JIC Fittings Guide › JIC vs BSPP
JIC vs BSPP: 37° Flare vs British Standard Parallel Pipe
Machines built in Europe, the UK, Asia and Australia often have BSPP ports, while North American hoses and tube use JIC. Both use straight (parallel) threads, so they can look alike, but thread form, sizes and sealing method are different. This guide explains how to tell them apart and how to adapt between them. See the main JIC fittings guide for JIC sizes.
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The Basics
JIC (SAE J514 / ISO 8434-2) uses unified inch threads (60° thread angle) and seals on a 37° flare. BSPP, also called BSP parallel or "G" thread, uses ISO 228-1 Whitworth-form threads with a 55° thread angle and rounded crests and roots. BSPP does not seal on the threads; it seals with either a 60° cone seat (common on hose ends), a bonded/Dowty washer, or an O-ring or elastomer seal at the port face (ISO 1179). BSPT is the tapered version that seals on the threads, like NPT.
Common BSPP Sizes
| BSPP size | TPI | Approx. male OD | Nearest JIC by tube size |
|---|---|---|---|
| 1/8" | 28 | 0.38" (9.7 mm) | -2/-3 |
| 1/4" | 19 | 0.52" (13.2 mm) | -4 |
| 3/8" | 19 | 0.66" (16.7 mm) | -6 |
| 1/2" | 14 | 0.83" (21.0 mm) | -8 |
| 3/4" | 14 | 1.04" (26.4 mm) | -12 |
| 1" | 11 | 1.31" (33.2 mm) | -16 |
BSPP thread dimensions per ISO 228-1. Like NPT, BSP sizes are nominal pipe sizes, so the measured thread OD is larger than the name suggests.
How to Tell JIC and BSPP Apart
- Check pitch. BSPP uses 28, 19, 14 and 11 TPI. JIC uses 24, 20, 18, 16, 14 and 12. 19 and 11 TPI point to BSP; 14 appears in both.
- Look at the thread profile. BSP threads have rounded crests and a 55° angle; a 55° gauge sits cleanly.
- Check the seat. A JIC male has a 37° cone. BSPP hose ends typically have a 60° cone; BSPP ports have a flat spot face for a washer or O-ring.
- Measure the OD. A 1/2" BSPP measures about 0.83", while -8 JIC measures about 0.75".
Adapting Between JIC and BSPP
- JIC male × BSPP male (port end): the most common adapter. The BSPP end seals with a bonded washer or an ISO 1179 elastomer seal; the JIC end mates to a female swivel hose end.
- JIC male × BSPP female swivel and BSPP male 60° cone × JIC adapters also exist for hose-to-hose connections.
- Never use tape on BSPP or JIC; neither seals on the thread. Replace bonded washers when remaking the joint.
Specify each end separately when ordering, e.g. "-8 JIC male × 1/2" BSPP male with bonded seal, zinc-plated steel." See also JIC vs metric 24° DIN and JIC vs NPT.
FAQ
Is BSPP the same as JIC?
No. BSPP uses 55° Whitworth threads per ISO 228-1 and seals with a 60° cone, washer or O-ring. JIC uses 60° unified threads and seals on a 37° flare.
Will a 1/2 BSPP fit a -8 JIC?
No. 1/2" BSPP is 14 TPI and about 0.83" OD; -8 JIC is 3/4-16 and about 0.75" OD. Use an adapter.
What is the difference between BSPP and BSPT?
BSPP threads are parallel and seal with a washer, O-ring or cone. BSPT threads are tapered and seal on the threads with sealant.
How do I seal a BSPP port?
Use a bonded (Dowty) washer, an ISO 1179 elastomer-sealed stud end, or an O-ring, as specified for the port. Do not use thread tape.
What does G thread mean?
G is the ISO 228-1 designation for BSP parallel threads, e.g. G1/2.
Related guides
- JIC Fittings Guide (main)
- JIC vs NPT
- JIC vs ORFS
- JIC vs AN
- How to Identify a JIC Fitting
- JIC Thread Size Chart
- -4 JIC Fittings
- -6 JIC Fittings
- -8 JIC Fittings
- -10 JIC Fittings
- -12 JIC Fittings
- -16 JIC Fittings
- JIC vs SAE 45° Flare
- JIC vs Metric (DIN 24°)
- JIC Torque Specs
- JIC Fitting Types
- JIC Materials & Pressure Ratings
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