AN threads refer to the outside diameter of the pipe used with the fitting. AN fittings use a 37-degree flare, superior to SAE’s 45-degree flare. AN fittings are used in the military, NASA, aviation, and racing industries. AN fittings require special aluminum wrenches and a drop of oil during assembly. Overtightening is the main cause of AN fitting failure.
An AN thread is relative to the size of the fitting. The AN designation refers to the RN as the design of the siding was a joint effort between the two military branches. The AN measurement refers to the outside diameter of the pipe that will properly match the fitting. These thread sizes easily match the Society of Automotive Engineers (SAE) thread sizes. AN fittings use a special 37 degree flare tested and found to be superior to common SAE flare fittings, which are a 45 degree flare.
While an AN threaded fitting refers to the outside diameter of the pipe used with the fitting, a National Pipe Threads (NPT) fitting refers to the inside diameter of the fitting. AN threaded fittings can be connected to SAE threads and vice versa; however, NPT threads must use an adapter to connect with AN threaded fittings. The reason for this is that NPT threads are tapered and are narrower at one end than the other. This allows the fittings to be connected in a flare type method once tightened. SAE and AN threaded fittings are straight cut threads without a taper.
AN threaded fittings have been used extensively by the military, the US National Aeronautics and Space Administration, the aviation industry and the racing community. Most high-horsepower engines use AN fittings exclusively for plumbing vital fluid lines such as oil, fuel, and coolant. The success of these fittings has been undisputed in almost all forms of competition around the world. It is imperative that only special aluminum wrenches are used on the fittings to avoid damage. By using a steel wrench on the aluminum fittings, the corners can easily be rounded off and the bright anodized red and blue finish destroyed.
Unlike many other fasteners, when assembling AN threaded fittings, a small drop of light oil should be applied to the threads to prevent wear and damage as well as sticking and freezing of the fitting halves. The main cause of AN fitting failure is overtightening. The 37 degree flare of the fitting does not require extreme force to ensure a secure seal. Simply snug fittings, then a slight twist will be enough to create a leak proof seal in most cases. One of the most critical steps to take when assembling AN threaded fittings is to ensure that the threads and flare of the fitting are clean and free of contaminants during assembly.
Protect your devices with Threat Protection by NordVPN
