Which process would require careful control of atmospheric conditions to avoid oxidation?

Gas welding is a process that involves the melting of metals using a flame produced by burning a fuel gas, typically acetylene, in conjunction with oxygen. During this process, it is crucial to control atmospheric conditions to prevent oxidation of the molten metal. Oxidation can lead to contamination and weaken the joint being welded, potentially resulting in structural failures.

In gas welding, if the environment is not adequately controlled, oxygen can react with the molten metal, forming oxides that compromise the integrity of the weld. This is particularly important when working with metals that have a propensity for oxidation, such as aluminum, where the presence of oxygen can severely affect the quality of the weld.

While other processes like vacuum forming, blow moulding, and rotational moulding do involve concerns with temperature and material properties, they are typically less sensitive to atmospheric oxidation than gas welding, making proper control of the atmosphere more crucial in welding applications.