The common standard in India is usage of Carcinogenic Asbestos Fiber (or CAF) based Gaskets. Ring Gaskets are also sometimes called as Slip-on Flanges and convenient and easy to replace. They are consumed in Sheets form or in pre cut rings form. However, please note, usage of Asbestos is against the health and Safety of your fellow employees and Company OHSAS Policy.
Asbestos is extremely dangerous and even in the bonded form still releases the dangerous fibers when Cut, Sawn, Grinded or removal of old & used Gaskets from the flange.