Tight and All Right: Using Polymer Seals

Most mechanical devices aren't composed of just a single piece; they're usually a well-organized assembly of various components that work in conjunction with each other to produce the desired effect. Naturally, these parts need to be joined securely lest the entire device fails to work or falls apart. However, linked parts, particularly those parts that aren't made to be permanently linked together, are sure to leak essential mechanical fluids without any form of sealing.

Sealing two parts together involves more than just covering up the seam. It often entails pressurizing the joint to guarantee absence of leakage without having to resort to welding both parts together. Seals made from polymer such as gaskets and o-rings are some of the more common sealing materials used for engines and such.

It's important for engines and other devices that experience high pressures and temperatures to have resilient polymer seals installed in vital areas. Temperature can warp or even outright destroy seals, and that's never good for an engine. Thankfully, modern seals are made from specially developed polymers that are very resistant to heat and even the cold. Operators of these machines should still be wary of the condition of their seals, and shouldn't hesitate to have their machinery examined if something doesn't feel right about it.

Source: http://www.ehow.com/how_7902518_shrink-rubber-seals.html