The anti extrusion ring choice and the design

The choice of the anti-extrusion ring to rest alongside the O-Ring in a seal system, is driven from the coding system that Elastotech adopted for the cataloguing of the rings. Every anti-extrusion ring is identified by a prefix AAE which is then followed by a number which corresponds to that which identifies the dimensions of the O-Ring to which it must be associated.

Example
The anti-extrusion ring must be chosen to accompany an O-Ring with the following characteristics:

• cross section diameter ds = 5,33 mm
• internal diameter di = 50,17 mm
• O-Ring code 2-329
• O-Ring mix ME0070/70

This O-Ring must be associated with the following anti-extrusion ring:

• anti-extrusion ring code AAE-329
• anti-extrusion ring mix ME0073/90

Once the anti-extrusion ring to accompany the O-Ring has been chosen, it must then be set in the elements of the seal system, the eligible housing for both. The housing will have different measurements depending on if the O-Ring is to be protected by one or two anti-extrusion rings, the choice of which as we have seen is linked to the solicitation imposed by the system pressure. The housing which hold anti-extrusion rings present some characteristics which differentiate them from those destined to house only the O-Ring (see chapter 4).

The main differences are:

• the side walls of the housing must not be inclined to allow the anti-extrusion ring to remain in a ver tical position;
• the internal joint radius between the housing's walls and the base must be as small as possible.

In figure 6.5 and 6.6 the housings that hold one or two anti-extrusion rings respectively are shown, and as done previously in chapter 4 for the housings with only the O-Rings, we show the dimensional values (Table 6.1) and surface finishing (Table 6.2).
In Table 6.3 the standard dimensions of the rings are brought produced antiestrusione from Elastotech.