Threaded Flanges are fitted to the pipe without welding. They are suitable for small diameter high pressure services. At larger diameters, the difficulty in machining the thread on to both the flange and pipe makes them unviable. They do not have a bore schedule, but have a description of the type of thread, such as casing, tubing or line pipe. They save time & cost and can be assembled without welding. This makes the flange well-suited to extreme pressure services that operate at normal atmospheric temperatures and in high explosive areas.