AL-6XN Tubes and Fittings
AL-6XN® Tube, UNS N08367
AL-6XN welding recommendations
Super Alloys™ range: tubes and fittings for corrosive fluids in hygienic environments.
The AL-6XN range is designed for fluids where 316L reaches its limits: high-chloride water, acidic condensates, brines, aggressive pharmaceutical processes and ultra-pure fluids in the presence of halogens.
It is used in biopharmaceuticals, high-acidity food processing, and chemicals.
Surface finishes and hygienic classes
| Finish | ASME BPE code | Internal Ra | External Ra |
| Mechanically polished | SF1 | ≤ 0.51 µm (20 µin) | ≤ 0.81 µm |
| Electropolished | SF5 | ≤ 0.51 µm (20 µin) | ≤ 0.81 µm |
| Standard mechanical polish | — | ≤ 0.81 µm (32 µin) | ≤ 0.81 µm |
Compliant with ASME BPE for codes SF1 and SF5.
Material
AL-6XN® super-austenitic alloy (UNS N08367, EN 1.4529 equivalent).
Typical composition: Cr: 20 – 22 % | Ni: 23.5 – 25.5 % | Mo: 6 – 7 % | N: 0.18 – 0.25 % | C: ≤ 0.01 % |
PREN = 45 versus 24 for 316L.
Very good resistance to chloride stress corrosion cracking.
Fully austenitic, non-magnetic microstructure.
Weldability
Controlled weldability under inert gas.
During fusion, molybdenum segregates and the weld root becomes the weak point for corrosion. This is offset by using a filler metal with a higher molybdenum content than the tube itself: ISO Ni Cr 22 Mo 9 Nb (ERNiCrMo-3) or ISO Ni Cr 25 Mo 16.
Heat input must remain limited to prevent precipitation of embrittling intermetallic phases between 600 and 1000 °C.
In multi-pass welding, the interpass temperature must drop below 100 °C before starting the next pass, checked with a temperature-indicating crayon or pyrometer.
Purge gas is maintained throughout cooling to prevent internal oxidation of the weld
Dimensional standards
Diameters from 1/2″ (12.7 mm) to 4″ (101.6 mm), wall thicknesses 1.65 mm to 2.11 mm.
Welded tubes compliant with ASTM A270, ASME SA249 and ASME SB676.
Traceability and packaging
Each tube is supplied with its 3.1 material certificate according to EN 10204.
Full-length marking on the OD: grade, heat number, batch, dimensions.
Polished and electropolished tubes are supplied in individual polyethylene sleeves with capped ends.
Lengths from 2 m.
Contact us directly for any enquiry.