NPT vs BSPT vs BSPP Threads on Camlock Fittings: The Complete Guide
The camlock body is rarely the leak. The thread connecting it to the pipe is. NPT, BSPT and BSPP look similar at arm’s length, and a mismatched thread will leak, cross-thread or fail under pressure — often months later, after the system is buried.
Threaded camlock fittings — the thread standard must match the port.
Brass threaded coupler — common on BSPT ports in older installations.
The three standards
| Standard | Taper? | Sealing method | Where used |
|---|---|---|---|
| NPT (National Pipe Taper) | Taper | Threads wedge + sealant | North America |
| BSPT (British Standard Pipe Taper) | Taper | Threads wedge + sealant | UK, Europe, Asia, most of the world |
| BSPP (British Standard Pipe Parallel) | Parallel | Gasket / O-ring / bonded washer | UK, Europe, hydraulic systems |
NPT vs BSPT: the same idea, different angles
Both are 55° vs 60° thread forms… no — that’s the common confusion. NPT has a 60° thread angle; BSPT has a 55° thread angle. NPT and BSPT are both tapered (about 1°47’ per side… the taper is 3/4” per foot for NPT, 1 in 16 for BSP — effectively the same taper), but the different thread angle means they do not seal with each other. An NPT male into a BSPT female can start, feel tight, and leak — or cross-thread under torque.
Pitch also differs: NPT is measured in threads per inch (11.5 TPI at 1”, 8 TPI at 2”), BSPT is also measured in TPI but at different values (11 TPI at 1”, 11 TPI at 2”). Close, but not interchangeable.
How to tell them apart
- Measure the angle: NPT = 60°, BSPT = 55°. A thread gauge settles it instantly.
- Measure the pitch: 1” NPT = 11.5 TPI, 1” BSPT = 11 TPI. Count threads over an inch.
- Check the context: American-made valves and North American plumbing → NPT. European/Asian equipment, compressors, hydraulics → BSP.
BSPP: the parallel one
BSPP is parallel and seals with a gasket or O-ring, not on the threads. A parallel thread into a taper thread will not wedge — it needs the sealing washer. Mixing BSPP male into BSPT female strips the seal and leaks at low pressure.
The camlock connection
On a camlock adapter (types A, B, C, D), the thread standard is cast into the part’s spec. Ordering the wrong one is the second most common camlock mistake (after wrong size):
- NPT camlocks for North American pipe systems
- BSPT camlocks for European/Asian pipe systems
- BSPP camlocks with O-ring for parallel-thread hydraulic/compressor connections
How to avoid the mismatch
- State the thread standard on every order — never assume “standard threads”
- Check both sides of the connection — the pipe/fitting side and the camlock side must match
- Use adapters for mixed systems — NPT-to-BSPT adapters exist; fit them rather than forcing threads
- Test-fit before pressurizing — a thread that starts and stops in the first two turns is probably the wrong standard
Thread standards are the cheapest thing to get right at order time and the most expensive to fix after installation. Confirm NPT or BSPT before you buy, and send us a photo of the mating fitting if you are not sure — we will identify the standard and confirm the right camlock.