Why TIG welding is non-negotiable for food and medical stainless components
In food processing, pharmaceutical manufacturing, and medical device production, a weld must be more than strong — it must be perfectly clean. A standard MIG weld on stainless steel leaves behind rough surfaces, porosity, and micro-crevices — all of which harbor bacteria and cannot be fully sanitized.
TIG welding (GTAW — Gas Tungsten Arc Welding) is the only method that meets these stringent requirements because:
Precise heat control — the non-consumable tungsten electrode produces a stable arc, giving the welder full control over heat input. The result: uniform, spatter-free welds with no slag inclusions.
Full argon shielding — 99.99% argon gas blankets the weld zone, preventing oxygen from reaching the molten stainless steel. Without argon, the chromium in stainless steel combines with oxygen to form black oxide scale (known as “sugaring”) — this layer is brittle, flakes off, and causes localized corrosion.
Argon back-purge — this is the critical factor for tube and enclosed-box components. When welding stainless tubes, the interior surface exposed to air will oxidize heavily without protection. Back-purging floods the inside with argon, ensuring both sides of the weld are clean, bright, and oxide-free.
In short: TIG welding with argon back-purge is the mandatory standard for any stainless steel component that contacts food, pharmaceuticals, or operates in a cleanroom environment.
Our TIG welding capabilities
Our workshop in Thu Dau Mot, Binh Duong is equipped with dedicated TIG welding systems for stainless steel and aluminum:
Equipment specifications
| Parameter | Details |
|---|---|
| Method | TIG (GTAW) — DC for stainless steel, AC for aluminum |
| Pulse mode | Yes — reduces heat input, minimizes warping on thin sheets |
| Shielding gas | 99.99% argon (front shielding + back-purge) |
| Current range | 5A – 300A |
Materials and thickness range
| Material | Weldable thickness | Filler rod |
|---|---|---|
| 304 stainless (SUS304) | 0.8 – 6mm | ER308L |
| 316 stainless (SUS316) | 0.8 – 6mm | ER316L |
| 430 stainless | 1 – 4mm | ER309L |
| Aluminum 5052/6061 | 1 – 4mm | ER5356 |
| Cast aluminum/ADC12 | 1 – 4mm | ER4043 |
Important note: Filler rods must match the base material grade. Using ER308L for 304 stainless, ER316L for 316 — incorrect filler selection causes intergranular corrosion, which is particularly dangerous in chemical and food environments.
Pulse TIG for thin sheet
For stainless steel at 0.8–1.5mm thickness, we use pulse mode to:
- Reduce average heat input by 30–40%, minimizing warpage
- Achieve better weld pool control on thin materials
- Produce evenly spaced “fish-scale” bead patterns with high aesthetic quality
- Weld thin materials without burn-through or distortion
Food-grade welding standards
Stainless components that contact food must comply with hygienic design principles per EHEDG (European Hygienic Engineering & Design Group):
Weld requirements
| Criterion | Requirement | Reason |
|---|---|---|
| Weld surface | Smooth, flush with base metal | Crevices and ridges harbor bacteria |
| Interior (back weld) | No oxide, no protrusions | CIP cleaning cannot reach interior obstructions |
| Surface roughness | Ra ≤ 0.8 μm (after polishing) | Surfaces rougher than 0.8μm retain microorganisms |
| Crevices | Not permitted | Bacteria grow in crevices despite cleaning |
| Internal corners | Radius ≥ 3mm | Sharp 90-degree corners cannot be cleaned |
Post-weld passivation process
Even clean TIG welds destroy the natural chromium oxide layer (passive layer) on the stainless surface surrounding the weld. Passivation is a mandatory step to restore this protective film:
- Mechanical cleaning — remove discoloration and heat tint around the weld
- Acid pickling — HNO₃ + HF solution removes the chromium-depleted oxide layer
- Passivation — immersion in nitric acid (HNO₃ 20–30%) at 50 degrees C for 30–60 minutes
- Rinsing — deionized (DI) water rinse, then drying
After passivation, the stainless surface reforms a Cr₂O₃ layer of 2–3nm thickness, providing superior corrosion resistance compared to the pre-weld condition.
Medical and pharmaceutical requirements
Medical and pharmaceutical components have requirements beyond food-grade:
Material traceability
- EN 10204 Type 3.1 material certificates — confirming chemical composition and mechanical properties from the steel manufacturer, signed by an independent inspection body
- Heat number traceability — every stainless sheet traceable to its specific production melt
- Weld documentation (WPS/PQR) — qualified welding procedures for each critical weld joint
Advanced surface treatment
| Method | Achievable roughness | Application |
|---|---|---|
| Mechanical polish (grit 240) | Ra ≤ 0.8 μm | Standard food processing |
| Fine polish (grit 400) | Ra ≤ 0.4 μm | Pharmaceutical, dairy |
| Electropolish | Ra ≤ 0.25 μm | Cleanroom, medical devices |
Electropolishing is the gold standard for pharmaceutical equipment — it does not just reduce roughness but also eliminates micro-pits, creating an ultra-smooth surface that bacteria cannot adhere to. We provide electropolishing through a specialized partner facility.
Common component examples
Food and beverage industry
- Chutes — product guide chutes on production lines, TIG welded with fully smooth interior surfaces
- Hoppers — feed hoppers in 304 stainless, corner radii ≥ 3mm, zero crevices
- Conveyor guides — stainless guide rails in 1.5–3mm sheet, continuous welds with no interruptions
- Mixing vessel parts — flanges, nozzles, impeller blades — all TIG welded with back-purge
- Processing table frames — 304 stainless square/rectangular tube frames, watertight corner welds
Medical and pharmaceutical industry
- Instrument trays — 316L stainless, TIG welded then electropolished, used in operating rooms
- Cleanroom brackets — 304/316L stainless, grit 400+ surface finish, zero burrs
- Pharma tank fittings — nozzles, valves, flanges for pharmaceutical vessels, orbital or manual TIG with back-purge
- Lab equipment frames — precision stainless structures for analyzers, centrifuges
Chemical industry
- Control cabinet enclosures — 316L stainless for chemical corrosion resistance, sealed to IP65
- Pipe supports — pipe clamps, U-bolts, saddle clamps in 316 stainless
Integrated process: Cut — Bend — Weld — Passivate — Polish
The greatest advantage of fabricating at Tuan Thinh is our single-workshop, end-to-end process:
| Step | Process | Capability |
|---|---|---|
| 1 | Fiber laser cutting | Stainless 0.5–20mm, tolerance ±0.1mm |
| 2 | CNC press brake bending | 30-ton capacity, 1000mm bending length |
| 3 | TIG welding | Argon back-purge, pulse mode |
| 4 | Passivation | Nitric acid immersion per ASTM A967 |
| 5 | Polishing | Mechanical (grit 240–400) or electropolish |
Why does a single-workshop process matter?
- Shorter lead times — no waiting for transfers between separate shops
- End-to-end quality control — the same team oversees every step from cutting to polishing
- Full traceability — each part tracked from raw sheet to finished component
- Reduced contamination risk — stainless steel is never transported between multiple workshops, avoiding contact with carbon steel (which causes surface rust)
TIG welding pricing reference
TIG welding is priced per centimeter of weld (cm), depending on material and thickness:
| Material | Thickness | Reference price (VND/cm of weld) |
|---|---|---|
| 304 stainless | 0.8–1.5mm | 3,000 – 5,000 |
| 304 stainless | 2–3mm | 4,000 – 7,000 |
| 304 stainless | 4–6mm | 6,000 – 10,000 |
| 316L stainless | 0.8–1.5mm | 4,000 – 6,000 |
| 316L stainless | 2–3mm | 5,000 – 8,000 |
| 316L stainless | 4–6mm | 7,000 – 12,000 |
| Aluminum 5052/6061 | 1–2mm | 5,000 – 8,000 |
| Aluminum 5052/6061 | 3–4mm | 7,000 – 11,000 |
Add-on services
| Service | Reference price |
|---|---|
| Argon back-purge (tube/enclosed box) | +30–50% over standard welding price |
| Nitric acid passivation | 50,000 – 200,000 VND/part |
| Mechanical polish grit 240 | 30,000 – 100,000 VND/part |
| Fine polish grit 400 | 50,000 – 150,000 VND/part |
| Electropolish | Quoted per part based on size |
Prices are for reference only. Send your drawings for an accurate quote on your specific components.
Binh Duong — Southern Vietnam’s food and pharma manufacturing hub
Binh Duong is one of Vietnam’s most dynamic industrial provinces, particularly in food processing and pharmaceutical manufacturing:
- VSIP I & II — home to numerous international food and beverage manufacturers requiring a continuous supply of food-grade stainless components
- My Phuoc Industrial Zones 1, 2, 3 — pharmaceutical and chemical cluster with high demand for corrosion-resistant 316L stainless
- Dong An Industrial Zone — medical devices and electronics, requiring precision stainless components with clean finishes
- Nam Tan Uyen, Bau Bang Industrial Zones — food and agricultural processing, needing production line equipment and stainless accessories
Our workshop in Thu Dau Mot is centrally located, within 15–30 minutes of all these industrial zones. Same-day delivery is available for urgent orders within Binh Duong, Thu Duc, Di An, and Thuan An.
Order TIG-welded stainless components from Tuan Thinh
We fabricate TIG-welded stainless steel components for food, medical, pharmaceutical, and industrial applications with:
- TIG argon back-purge welding for clean, oxide-free joints
- 304, 316L, and 430 stainless from 0.8mm to 6mm
- Passivation and surface polishing to your specifications
- EN 10204 3.1 material certificates when required
Send your drawings via Zalo or email for a quote within hours.
Learn more about our welding services or request a quote now.