Chapter 32, Problem 1R

What protects the molten weld pool from oxidation during a gas weld?

To determine

The protection mechanism of molten weld pool from oxidation during a gas weld.

Answer to Problem 1R

The carbon dioxide produced by the reaction of carbon mono-oxide and atmospheric air protects the molten weld pool.

Explanation of Solution

The gas welding process is defined as the welding process in which a mixture of fuel gas and oxygen is burned to produce the flame. This flame is used to provide the heating effect to melt the metal to be welded. The fuel gas used is generally acetylene.

In oxy-acetylene gas welding, a torch is used to prepare a proportionate mixture of oxygen and acetylene coming out of different cylinders. The torch prepares the mixture and burned so that a flame is produced.

The atmospheric air is the culprit which oxidizes the molten weld pool, the outer portion of the flame protects the molten weld pool from the atmospheric air. The carbon mono oxide (CO) present in the outer flame combines with the atmospheric air to produce the carbon dioxide which acts as the inert gas and creates an envelope to protect the molten weld pool.

This carbon dioxide also forces the surrounding atmospheric air away from the weld.

Conclusion:

Thus, carbon dioxide produced by the reaction of carbon mono-oxide and atmospheric air protects the molten weld pool.