Thread gauges are used to measure the thread pitch or its size. Every thread has kind of valleys and peaks which are also called crest and root. Threads can be defined as the tapered at the end or straight throughout ones. Those which are bend to the centerline are known as tapered thread while those which are straight horizontal or parallel are called a parallel thread. Our topic of consideration is; thread plug gauges.
The main function of thread gauges is very simple that is to measure the thread of the component. There are many types of thread gauges that can be used to measure different thread components. One of the important one among many is thread plug gauges.
The thread plug gauges are rod-shaped ones giving a look of a dumbbell. It has a varying size of measuring sides which fits into the perfect mating thread hence, showing the size and number of the subsequent thread. It can match a vast variety of the thread of countless components like nuts and pipes.
Thread plug gauges are used to measure the female threads. These may include nuts or ring-type tools. It is exclusively used to measure the internal surface diameter of the thread. Thread plug gauges are a two-sided tool. This is due to the reason; if one side is not fitting in then you are free to replace it with the other side. It totally depends whether the plug gauge is a parallel one (has the same diameter throughout the entire length) or it is tapered one (thick above diameter and thin end diameter).
Thread plug gauges are available in APNT, ACME, straight pipe, taper lock, and other different types. Thread plug gauges are used to check the tolerance of certain object and to ensure that the mating parts are of equal size and control. It has GO and NO-GO Gauge technology. The GO gauge must be dragged all the way down till the end while the NO GO gauge must not. If it goes then the object is simply not to be qualified for the selling purpose.
ACME thread plug gauges are used checking the internal thread. This type of thread plug gauges has three classes of sets; 2G, 3G, and 4G while centralizing ACME threads classes are 2C, 3C, and 4C.
ANPT thread plug gauges are used on piping and fitting where O-rings might not help.
Pg. Conduit thread plug gauges are used to check the pipes for electrical wiring purposes.
Unified Miniature thread plug gauges are used for watches and small instruments.
A GO work plug is the type of gauge that makes its way entirely through the ring. This needs to be smooth depending upon the size, pitch, and diameter, till the end. The counterpart of such thread plug gauge; the NO GO plug should not enter more than 3 times.
GO and NO GO is the best qualitative test in the manufacturing and production industry. Thread gauges are manufactured to Class X tolerance which tells about the major diameter, minor diameter, and pitch diameter. Tolerance is plus for GO gauge and negative or below 0 for the NO GO thread gauges.
