What The Differences between NPT, BSPP and BSPT Pipe Thread

Pipe thread mainly used for pipe connection, the internal and external thread can be tight; it has straight tube and cone tube two specifications. Recently, a handful of people are confused by different threads requirements in different drawings. In order to help you figure out the differences, we accessed relevant information and summarized as below:

Common pipe thread mainly includes the following: NPT, BSPT, BSPP and so on.

First, let's make it clear that what are they means exactly:

·BSPT -British Standard Pipe Taper

·BSPP -British Standard Pipe Parallel

·NPT -National Pipe Taper

Different ways of sealing are applied in different process due to the geographical region, size of the pressure system and the environment. For example, many pressure systems onboard ships use BSPP adapters while many applications in the oil and gas industry use NPT fittings. Next, let’s explain in detail one by one.

NPT Connections

NPT is an American standard thread. Itmay also be referred to as MPT, MNPT or NPT (M) for male external threads and FPT, FNPT or NPT (F) for female internal threads. A thread sealant must always be used to achieve a leak free seal (except for NPTF). It is also based on Trade Size rather than actual diameter (similar to BSP in this regard).

BSPT Connections

BSP is common in Australia and the commonwealth countries. It is based on trade size rather than actual diameter which can lead to some confusion when measuring ports. There are two types of BSP threads;

- Parallel (BSPP) - also known as G or Rp

- Tapered (BSPT) - also known as R or Rc

BSPP Connections

BSPP is a parallel thread fitting that uses a bonded seal ring to do the sealing. This bonded ring seal is sandwiched in-between a shoulder on the male fitting and the face of the female fitting and is squeezed in place. BSPP pressure gauges have a longer male thread and use a copper crush washer that is squeezed in between the bottom of the male fitting and the bottom of the female BSPP hole forming a pressure tight seal. No thread sealant is needed to form a seal.

This article above is a brief introduction about three main connections of pipe thread. If you want to have more information, please contact us.