The fuel gas ring main in benzene production is a looped piping system that distributes fuel gas to heaters efficiently. It ensures that the gas can be supplied from two directions, maintaining consistent pressure and flow to multiple burners. This design prevents the activation of one burner from impacting the performance of others, thus optimizing the heating process. The concept is similar to other ring mains used for water or electricity, where redundancy is built in to support various loads. Understanding this system is crucial for effective benzene production from toluene.