What do FF, RF, and RTJ stand for in Flange Face and Finish specifications?

• FF stands for Flat Face.
• RF stands for Raised Face.
• RTJ stands for Ring Type Joint.

These terms describe the surface finish and sealing characteristics of flanges. FF has a flat, smooth face, RF has a raised face with a gasket sealing surface, and RTJ has a groove to accommodate a ring gasket for high-pressure applications.