threaded flange

Plate flange is also named plain flange, flat flange and slip on flange etc. A plate flange is a flat, circular disk that is welded onto the end of a pipe and allows it to be bolted to another pipe. Typically used in fuel and water pipelines, the two plate flanges will be bolted together with a gasket in between them. The plate flange will have bolt holes all around the perimeter and will be used to create junctions, tees and joints.

Socket weld flanges are a less common but equally effective connection for flanges which require less overall available space than a traditional weld neck flange, with a counterbore in the center to allow for a clean weld of pipe into the socket.

Slip-on Flange is essentially a ring that is placed over the pipe end, with the flange face extending from the end of the pipe by enough distance to apply a weld bead on the inside diameter.

Threaded flanges, also sometimes referred to as companion flanges / screw flanges / NPT flanges, contain a female NPT thread in the center for connection to male NPT threaded piping. Threaded flanges are common when creating reducing connections. Other thread styles are available for machining, aside from the standard NPT form as designated by the ASME B16.5 specification.