Wall thickness sets the internal diameter: ID = OD − (2 × wall). Take a 10 mm OD tube with a 1.0 mm wall, and you get an 8.0 mm ID; bump the wall to 1.5 mm and the ID drops to 7.0 mm. The fitting seals against the OD, so none of this touches fit. It does, however, affect flow rate and pressure rating (figures follow standard metric tube tables and can be adjusted to the requirement).
Don't force a mismatched tube when moving between metric and fractional lines. Use a metric-to-fractional reducing union instead. The full metric tube fitting range covers the options, and the tube fitting size chart gives OD and wall data. Matching 10 mm instrumentation tubing is available too. Need more detail? Read metric vs imperial tube fittings.
10 mm Tube Fitting Configurations: Unions, Elbows, Tees, Connectors & Bulkheads
Every configuration in the compression family comes in the 10 mm size. That covers both single- and double-ferrule designs, with hardened or non-hardened ferrules available to requirement.
| Configuration | Description | Ends | Page |
|---|---|---|---|
| Union | Straight tube-to-tube joiner | 10 mm × 10 mm tube | Union |
| Union elbow | 90° tube-to-tube turn | 10 mm × 10 mm tube | Elbow |
| Union tee | Three-way branch | 10 mm tube ports | Tee |
| Union cross | Four-way branch | 10 mm tube ports | Cross |
| Reducing union | Metric/fractional size change (e.g. 10 mm–6 mm, 10 mm–3/8") | Mixed tube | Reducer |
| Male connector | Tube to male pipe thread | Tube × NPT/BSPT | Male connector |
| Female connector | Tube to female pipe thread | Tube × NPT/BSPP | Female connector |
| Bulkhead union | Panel / enclosure pass-through | 10 mm tube, bulkhead | Bulkhead union |
| Port connector | Instrument / port interface | Tube × port | Port connector |
| Cap / plug | Close a tube end / a fitting body | 10 mm | Cap · Plug |
| Nut & ferrule set | Replacement / spare grip components | 10 mm | Nut & ferrule · Ferrules |
Bite-type metric hydraulic connectors are covered here: DIN 2353 fittings. Still deciding on a ferrule design? Weigh single vs double ferrule against the single-ferrule build.
End Connections & Thread Types for 10 mm Fittings: NPT, BSPT, BSPP, ISO & JIC
The 10 mm tube end forms a threadless compression joint. Threads show up only on the connection at the opposite end. Here's what's available in terms of thread and end families:
| Thread / end family | Standard | Page |
|---|---|---|
| NPT tapered pipe | ASME B1.20.1 | NPT |
| NPTF dryseal | ASME B1.20.3 | NPTF |
| BSPT tapered | ISO 7 | BSPT |
| BSPP parallel | ISO 228 | BSPP |
| ISO parallel | ISO 228 | ISO parallel |
| JIC 37° flare | ISO 8434-2 | JIC-37 |
| SAE-ORB | SAE J1926 | SAE-ORB |
| Socket / butt weld | ASME | Socket-weld · Butt-weld |
Thread dimensions are per the applicable standard; customizable to requirement.
10 mm Tube Fitting Materials: 316/316L Stainless, Duplex, Inconel, Monel & Hastelloy
Crestflo supplies 10 mm fittings across the full range of instrumentation alloys: stainless, super-austenitic, duplex, and nickel. Each one links to its own grade page, where the composition and properties are laid out.
| Alloy | UNS | When to choose | Grade page |
|---|---|---|---|
| 316 / 316L | S31600 / S31603 | Default instrumentation grade; broad corrosion resistance | 316/316L |
| 304 / 304L | S30400 / S30403 | General service, lower chloride exposure | 304/304L |
| 904L | N08904 | Higher chloride and sulfuric resistance | 904L |
| Duplex 2205 | S32205 | Chloride stress-corrosion and strength | Duplex 2205 |
| Super Duplex 2507 | S32750 | Seawater / high-chloride, high-strength | Super Duplex 2507 |
| 254 SMO | S31254 | Severe chloride / bleach service | 254 SMO |
| AL-6XN | N08367 | High-purity, chloride-rich media | AL-6XN |
| Alloy 20 | N08020 | Sulfuric-acid processes | Alloy 20 |
| Inconel 625 | N06625 | High-temp, oxidising and reducing media | Inconel 625 |
| Inconel 825 | N08825 | Acids and sour hydrocarbons | Inconel 825 |
| Monel 400 | N04400 | Hydrofluoric acid, seawater | Monel 400 |
| Hastelloy C-276 | N10276 | Wet chlorine, severe reducing/oxidising | Hastelloy C-276 |
| Titanium Gr 2 | R50400 | Chloride and oxidising acids, low weight | Titanium Gr2 |
UNS designations follow the published ASTM/UNS references. For sour (H₂S) service, 10 mm fittings are supplied in NACE MR0175 / ISO 15156-compliant alloys; see the NACE MR0175 standard for the full spec. Browse all instrumentation fitting materials for the complete range.
10 mm Fitting Pressure Ratings, Temperature Limits & Standards Compliance
A 10 mm fitting's working pressure and temperature aren't set by the fitting itself. The tube wall and the alloy decide that. Rated pressures come from standard tube working-pressure tables, built on ASME B31.3 allowable stresses for whichever wall and alloy you've chosen. 316/316L stainless covers everything from cryogenic conditions up through elevated temperatures, and high-nickel alloys push that upper range further still. Figures vary by the standard in play and can be tailored to your needs. For a rating specific to size, wall thickness, and alloy, run the numbers through the tube pressure calculator or ask for it directly in your RFQ.
Quality and traceability on every 10 mm fitting:
- Certifications: Certified to ISO 9001, 14001, and 45001; PED-compliant as well. Compression-fitting performance is qualified to ASTM F1387.
- Standards referenced: Tubing meets ASTM A269. Sour service applications follow NACE MR0175 and ISO 15156. Thread specs come from ASME B1.20.1.
- Traceability: Each part's marked with its heat or lot number. EN 10204 MTC 3.1 is the standard offering; 3.2's available on request.
- Testing: The lineup includes hydraulic proof, burst, and impulse tests, along with pneumatic, fatigue, vibration, thermal-cycling, pull-out, and vacuum testing. PMI is standard practice, NDT is done in-house, and third-party inspection can be arranged on request.
- Finishes: material finish, electropolish, passivation, and silver anti-galling plating; oxygen-clean on request.
Datasheets and CAD models are available to customers on request.
10 mm Swagelok Cross-Reference & Metric Interchange
Crestflo 10 mm fittings are built for dimensional interchange with metric fittings from Swagelok®, Parker®, Hy-Lok®, Fitok® and other manufacturers, qualified under ASTM F1387. We don't publish a part-number table. Instead, our engineering team builds the exact equivalents for your line: request your Swagelok metric cross-reference, or start at the cross-reference hub. Swagelok® and other names are trademarks of their respective owners, used only for identification.
Products & How to Order 10 mm Tube Fittings
Crestflo works on an RFQ model. No e-commerce, no live pricing. Standard items ship from ready stock; specials get made to order, with delivery running six to eight weeks. Small MOQs are available, and so are private-label and made-to-print builds.
- Request a Quote, send size, configuration, material, and end connection for a 10 mm RFQ.
- Request a Sample, evaluate the fit and finish before committing.
- Private-label program, for distributors and OEMs.
- US origin & compliance, origin, melt, and traceability options.
Origin is Indian, with US or European melt available on request and full material traceability provided. Reach Crestflo's US contact at sales@crestflousa.com, or call +1 346 594 9005. The office sits in Houston, TX.
Why Crestflo for 10 mm Instrumentation Tube Fittings
Crestflo is the instrumentation division of a four-decade-old, Government-of-India-recognized export house with a long Middle-East delivery record. That heritage backs a focused instrumentation offer: every fitting is available in both metric and imperial, so metric-buyers under-served by fractional-only US distributors get their 10 mm size directly. Fittings carry ASTM F1387 interchange qualification, a heat number on every part with EN 10204 MTC 3.1 (3.2 on request), the full SS-through-nickel alloy range, and a 6–8 week lead time against the 20-plus weeks typical of the majors. We Engineer Confidence.
10 mm Tube Fitting FAQs
What is the internal diameter of 10 mm tubing?
The internal diameter is the 10 mm outside diameter minus twice the wall thickness (ID = OD − 2 × wall). Take a 10 mm OD tube with a 1.0 mm wall, and you get an 8.0 mm ID; bump the wall to 1.5 mm, and it drops to 7.0 mm. Compression fittings seal on the tube OD, so the ID has no bearing on fit. What it does affect is flow area and pressure rating.
Will 1/4" tube or pipe work in a 10 mm compression joint?
No. 1/4 in equals 6.35 mm; 3/8 in equals 9.525 mm. Neither one lines up with 10 mm. A compression fitting only grips the exact tube OD it's built for, so a 10 mm fitting takes 10 mm tube and nothing else. Crossing from metric to fractional lines calls for a reducing union sized to fit both ends.
What are the different types of 10 mm tube fittings?
The 10 mm family covers unions, union elbows, union tees, crosses, reducing unions, male and female connectors, bulkhead unions, port connectors, caps, plugs, and nut-and-ferrule sets. Buyers can choose single- or double-ferrule designs, and the alloy range is wide.
What is the thread size of a 10 mm compression fitting?
The 10 mm tube end carries no thread at all. Instead it forms a compression joint with a ferrule, sealing directly against the tube OD. The opposite end is where the threads live, and here you have options: NPT, NPTF, BSPT, BSPP, ISO parallel, JIC 37° or SAE-ORB. Dimensions follow whichever standard applies.
Are 10 mm fittings single- or double-ferrule, and suitable for sour service?
Both single- and double-ferrule 10 mm fittings are available, with hardened or non-hardened ferrules supplied to suit the job. For sour, H₂S service, Crestflo turns to NACE MR0175 / ISO 15156-compliant alloys for its 10 mm fittings.
Do Crestflo 10 mm fittings interchange with Swagelok metric fittings?
They're built to swap dimensionally with metric fittings from Swagelok®, Parker®, Hy-Lok® and other brands, qualified under ASTM F1387. Skip the generic table. Ask the engineering team for a cross-reference specific to your part instead.
What certification, traceability, and lead time come with 10 mm fittings?
Every part leaves our facility under an ISO 9001 / 14001 / 45001 & PED certified system. Each one carries a heat/lot number stamped right on it, backed by EN 10204 MTC 3.1 (3.2 available on request). Standard items sit in ready stock. Specials get made to order, and those typically take 6-8 weeks to deliver.
Related Tube Fitting Sizes, Configurations & Resources
- For sizes near this one on the metric side, browse 8 mm tube fittings, 12 mm tube fittings, and 6 mm tube fittings.
- Prefer fractional sizing? The closest matches are 1/4 inch and 3/8 inch.
- For the wider picture, start at the tube fittings hub, check the metric range, or pull up the size chart.
- Worth a read before you decide: single vs double ferrule, metric vs imperial tube fittings, and tube sizing & wall thickness.
The Crestflo Engineering Team reviewed this document. Certifications listed here are stated as held, and copies of the certificates can be found in the quality section.