Introduction
BSP and NPT are pipe thread families used in hydraulic and industrial connections. They are not interchangeable simply because nominal sizes appear similar; selection must be verified by measurement, drawing and mating port specification.
Quick Comparison Table
| Feature | BSP | NPT |
|---|---|---|
| Thread family | BSPP parallel and BSPT tapered | Tapered pipe thread |
| Thread angle | 55-degree Whitworth thread form | 60-degree thread form |
| Parallel or tapered | BSPP is parallel; BSPT is tapered | Tapered |
| Typical sealing method | BSPP may use bonded washer, O-ring, cone seat or specified interface; BSPT uses tapered engagement with suitable sealing method where required | Tapered thread interference with suitable thread sealant where required |
| Common regions or systems | Many European and international hydraulic systems | Common in North American pipe systems |
| Interchangeability | Not interchangeable without a correctly designed adapter | |
What Is BSP?
BSP is a British Standard Pipe thread family. It includes BSPP parallel thread and BSPT tapered thread, both based on a 55-degree Whitworth thread form.
BSPP vs BSPT
BSPP is parallel and may seal through a bonded washer, O-ring, cone seat or another specified sealing interface. BSPT is tapered and normally relies on tapered thread engagement with a suitable sealing method where required.
What Is NPT?
NPT is a tapered pipe thread with a 60-degree thread form. It commonly seals through tapered thread interference with suitable thread sealant where required.
Thread Angle and Profile
The difference between 55-degree BSP and 60-degree NPT thread forms is one reason similar nominal sizes should not be treated as compatible.
Parallel vs Tapered Threads
Confirm whether the thread is parallel or tapered by measurement rather than appearance alone.
Sealing Methods
Identify the specified sealing interface, washer, O-ring, cone seat or sealant requirements before ordering.
How to Identify BSP and NPT
Use a thread gauge, outside diameter, pitch, taper check, mating port specification and drawing or equipment documentation. Appearance alone is not enough.
Why They Should Not Be Interchanged
Different thread forms and sealing methods can cause poor fit or sealing problems if mismatched.
Information Needed for Selection
- Thread family and size
- Outside diameter and pitch
- Taper check
- Mating port specification
- Drawing or equipment documentation
FAQ
Are BSP and NPT threads interchangeable?
No. BSP and NPT should not be interchanged solely because nominal sizes appear similar; the thread angle, profile and sealing method differ.
What is the difference between BSPP and BSPT?
BSPP is a parallel thread, while BSPT is a tapered thread. Both use a 55-degree Whitworth thread form.
Do BSPP threads seal on the thread?
BSPP may seal through a bonded washer, O-ring, cone seat or another specified sealing interface rather than relying only on the parallel thread.
What thread angle does NPT use?
NPT uses a 60-degree thread form.
How can I measure an unknown thread?
Use a thread gauge, outside diameter measurement, pitch measurement, taper check and the mating port specification or drawing.
Can Wei Xing Machinery manufacture BSP-to-NPT adapters?
Yes, BSP-to-NPT adapters can be reviewed and manufactured according to drawings, thread details, material and application requirements.
Related Products
Review BSP hydraulic adapters and NPT pipe fittings, or compare ORFS vs JIC sealing methods.
Need help identifying a thread?
Send thread measurements, photos, drawings and mating port details for review.
Contact Wei Xing Machinery