Flanges are relatively simple mechanical connectors that have been used successfully for high-pressure piping applications. They are well understood, reliable, cost-effective, and readily available from a wide range of suppliers. In addition, the moment-carrying capacity of flanges is significant compared to other mechanical connectors. This is an important feature for systems that experience pipe-walking or lateral buckling from temperature and pressure variations (e.g. deep water lines). Flanges can be designed to meet a wide range of application requirements such as high-temperature and corrosion resistance.

Operation

Pipe flanges have flush or flat surfaces that are perpendicular to the pipe to which they attach. Two of these surfaces are mechanically joined via bolts, collars, adhesives or welds.

Typically, flanges are attached to pipes via welding, brazing, or threading.

Welding joins materials by melting the workpieces and adding a filler material. For strong, high pressure connections of similar materials, welding tends to be the most effective method of flange connection. Most pipe flanges are designed to be welded to pipes.

Brazing is used to join materials by melting a filler metal which solidifies to act as the connector. This method does not melt the workpieces or induce thermal distortion, allowing for tighter tolerances and clean joints. It also can be used to connect very dissimilar materials such as metals and metalized ceramics.

Threading is applied to flanges and pipes to allow the connections to be screwed together in a manner similar to nuts or bolts.

While the method of attachment can be a distinguishing feature, there are other considerations more important to pipe flange selection. Factors an industrial buyer should consider first are the flange’s physical specifications, type, material, and performance features most suitable for the application.