Welding neck flanges are usually used for which type of plate flanges?

Welding neck flanges are specifically designed to be welded to the piping system, providing a strong and robust connection that can handle pressure and temperature variations. They are most commonly associated with orifice plate flanges due to their ability to ensure a proper alignment and sealing surface for flow measurement in pipelines.

In the case of orifice plate flanges, the welded neck helps to support the decision to maintain the integrity of the measurement, allowing for accurate flow readings. The neck of the flange also allows for a gradual transition between the outer diameter of the flange and the pipe, which minimizes turbulence and flow disturbances.

Other types of plate flanges—such as slip-on, blind, and threaded plate flanges—have different designs and applications that may not require the same welding characteristics or structural integrity that a welding neck provides, making them unsuitable for high-pressure applications like those typically seen with orifice plate flanges.