BSP vs NPT vs JIC vs ORFS: Hydraulic Fitting Threads Explained
Choosing the wrong fitting thread is one of the most common and most expensive mistakes in hydraulic sourcing. Two threads can look almost identical, thread together by a turn or two, and still leak under pressure because they seal in completely different ways. This guide explains the four thread families you will meet most often, how each one actually seals, and how to specify the right one so your quote and your delivered parts match your system.
What is the difference between BSP, NPT, JIC and ORFS fittings?
The short answer: they differ in thread angle and, more importantly, in how they seal. BSP uses a 55-degree thread; NPT uses a 60-degree tapered thread that seals on the threads themselves; JIC seals on a 37-degree metal flare, not the threads; and ORFS seals on a flat face with an O-ring. Because the sealing method is different, these standards are generally not interchangeable even when the thread appears to fit.
Everything below expands on that, one family at a time.
BSP (British Standard Pipe)
BSP is the dominant standard across Europe, the Middle East, India, Australia and much of Asia. It has a 55-degree thread angle and comes in two forms that are easy to confuse:
- BSPP (parallel, marked G): the threads are straight and do not seal by themselves. The seal is made at the port face using a bonded (dowty) washer, an O-ring, or a 30-degree cone seat.
- BSPT (tapered, marked R): the threads taper and wedge together to form the seal, similar in principle to NPT but at a different angle.
Because BSPP and BSPT share the same nominal sizes, they will start to thread together, but only one will seal correctly for a given port. Always confirm parallel vs tapered before ordering.
NPT (National Pipe Taper)
NPT is the North American workhorse for general pipe and lower-pressure connections. It has a 60-degree tapered thread and seals by the threads wedging and deforming against each other, which is why a thread sealant such as PTFE tape or anaerobic paste is normally required.
The critical warning: BSP and NPT are not interchangeable. They look similar but have different thread angles (55 vs 60 degrees) and different pitch geometry. Forcing them together damages both parts and produces a connection that leaks or fails under pressure.
JIC (37-degree flare, SAE J514)
JIC is a true high-pressure hydraulic connection and is extremely common in North American mobile and industrial equipment. The threads are a straight UNF (Unified National Fine, 60-degree) form, but here is the key point: the threads do not seal. Sealing happens where a 37-degree cone on the male fitting meets a matching 37-degree flare seat, metal to metal.
That metal-to-metal flare is what makes JIC reliable at pressure and easy to service, and it is the feature to check when you are identifying a fitting: look at the seat angle, not the thread.
ORFS (O-Ring Face Seal, SAE J1453)
ORFS is the standard to reach for when leak-free performance under high pressure and heavy vibration matters most. The male fitting has a flat face with an O-ring set into a groove; when tightened, that O-ring compresses against the flat face of the mating part to form the seal. The thread (also UNF, 60-degree) only holds the joint together.
Because the seal is a captured O-ring on a flat face rather than metal-on-metal or a taper, ORFS is the most forgiving of vibration and the least prone to slow weeping over time, which is why it is favoured on demanding mobile and industrial hydraulics.
Two more you should know: DIN 24-degree and SAE ORB
- Metric DIN 2353 (24-degree cone / DKO): a metric-threaded connection that seals on a 24-degree cone, standard across German and wider European machinery.
- SAE ORB (O-Ring Boss, SAE J1926): a straight thread with an O-ring that seals into a chamfer at the top of a boss port. Common as the port-end connection on pumps, valves and manifolds.
Quick comparison table
| Standard | Thread angle | How it seals | Typical region / use |
|---|---|---|---|
| BSPP (G) | 55° parallel | Bonded washer / O-ring / 30° cone at port | Europe, India, Middle East, Australia, Asia |
| BSPT (R) | 55° tapered | Threads wedge together | Same regions, lower-pressure pipe work |
| NPT | 60° tapered | Threads + sealant (PTFE) | North America, general pipe |
| JIC | 60° UNF thread | 37° metal flare (metal-to-metal) | North America, high-pressure hydraulics |
| ORFS | 60° UNF thread | Flat-face O-ring | High-pressure, high-vibration hydraulics |
| DIN 2353 | Metric | 24° cone | European machinery |
| SAE ORB | UNF thread | O-ring into boss chamfer | Pump / valve / manifold ports |
How to avoid a mismatched connection
Three checks prevent almost every fitting mistake:
- Identify by the seal, not the thread. Look at where the joint actually seals: a flare angle (JIC), a flat face with an O-ring (ORFS), a taper (NPT/BSPT), or a port-face seal (BSPP). The thread alone will mislead you.
- Measure, do not guess. Confirm thread diameter and pitch (threads per inch or metric pitch) with a thread gauge and calipers before ordering. A part that is “close” is a leak waiting to happen.
- Match the port, not just the hose end. The fitting has to suit the component port it screws into, so specify both ends of every connection.
The goal is the right connection, whether you buy from us or not
We wrote this so you can specify the correct thread and seal and avoid a leaking joint, full stop, wherever you source it. Identify by how a fitting seals, measure the thread, and match both ends of every connection, and you will rarely go wrong on your own.
If you do want it sourced to spec, here is how we work: Velqor supplies fittings built to your drawing, sample or application, not a fixed SKU list, so the thread standard, seat type, material and pressure class are confirmed before anything is made, then quality-checked and documented. Send the connection detail for both ends and you get a straight answer and a part that matches. And if a standard catalogue fitting would serve you better and cheaper than a custom one, we will tell you that too.
Frequently Asked Questions
Are BSP and NPT interchangeable?
No. They look similar but have different thread angles (55 degrees for BSP, 60 degrees for NPT) and different pitch geometry. Threading them together damages both parts and produces a joint that leaks or fails under pressure.
Does a JIC fitting seal on the threads?
No. JIC threads only hold the joint together. The seal is made metal-to-metal where a 37-degree cone meets a matching 37-degree flare seat, so you identify JIC by the seat angle, not the thread.
When should I choose ORFS over JIC?
Choose ORFS when the connection sees high pressure combined with heavy vibration. Its flat-face O-ring seal resists loosening and slow weeping better than a metal-to-metal flare, at the cost of a slightly bulkier fitting.
Do I need PTFE tape on hydraulic fittings?
Only on tapered thread-sealing types such as NPT and BSPT, where the threads themselves form the seal. Flare (JIC), O-ring face (ORFS) and port-face (BSPP) connections seal on a dedicated surface and should not be taped.
How do I identify an unknown fitting?
Check the sealing feature first (flare angle, flat face with O-ring, taper, or port-face seal), then measure thread diameter and pitch with a gauge and calipers. Together these two pieces of information identify the standard reliably.