TES-LOK Female Connector Tube Fittings — double-ferrule compression tube one end, female NPT / BSP internal thread the other. Straight tube-to-thread transition in one fitting. SS 316 · Brass · Monel · Inconel · Equal & Reducing · Bulkhead Variant · Up to 6,000 PSI · ISO 9001:2015 certified.
Female Connector (Equal & Reducing)
Bulkhead Female Connector
A female connector tube fitting is a two-port, straight fitting that bridges an instrument or process tube to a male-threaded equipment port. One end is a double-ferrule compression connection — the same bite-type mechanism used across the entire TES-LOK range — that grips the tube OD and forms a leak-tight, pull-out-resistant joint without tube flaring or soldering. The opposite end is a female-threaded internal socket (NPT, BSP, BSPT, UNF, ISO, or SAE) that receives the male-threaded stud, nipple, or outlet port of a valve, gauge, transmitter, or instrument body.
The female connector is one of the most common fittings in an instrument tube system. Wherever a tube run terminates at a threaded equipment port — a pressure gauge, a needle valve root connection, a transmitter process connection, a manifold port, or a pneumatic actuator supply — a female connector makes the transition in a single compact body with no intermediate adapters.
| Port | Connection Type | Function |
|---|---|---|
| Port 1 | Double-ferrule compression tube (TES-LOK) | Connects to instrument or process tube (tube OD from 1/16" to 1") |
| Port 2 | Female internal thread — NPT, BSPP, BSPT, UNF, ISO, SAE | Receives male-threaded stud, nipple, or equipment outlet port |
Equal female connector: Both the compression tube OD and the female thread are the same nominal size (e.g. ¼" tube × ¼" NPT female). Used when the equipment port thread size matches the instrument tube OD.
Reducing female connector: The compression tube OD and the female thread are different nominal sizes (e.g. ¼" tube × ½" NPT female, or ½" tube × ¼" NPT female). Used when an equipment port thread is larger than the tube OD, or when a smaller tube run must connect to a larger process connection — eliminating a separate reducing nipple or adapter.
The bulkhead female connector is a panel-mount variant of the standard female connector. It has a hexagonal body machined to a specific panel-hole diameter, with a locknut that secures it from the opposite face of the panel. Once installed, one side of the panel has the compression tube connection (for the internal tube run) and the other side has the female thread (for the external connection or equipment interface). The locknut clamps the fitting body against the panel face, forming a seal-tight feedthrough.
| Tube OD (Imperial) | Female Thread Size | Thread Standard | Max. Working Pressure (SS 316) |
|---|---|---|---|
| 1/16" | 1/16" | NPT / BSP | 6,000 PSI |
| 1/8" | 1/8" | NPT / BSP | 6,000 PSI |
| 3/16" | 1/4" | NPT / BSP | 6,000 PSI |
| 1/4" | 1/4" · 1/8" (reducing) | NPT / BSP | 6,000 PSI |
| 3/8" | 3/8" · 1/4" (reducing) | NPT / BSP | 6,000 PSI |
| 1/2" | 1/2" · 3/8" · 1/4" (reducing) | NPT / BSP | 6,000 PSI |
| 3/4" | 3/4" · 1/2" (reducing) | NPT / BSP | 6,000 PSI |
| 1" | 1" · 3/4" (reducing) | NPT / BSP | 6,000 PSI |
Metric sizes (3 mm – 25 mm OD) and special reducing combinations available. Contact Tesco Steel for the complete size matrix.
| Thread Type | Thread Form | Sealing Method | Sealant |
|---|---|---|---|
| NPT | Tapered (American) | Thread flanks seal on taper interference | PTFE tape (2–3 wraps) or anaerobic thread sealant on male thread |
| BSPT | Tapered (British) | Thread flanks seal on taper interference | PTFE tape (2–3 wraps) or anaerobic thread sealant on male thread |
| BSPP (BSP parallel) | Parallel (British) | Face seal — bonded seal (Dowty washer) on flat face of port | No PTFE tape. Fit bonded seal or copper washer on male thread shoulder |
| UNF / ISO / SAE | Parallel | O-ring or bonded seal on port face | Appropriate O-ring or bonded seal per thread specification |
| TES-LOK Female Connector Tube Fitting — Specifications | |
|---|---|
| Brand | TES-LOK (by Tesco Steel & Engineering) |
| End connection 1 | Double-ferrule compression tube (TES-LOK bite-type) |
| End connection 2 | Female internal thread — NPT · BSPP · BSPT · UNF · ISO · SAE |
| Tube OD range | 1/16" – 1" (imperial) · 3 mm – 25 mm (metric) |
| Thread size range | 1/16" NPT – 3/4" NPT (and equivalent BSP) |
| Configurations | Equal · Reducing · Bulkhead (panel-mount with locknut) |
| Body materials | SS 316 / 316L (standard) · SS 304 · Brass · Monel 400 · Inconel 600 · Hastelloy C-276 |
| Ferrule material | Matching body material (SS 316 standard) |
| Max. working pressure | 6,000 PSI (SS 316) · 3,000 PSI (Brass) |
| Temperature range | −196°C to +400°C (SS) · −29°C to +260°C (Brass) |
| Standards | ASTM D1710 · ASTM D3294 |
| Certifications | ISO 9001:2015 · EN 10204 3.1 MTC available |
| Compatible tube fitting systems | TES-LOK (standard) · Swagelok · Parker A-LOK · Ham-Let (interchangeable ferrules) |
| Country of manufacture | India — ISO 9001:2015 certified facility |
| Fitting | Port 1 | Port 2 | Use When |
|---|---|---|---|
| Female Connector | Compression tube | Female internal thread (receives male stud) | Equipment port has a male-threaded stud or nipple projecting outward |
| Male Connector | Compression tube | Male external thread (screws into female port) | Equipment port is a female-threaded socket — e.g. female NPT port on a valve body |
| Union Connector | Compression tube | Compression tube | Joining two tube runs of the same OD — no threaded equipment involved |
| Female Elbow | Compression tube | Female internal thread — at 90° | Same as female connector, but a 90° direction change is also needed to reach the equipment port |
| Female Branch Tee | Compression tube (run-through) | Female internal thread on branch (perpendicular) | Tapping a female-thread port off a continuing tube run — three ports total |
| Bulkhead Female Connector | Compression tube (inside panel) | Female internal thread (outside panel) | Tube line must cross a panel or bulkhead wall in a sealed manner |
The TES-LOK female connector makes the tube-to-thread transition in a single machined body. There is no need for a separate compression union plus a threaded nipple — the female connector eliminates one fitting and one potential leak joint per connection point. In a typical instrument loop with 10–20 tube-to-equipment terminations, this directly reduces leak-path count.
The compression tube end uses the TES-LOK double-ferrule mechanism: a front ferrule bites into the tube OD and a back ferrule provides a spring-loaded grip against the fitting body. This dual-action mechanism provides exceptional pull-out resistance and vibration fatigue resistance — critical for instrument connections on pumps, compressors, and reciprocating equipment.
The bulkhead female connector creates a neat, sealed tube-to-thread panel feedthrough — one locknut, one body, zero separate sealing components. Used in instrument shelters, junction boxes, and sample conditioning enclosures where tube lines must cross an enclosure wall cleanly without exposed compression unions on both faces.
TES-LOK female connectors are available in equal (tube OD matches thread size) and reducing (different tube OD and thread size) configurations in the same body design. A reducing female connector replaces a standard female connector plus a separate reducing nipple — useful when equipment ports are larger than the instrument tube OD, or when a smaller tube run must interface with a larger process thread.
Available in SS 316/316L (standard), Monel 400 (seawater, HF acid), Inconel 600 (high-temperature oxidising service), and Hastelloy C-276 (widest corrosion resistance). Ferrules are supplied in matching CRA to maintain galvanic compatibility. EN 10204 3.1 material test certificates and PMI available for all CRA grades.
TES-LOK female connectors are dimensionally compatible with Swagelok, Parker A-LOK, and Ham-Let double-ferrule tube fitting systems. TES-LOK ferrules can be used in Swagelok bodies and vice versa — maintaining full interchangeability on multi-vendor sites and during field replacement without disrupting the tube connection.
▶ What is a female connector tube fitting?
A female connector tube fitting is a two-port straight fitting that connects instrument or process tubing to a male-threaded port on a valve, instrument, or equipment body. One end is a double-ferrule compression tube connection that bites onto the tube OD. The other end is a female-threaded internal socket (NPT, BSP, or BSPT) that receives the male-threaded stud, nipple, or outlet port of a valve, gauge, transmitter, or instrument body.
▶ What is the difference between a female connector and a male connector tube fitting?
A female connector has an internal (female) thread on the non-tube end — it receives a male-threaded stud or nipple from the equipment. A male connector has an external (male) thread — it screws into a female-threaded port on the equipment. Use a female connector when the equipment has a male stud or nipple projecting outward. Use a male connector when the equipment has a recessed female-threaded socket or port.
▶ What is a bulkhead female connector tube fitting?
A bulkhead female connector is a panel-mount variant with a hex body sized to pass through a panel hole, secured by a locknut from the opposite face. It creates a sealed tube-to-female-thread feedthrough through a panel or enclosure wall. Used in instrument enclosures, junction boxes, and sample conditioning cabinets where tube lines must cross a panel boundary in a gas-tight or liquid-tight manner.
▶ Can female connector tube fittings be used with both NPT and BSP threads?
Yes. TES-LOK Female Connector Tube Fittings are available with NPT, BSP (BSPP parallel and BSPT tapered), ISO, UNF, and SAE thread forms. NPT and BSPT are tapered threads sealed with PTFE tape. BSPP is a parallel thread that requires a bonded seal (Dowty washer) on the flat face — do not use PTFE tape on BSPP threads.
▶ What tube OD sizes are available for female connector tube fittings?
TES-LOK Female Connector Tube Fittings are available for tube OD from 1/16" to 1" imperial and 3 mm to 25 mm metric. Female thread sizes range from 1/16" NPT to 3/4" NPT and equivalent BSP. Equal and reducing combinations are available. Contact Tesco Steel for the complete equal and reducing size matrix.
▶ What is the maximum pressure rating for a TES-LOK female connector tube fitting?
TES-LOK Female Connector Tube Fittings in SS 316 are rated up to 6,000 PSI working pressure at ambient temperature. Brass connectors are rated up to 3,000 PSI. Pressure ratings derate at elevated temperature per the published pressure-temperature curves. The compression tube end and the female-threaded end share the same body — there is no pressure discontinuity between the two ports.
▶ What thread sealant should I use on a female connector tube fitting?
For NPT and BSPT (tapered threads): apply 2–3 wraps of PTFE tape to the male thread of the mating fitting before engaging the female connector. For BSPP (parallel BSP threads): fit a bonded seal (Dowty washer or copper washer) on the flat shoulder of the male port — do not use PTFE tape on parallel threads. PTFE on parallel threads causes over-tightening without achieving a seal.
▶ What materials are available for TES-LOK female connector tube fittings?
TES-LOK Female Connector Tube Fittings are available in SS 316 (standard), SS 316L, SS 304, Brass, Monel 400, Inconel 600, and Hastelloy C-276. Ferrules are supplied in matching material. EN 10204 3.1 material test certificates and PMI are available on request.
Equal & Reducing · Bulkhead Variant · SS 316 · Brass · CRA Alloys · NPT · BSP · 1/16"–1" Tube OD · Up to 6,000 PSI
ISO 9001:2015 certified · EN 10204 3.1 MTC · Fast delivery worldwide