Stainless steel rules the food, pharma, chemical and naval industries. But welding it demands far more than carbon steel: absolute cleanliness, controlled interpass temperature and the right process. Every mistake is billed back in rework.
Which process to choose
- 141 (TIG) — the reference for stainless on food and pharma piping and any sanitary finish: clean bead, low heat input.
- 135/136 (MIG/MAG) — for stainless structures and tanks where speed offsets a rougher finish.
- 111 (stick) — for repairs and spots where TIG is not viable, but it needs a well-seasoned welder.
The defects that reject batches most
- Intergranular corrosion — if the joint lingers between 450 and 850 °C, chromium carbides precipitate and corrosion resistance is lost. Fix: control interpass temperature (typically 150 °C max) and use low-carbon grades (304L, 316L).
- Root oxidation — brown or bluish stains inside the pipe. Fix: argon backing gas on the reverse of the joint.
- Carbon-steel contamination — brushing stainless with carbon tools causes localized corrosion. Fix: brushes and grinders reserved for stainless only.
- Hot cracking — low delta ferrite in the bead. Fix: the right filler (ER308L for 304, ER316L for 316).
The discipline before striking an arc
- Degrease the joint with solvent.
- Use brushes and grinders exclusive to stainless.
- Pick compatible filler (rule: one carbon grade lower, or "L", versus the base).
- Set the shielding: pure argon for TIG, argon-CO₂ mix for MIG.
Why the specialist pays off
A UNE-EN ISO 9606-141 welder experienced in food-grade stainless is a scarce, well-paid profile. The project that saves with generic labor ends up redoing joints — far dearer than the right welder from day one.
Iron Pulse mobilizes UNE-EN ISO 9606 welders qualified on stainless. Meet our welders or talk to the team.
