NPT thread gauge is one of the accepted and commonly used pipe thread standards for screw threads used on pipes. It not contrary to the straight threads that are found on bolts because it pulls tight, giving results to a closer seal. NPT threads are known to have a 60° angle, unlike the BSS having 55°angles, and they differ from the BST thread with rounded peaks and valleys. However, it is similar to later in regards to the trade size rather than the use of the actual diameter.

The ASME/ANSI standard B1.20.1 is used to define NPT. For the best leak free seal, emsure you use a thread sealant. Thread check offers a total line of plug and ring gages to ensure General purpose National Taper {NPT} pipe thread (it ensures the threading from 1/ 16 – 6.0 inches). Threads made to this specification includes external taper and internal taper to form a normal type of joint fitting for a general application in the pipe.

NPT threads gauge are trying to be made of wrench tight and a sealant should be applied in pressure-tight joint applications. When threads get to the permissible limits of the tolerances when the gaging notch of the plug or gaging front of the ring is plus or minus one turn from being flush.

Sometimes an NPT thread gauge can be mistaken for an ISO7_1 thread because they look so much alike, but then, they shouldn’t be mixed up. One vital characteristic of the NPT thread gauge is that the angle between the taper and the center axis of the pipe is  1o 47′ 24” (1.7899o), with each thread having unique numbers of TPI. The NPT thread gauge is well known and widely used for pipes transporting liquids, steam, gases, and hydraulic fluid. When torqued, the taper allows seals, and it occurs when there is compression of the flank of the thread. This typically opposes the parallel or straight thread fittings that do not provide seals but rather a mere holding together of the pieces.

On the other hand, the ACME thread gauge is designed for the sole purpose of gauging internal and external thread products. In simple terms, you can say that they are used to grind and cut ACME thread cutting tools. They are available in different sizes and types. The most commonly and most economically used ACME thread is a general-purpose ACME thread gauges. It has three classes of fit, namely the 2G, the 3G, and the 4G. It is recommended to ensure that the internal and the external thread class are used together when making use of the general-purpose ACME thread gauge for general assemblies to maximize productivity.