NPT vs BSP Fittings: Which One Do You Actually Need?

Choosing the wrong fitting thread standard can lead to leaks, system failures, or costly downtime. Whether you're working on industrial hydraulics, construction equipment, or fluid power systems, understanding the difference between NPT and BSP fittings is critical. This guide breaks it down clearly and shows you exactly which products Gear House Hydraulics stocks for each standard.

Quick Comparison: NPT vs BSP

Feature	NPT (National Pipe Thread)	BSP (British Standard Pipe)
Origin	United States	United Kingdom / International
Thread Angle	60 degrees	55 degrees
Seal Method	Thread interference (tapered)	O-ring or PTFE tape (BSPP) / Tapered thread (BSPT)
Primary Use	North American hydraulic & industrial systems	European, Asian, and international systems
Common Types	NPT, NPTF, NPSM	BSPP (parallel), BSPT (tapered)
Interchangeable?	No — do not mix with BSP	No — do not mix with NPT

 

Thread Angle: The Key Difference

The most important technical distinction is the thread angle. NPT threads have a 60-degree thread angle, while BSP threads use a 55-degree angle. This seemingly small difference means NPT and BSP fittings are NOT interchangeable mixing them will result in cross-threading, improper sealing, and potential system failure under pressure.

How Each Standard Seals

NPT Fittings — Thread Interference Seal

NPT (and NPTF) fittings create a seal through metal-to-metal thread interference as the tapered threads are tightened. PTFE tape or thread sealant is typically used to ensure a leak-free connection.

BSP Fittings — Two Types

•      BSPP (Parallel): Threads do not taper. The seal is achieved using a bonded seal washer or O-ring at the face/port.

•      BSPT (Tapered): Similar to NPT in concept  tapered threads create the seal with PTFE tape or sealant. Taper ratio is 1:16.

Available at Gear House Hydraulics

Gear House Hydraulics stocks both NPT and BSP fittings in steel and stainless steel, across multiple configurations:

NPT Fittings (Steel & Stainless)

 

Product Line	Material
NPT Fittings	Carbon Steel
NPTF Pipe Male to NPSM Female Pipe Swivel (45° Elbow, Branch Tee, Straight)	Carbon Steel
NPT Male to NPSM Female Pipe Swivel Straight	Stainless Steel (SS)
Stainless NPT Fittings (full range)	Stainless Steel

BSP Fittings (BSPP & BSPT — Steel & Stainless)

 

Product Line	Material
BSPP/BSPT Fittings (full range)	Carbon Steel
Stainless BSPP/BSPT Fittings (full range)	Stainless Steel

 

When to Use NPT vs BSP

Choose NPT When:

•      Your equipment is manufactured in the United States

•      You are connecting to existing NPT ports on pumps, valves, or cylinders

•      Your system follows SAE or ANSI standards

•      You are working in construction, agriculture, or automotive applications in North America

Choose BSP When:

•      Your ports are marked BSP, BSPP, or BSPT

•      You need metric-compatible hydraulic systems

•      Your application requires an O-ring face seal (BSPP with bonded seal)

Pro Tips: Avoid Costly Mistakes

1. Always identify your existing port thread before ordering. Use a thread gauge or measure the thread angle.

2. Never force NPT into a BSP port the different thread angles will cause immediate damage.

3. BSPP (parallel) threads require a face seal (O-ring or bonded washer) do not rely on thread alone.

4. For NPTF connections, Gear House stocks swivel variants that allow alignment without stress on the line.

Other Fitting Standards Available at Gear House Hydraulics

In addition to NPT and BSP, Gear House Hydraulics stocks a full range of hydraulic fitting standards:

•      37° JIC/AN Fittings (Steel & Stainless) — widely used in mobile hydraulics and aerospace

•      ORB Fittings (O-Ring Boss) — Steel & Stainless

•      ORFS Fittings (O-Ring Face Seal) — Steel & Stainless  the highest leak-free performance

•      Flange Components (Code 61 & Code 62 SAE Flanges) Steel & Stainless

•      Hose Steel & Stainless Hydraulic Fittings

Shop NPT and BSP Fittings at Gear House Hydraulics

Gear House Hydraulics stocks both NPT and BSP fittings in carbon steel and stainless steel for industrial, mobile, marine, construction, agriculture, and oil & gas applications. Need help choosing the right fitting? Their expert team provides technical guidance to ensure you get the right product for your system.