What is the Difference Between Asbestos and Non-Asbestos Gaskets
One gasket type contains asbestos as a reinforcing fiber while the other does not. As a reinforcing fiber, asbestos is strong, can withstand high temperatures and chemical attack, and is relatively cheap
compared to many other materials. The physical properties that make asbestos an excellent gasket fiber also make it a hazardous substance to work with.
Asbestos fibers are long, thin and extremely small. Exposed fibers easily shred into thin needle-like strands that can drift in the air and be inhaled. The fibers lodge deep in the lungs where their sharp needle-like presence becomes a source of constant irritation. Over time, the accumulation of asbestos fibers can lead to a variety of lung ailments, including cancer.
Because of that, the government has tried to ban asbestos. A court ruling has put the proposed ban on temporary hold. Even so, all domestic gasket manufacturers are now using non-asbestos materials in their U.S. gasket plants. Asbestos is still being used by offshore manufacturers and is still found in many import applications.
The asbestos hazard is only a concern to those who work in the asbestos handling and processing industries, including companies that supply gasket manufacturers with rolls of gasket facing material and paper.
Once fibers are encapsulated in the filler material used to make gaskets, they cannot escape and pose no significant health hazard to those who work in gasket manufacturing plants, the distribution system, or installers.
Most domestic gasket manufacturers today use a proprietary mix of non-asbestos reinforcing fibers to produce gaskets equal to or better than asbestos gaskets they used to make. One type of fiber being used is aramid fiber (Kevlar), which is two to nine times stronger than asbestos.
Kevlar lacks the temperature resistance of asbestos and cannot be used on exhaust manifolds or certain head gasket applications. Kevlar also costs a lot more than asbestos. The amount of Kevlar typically used in an asbestos-free gasket material is usually no more than 10%.
Expanded graphite is another material being used in place of asbestos. Graphite is an excellent conductor of heat and can easily handle temperatures as high as 1,800 degrees F. It is ideal for high heat applications such as exhaust manifolds and head gaskets in diesel and high output engines. Graphite is also a natural lubricant, making it well suited to engines with cast iron blocks and aluminum heads. Like Kevlar, graphite is expensive.
