TES-LOK double-ferrule Female Branch Tee Fittings — compression tube on both inline run ends, female NPT/BSP thread on perpendicular branch. The tube run passes straight through while the branch receives a male-threaded nipple, stud, or pipe end. SS 304 · SS 316 · Brass · Alloy 400 · 6,000 PSI · ISO 9001:2015 certified.
A female branch tee tube fitting is a three-port instrumentation fitting shaped like a T. Both inline ports — the run ends — use double-ferrule compression tube connections; the perpendicular port — the branch — carries an internal (female) thread: NPT, BSP, BSPT, or other standards.
The design lets a continuous tube run pass straight through the fitting while the branch mounts directly onto a male-threaded nipple, stud end, or pipe such as a transmitter process connection, manifold stud, or control-valve body. This eliminates the need for an intermediate union or elbow and reduces the fitting count, potential leak points, and overall system length.
TES-LOK Female Branch Tee Fittings are manufactured from bar stock or forged blanks to ASTM D1710 and D3294 dimensional standards. The double-ferrule design provides independent sealing (front ferrule) and gripping (back ferrule) actions, making them suitable for high-vibration, high-pressure, and cyclic-temperature environments up to 6,000 PSI.
| Port | Connection Type | Function |
|---|---|---|
| Run End 1 (inline) | Compression tube | Incoming tube run — double-ferrule grip & seal |
| Run End 2 (opposite) | Compression tube | Continuing tube run — passes straight through |
| Branch (perpendicular) | Female thread (NPT / BSP) | Receives male-threaded nipple, stud, or pipe end |
The inline run ends are interchangeable — fluid flows through either direction. The branch thread axis is perpendicular (90°) to the run axis. Compare with the Male Branch Tee (external thread on branch) or the Female Run Tee (female thread on one run end).
| Parameter | Details |
|---|---|
| Product name | Female Branch Tee Tube Fitting |
| Brand | TES-LOK (Tesco Steel & Engineering) |
| Run connection type | Double-ferrule compression tube (both run ends) |
| Branch connection type | Female thread — NPT, BSP, BSPT, UNF, ISO metric, SAE/JIC |
| Tube OD range | 1/16" to 2" (imperial) · 2 mm to 50 mm (metric) |
| Branch thread range | 1/8" to 1" NPT(F) · 1/8" to 1" BSP(F) |
| Max working pressure | Up to 6,000 PSI (SS 316, ambient temperature) |
| Materials | SS 304, SS 316, SS 316L, Brass, Alloy 400 (Monel), Alloy 600 (Inconel), Alloy C-276 (Hastelloy), Duplex 2205, Super Duplex 2507 |
| Temperature range | −65 °F to +1200 °F (material dependent) |
| Dimensional standard | ASTM D1710 / D3294 |
| Quality certification | ISO 9001:2015 · Material test certificates · 3.1 / 3.2 MTCs on request |
| Compatibility | Swagelok · Parker A-LOK · Ham-Let · Gyrolok |
| Industries | Oil & Gas · Petrochemical · Refinery · Power · Marine · Pharma |
| Tube OD (Run) | Branch Female Thread | Typical Application |
|---|---|---|
| 1/4" | 1/8" NPT(F) | Instrument impulse lines, analyser sample tubing |
| 1/4" | 1/4" NPT(F) | Pressure transmitter tap-off, gauge connections |
| 3/8" | 1/4" NPT(F) | Process impulse loops, control valve branch |
| 1/2" | 1/4" NPT(F) | High-flow sampling, pneumatic lines |
| 1/2" | 3/8" NPT(F) | Chemical injection, dosing headers |
| 3/4" | 1/2" NPT(F) | Hydraulic circuits, steam trap branches |
| 6 mm | 1/4" BSP(F) | Offshore metric tube runs, European instruments |
| 12 mm | 1/2" BSP(F) | Marine / offshore metric headers |
The branch female thread is oriented exactly 90° to the tube run, so a male-threaded nipple or stud can be screwed directly into the fitting — no adapters, no elbows, no extra unions required. Ideal for tapping off a tube run to a fixed instrument connection point.
Both inline compression ports maintain full tube bore through the fitting. The main process line continues without a break; the branch is purely additive. This minimises flow resistance and avoids dead-leg contamination concerns in clean or sterile systems.
Each of the three ports seals independently. A leak at one port — during assembly or re-make — does not compromise the other two. The double-ferrule compression ports also provide vibration resistance superior to standard single-ferrule or flare designs.
Once the back ferrule is set, the compression run ends can be remade up to ten times by tightening just an additional ¼ turn. This simplifies maintenance in remote or hard-to-access installations — tubes can be disconnected and reconnected without replacing any components.
TES-LOK fittings are manufactured to ASTM D1710/D3294 dimensions and are verified compatible with Swagelok, Parker A-LOK, Ham-Let, and Gyrolok ferrule sets. You can mix brands in the same tube system without re-tooling or retraining installation crews.
The female branch tee is available in SS 304, SS 316, SS 316L, Brass, Monel 400, Inconel 600, Hastelloy C-276, Duplex 2205, and Super Duplex 2507. Each alloy is certified with Mill Test Certificates; 3.1 and 3.2 MTCs are available on request for critical applications.
| Fitting | Run End 1 | Run End 2 | Branch | When to Choose |
|---|---|---|---|---|
| Female Branch Tee | Compression tube | Compression tube | Female thread | Run passes through; branch mounts on male nipple/stud |
| Male Branch Tee | Compression tube | Compression tube | Male thread | Run passes through; branch screws into female port |
| Female Run Tee | Female thread | Compression tube | Compression tube | Thread on the inline run; branch is all-compression |
| Union Tee | Compression tube | Compression tube | Compression tube | All-compression T-junction; no threaded ports |
| Female Connector | Compression tube | Female thread (inline) | Only two ports; no branch | |
Step 1 — Prepare the tube. Cut the tube square using a tube cutter (not a hacksaw). Deburr the inside and outside of the cut end. Wipe clean with a lint-free cloth. Do not use lubricant on tube ends.
Step 2 — Thread the branch first. Screw the female branch port onto the male nipple or stud using appropriate thread sealant (PTFE tape, 2–3 wraps for NPT/BSPT; no sealant for BSPP parallel). Use a back-up wrench on the body hex — never torque through the ferrule nuts — and tighten to standard NPT/BSP hand-tight + 1½–2 turns.
Step 3 — Initial make-up of compression ends. Slide the ferrule nut and then the back ferrule and front ferrule (in that order) onto each tube end. Push the tube fully into the compression port until it bottoms against the internal shoulder. Hand-tighten the ferrule nut.
Step 4 — Mark and tighten. Using a permanent marker, place a reference line on each ferrule nut at the 6 o'clock position. Using two wrenches (one on the body hex, one on the ferrule nut), tighten 1¼ turns for the initial make-up. The back ferrule bites into the tube and the front ferrule compresses against the body seat to form a metal-to-metal seal.
Re-make: Disconnect the tube, reinsert fully, and tighten just ¼ turn past hand-tight. No new ferrules are required for re-make.
| Industry | Typical Application |
|---|---|
| Oil & Gas | Wellhead instrument tap-offs, subsea control module tubing, topside process loops |
| Refinery / Petrochemical | Analyser sample conditioning, DCS pressure transmitter branches, reactor feed lines |
| Power Generation | Steam impulse taps, boiler drum level gauges, turbine lube oil branches |
| Chemical & Pharma | Chemical dosing branches, CIP/SIP monitoring tees, sterile process taps |
| Marine & Offshore | Deck hydraulic systems, tank monitoring branches, HVAC panel tubing |
| Semiconductor / Cleanroom | High-purity gas distribution branches, particle-sensitive analyser loops |
▶ What is a female branch tee tube fitting?
▶ How does a female branch tee differ from a male branch tee?
▶ How does a female branch tee differ from a female run tee?
▶ What thread standards are available on the branch port?
▶ What tube OD and thread sizes are available?
▶ What is the maximum pressure rating?
▶ How do I install a female branch tee tube fitting?
▶ Which industries use female branch tee tube fittings?
ISO 9001:2015 certified manufacturer. SS 304 · SS 316 · Brass · Special Alloys. 1/16"–2" OD. NPT / BSP / BSPT. Short lead times. Mill test certificates included.
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