Most data centre coolant loops are well served by 316L stainless steel. Where coolant chemistry, water quality or a 20-year-plus design life push harder — high chlorides, aggressive biocide regimes, heat-reuse circuits with elevated temperatures — Neumo’s special alloy range steps up: 904L, AL-6XN and Hastelloy C22 tube from ½” to 4″, certified to EN 10204 3.1.
Choosing the right grade
| Grade | When to specify it |
|---|---|
| 304 / 1.4301 | Benign treated-water and glycol loops, cost-optimised FWS duty |
| 316L / 1.4404 | The default for TCS loops — added molybdenum for chloride and inhibitor-package tolerance |
| 904L | Elevated chlorides or acidic excursions in makeup water |
| AL-6XN / Ultra 6XN | Superaustenitic performance approaching nickel alloys at lower cost |
| Hastelloy C22 | The most demanding chemistries — rarely needed in cooling, available when it is |
Corrosion in a coolant loop isn’t just a leak risk: dissolved metal ions consume inhibitors, discolour coolant and end up in cold-plate microchannels. Matching alloy to chemistry at design stage costs little; requalifying a live loop costs a lot. More on grade selection: 304 vs 316L for coolant loops.
Range details
Special alloy tube ½” – 6” SF1/SF4, complying with ASME BPE A270 and other ASME equivalents MTRs to EN 10204 3.1. Matching hygienic fittings available across most of the range.
Frequently asked questions
Is 304 ever wrong for a coolant loop?
It’s fine for benign duty, but many end-client standards simply mandate 316L for TCS (Technology System Cooling) — check the basis of design before value-engineering the grade.
Do glycol coolants attack stainless?
No — propylene glycol itself is benign; it’s the water quality, chlorides and additive package that drive grade selection.
Can you advise on grade selection?
Send us the coolant spec and water analysis and we’ll recommend against it.
Talk to us about your project
Kevin Windsor — Product Manager, Data Centre Liquid Cooling
kw@neumo.co.uk · 01952 583 999