Backing gas protects the root pass back side from atmospheric contamination, essential for critical applications where root pass quality affects structural integrity. FORMIER® N5 provides optimal protection through nitrogen shielding with hydrogen cleaning action for bright, clean root beads.
Backing Gas Techniques: Root Pass Protection and Setup
Essential Backing Gas Setup
- Gas Selection. Use FORMIER® N5 for stainless steel, pure argon for aluminum, nitrogen for carbon steel non-critical applications.
- Flow Rate Control. Set 5-8 L/min through backing strip or purge blocks. Higher flows waste gas without improved protection.
- Purge Timing. Start flow 30 seconds before welding, continue 30 seconds after arc extinction for complete protection.
Root Protection
FORMIER® N5 (95% N2 + 5% H2)
Premium Backing GasWhy FORMIER® N5 superior for backing: Nitrogen prevents oxidation while hydrogen provides reducing atmosphere that cleans the root bead, essential for stainless steel and critical carbon steel applications.