Threaded fittings are piping components that join two pipes or other components together using threaded connections. They are made from a variety of materials, including steel, stainless steel, brass, and plastic. The most common types of threaded fittings are: Elbows: These fittings are used to change the direction of a pipe. Tees: These fittings are used to create a branch in a pipe. Couplings: These fittings are used to connect two pipes of the same size. Unions: These fittings are used to disconnect two pipes for maintenance or repair. Caps: These fittings are used to close off the end of a pipe. Plugs: These fittings are used to block a hole in a pipe. Bushings: These fittings are used to reduce the size of a pipe. Threaded fittings are specified by their size, material, and type. The size of a threaded fitting is the nominal diameter of the pipe it is designed to connect. The material of a threaded fitting is the type of metal or plastic it is made from. The type of a threaded fitting is the specific design of the fitting, such as an elbow, tee, or coupling. The technical specifications of threaded fittings include the following: Pressure rating: This is the maximum pressure that the fitting can withstand. Temperature rating: This is the maximum temperature that the fitting can withstand. Thread type: This is the type of thread used on the fitting. The most common thread types are NPT (National Pipe Thread) and PT (Pipe Thread). Finish: This is the surface finish of the fitting. The most common finishes are smooth and threaded. Coating: This is a protective coating applied to the fitting. The most common coatings are zinc and epoxy.