Tee Tube Fittings: Stainless Steel & High-Alloy Instrumentation Tees
A tee tube fitting is a three-port, gaugeable compression fitting that joins three tube runs at a 90° branch, sealing each tube end by ferrule pull-up onto the tube outside diameter. Crestflo manufactures the full instrumentation tee set, union, branch and run tees, in 316/316L stainless through Hastelloy, Inconel and titanium, in both imperial and metric sizes, qualified to ASTM F1387. This is a gaugeable instrumentation compression tee for fluid and gas systems, not a PVC, copper or threaded pipe street tee.
Also Known As: Union Tee, Instrumentation Tee & Compression Tee Fitting
Engineers and buyers specify this fitting under several names depending on region, brand history and port arrangement. Common designations include tube fitting tee, tube tee, "T fitting", union tee, tee union, tube union tee, instrumentation tee, instrument tube tee, compression tee fitting, tee compression fitting, gaugeable tee, double-ferrule tee, two-ferrule tee, branch tee and run tee. Threaded variants are called male run tee (MRT), male branch tee (MBT), female run tee (FRT) and female branch tee (FBT). Where sizes step down across the fitting it is a reducing tee or reducing union tee; where one leg carries a positionable port it is a port-connector tee. No UNS or Werkstoff number applies to the tee itself, those numbers attach to the alloy, while ASTM F1387 is the governing performance specification for the fitting.
Tee Configurations: Union, Run, Branch, Male & Female Tees
A tee has two in-line ports (the straight-through run) and one perpendicular port (the branch). Which leg carries the special end connection determines the name: a run tee places the thread or special end on the run, and a branch tee places it on the branch. The table below enumerates the standard configuration set.
| Configuration | Port 1 (run) | Port 2 (run) | Port 3 (branch) | Also called |
|---|---|---|---|---|
| Union tee | Tube | Tube | Tube | tube tee, tee union |
| Male run tee (MRT) | Male thread | Tube | Tube | male run tee |
| Male branch tee (MBT) | Tube | Tube | Male thread | male branch tee |
| Female run tee (FRT) | Female thread | Tube | Tube | female run tee |
| Female branch tee (FBT) | Tube | Tube | Female thread | female branch tee |
| Reducing (union) tee | Tube (size A) | Tube (size A) | Tube (size B) | reducing tee |
| Port-connector tee | Tube | Tube | Port / positionable | positionable tee |
Threaded ports are available in NPT, NPTF, BSPT, BSPP and ISO parallel, see the NPT run tees, BSPT, BSPP and ISO-parallel thread pages for thread-family detail. A straight union, elbow, four-way cross or port connector covers the geometries a tee does not.
Tee Tube Fitting Sizes: 1/8″–1″ Imperial & 6–12 mm Metric
Tee tube fittings are furnished with tube-end connections up to 2″ (50 mm) OD. Imperial fractional sizes run 1/8″, 1/4″, 3/8″, 1/2″, 5/8″, 3/4″ and 1″; metric sizes run 6, 8, 10 and 12 mm. Every tee is offered in both imperial and metric, and reducing tees join unequal run and branch sizes in a single body. Dimensional values follow the applicable standard and are customizable to requirement.
| System | Sizes offered | Notes |
|---|---|---|
| Imperial (fractional) | 1/8″, 1/4″, 3/8″, 1/2″, 5/8″, 3/4″, 1″ | Tube ends to 2″ OD max |
| Metric | 6, 8, 10, 12 mm | Tube ends to 50 mm OD max |
| Reducing | Mixed run/branch | Unequal sizes in one body |
For the full dimensional data see the tube fitting size chart, or the 1/4-inch and 6 mm size hubs. Imperial and metric ranges are covered on the imperial-fractional and metric pages.
Stainless Steel Tee Fitting Materials: 316/316L, Duplex, Inconel, Hastelloy & Titanium
Crestflo stainless steel tee fittings are produced in 316/316L as the default grade, with the alloy range extending through duplex, super-austenitic, nickel-alloy and titanium. Grade selection is driven by the service medium, chloride and sour-service exposure, temperature and pressure. A 316 tee fitting suits most general instrumentation service, while an SS tee fitting in 904L, 254 SMO or a nickel alloy is specified where chloride pitting or sour service rules out 316. Material pages carry the composition and property data; the tee page links each grade to the form you can order.
| Alloy family | Grades | Grade reference |
|---|---|---|
| Stainless | 304/304L, 316/316L, 904L | 316/316L, 304/304L, 904L |
| Duplex / super-austenitic | Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20 | Duplex 2205, Super Duplex 2507, 254 SMO |
| Nickel alloy | Inconel 625/825, Monel 400, Hastelloy C-276 | Inconel 625, Inconel 825, Monel 400, Hastelloy C-276 |
| Titanium | Titanium Gr2 | Titanium Gr2 |
Sour-service tees are supplied in alloys that meet NACE MR0175 / ISO 15156 with heat-number traceability. Crestflo offers tees in instrumentation form only, we do not sell bar, sheet or mill stock.
Ferrules & Sealing: Single- and Double-Ferrule Gaugeable Tees
Every tee port seals with a compression ferrule set drawn onto the tube OD as the nut is pulled up, a mechanical, reusable, gaugeable seal that can be gap-inspected after make-up. Crestflo tees are available in single- and double-ferrule design, with hardened or non-hardened ferrules to suit the tube material and service. See single- and double-ferrule design, the single vs double ferrule comparison, and ferrule installation and gauging for make-up and inspection guidance.
Pressure, Temperature & Testing: ASTM F1387 Qualification
Compression tube fittings are qualified per ASTM F1387, the performance standard covering pull-out, pressure, rotary-flex, impulse and other tests for gaugeable fittings. Rated working pressure and temperature for any tee are a function of tube OD, wall thickness and alloy; values follow the applicable standard tube and material data and are customizable to requirement. Crestflo's test capability includes hydraulic proof, burst and impulse, pneumatic, flexure and rotary-flex fatigue, vibration, thermal cycling, vacuum and PMI. For service above standard instrumentation ratings, route to the high-pressure fittings range.
End & Thread Connections: Tube, NPT, BSP, JIC, SAE-ORB & Weld Ends
Tee legs combine tube ends with threaded and weld ends as required: NPT and NPTF, BSPT, BSPP and ISO parallel threads; JIC 37° and SAE-ORB ends; and socket-weld or butt-weld ends. Thread and end dimensions follow the applicable standard and are customizable to requirement.
Certifications, Traceability & Origin
Crestflo is ISO 9001 / 14001 / 45001 & PED certified, and manufactures instrumentation tees to the standard approvals applicable to compression tube fittings, including ASTM F1387 and, for sour service, NACE MR0175 / ISO 15156. Every part carries a heat/lot number, supplied with an EN 10204 3.1 material test certificate (3.2 on request). Standard product is of Indian origin; US / European melt is available on request, with full material traceability. See material test certificates, ASTM F1387, EN 10204 MTC and TAA & origin. Oxygen-clean and UHP cleaning are available, see oxygen / UHP cleaning.
Swagelok & Parker Tee Interchange
Crestflo tees are engineered as dimensional drop-in equivalents for common gaugeable-tube geometries, with interchange backed by ASTM F1387 performance qualification rather than by brand affiliation. Swagelok® and Parker® are trademarks of their respective owners; Crestflo is not affiliated with, endorsed by, or sponsored by them. Rather than publish a part-number table, we build your mapping on demand: request your Swagelok cross-reference, Parker A-Lok cross-reference, or Hoke, Hy-Lok and Fitok equivalents from our engineering team. We also build equivalents for Parker's CPI single-ferrule tee line and for Gyrolok, the Parker Hannifin compression tee line, to the same ASTM F1387 basis.
Applications
Instrumentation tees route sensing, sampling and supply lines in oil and gas, petrochemical, hydrogen, semiconductor, LNG and cryogenic, power, analytical sampling systems and instrument air service. Alloy and ferrule selection follow the medium and pressure of each system.
Why Crestflo for Tee Tube Fittings
Crestflo is the instrumentation division of a four-decade-old, Government-of-India-recognized export house with a proven Middle-East delivery record, engineering discipline applied to a new instrumentation brand. For tee tube fittings that means: ASTM F1387-qualified drop-in interchange; single and double ferrules, hardened or non-hardened; the full alloy range from 316/316L to Hastelloy, Inconel and titanium; both imperial and metric on every fitting; heat-number traceability with EN 10204 3.1 certificates; small MOQ and private-label programs. Stocking is ready stock for standard items, made-to-order for specials, with 6–8 week delivery, see lead time. We Engineer Confidence.
Get a Quote for Tee Tube Fittings
US buyers can reach the sales team at sales@crestflousa.com or +1 346 594 9005 (Houston, TX). Request an RFQ, request a sample, become a distributor, or download the line card. Datasheets and CAD are available to customers on request. Browse all tube fittings for matching unions, elbows and crosses.
Frequently Asked Questions
What is a tee tube fitting?
A tee tube fitting is a three-port gaugeable compression fitting that joins three tube runs at a 90° branch, sealed by ferrule pull-up onto the tube OD. It is an instrumentation fitting for fluid and gas systems, not a PVC or threaded pipe street tee.
What is the difference between a run tee and a branch tee?
In a run tee the special or threaded end sits on the straight-through run; in a branch tee it sits on the perpendicular branch leg. The remaining ports are tube ends in both cases.
What is the difference between a male run tee and a male branch tee?
A male run tee (MRT) carries the male thread on the run, while a male branch tee (MBT) carries it on the branch. The two tube ends are otherwise identical.
Are Crestflo tees single or double ferrule?
Both single- and double-ferrule tees are available, with hardened or non-hardened ferrules selected to suit the tube material and service.
What sizes do tee tube fittings come in?
Tube ends are furnished up to 2″ (50 mm) OD, in imperial sizes 1/8″–1″ and metric sizes 6–12 mm. Reducing tees join unequal run and branch sizes in one body.
What materials are tee fittings available in?
304/304L, 316/316L and 904L stainless; Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN and Alloy 20; Inconel 625/825, Monel 400 and Hastelloy C-276; and Titanium Gr2.
Are tee tube fittings suitable for sour (NACE) service?
Yes, they are supplied in NACE MR0175 / ISO 15156-compliant alloys with heat-number traceability and material test certificates.
Will Crestflo tees interchange with Swagelok or Parker tees?
They are engineered as dimensional drop-in equivalents, backed by ASTM F1387 performance qualification. Request your part-number cross-reference from the engineering team. Swagelok® and Parker® are trademarks of their respective owners; Crestflo is not affiliated with them.
What certifications come with the fittings?
Crestflo is ISO 9001 / 14001 / 45001 & PED certified, manufactures to ASTM F1387, and marks a heat/lot number on every part with an EN 10204 3.1 certificate (3.2 on request).
Where are the tees made and what is the lead time?
Standard product is of Indian origin, with US / European melt available on request and full material traceability. Stocking is ready stock for standard items, made-to-order for specials, with 6–8 week delivery.