Gaskets usually stop liquids, often under pressure, from leaking out or getting in through the cracks between two mating parts. Here are 10 tips for ensuring the gaskets will indeed make the joint or connection leak-free:

1. Use a gasket material that conforms easily to flange surfaces. Such materials have a low required-seating stress. In general, the material should be impermeable and able to flow into joint imperfections when compressed. The materials should maintain their ability to seal despite aging and variations in temperature and pressure. The materials should also not deteriorate over time.

2. Be generous with the bolts. Most gasket materials leak less with high and well-distributed clamping forces. The clamping force must be at least enough to seat the gasket.

3. Use gasket materials with low material factors, thereby reducing the clamping force needed to hold the seal.

4. Lay the gasket as closely as possible to the inside of the bolts to help reduce flange distortion.

5. Eliminate radial flaws and scratches in the flange near the outer edge of the gasket. Under high pressures, only the outer portion of the gasket is clamped tightly enough to seal.

6. If flaws and scratches cannot be eliminated, fill them with a highly compressible gasket material.

7. Make the flanges as stiff as possible. The stiffer the flange, the less it tends to pivot about the bolt, and the less the gasket gets unloaded.

8. Use a gasket material with a low modulus of elasticity in recovery. A low modulus lets the gasket expand when bolts stretch and flanges distort.

9. If a fibrous gasket material is used, ensure the gasket is wide enough to seal all potential paths for leaks.

10. Be sure the flanges are clean. The dirt on flanges is usually made up of leachable solids and oxides. Leachable solids leave a void, and oxides are frangible porous solids. Both create leak paths.