Root Backing
Back purging is the supply of inert gas to the back side of the weld to prevent oxidation and metallurgical defects. This is especially important for corrosion-resistant steels and titanium materials.
Physical-Chemical Mechanism of Action
Inert gas such as helium or argon protects the weld from oxygen, preventing oxidation. This is especially important in the root zone, where the metal is under high pressure and temperature.
Metallurgical Relevance & Welding Risks
Without root protection, oxide films can form, affecting the strength and corrosion resistance of the weld. This can lead to cracks and distortion. This is especially dangerous in corrosion-resistant steels and titanium materials.
Workshop Practice & Action Guidelines
Use inert gas with a hose placed directly on the back side of the weld. Set the gas pressure so that a tight shielding layer is formed. For corrosion-resistant steels and titanium materials, strong root protection is essential.