BSPT Thread Pitch Chart

What is a BSPT Thread?

BSPT stands for British Standard Pipe Taper. BSPT threads are part of the British Standard Pipe thread family and are commonly used for creating pressure-tight connections in pipes, fittings and industrial equipment.

BSPT threads use a 55° Whitworth thread form and are tapered, meaning the diameter gradually increases along the length of the thread. This taper allows the male and female threads to tighten together and create a mechanical seal, often with the use of thread sealant. BSPT is also commonly referred to as R thread, such as R1/4, R1/2 and R1.

BSPT vs BSPP Threads

While BSPT and BSPP threads share the same thread form and sizes, they are not interchangeable and serve different purposes.

BSPT (Tapered Thread) tapers along the thread length and creates a pressure seal through thread engagement. It is commonly used for hydraulic, pneumatic and pipe connections where a tight seal is essential.

BSPP (Parallel Thread) features a straight, non-tapered design and requires sealing using washers, O-rings or other sealing methods. It is commonly used where components need to be removed or adjusted regularly.

How to Read the BSPT Thread Chart

The BSPT Thread Dimensions chart above includes the following columns:

• Diameter – The nominal pipe size designation
• TPI – Threads Per Inch, indicating thread density
• Drill Size (mm) – The tap drill size required for creating BSPT threads

It is important to note that BSPT sizes are based on pipe sizing and do not directly match the measured outside diameter of the thread. Always refer to the chart when selecting the correct tap drill size for your application.

Common Applications

BSPT threads are widely used across many industries and applications, including hydraulic systems, pneumatic equipment, compressed air systems, pumps and valves, industrial machinery, agricultural equipment, engineering workshops, and pipe and fluid handling systems. Their ability to create reliable pressure-tight seals makes them essential in environments where leakage cannot be tolerated.

Frequently Asked Questions

What does BSPT stand for?
BSPT stands for British Standard Pipe Taper. It is a tapered thread standard used primarily in the United Kingdom and Commonwealth countries.

Is BSPT the same as NPT?
No. While both are tapered pipe threads, BSPT uses a 55° Whitworth thread form, whereas NPT (National Pipe Thread) uses a 60° thread form. They are not compatible and should not be mixed.

What is the difference between BSPT and BSPP?
BSPT is tapered and creates a seal through thread engagement, while BSPP is parallel and requires additional sealing components like O-rings or washers.

Are BSPT threads used in Australia?
Yes. BSPT threads are commonly used in Australia, particularly in hydraulic, pneumatic and industrial applications, making them an important standard for Australian engineers and machinists.

Do BSPT threads require thread sealant?
While the tapered design creates a mechanical seal, thread sealant is often applied to ensure a leak-free connection and improve reliability in high-pressure applications.

Can BSPT taps and dies be used for BSPP threads?
No. BSPT taps and dies are designed specifically for tapered threads and should not be used for BSPP parallel threads, as this will result in poor thread quality and potential leakage.

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