BSPT Tube Fittings: Instrumentation Fittings with British Standard Pipe Taper (ISO 7-1) Ends
A BSPT tube fitting is a compression fitting built for instrumentation work. Its pipe end carries a British Standard Pipe Taper thread, a 55° taper cut to ISO 7-1 (part of the ISO 7 family, formerly BS 21), and that thread seals simply by being drawn up tight. The other end grips tubing with a ferrule set instead. When tubing needs to land on a BSPT-threaded gauge, valve, transmitter or manifold, this is the fitting a system turns to. It's the standard choice on metric equipment and gear built outside the US.
Scope note: on this page, "BSPT fitting" refers to an instrumentation-grade stainless or high-nickel-alloy tube fitting with a British Standard Pipe Taper end. It doesn't mean a brass plumbing fitting or a general hydraulic pipe fitting.
Crestflo is the instrumentation arm of an export house that's been in business for four decades and carries Government-of-India recognition. It builds these fittings for the US market as drop-in replacements, and delivery runs 6-8 weeks. We Engineer Confidence.
BSPT Thread: Also Known As
Crestflo quotes the same thread and its matching fittings under whichever name a buyer knows them by: BSPT, B.S.P.T., British Standard Pipe Taper, British Standard Pipe Thread (Tapered), BS pipe taper thread, and BSP taper. The standard itself carries several labels too: ISO 7-1, ISO 7/1, BS 21, EN 10226-1, or the equivalent JIS B 0203 taper. Designation letters mark the male taper as R, for example R 1/4, and the female taper as Rc. Its parallel internal counterpart, the Rp thread, belongs to the BSPP family. On the product side, you'll hear it called a BSPT fitting, BSPT connector, BSPT adapter, BSPT male or female connector, BSPT elbow, tee, or union, an R-thread or Rc-thread fitting, and a BSPT compression or tube fitting.
What Is a BSPT Thread?: 55° Whitworth Form, 1:16 Taper, R & Rc
British Standard Pipe Taper is a jointing thread defined by ISO 7-1, part of the wider ISO 7 series (harmonised as EN 10226-1, historically BS 21, and matched by JIS B 0203). It cuts a 55° Whitworth thread form on a 1:16 taper, so the thread tightens and seals through flank interference as it makes up into its port. Two designations cover the assembly: R is the external, or male, taper thread; Rc is the internal, or female, taper thread. A male R thread can also engage a parallel internal Rp thread. Values follow the applicable standard, and they're customizable to requirement.
BSPT doesn't seal on a fully self-sealing dryseal form; it seals on the thread itself. That's why a thread sealant, PTFE tape or a liquid pipe sealant, is recommended if you want a joint that stays reliably leak-tight. Two contrasts matter when you're specifying:
- BSPT vs NPT. NPT tapers too, but it's cut to a 60° form on ASME B1.20.1, and the pitch differs from BSPT's. Don't mate the two threads; they aren't interchangeable. Use a BSPT×NPT adapter instead. For more detail, see NPT vs BSP and ASME B1.20.1.
- BSPT vs BSPP. BSPP (G / Rp) is different again: it's a parallel thread, and it seals on a bonded washer or O-ring rather than on the taper itself. The right choice comes down to how the port needs to seal. See BSPP vs BSPT for guidance.
| Designation | Gender | Taper / parallel | Standard | Seals on |
|---|---|---|---|---|
| R | External / male | Taper 1:16 | ISO 7-1 / BS 21 / EN 10226-1 | Thread engagement (sealant recommended) |
| Rc | Internal / female | Taper 1:16 | ISO 7-1 / BS 21 / EN 10226-1 | Thread engagement (sealant recommended) |
| Rp | Internal / female | Parallel | ISO 7-1 (mates with R) | Thread + sealant, see BSPP |
BSPT Sizes & Thread Dimensions (1/16″–1″, R & Rc)
BSPT ports are called out by nominal thread size and threads per inch. These fittings mate those ports to tube ends as large as 2″ (50 mm) OD, spanning both imperial and metric sizes. The thread pitches listed below reflect the published ISO 7-1 / BS 21 values. Actual numbers follow whichever standard applies. They're customizable to the job at hand.
| BSPT size (R / Rc) | Threads per inch (TPI) | Pitch (mm) | Typical paired tube OD |
|---|---|---|---|
| 1/16 | 28 | 0.907 | 1/16″–1/8″ · up to 3 mm |
| 1/8 | 28 | 0.907 | 1/8″–1/4″ · 3–6 mm |
| 1/4 | 19 | 1.337 | 1/4″–3/8″ · 6–10 mm |
| 3/8 | 19 | 1.337 | 3/8″–1/2″ · 10–12 mm |
| 1/2 | 14 | 1.814 | 1/2″ · 12 mm |
| 3/4 | 14 | 1.814 | 3/4″ · 18–20 mm |
| 1 | 11 | 2.309 | 1″ · 25 mm |
Check the full range in the tube fitting size chart. If you're staring at an unfamiliar port, Crestflo's thread identification guide and the thread identifier tool will help you pin it down.
BSPT Fitting Types & Configurations: Male, Female, Elbow, Tee & Union
Almost any tube-fitting body can take a BSPT end. Below, each shape links to its family page, pick the R or Rc size that matches the tube OD you need.
| Configuration | BSPT end | Owner page |
|---|---|---|
| BSPT male connector | R (external) | male connector |
| BSPT female connector | Rc (internal) | female connector |
| BSPT adapter / tube-to-thread | R or Rc | adapter |
| BSPT connector | R or Rc | connector |
| BSPT elbow | R or Rc | elbow |
| BSPT tee | R or Rc | tee |
| BSPT union | tube × tube | union |
| BSPT cap / plug | closes an Rc / R port | cap · plug |
Cross-thread transitions need an adapter to work. Going from BSPT to NPT, or from BSPT to a tube OD, that's simply how they're built. Note both ends clearly on your RFQ. For the full lineup, see all tube fittings.
BSPT Fitting Materials: 316/316L Stainless, Duplex, Inconel, Monel & Titanium
BSPT fittings get machined across the full instrumentation alloy range; brass and aluminum fall outside that scope. Each part carries a heat/lot number along with EN 10204 MTC 3.1, and 3.2 is available on request. Grade compositions appear on their ASTM standards on each material page.
| Family | Grades | Material page |
|---|---|---|
| Austenitic stainless | 304/304L, 316/316L, 904L | 316/316L · 904L |
| Duplex / super-austenitic | Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20 | Super Duplex 2507 · 254 SMO |
| Nickel alloy | Inconel 625/825, Monel 400, Hastelloy C-276 | Inconel 625 · Monel 400 · Hastelloy C-276 |
| Titanium | Titanium Gr2 | Titanium Gr2 |
For sour-service duty, BSPT fittings ship compliant with NACE MR0175 / ISO 15156. Full grade-by-grade composition, PREN and mechanicals live in Crestflo's materials library.
BSPT Fitting Pressure & Temperature Ratings
A BSPT fitting's working envelope isn't set by one fixed number. It comes from the tube OD, wall thickness and alloy on one side, and the mating BSPT port on the other. Because this is an all-metal fitting with no elastomer seat, the temperature limit tracks the alloy and the tube themselves. Working pressures come from the standard tube pressure-allowable tables (ASTM A269 / A213 tube data evaluated per ASME B31.3, for instance), while the thread is rated to ISO 7-1, part of the broader ISO 7 series. Values follow the applicable standard and can be adjusted to the specific requirement. For a given OD, wall, alloy and thread combination, ask Crestflo's engineering team for the rated build, and check the pressure-temperature derating and tube sizing and wall thickness guides.
Standards, Testing & Traceability
Crestflo compression tube fittings, including BSPT-ended builds, are performance-qualified to ASTM F1387. That standard serves as the interchange anchor, letting them work as a dimensional drop-in for major two-ferrule systems. They carry ISO 9001 / 14001 / 45001 & PED certification and ship NACE MR0175 / ISO 15156 compliant. We hold the standard approvals that apply to compression tube fittings.
| Item | Standard | Basis |
|---|---|---|
| Performance qualification | ASTM F1387 | Compression tube-fitting testing |
| Thread form (BSPT) | ISO 7-1 / BS 21 / EN 10226-1 | Published 55° taper thread dimensions |
| Sour-service compliance | NACE MR0175 / ISO 15156 | Materials for H2S service |
| Material certificate | EN 10204 MTC 3.1 (3.2 on request) | Heat/lot traceability |
Testing covers hydraulic proof, burst and impulse, pneumatic, vibration, thermal cycling, pull-out, and vacuum, along with PMI and in-house NDT. Destructive testing happens at ISO/IEC 17025-accredited labs. Third-party inspection is available too, on request. Every part gets its heat/lot number stamped on it; details are in material traceability.
Ordering & Part-Number Cross-Reference
Configure a BSPT fitting by shape, tube OD, thread (R or Rc size), alloy, ferrule type (single or double, hardened or non-hardened) and finish, material finish, electropolish, passivation or silver anti-galling plating. That last option is worth specifying on stainless and nickel-alloy threads, where galling is the usual assembly failure. Crestflo doesn't publish its ordering-code series or the competitor part-number equivalents; both are available on request. Ask our engineering team for the ordering-code guide, or request your Swagelok® or Parker® cross-reference, through the Swagelok cross-reference page or a direct RFQ. Datasheets and CAD models go out to customers on request as well. Swagelok® is a trademark of Swagelok Company; Parker® is a trademark of Parker Hannifin. Crestflo has no affiliation with either company, and neither endorses Crestflo.
Why Crestflo for BSPT Fittings
- ASTM F1387 drop-in. These fittings interchange dimensionally with the majors, and that's proven through test qualification, not just a resemblance claim.
- 6-8 week delivery. Standard items ship from ready stock; specials are made to order. Compare that to the 20+ weeks typical among incumbent suppliers.
- Full alloy range. Coverage runs from 316/316L through Duplex, Inconel, Monel, Hastelloy and Titanium. Most tube-fitting suppliers stop at stainless.
- Imperial and metric, single and double ferrule, hardened or non-hardened. Thread ends span BSPT, NPT, NPTF, BSPP, ISO parallel, metric, JIC 37° and SAE-ORB.
- Heat-number traceability + MTC on every part; NACE compliance for sour service.
Small MOQ and private label: it's the instrumentation division of an export house recognized by the Government of India, with a delivery record across the Middle East and buyers throughout the US.
Origin's straightforward here: Indian-origin material, with US or European melt available on request, backed by full material traceability. For domestic-melt or TAA needs, see US-origin compliance at Crestflo.
Applications
BSPT-ended instrumentation fittings terminate tubing on metric-standard gauges, transmitters, analyzers, valves and manifolds. They're used across oil and gas, offshore and subsea operations, petrochemical plants, power generation facilities, marine and shipbuilding yards and instrument air systems.
Request a BSPT Fitting Quote
Send along your specification: shape, tube OD, R or Rc thread size, alloy, ferrule, and finish. You'll get back a quoted, drop-in build. The primary path is to request a quote. A sample can be requested too. Ask for the line card, look into the private-label program, or speak with a Crestflo engineer through OEM support. US sales: sales@crestflousa.com, +1 346 594 9005, Houston, TX.
Frequently Asked Questions
Are BSPT and NPT the same?
No. Both are tapered pipe threads, yet the two aren't cut the same way. BSPT follows a 55° Whitworth form under ISO 7-1 / BS 21. NPT, by contrast, uses a 60° form specified in ASME B1.20.1. Mating the two isn't safe, and they shouldn't be forced together. Grab a BSPT×NPT adapter instead, and check the NPT vs BSP guide for more detail.
What are BSPT fittings?
BSPT stands for British Standard Pipe Taper, a thread that seals through engagement itself rather than needing a separate seal. Crestflo builds these as instrumentation compression tube fittings, offered in stainless steel and high-nickel alloys. Ends come as R (male) or Rc (female), and tube sizes go up to 2 inch (50 mm) OD.
Is 1/4 NPT the same as BSPT?
1/4 NPT cuts 18 threads per inch at a 60° angle. R 1/4 BSPT cuts 19 threads per inch at 55°. The thread form and the pitch don't match, so the two won't seal against each other no matter how tight you turn them. Bridge the gap with a BSPT-to-NPT adapter.
Does a BSPT thread need PTFE tape or sealant?
Yes. BSPT seals through thread flank interference, not a self-sealing dryseal form, so you'll want a thread sealant on the joint. PTFE tape works, or a liquid pipe sealant. Either gives you a reliable, leak-tight connection.
What do R and Rc mean on a BSPT fitting?
R marks the external, male taper thread; Rc marks the internal, female one. ISO 7-1 defines both. A designation such as R 1/4 or Rc 1/2 isn't arbitrary: it spells out the nominal thread type and size at once.
What sizes do BSPT fittings come in?
Common R and Rc sizes span 1/16 to 1 inch, matched with tube ends up to 2 inch (50 mm) OD in both imperial and metric. Thread pitches follow the published ISO 7-1 / BS 21 values.
What materials are BSPT fittings available in?
We stock 316/316L and 304/304L stainless, plus 904L, Duplex 2205, Super Duplex 2507, 254 SMO, AL-6XN, Alloy 20, Inconel, Incoloy, Monel, Hastelloy, and Nickel 200/201, along with Titanium Gr2. Every grade ships with MTC and heat-number traceability. Brass isn't part of what we offer.
Where can I buy BSPT fittings in the US?
Crestflo manufactures instrumentation BSPT fittings and serves customers across the US. Orders run through RFQ. Standard items ship from ready stock, while specials are made to order, with delivery running 6-8 weeks. Small MOQs are available, and private-label options can be arranged. Reach US sales at sales@crestflousa.com or +1 346 594 9005.
Can Crestflo BSPT fittings replace Swagelok, Parker or Hy-Lok?
Yes. They're dimensionally interchangeable with major two-ferrule systems, and equivalent to them, backed by ASTM F1387 performance qualification. Swagelok, Parker and Hy-Lok are trademarks of their respective owners. Crestflo isn't affiliated with or endorsed by any of them.
BSPT vs BSPP, which do I need?
BSPT is a tapered thread; it seals right on the thread itself. BSPP, by contrast, runs parallel and relies on a bonded washer or O-ring to get a seal. Which one you need comes down to how the mating port is built to seal, check the BSPP vs BSPT guide for that.