Mechanical Seal Materials Guide
Mechanical seals are available in a variety of materials depending on the seals purpose. By selecting the correct material for your pump seal it will last a lot longer, prevent unnecessary maintenance and failures.
Abrasive and harsh environments mean that the material selected must be able to withstand this, which can be more expensive. However the cost will be returned to you over time as poor material grade selection will only result in costly shut downs, repairs, refurbishments or replacements of the seals once again.
The most common types of mechanical seal faces are as follows:
- Carbon (CAR)
- Ceramic (CER)
- Silicone Carbide (SiC)
- Tungsten Carbide (TC)
- Glass Filled PTFE (GFPTFE)
Carbon / Ceramic - This material generally comprises of 99.5% aluminium oxide which offers good abrasion resistance due to its hardness. As carbon is chemically inert it can withstand many different chemicals, however it is not suitable when thermally 'shocked'. Under extreme temperature changes it can shatter or crack.
Silicone Carbide - This material is created by fusing silica and coke and is chemically similar to Ceramic, however it has improved lubrication qualities and is much harder. Silicone carbide's hardness make it an excellent hard-wearing solution for harsh environments and it can also be re-lapped and polished to refurbish the seal multiple times over its lifetime.
Tungsten Carbide - A highly versatile material like silicone carbide but it is more suited to high pressure applications due to having high elasticity in comparison. This allows to to 'flex' very slightly and prevent face distortion. As with Silicone Carbide it can be re-lapped and polished.
GFPTFE - This material has good chemical resistance and the glass is added to reduce the friction nof the sealing faces. It is ideal for relatively clean applications and a cheaper alternative than other materials.