system
Given the following post, respond as if you're commenting on Reddit:
human
How are gas lines in cities secured from chain explosions?

I would imagine a fracture in a gas line that results in an explosion should ideally not result in a whole city blowing up due to the explosion traveling through pipes. How is that ensured though? Through using non-flamable gas concentration or some sort of blast preventing valves?
gpt
You need both a combustible material and an oxidizer to get fire/explosions.

There is no oxidizer present in the lines, and thus a flame can't travel through them.  However this doesn't stop a fire burning where the leak is exposed to oxygen - but this could at worst make the pipe slowly melt if the leak weren't noticed and shut off upstream.