This document summarizes gas welding, specifically oxy-acetylene welding. It describes how oxy-acetylene welding uses oxygen and acetylene gases to produce a flame at the torch tip. The flame can be adjusted to be neutral, carburizing, or oxidizing depending on the metal being welded. Neutral flame is used for welding ferrous metals and aluminum. The equipment used includes oxygen and acetylene cylinders, regulators to control gas pressure, hoses to connect components, check valves, welding torches with mixing chambers, and welding tips.