Gas welding / oxy-fuel
Oxy-fuel is one of the oldest welding processes where you use oxygen and acetylen gas combined. In recent decades it has been obsolesced in most all industrial uses due to various arc welding methods offering more consistent mechanical weld properties and faster application. Gas welding is still used for metal-based artwork and in smaller home based shops, as well as situations where accessing electricity (e.g., via an extension cord or portable generator) would present difficulties.
