Carbon Graphite is probably the best seal face you can use in most of your water and chemical applications. Its corrosion resistance and natural lubricity provides two of the features we need in a good seal face material. The question sometimes comes up about how to insert the carbon into the mechanical seal. Should it be captured into some type of a metal holder or would you be better off using a "monolithic" or solid version?

And to make it even more confusing, the top seal companies use both versions interchangeably. Let's see if we can make any sense out of the subject

Here is a picture of a carbon/graphite seal face sometimes called a "monolithic" face

This is a picture of a carbon/graphite face inserted into a metal holder. This design is often called a "composite.

Although monolithic faces have become popular in recent years, there are some real advantages in using a carbon/metal holder composite over a solid carbon/graphite face:

The are some disadvantages to a carbon/metal composite:

There are at least three ways to insert the carbon into the metal holder:

Let's look at each of the methods:

There does not appear to be a straightforward answer to this composite / monolithic subject so seal designers choose one or the other to simplify or lower the cost the of their particular seal design. Metal bellows designs almost exclusively use the composite version because of problems attaching a monolithic face to a welded metal bellows.

Now you know about the advantages and disadvantages of both designs for those few times you get to make a choice.

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