Cherepovets, Moscow Sheremetyevo, and Saint Petersburg Pulkovo are the top airports Severstal flies into and out of during the year.
Severstal does not have flights from Denpasar Bali Ngurah Rai at the moment. There are scheduled flights with Severstal out of Ekaterinburg though (if you don’t mind flying from this airport). Flying with Pobeda is recommended if you still want to fly from Denpasar Bali Ngurah Rai.