The Castair JICA12X38BSPP is a cross-standard adapter fitting — JIC-12 (1-1/16-12 UNF, 37-degree flare) on one end and 3/8-inch BSPP (British Standard Pipe Parallel) on the other. This adapter is specifically for installations that need to connect American-standard JIC-12 air line hardware to equipment or components with metric BSPP ports — common in imported compressors, European air tools, and industrial equipment manufactured to ISO/BSP thread standards.
BSPP (British Standard Pipe Parallel, also known as G-thread) is a parallel thread fitting that seals with a bonded seal washer or O-ring face seal at the port face — not by thread taper. This is different from NPT, which seals on the thread taper. If your equipment has metric ports and you're integrating it into a JIC-12 compressed air system, the JICA12X38BSPP eliminates the need for thread adapters in between.
JIC to BSPP — When You Need This Adapter
- Imported air equipment: European and Asian-manufactured compressors, air dryers, filters, and regulators frequently use BSPP threads at their service ports — specifically 3/8" BSPP (G 3/8") for medium-flow connections
- Mixed piping systems: If your shop has a mix of American and imported equipment on a shared air system, cross-standard adapters like this eliminate the need for multiple adapters in series
- Aftercooler or filter connections: Many imported after-treatment components use BSPP ports and need an adapter to connect to JIC air lines
About JIC Fittings in Compressed Air Systems
JIC (Joint Industry Council) fittings use a 37-degree flare seating surface. This seating angle creates a metal-to-metal seal that is leak-resistant under pressure and does not require sealant tape or thread compound on the flare seating surface (though thread sealant is still appropriate on the straight threads in certain configurations). JIC fittings are widely used in hydraulic systems and increasingly in compressed air distribution where secure, serviceable connections are needed at equipment connections, regulator ports, and manifold tees.
The dash number in JIC sizing corresponds to the tubing OD in 1/16-inch increments: JIC-10 fits 5/8-inch OD tubing (7/8-14 UNF thread), JIC-12 fits 3/4-inch OD tubing (1-1/16-12 UNF thread).
BSPP Thread Notes
- BSPP (G-thread) is parallel, not tapered: Unlike NPT, BSPP threads do not seal on the thread — the port face seals against an O-ring or bonded seal washer
- Do not use PTFE tape on the BSPP end: BSPP seals at the face. Use a copper or aluminum washer, or the O-ring supplied with the BSPP port if applicable
- 3/8" BSPP (G 3/8"): This is a common port size on European compressors and filter/regulator units for medium air flows
- Confirm thread type: BSPP and BSPT (tapered) look identical — BSPT tapers slightly along the thread length. Confirm your equipment has BSPP (parallel) ports before using this adapter
Fitting Details
- Part Number: JICA12X38BSPP
- Connection 1: JIC-12 (1-1/16-12 UNF, 37-degree flare, 3/4-inch OD tubing)
- Connection 2: 3/8-inch BSPP (G 3/8", parallel thread, face seal)
- Seating (JIC end): 37-degree flare metal-to-metal seal
- Seating (BSPP end): O-ring or bonded seal at port face
- Category: Air Distribution Piping / JIC Fittings
Installation Notes
- JIC-12 end: no sealant on the 37-degree flare seat. Torque to seat the flare
- BSPP end: use an O-ring or copper sealing washer as required by the mating port. No PTFE tape on the thread
- Verify your equipment port is BSPP (parallel) before ordering — using a parallel-thread fitting in a tapered port or vice versa will leak
- Leak-check both connections after pressurizing
Technical Specifications
- Part Number: JICA12X38BSPP
- Connection 1: JIC-12 — 1-1/16-12 UNF, 37-degree flare, 3/4-inch OD tubing
- Connection 2: 3/8-inch BSPP (G 3/8") parallel thread, face seal
- Application: Cross-standard connection between American JIC-12 air lines and metric BSPP-ported equipment
Why Buy From Air Compressor Factory Direct?
We stock Castair air distribution fittings and accessories. If you're planning or expanding your shop's compressed air piping system, we can help you spec the right fitting combinations for your line sizes and equipment. Free shipping on qualifying orders. Call 866-217-0063 for help selecting the right fittings for your installation.
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