Types of Pipe and categories

Orifice Flanges are widely used in conjunction with orifice meters for measuring the rate of flow of liquids and gases. They are basically the same as a standard welding neck, slip on and screwed flanges except for the provision of radial, tapped holes in the flange ring for meter connections and additional bolts to act as jack screws to facilitate separating the flanges for inspection or replacement of the orifice plate. In choosing the type of orifice flange, the considerations affecting the choice of welding neck, slip on and screwed standard flanges apply with equal force.

Reducing Flanges can be used to change the size of a pipe run. The main concern in using this flange is that the sudden change in run size creates turbulence in the flow. For this reason it should not be used as a pump connection.

Expander Flanges can be used to change the size of a pipe run. These are usually used to increase the line size to the first or second larger size. This is an alternative to using a separate reducer and weld neck flange combination. The expander flange can be used to connect pipe to pumps, compressors and valves.

Blind Flanges are used to blank off the ends of piping, valves and pressure vessel openings. From the standpoint of internal pressure and bolt loading, blind flanges, particularly in the larger sizes, are the most highly stressed of all American Standard flange types; however since the maximum stresses in a blind flange are bending stresses at the center, they can safely be permitted to be higher than in other types of flanges. Where temperature is a service factor, or repeated severe water hammer, consideration should be given to closures made of welding neck flanges and caps.