The AN thread ensures bombproof connections
Well, if we woke you up at three in the morning, how many types of thread could you name off the top of your head? Maybe a few, maybe even a lot - but the AN thread is probably not the first one on the list. Unless perhaps you are active in motor sports. But let's start from the beginning. The AN thread is one of those very special thread types with a long history and very specific applications. For you, this means that you may never have to deal with the AN thread once in your life as a craftsman. But perhaps you will, and it is precisely at these times that we are at your side to explain everything you need to know about the AN thread.
Where does the AN thread come from?
You are probably not familiar with the AN thread in this country because it is a very American thread. So American, in fact, that the letters A and N stand for Army Air Corps and Navy. These two subdivisions of the American armed forces developed the AN thread during the Second World War. The AN thread therefore originally came from the military sector and was used in the aerospace industry, but its range of applications has grown far beyond these sectors in recent decades.
The special features of the AN thread
The AN thread is a classic thread for fittings, i.e. connecting pieces for pipes. It is used in particular for connections where a flexible hose is to be connected to a rigid pipe.
AN thread for flared fittings
The fittings for which the AN thread is often used are flare fittings. These are fittings for pipe systems that are exposed to heavy loads, vibrations or high pressure. In a flared fitting, one end of the pipe is flared while the other is tapered. When the nut is tightened, a flared union with an AN thread creates a good seal in this way. The decisive factor here is the angle of the cone, which is 37° for fittings with AN threads.
The most important key data on the AN thread
Traditionally, fittings with AN thread were produced in red and blue. This was intended to reflect the interplay between the Air Corps and the Navy and has certainly brought a bit of color into many a gray everyday life of a craftsman. Nowadays, however, special coloring is largely dispensed with.
The size specifications of the AN thread are somewhat more complex than we are used to with other thread types. AN threads are specified in dash sizes. They are called this because there is a dash in front of the number. AN threads therefore have sizes such as -2, -6 or -24. These numbers result from the specification of the outer diameter in 1/16". This sounds very complicated, but for you it simply means that you have to multiply the outer diameter in inches by 16 to arrive at the dash size. Let's try it together: The outer diameter of the AN thread you are looking for is 5/8 inch. 5/8 multiplied by 16 equals 10. The AN thread with an outer diameter of 5/8 inch therefore has a size of -10.
Why the inside diameter of the AN thread can cause problems
The diameter information in the AN thread table refers to the outside diameter. The problem with this is that the ratio between the outer and inner diameter of hoses and pipes can vary depending on the material and intended use. This is why there is a separate designation system for the AN screw thread, in which the corresponding number is appended to the abbreviation AN. The AN6 thread therefore fits into the -6 AN thread, but the actual thread sizes differ.
The AN thread is used here
Now we come to perhaps the most important point for you - why do you need the AN thread at all? The AN thread is still frequently used in the aerospace industry and in some branches of industry, particularly in the USA. Here in Germany, however, it is more familiar from a related but different area. In the automotive industry and especially in motorsport, flare fittings with AN threads are used for robust and tight connections in the fluid circuit of vehicles. Adapters and connections with AN threads are available in all possible variants, colors and shapes. In addition to the less frequently used abbreviation AN, these components can also be recognized by the Dash component in the name, which refers to the Dash sizes mentioned above.
Are there alternatives to the AN thread?
Admittedly, the AN thread has not reinvented the wheel and is not entirely without competition, even in the motorsport sector. The dimensions of the AN thread are identical to the somewhat better-known threads on SAE flare fittings. However, caution is advised here! Because even if the threads are identical, the actual fittings are not. While AN fittings are 37° flared fittings, SAE fittings have a 45° angle. A combination of components with each other can therefore jeopardize the tightness of the connection.
The second close relative is the JIC flare fitting, which even has the required 37° angle on the cone. These threads are interchangeable with AN threads and can also be combined with each other. However, you should also be careful here, as the combination of components with different standards may be prohibited even with a perfect fit. This applies in particular to sensitive areas such as aviation. However, if you come across thread tables that obviously consider JIC and AN threads to be identical, then you now know why.
Still haven't had enough of threads? You can also find threading tools for all standards and applications in our BAER online store. And our friendly customer service staff will be happy to answer any further questions you may have.