It stands for:
Distance
Angle
Speed
Heat
Recommendations for Oxygen Acetylene Welding (OAW) are as follows:
Distance: the cone should always be 1/8" away from the base metal. Although heat is dependent on this distance, do not change distance in order to change heat.
Angle: the more perpendicular the torch to the base metal, the more heat will enter the base metal. Travel angle is the measured in a plane that includes the weld's longitudinal axis (direction of travel) while work angle is measured in the plane perpendicular to the weld's longitudinal axis. Travel angle is sometimes called "push angle" for forehand welding and "drag angle" for backhand welding.
Speed: consistent speed throughout the weld length is key. The slower the speed, the more heat enters the base metal. Too slow and burn through could occur. Too fast and fusion may not occur.
Heat: volume of heat depends on size of torch tip and amount of acetylene in the gas mixture.
