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Difference Between BSP & NPT?

BSP & NPT are two different thread standards that originate from two different countries. BSP stands for British Standard Pipe & NPT stands for National Pipe Taper. BSP, as in the name, is from England while NPT is from the USA.

In New Zealand, BSP is far more common than NPT although NPT is often found in the oil and gas industry, where equipment from the United States is used. Most plumbing fittings with threads in New Zealand use the BSP standard.

The difference between BSP & NPT fittings is the Threads per inch, shape and angle the threads are cut on. At some sizes threads per inch are very similar but there are other differences that make the threads incompatible.

The second difference is the shape of the threads. With BSP, the peaks and valleys of the threads are rounded. In NPT, they are flat and sharp.

The third difference is the cut angle of the thread. BSP threads are cut at 55 degrees, while NPT are cut at 60 degrees.

You can typically identify between BSP & NPT by feeling whether the threads are flat and sharp or rounded on top. NPT feels a lot sharper than BSP. You can also measure the threads per inch and use the handy table on our website to identify your fitting.

The Metal Company stocks both male and female NPT to BSP adapters, so you can easily work with both threads.

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