The oxygen and acetylene are mixed into weld for different proportion and its result in different types of flames, each the flames are based on advantage and application. The correct composition of gas mixture and gas welding flames is important for gas welding process.
Neutral gas welding flames :
In this types of gas welding flames is provided the equal amount of oxygen and acetylene are mixed and to allow burn with above 3260⁰C. It has been two zones. The neutral frame is consisting of sharp cone extended from tip of torch and surrounded by envelope. This configuration the blue color by means of inner cone and it heat for melting. The cone envelope provides the combination of oxygen and small volume of acetylene from inner cone. It combination develop a cover for molten metal because of to avoid the oxidation process. It has been two zones. That combination no effect on the neutral flame in welding process, so that are desired to most of industrial application.
The neutral gas welding flames can be weld for following metals.
- Mild Steel
- Stainless steel
- Cast iron
In this flame is excess amount of oxygen supplied to the welding process. The ratio of oxygen and acetylene is 1.5:1. In this type of zone having two Zones.
It will be hotter than the neutral frame because of excess amount of oxygen combination to acetylene, So it provide mush amount of heat at temperature of 3482⁰C. Thus temperature is higher than flame, so it is used to easily heat the metal but excess amount of oxygen combine to base metal form of oxide. The oxide will reduce the weld joint strength. For this reason only possible for following metal to be welded.
- Zinc based alloy
- Cast iron
- Copper based alloy (Brass)
- Manganese steels
In this carburizing flame will be reduce the volume of oxygen and excess the acetylene volume. It contain three zone. They are
- Sharply define for inner cone
- Bluish outer envelope
- Intermediate whitish acetylene feather.
It outer envelope is longer than the neutral flame. The intermediate cone is excess amount of acetylene volume in the flame. It made temperature range of 3038⁰C. In this flame having not completely burnt in the excess acetylene. The unborn carbon is left on the molten metal. In this forms brittle substance called by iron carbide at weld joint. It only limited application only possible.
- Low alloy steel rod
The flame temperature is melting the base metal; it flows and fill the gap between the work piece. It base metal thickness will be low. The coalescence liquid is enough to fill the gap. If want to more thickness of base metal and additional metal (filler metal) required. The Base metal thickness may be as 1.5 mm, the combination of filler metal same or near same as base metal.