Threaded flange is connecting with pipe without welding. It is similar to slip on flange or a socket weld flange, fitted with a tapered thread (screw) inside the flange bore that is mounted on the pipe with corresponding external threads. In some cases a seal weld also applied in conjunction with threaded pipe flange.
Though threaded pipe flange is available in different dimensions, threaded fittings mostly is used in small diameters pipeline. (Below 4 inch normally.)
On the other hand, it is not compatible with a pipe system in thin wall thickness, since there is no space for doing the threading.
There are two types of threaded flanges. One is to seal the two pipe ends with a certain sealing surface and a lens pad. This type of flange is mostly used for ammonia production. But it has been used less recently, and the lens pad has been replaced by a metal ring.
The other type is the same as a normal flange, sealed with two flange sealing faces.
There are two facing types for threaded flange, raised face flange and ring joint flange.
When the gasket surface area is above the bolted line of the flange, the raised face flange is easily identified. It is compatible with a wide range of gaskets, from flat to semi-metallic and metallic types, either ring or full.
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