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Brief description of metric and inch threads
Metric, American and British thread standards NPT, PT, G are pipe threads. NPT is National (American) Pipe
The abbreviation of Thread belongs to the American standard 60 degree taper pipe thread and is used in North America. National standards can be found in GB / T12716-1991 PT Yes
Abbreviation for Pipe Thread, 55
Degree sealed conical pipe thread, belongs to the Wyeth thread family, mostly used in Europe and the Commonwealth countries. Commonly used in the water and gas pipe industry, the taper is specified as 1:16. National standards available
GB / T7306-2000 G is a 55-degree non-threaded sealed pipe thread, which belongs to the Wyeth thread family. Marked as G represents a cylindrical thread. National standards available
GB / T7307-2001 1/4, 1/2, 1/8 in other threads
The mark refers to the diameter of the thread size in inches. Insiders usually refer to the thread size in minutes. One inch is equal to 8 minutes, 1/4 inch is 2 minutes, and so on. G
It seems to be the general name of the pipe thread (Guan). The division of 55 and 60 degrees is functional, commonly known as the pipe circle. That is, the thread is machined from a cylindrical surface.
ZG is commonly known as pipe cone, that is, the thread is processed by a conical surface. The general water pipe joints are like this. The old national standard is marked as Rc.
The metric thread is expressed by the pitch, and the American and British threads are expressed by the number of threads per inch. This is their biggest difference. The metric thread is a 60-degree equilateral tooth type, the inch thread is an isosceles 55-degree tooth type, and the American thread. 60 degrees. Metric units for metric threads,
Inch units for American and British threads.
Pipe threads are mainly used to connect pipes. The internal and external threads are closely matched, and there are two kinds of straight pipes and tapered pipes. The nominal diameter refers to the diameter of the pipe to be connected. Obviously, the larger diameter of the thread is larger than the nominal diameter.
1/4, 1/2, 1/8 are the nominal diameters of inch threads, in inches
The differences are as follows:
(1) Metric thread is a kind of thread standard, also known as metric thread. The biggest difference from inch thread is that the pitch is measured in millimeters. There are ordinary threads (tooth profile angle 60 °); trapezoidal threads (tooth profile angle 30 °); serrated threads (tooth profile angle 33 °); square thread and so on.
The inch system is also a type of thread standard, which is divided into two types according to the shape of a cylinder and a cone; two types of teeth are divided into 55 ° and 60 °. The 1/4, 1/2, and 1/8 marks in the thread refer to the diameter of the thread size in inches. An inch is 8 points, a 1/4 inch is 2 points, and so on.
(2) The number of the metric thread indicates the distance of the thread. Numbers for inch threads represent the number of teeth per inch. The metric thread anastomosis is a metric thread, and the inch thread is an inch thread. The outer diameter of the metric thread is in millimeters, such as 6, 8, 10, 12, 18, 20 mm, etc. The pitch is also in millimeters, such as 0.5, 0.75,1,1.5,2,3, and so on.
The outside diameter of inch thread is in inches, (each inch is equal to 25.4 millimeters) such as 3/16, 5/8, 1/4, 1/2, etc. So metric calipers are used to read the outside diameter with irregular decimals. .
The imperial pitch is expressed as the number of teeth per inch. Set the caliper at 25.4 mm, and align one tip of the ruler with the thread tip, and the other ruler tip, if aligned with the thread tip, is an inch thread. If the tip of the non-uniform thread is metric thread.
2. Metric and inch thread representation:
Metric: For example, M27X2 (27 is the outer diameter of the thread, and 2 is the pitch of the buckle rail).
Imperial: For example, 1 / 2NPT (1/2 means that the number of teeth per inch is 14, the major diameter is 20.955, the median diameter is 19.793, and the minor diameter is 18.631.
Editor of Shanghai Nuoyou Valve Industry Co., Ltd.