What is the use of insulating gasket?

The use of insulating gasket is to avoid electrical charge continuity and it is mostly used at above ground & U/G interphase to avoid cathodic protection. Very common in pipelines where insulating joint, which is very costly, may be avoided by using insulation gasket assembly This is also used extensively at dissimilar metal flanged joint wherein the difference of electronegativity of the 2 disimilar metal may lead to galvanic attack/corrosion.

Protect from mechanical damage & Climatic condition

Insulation kit Gaskets provides greater resistance to over compression and cracking. These insulation kits are also used to electrically isolate flange joints, preventing flow ofelectrostatic charges along the pipeline.For best results, the flanges must be wrapped with Flange Band Protectors. So foreign materials are prevented from collecting and creating a bridge, thus shorting out the isolation.

Insulating Gasket are used at transition joints from U/G to A/G

to protect flange from corrosion and also electrically  to isolate and prevent flowing  electrostatic charges .

Isolation gaskets (Flange Insulating Kit) are used to stop the current flow across metallic pipelines by separating two flanges. The isolation of these pipeline segments allows cathodic protection for underground and above ground pipelines to control the stray electric current flow

Use of dissimilar metallic flanges with a conductive gasket material assisted by a suitable electrolyte sets up a galvanic cell, corroding the anodic metal. It is here that the flange insulating kit gasket or insulation kit comes into use protecting pipeline flange corrosion. These insulation kits are also used to electrically isolate flange joints, preventing flow of electrostatic charges along the pipeline.

Insulation Kits are High-Integrity Flange Gaskets & Seals for Increased Pressure & Critical Service Applications. Flange Insulation Gasket Kits are designed for preventing electrical conductivity between the flanges.

Insulating gasket is used with Insulating Flange.

To break the spec ... In case 2 different material in one flange use insulation kit.