The combination of Oxygen and Acetylene is another option, when it comes to the welding world. If you look, these torches have to pipelines coming to the tip. Each has its own valve and tank to regulate pressure and amount of each gas. When the two come together and are sparked, this creates an extremely hot-burning flame. This gets the metal close to its melting point. Then, a second stream of oxygen is pumped in, oxidizing the spot, and essentailly cutting through the metal.