EN 10253-2 Type B buttweld pipe fittings for kraft pulp mills, bleach plants, chemical recovery, and paper machine wet-end piping. Material selection mapped by process area — from 316L in alkaline stages to Hastelloy C-276 in chlorine dioxide and hypochlorite bleaching circuits.
| Process Area | Fluid | Grade | W.Nr. | Reason |
|---|---|---|---|---|
| White liquor / kraft digester | NaOH + Na₂S alkaline | 316L | 1.4404 | Alkaline sulphide; austenitic SS standard |
| Brown stock washing | Dilute black liquor + water | 316L / Duplex 2205 | 1.4404 / 1.4462 | Mild chloride from process water |
| O₂ delignification | Alkaline pulp + O₂ + steam | Duplex 2205 | 1.4462 | Hot alkaline + oxidising — duplex preferred |
| D-stage (ClO₂ bleaching) | ClO₂ + chloride, 60–75°C | 254 SMO / 2507 | 1.4547 / 1.4410 | High oxidant + chloride at temperature — PRE ≥40 required |
| E-stage (caustic extraction) | Hot NaOH | 316L | 1.4404 | Alkaline, no significant chloride |
| Hypochlorite (NaOCl) stage | NaOCl + chloride | Hastelloy C-276 | 2.4819 | High-oxidant chlorine — C-276 standard |
| Recovery boiler (steam service) | High-pressure steam | P11 / P22 | 1.7335 / 1.7380 | High-temperature steam — PWHT required |
ECF D-stage bleaching, bleach plant filtrate. No 250°C sigma phase restriction. Used where hot ClO₂ + chloride exceeds duplex limits.
Full grade page →Hypochlorite stages, ClO₂ make-up piping, chlorine-bearing waste streams. Highest chloride + oxidant resistance.
Full grade page →Moderate-temperature ClO₂ stages, chloride-bearing bleach filtrate. High strength — cost saving at large diameters.
Full grade page →Alkaline stages (white liquor, caustic extraction, green liquor), brown stock washing, non-chloride process piping.
Full grade page →EN 10204 3.1 mill certificates standard. EN 10204 3.2 (TÜV) available for critical bleach plant fittings. PED 2014/68/EU compliant.
