Don't Blow A Gasket!
Don't blow a gasket! Who hasn't heard this old adage at some time? What does it actually mean, and for that matter, what is a gasket? Gaskets are simple structures used to fill in and seal the spaces where two surfaces meet, usually to prevent the leakage of a material under pressure. A good example is the interfacing of two machined flat surfaces, as occurs with various gasoline or diesel engine parts. The proper and continued functioning of an automobile engine, and most other machinery, requires that no fluids leak in or out in an uncontrolled manner. To prevent such leaks, the various machined surfaces must have all gaps and spaces between them perfectly filled and sealed. Machined surfaces, although quite smooth, contain numerous small imperfections and may not be true from one end to the other.
When two such surfaces are brought together, it is generally true that they cannot form a tight seal against each other without being placed under undue or excessive stress when the bolts are tightened to join the two pieces. It is entirely possible to machine surfaces of parts so that a nearly perfect surface match between them is achieved, but this is a very expensive proposition, and does not work well in the context of any fast-paced high-production industry. To reduce machine operations and the associated costs, gaskets are commonly used to mate flat surfaces.
A gasket is a thin layer of material that readily conforms to the surface of the material around it, and ideally does not interact with the fluids that it must contain. The shape of the gasket matches the shape of the two surfaces that it joins. The gasket material deforms under the applied pressure to fill in the tiny imperfections and compensate for any lack of trueness in the machined surfaces. This ensures that fluids passing from one part to another do not leak out into the environment. Generally the more pressure that can be safely applied to a gasket, the better it serves.'To blow a gasket' means that it has failed during operation and allowed pressurized fluids to blow out of the machine. A fluid leak can result, with fluid 'blowing out' under pressure, and the effects can range from a relatively innocuous but noisy exhaust gas leak to a severely damaging internal coolant or oil leak.
