Here’s a fun fact: A majority of the heat needed to cut steel while using an oxy-acetylene cutting torch is generated from the oxidation of the steel. To make a cut using a cutting torch, you first apply heat to the steel until it reaches its kindling temperature and then a stream of oxygen is trained on the steel that literally burns the steel and blows the steel oxide out of the kerf. The oxy-acetylene reaction is not intended to melt the steel but rather bring it to the kindling temperature, which occurs at around 1600˚F for mild steel. The stream of oxygen starts a series of chemical oxidation reactions that are highly exothermic. The exothermic reactions generate enough heat that you can stop the flow of acetylene fuel during a cut and keep cutting. Need proof? Check out the video I just made. I cut the flow of acetylene shortly after starting the cut and I think if I was better at using the torch I could probably keep the cut going longer.