Stainless application
Stainless Steel for Water Treatment
Water treatment is chloride chemistry by another name. Desalination moves hot, oxygenated, chloride-rich brine; municipal water is chlorinated; wastewater adds sulfides and microbes. The grade ladder is the same one seawater forces — 316L for fresh and lightly chlorinated water, 2205 and 2507 once the chloride and temperature climb.
Specification
What Water Treatment Specifies
| Grades normally used | 316L · 2205 · 2507 |
|---|---|
| Product forms | Pipe · Tube · Fittings · Flanges · Plate |
| Standards & approvals | ASTM A790 (duplex pipe) · ASTM A789 (tube) · ASTM A312 (pipe) · ASTM A182 (fittings) · NSF/ANSI 61 (drinking water) |
Grade by grade
What Each Grade Does in Water Treatment
A stainless application page that lists grades without saying what each one is for is a catalogue, not a specification. These are the roles they actually play here.
| Grade | The job it does here | Detail |
|---|---|---|
| 2507 | The grade for desalination brine lines, evaporator and high-pressure RO duty. PREN above 42 and high yield let it carry hot brine that pits 2205, and its strength cuts wall thickness on high-pressure reverse-osmosis pipe. | On request |
| 2205 | Where the water is chlorinated, brackish or warm. The duplex structure resists the chloride stress-corrosion cracking and pitting that attack 316L in the same service, at roughly twice the strength. | Specs → |
| 316L | The default for fresh, potable and lightly chlorinated water — pipe, fittings and treatment skids. The molybdenum handles the residual chlorine; it is the economical ceiling until the water turns brackish or hot. | Specs → |
Before you send the enquiry
Specification Mistakes That Cost Money Here
None of this is exotic. All of it arrives on real enquiries, and each one adds a round trip before a price can be issued.
1. Specifying 304 for a chlorinated or RO water line. Residual chlorine and concentrate attack 304; 316L is the floor for treated water, and 2205 or 2507 once the water is brackish or hot.
2. Ignoring the concentrate, not just the feed. Reverse-osmosis concentrate is far more aggressive than the feed water — the brine side, not the product side, is what decides the grade.
3. Welding duplex without restoring the phase balance. A 2205 or 2507 weld without a matching nitrogen-bearing filler loses corrosion resistance exactly where the water is most aggressive.
4. Leaving the drinking-water certification off the order. Potable service needs NSF/ANSI 61 or the equivalent listing; writing "stainless pipe" without it does not satisfy a drinking-water specification.
Categories that serve it
What We Supply Into Water Treatment
Stainless Steel Coil
Cold-rolled and hot-rolled coil in 200 / 300 / 400 series.
Stainless Steel Sheet & Plate
Cold-rolled sheet and hot-rolled plate for structural and decorative use.
Stainless Steel Tube & Pipe
Seamless and welded round, square and rectangular tube.
Stainless Steel Bar & Rod
Round, flat, square and hexagonal bar, cold drawn or hot rolled.
Verification
What We Put in Writing for This Application
- Mill test certificate to the class your file requires — 2.2 or 3.1 — carrying the actual composition and mechanical values for the heat, so the grade is checkable against the order.
- Surface finish and gauge recorded before packing; photos of the sealed container.
- Where the market requires it, the food-contact, 3-A or coating test report with the issuing body named.
Before you ask
Water Treatment — Questions That Come Up
When does water treatment need duplex instead of 316L?
When the water is brackish, hot, chlorinated, or the line carries desalination brine or RO concentrate. 316L is fine for fresh and lightly chlorinated water; once chlorides and temperature climb, 2205 and 2507 resist the pitting and stress-corrosion cracking that 316L cannot.
What grade for a reverse-osmosis brine line?
2205 as the baseline, 2507 where the brine is hot or the pressure high. The concentrate side is far more aggressive than the feed, so the brine chemistry — not the product water — sets the grade.
Does drinking-water stainless need a certification?
Yes. Potable-water components should be listed to NSF/ANSI 61 or the equivalent local standard. Name the listing on the enquiry; it changes the material traceability and the documentation that ships with the order.