How should flanges installed underground be designed?

Flanges that are installed underground should be designed with flat faces. This design is important because it helps to ensure a proper sealing surface to prevent leakage, which can be critical in underground applications. Flat-faced flanges provide a consistent and stable surface for the gasket, allowing for even distribution of pressure across the sealing area. This is particularly important in underground installations where soil movement and other environmental factors may exert different stresses on the piping system.

In contrast, raised-faced flanges can create uneven contact with gaskets, which may not perform well under soil pressure and could lead to potential leaks. The other designs, such as concave and convex faces, are not typically recommended for underground applications due to their inability to provide an adequate seal under the conditions that underground pipes face. Hence, utilizing flat-faced flanges ensures reliability and safety in buried piping systems.