What are Mechanical Seals Made of? A Complete Guide

A mechanical seal helps contain fluid in a vessel (typically mixers and pumps) where a rotating shaft passes through a stationary casing. Before assessing how mechanical seal functions, it’s important to know what it’s made of.

You can find mechanical seals in a wide variety of materials based on the seal’s purpose. Selecting the right material for your pump seal ensures it lasts longer and prevents unnecessary failures and maintenance.

Mechanical seals made of resistant materials to withstand harsh and abrasive environments can be more expensive. But, the cost will be returned over time by reducing the chances of refurbishments, costly shutdowns, repairs, or replacements. Here are the most common types of mechanical seal faces.

Carbon (CAR)

This material typically consists of 99.5% aluminum oxide, offering good abrasion resistance because of its hardness. Since carbon is chemically inert, it can resist several different chemicals. However, under extreme temperatures chances, it can crack or shatter.

Carbon seals prevent gas leakage through the space between a static and rotating device. They have various applications, such as air turbine motor starters and aircraft gearboxes.

Silicon Carbide

Mechanical seals made of this material are created by combining coke and silica — chemically similar to Ceramic. However, it’s much harder and has improved lubrication qualities.

The hardness of these mechanical seals makes them an ideal hard-wearing solution for harsh environments. Moreover, it can be polished and re-lapped to refurbish the seal several times throughout its lifetime.

Tungsten Carbide

Mechanical seals made of tungsten carbide are very versatile, like silicon carbide. However, t’s extremely hard and heavy to the touch, making it easy to distinguish from silicon carbide.

Tungsten carbide is best used in high-pressure applications because of its high modulus of elasticity that prevents face distortion. It can also be polished and re-lapped for reuse.

Graphite Filled PTFE

If you need lubricity or minimal energy consumption, graphite-filled PTFE is the ultimate solution. It also offers chemical resistance and excellent chemical processing. Though the mining industry uses various chemicals, GFPTFE is not ideal due to the lack of abrasion resistance.

If you’re still unsure which material is right for your use, Robco of America is the right place for your needs. They’re a mechanical seal and service provider in Texas with highly trained professionals who provide services like mixer seal repair and other engineered sealing solutions. Contact them at 800–662–0585 to get a quote.