EN 10253-2 Type B buttweld pipe fittings for chemical manufacturing — inorganic acids, organic acid processes, chloride-bearing chemical streams, alkali service, and mixed solvent environments. The chemical industry demands the widest material range: 316L for mild service through Hastelloy C-276 (PRE ~73) for the most aggressive reducing acid and mixed acid environments.
| Environment | Grade | W.Nr. | Note |
|---|---|---|---|
| Dilute NaOH / KOH (caustic) — ambient | 316L | 1.4404 | 316L adequate; Inconel 600 for hot concentrated caustic |
| Chloride-bearing process, ambient temp | 316L / Duplex 2205 | 1.4404 / 1.4462 | Grade by chloride concentration |
| Chloride process, elevated temperature | Super Duplex 2507 / 254 SMO | 1.4410 / 1.4547 | 254 SMO if above 250°C (duplex limit) |
| HCl (hydrochloric acid) — any concentration | Hastelloy C-276 | 2.4819 | No standard SS resists HCl; C-276 with 16% Mo is standard |
| H₂SO₄ reducing conditions / dilute | Hastelloy C-276 | 2.4819 | Reducing dilute H₂SO₄ attacks SS; C-276 resists broadly |
| HNO₃ (nitric acid) — oxidising | 304L / 316L | 1.4307 / 1.4404 | Oxidising nitric acid compatible with austenitic SS |
| HNO₃ + HF (mixed pickling acid) | Inconel 625 | 2.4856 | HF attacks all SS; 625 resists both acids simultaneously |
| Phosphoric acid — moderate temp | 316L / Duplex 2205 | 1.4404 / 1.4462 | H₃PO₄ compatible at moderate concentration and temperature |
| Phosphoric acid — high temp or conc. | Inconel 625 / C-276 | 2.4856 / 2.4819 | Hot concentrated H₃PO₄ requires Ni alloy |
| FGD scrubber (SO₂ + HCl wet gas) | Hastelloy C-276 | 2.4819 | Combined wet SO₂ + HCl attacks all SS and duplex |
Mild chloride, dilute alkali, many organic solvents, nitric acid service. UK/NL/Scandinavia/USA standard. Most widely specified SS in chemical plants.
Full grade page →Hot chloride processes above 250°C (where duplex is restricted), FGD, bleach, high-chloride scrubbing. Fully austenitic — no intermetallic ceiling.
Full grade page →Mixed acid service (HNO₃ + HF), aggressive chloride at temperature, phosphoric acid (hot/concentrated), chemical waste with mixed corrodants.
Full grade page →HCl at any concentration, reducing H₂SO₄, mixed acid + chloride, FGD absorber, chemical waste incineration scrubbing. Highest PRE of any commercial alloy.
Full grade page →Hot concentrated caustic (NaOH/KOH) where austenitic SS suffers caustic SCC. Alumina (Bayer process) caustic evaporators, high-temp dry gas chemical piping.
Full grade page →Equivalent to 316L for German, Austrian, Italian, and Central European chemical plant specifications. Same corrosion resistance — Ti stabilisation rather than low C.
Full grade page →EN 10204 3.1 standard. EN 10204 3.2 (TÜV) on request for critical service. PED 2014/68/EU and AD 2000-Merkblatt W0 compliant. Positive Material Identification (PMI) available. ATEX documentation on request.
