~Insulation sets are often used in petrochemical applications electrically isolate two mating flanges to reduce the likelihood of creating a galvanic cell which would result in corrosion of the flanges and pipework. Insulation sets are also used to prevent the flow of electrostatic charge to reduce sparking in hazardous environments.
Insulation sets often comprise an insulating gasket and set of two insulation and two steel washers and one insulating sleeve per bolt.
Type “E” is a full-face gasket with same outside diameter as the flange and precision cut bolt holes
This design facilitates proper alignment of the gasket during installation.
This assembly minimizes the ingress of conductive foreign matter between the portions of the flanges outside the raise face and reduces the risk of bridging.
Type “F” gasket are made to fit the raise face portion of the flange only.
As there are no bolt holes in the “F” gasket, the outside diameter of the gasket fit tightly into place assuring a well centered position.
Standard Insulation Sets
Neoprene-faced phenolic resin gaskets are often used in class 150 and 300 applications and for use between -40 and 100°C and often comprise a central gasket and two reinforced phenolic, two steel washers and one Mylar sleeve per bolt. Being an old design Neoprene-face d insulation sets are often only used for low pressure applications with low installation stresses and can manufactured in two styles Type E (full face gasket) and Type F (inside bolt circle gasket).
 
The insulation washers can be replaced with stronger G10 items with improved compressive strength. The insulating sleeves can also be supplied manufactured from phenolic resin or high-temperature Nomex fibre.