1. Flange facings Contact surfaces to seat the sealing gasket material.
Wide face:
Non-standard
Simple
Gasket extended beyond bolt holes
Soft gasket
P<20kg/cm2, T<220 C
Narrow face

2. Raised face Most common type Average service conditions
Gasket surfaces are raised above the bolting circle face.
The raised faces have a prescribed texture to increase their gripping and retaining force on this flat gasket. 

4. Male and Female Face
Flanges must be matched. One flange face has an area that extends beyond the normal flange face (Male). The other flange flange has a matching depression (Female) machined into it's face.
The female face is 3/16-inch deep, the male face is 1/4-inch high
Heat Exchanger shell to channel and cover flanges.

5. M & F flange face

6. Tongue and Groove face Gasket is placed inside the groove
They differ from male-and-female in that the inside diameters of the tongue-and-groove do not extend into the flange base, thus retaining the gasket on its inner and outer diameter. These are commonly found on pump covers and Valve Bonnets.
Self-aligning

7. Tongue and Groove face

8. Ring facing Two identical grooves made in both facings
Ring shaped gasket fits into the grooves
Severe conditions &/or hazardous fluids

9. Gaskets
Plastic/semiplastic material placed between two flanges & held tight by series of bolts
Tries to expand and occupy space between two flange facings, thereby sealing minute irregularities
Min force reqd by the gasket to flow and seal the surface is known as Yield or Seating Force
Ratio of gasket stress to internal pressure is called Gasket Factor

10. Requirements for a gasket
Good compressibility and face adaptability
Good recovery
Strength
Chemical resistance
Temperature resistance

11. Major Classification