Even though the threaded flange design is available in many sizes and pressure ratings, it is mainly used for small sized piping systems i.e. ≤ 4 inches. Its usage is also typically restricted to non-toxic systems, low pressure systems, and low temperature systems. ½ inch to 2-inch size threaded flanges are much more common than sizes of 2 inches and above. Due to their lower pressure applications, threaded flanges use flat and raised faces only. They are not suitable for high temperature applications because the thread geometry would distort, which often leads to leakage.
The major advantage with threaded flanges is that they can be connected to a pipe without the need for welding. Forming joints without needing to weld is a considerable advantage, and is essential in some locations and industries e.g. explosive areas (Ex rated areas) such as petrol stations, hexane plants, stores with flammable fluids etc. If no welding is required, a potential source of ignition is removed. Another advantage is that it is quicker and easier to assemble and disassemble a threaded flange joint than a welded flange joint.