NPT vs BSPT vs JIC: How to Identify Thread Types Fast
Half the leaking connections we see at the counter come down to one thing: mismatched threads that "felt like they fit." NPT onto BSPT will start by hand and leak forever. Here's how to identify what you're holding in under a minute with calipers and a pitch gauge.
The Three-Step ID Method
1. Taper or parallel? Lay a straightedge along the threads. Tapered = NPT or BSPT (pipe threads that seal on the thread). Parallel = BSPP, JIC, ORFS, or SAE O-ring boss (these seal on a face, cone, or O-ring, not the threads). 2. Measure the pitch. NPT uses threads-per-inch counts like 11.5 and 14; BSPT/BSPP use 11, 14, 19, 28 TPI at 55° thread angle vs NPT's 60°. A $10 pitch gauge settles it instantly. 3. Look at the sealing surface. A 37° flared cone = JIC. A flat face with an O-ring groove = ORFS. A straight thread with an O-ring at the base = SAE ORB port.
Quick Reference
| Thread | Angle | Seals via | Common where |
|---|---|---|---|
| NPT/NPTF | 60° taper | Thread wedging + sealant | US plants, ports, plumbing |
| BSPT (R) | 55° taper | Thread wedging + sealant | Imported/Asian & UK equipment |
| BSPP (G) | 55° parallel | Bonded washer / face seal | European hydraulics |
| JIC (SAE J514) | 60° parallel UNF | 37° metal cone | NA hydraulics |
| ORFS | Parallel UNF | Face O-ring | Zero-leak hydraulics |
| SAE ORB | Parallel UNF | Boss O-ring | Pump/valve ports |
Why NPT + BSPT = Leaks
The 60° vs 55° flank angle and different pitches mean the threads only contact at points, not along the flanks. Sealant may hide it at low pressure; vibration and thermal cycling will find it. On imported equipment — compressors, machine tools, Asian-built skids — assume BSPT until proven otherwise.
Adapting Between Systems
Never chase threads to "make it work." Use proper adapters: NPT-to-BSPT, JIC-to-metric, ORFS-to-JIC — they exist for every combination and cost less than one shutdown. For vibration-heavy hydraulic service, adapt to JIC or ORFS rather than relying on long strings of tapered joints.
Bring Us the Mystery Fitting
Can't identify it? Note the measurements — or just describe the equipment — in the quote form at the top of this page, or call (979) 233-6223. We stock adapters across NPT, BSP, JIC, ORFS, and metric, with quotes back in 1–2 business hours.