The thread shown in the NPT thread table is one of the American pipe thread types. Pipe threads are required, for example, in the sanitary sector and in air conditioning and heating technology to connect pipes, fittings and valves. The pipe thread according to the NPT thread table is one of several possible designs, all of which are defined and monitored by the American National Standards Institute (ANSI). The specifications in the NPT thread table correspond to the ANSI B 1.20.1 standard.
For pipe threads, a distinction is always made between conical and cylindrical and between sealing and non-sealing.NPT stands for National Pipe Taper, where "taper" is the English term for cone or taper. According to the NPT thread table, the thread is therefore a conical or tapered pipe thread that is not sealing in the thread. It has a flank angle of 60°. The conical shape of the NPT thread is defined by an angle of 1°47'.
As you can see from the NPT thread table, the thread designation is made up of the abbreviation NPT and a diameter in inches, which does not actually correspond to the nominal diameter of the thread. This is because the inches in the thread designation are based on historical pipe dimensions. These have changed over time, while the thread designation has remained the same. You can see this very clearly in the NPT thread table with the entry NPT 1". Instead of the 25.4 mm outer diameter that you would actually expect here, this thread size has an outer diameter of 33.23 mm.
To make it easier for you to get an overview of the American pipe threads, we have compiled further information in addition to the NPT thread table.You will also find an NPT thread table with all the dimensions for fittings and pipes that you need for your work with the NPT thread. We also explain the differences between the non-sealing NPT thread and the dry-sealing fine pipe thread NPTF in a graphic. And finally, in addition to the NPT thread table, we also provide you with an overview of all American pipe threads, which allows you to compare them based on important characteristics such as seal and shape.