Corrosion-resistant buttweld fittings for acids, solvents, chlorinated compounds, caustic, and mixed chemical environments. 316L to Hastelloy C-276 — the right alloy for every chemical service. EN 10253 Type B with PED certification for EU plants.
Request Chemical Plant Fittings Quote| Chemical / Service | Concentration | Recommended Material | EN W.Nr. | Notes |
|---|---|---|---|---|
| Hydrochloric acid (HCl) | Dilute to moderate | Hastelloy C-276 | 2.4819 | Avoid all stainless and duplex grades for HCl |
| Hydrochloric acid (HCl) | Hot / concentrated | Hastelloy B-3 (Ni-Mo) | 2.4600 | Reducing conditions only — B-3 fails if oxidising species (Fe³⁺, Cu²⁺, air) are present |
| Sulphuric acid (H₂SO₄) | Dilute <10% | 904L or Hastelloy C-276 | 1.4539 / 2.4819 | Temperature-dependent — consult |
| Sulphuric acid (H₂SO₄) | 10–80% | Hastelloy C-276 | 2.4819 | Most reliable across this range |
| Sulphuric acid (H₂SO₄) | >96% ambient | Carbon steel (passivation layer) | 1.0345 | Concentrated cold H₂SO₄ passivates CS |
| Nitric acid (HNO₃) | Dilute to concentrated (oxidising) | 304L / 316L; Hastelloy C-22 for contaminated or mixed streams | 1.4307 / 1.4404 / 2.4602 | Oxidising HNO₃ suits low-carbon austenitic SS; C-276 is a poor choice in strongly oxidising nitric acid |
| Phosphoric acid (H₃PO₄) | Moderate concentration and temperature | 316L / Duplex 2205 | 1.4404 / 1.4462 | Check chloride and fluoride impurities in wet-process acid |
| Phosphoric acid (H₃PO₄) | Hot or concentrated | 904L, Incoloy 825, Inconel 625 or Hastelloy C-276 | 1.4539 / 2.4858 / 2.4856 / 2.4819 | Selection depends on impurities and temperature |
| Caustic / NaOH, KOH | Dilute, moderate temperature | 304L / 316L | 1.4307 / 1.4404 | Avoid copper alloys; aluminium and zinc are attacked |
| Caustic / NaOH, KOH | Hot, concentrated | Inconel 600 or nickel 200/201 | 2.4816 | Austenitic and duplex SS are at risk of caustic SCC in hot concentrated caustic |
| Chloride-bearing process streams | Ambient temperature | 316L / Duplex 2205 | 1.4404 / 1.4462 | Grade by chloride level, pH and temperature |
| Chloride-bearing process streams | Elevated temperature | Super Duplex 2507 / 254 SMO | 1.4410 / 1.4547 | Duplex grades have a lower maximum service temperature than fully austenitic 254 SMO |
| Chlorinated solvents | — | 316L | 1.4404 | Check temperature — SCC risk above 60°C |
| Mixed acids (HNO₃ + HF) | — | Hastelloy C-22 or Inconel 625 | 2.4602 / 2.4856 | HF attacks stainless steels; choice depends on HF content and temperature |
| FGD scrubber / wet SO₂ + HCl gas | — | Hastelloy C-276 or C-22 | 2.4819 / 2.4602 | Acid condensate with chlorides; 254 SMO or super duplex only in milder zones |
| Acetic acid / organic acids | All conc. | 316L or 316Ti | 1.4404 / 1.4571 | 316L widely specified for organic acid plants |
| Chlorine / hypochlorite | — | 254 SMO or Hastelloy C-276 | 1.4547 / 2.4819 | SS grades must have PRE >40 for Cl₂ service |
| Ammonia (NH₃) | All concentrations | 316L or Carbon Steel | 1.4404 / 1.0345 | Avoid copper alloys — ammonia causes SCC in Cu |
Material selection is concentration- and temperature-dependent. This table provides general guidance — consult a corrosion engineer for definitive selection on safety-critical systems.
HCl (all conc.), H₂SO₄ (10–80%), seawater, FGD. Best single-alloy choice for mixed aggressive chemical service. Limitation: HNO₃ >50%.
Higher Cr — better oxidising acid resistance (HNO₃, hot H₂SO₄). Pharmaceutical API and pesticide synthesis. Mixed oxidising/reducing environments.
Universal chemical plant stainless — organic acids, acetic acid, caustic, mild acid service. Dominant EU specification. EN 10253-4 Type B available.
German chemical plant standard. Ti-stabilised — resists sensitisation to 550°C. Preferred over 316L in Germany for welded chemical plant applications.
25Ni-20Cr-4.5Mo-Cu. Exceptional H₂SO₄ and H₃PO₄ resistance. Pulp & paper bleach plants, phosphoric acid, sulphuric acid dilute streams. PRE ~33.
6% Mo super-austenitic. PRE ≥43. Chlorine, hypochlorite, bleach, seawater cooling. Step above duplex for pitting resistance without going to nickel alloy.
About 9% Mo, Nb-stabilised. Mixed acid service (HNO₃ + HF), aggressive chlorides at temperature, hot or concentrated phosphoric acid, chemical waste streams with mixed corrodants.
High-nickel alloy for hot concentrated caustic (NaOH / KOH), where austenitic stainless steel risks caustic SCC — caustic evaporators and alumina (Bayer process) caustic lines.
EN 10204 3.1 certificates as standard; EN 10204 3.2 with third-party inspection on request for critical service. PED 2014/68/EU and AD 2000-Merkblatt W0 documentation for EU plants. Positive Material Identification (PMI) available. Fittings are manufactured at our group manufacturing facility, which holds ISO, PED (TÜV), AD 2000, IBR and ASME approvals.
Hydrochloric acid (HCl) needs molybdenum-rich nickel alloys. Hastelloy C-276 (EN 2.4819, UNS N10276) is the usual choice for dilute and moderate HCl and for HCl contaminated with oxidising species. For hot, concentrated, purely reducing HCl, a nickel-molybdenum B-type alloy such as Hastelloy B-3 (2.4600) is used — but only where no oxidising contaminants (ferric or cupric ions, dissolved air) are present. Stainless steels (304L, 316L) and duplex grades are not suitable for HCl service: even low HCl concentrations cause rapid pitting and crevice corrosion.
Sulphuric acid material selection depends heavily on concentration and temperature. Dilute H₂SO₄ (<10%): 904L (1.4539) or Hastelloy C-276 (2.4819). Intermediate concentrations (10–80%): Hastelloy C-276 provides the most reliable corrosion resistance. Concentrated H₂SO₄ (>96%) at ambient temperature: carbon steel (a passive iron sulphate film forms). Hot concentrated H₂SO₄ (acid plant absorption towers): specialist high-silicon alloys. Hastelloy C-276 is the most reliable single alloy across the widest H₂SO₄ range.
Yes. For EU chemical plants regulated under PED 2014/68/EU, we supply EN 10253-2 (carbon and alloy steel) and EN 10253-4 (stainless steel) fittings in Type A and Type B. EN 10204 3.1 certificates are standard. EN 10204 3.2 certificates witnessed by TUV Rheinland or Lloyd's Register are available on request. Specify PED category, design pressure, temperature, fitting type and required TPI in your RFQ. Your pressure-equipment designer chooses Type A or Type B; the PED category does not fix the type.
304L and 316L are suitable for dilute caustic at moderate temperature. In hot, concentrated NaOH or KOH, austenitic and duplex stainless steels are at risk of caustic stress corrosion cracking, so high-nickel materials such as Inconel 600 (2.4816) or nickel 200/201 are specified. Carbon steel caustic lines need stress relief (PWHT) of welds above the temperature limits set by the plant's caustic service chart.
EN 10253 does not cover nickel alloys. Wrought nickel-alloy buttweld fittings are supplied to ASTM B366 (WPHC276, WPNCMC and similar grades) with dimensions to ASME B16.9, and with EN 10204 3.1 certificates. For PED projects the material route (for example a particular material appraisal) is agreed with the purchaser and the notified body.
