Profile seals – sealing solutions for particularly high temperatures and pressures
The thickness of seals and the seal material depend primarily on the usage conditions and the flange faces. The better the flange faces are with respect to surface quality and evenness, the thinner the seal can be. In this context, it is necessary to bear in mind that soft metals such as aluminium or copper require much lower surface pressures than harder materials such as steel.
The absolute level of the sealing forces can be reduced by using narrower seals. The use of profile seals instead of flat seals makes this possible.
Advantages of profile seals
In conventional flat seals, a slight twisting of the flange face can lead to sealing problems. The sealing diameter assumed in the centre of the sealing surface jumps to the dimension of the outer diameter due to the contact pressure. The lever arm ratio is unfavourably influenced by this. In addition, the now greater internal compressive force has a negative effect.
In the case of profile seals such as convex or round seals, a line contact sets in at first. The initially small contact area only expands once the tightening force is increased. This is why the screw forces are much lower than for flat seals. The resulting contact geometry has a self-sealing effect with high internal pressures. The sealing diameter is preserved and edge pressure is avoided.
However, it is necessary to bear in mind that narrow seals flow as a result of too high a tightening force and insufficient stability and can therefore cause a leak.
Similar sealing properties are demonstrated by the diamond seal, in which the edge can lead to the flange faces being damaged. The material of this profile seal should always be less hard than the flange material.