Carbon is used as one of the faces on many seal applications because of its self-lubricating properties, chemical inertness and relatively low cost. Silicon carbide and tungsten carbide seal faces account for the majority of the other applications. Carbon seal grades are available in a wide range of abrasion resistances. The softer, low hardness grades are preferred where the mating face is a relatively soft metal. Harder, more abrasion resistant grades are preferred where the fluid sealed contains suspended or dissolved solids.
Depending on the mechanical seal type, there is often additional assembly work such as placing the carbon primary ring into an adapter or assembling carbon components into a seal head. Other types of seals use carbon as a loose component that is combined with a retainer, disk, springs and the secondary seal such as a bellows or O-ring.