How does a “static” seal work?
A static seal is one used in an application that has no movement between mating surfaces, discounting such infinitesimal motion as may be caused by pressure and temperature variations, expansion and contraction, normal wear, and shock and vibration. Examples include seals for flanges, plugs, and tubing. If the static seal is an installation activated seal, the seal and its mating parts must be in contact at a pressure level greater that the pressure of the fluid to be sealed. This pressure level often is obtained mechanically. Other static seal installations are termed pressure-activated. Here the initial sealing pressure is quite low and is caused by the connecting squeeze of the joint. If that were the only pressure available, the seal would leak quickly. However, as system pressure increases, it deforms and reshapes the seal so that sealing pressure increases to withstand the greater containment requirements. O-rings, V-rings, and other shapes are typical examples.
