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EN 10253 Type B Specialists
ASTM B366 Alloy 825 · NiCr21Mo PRE ~32 · NACE MR0175

2.4858 (Alloy 825) Pipe Fittings

ASTM B366 buttweld pipe fittings in 2.4858 — Alloy 825 / Incoloy 825 (NiCr21Mo, N08825). A nickel-iron-chromium alloy with molybdenum, copper, and titanium additions. PRE ~32. The high nickel content (38–46%) provides SCC resistance in H₂S-containing environments per NACE MR0175, while Mo and Cu give resistance to sulphuric and phosphoric acids. Cost-positioned between 316L (too low PRE for sour gas) and Inconel 625 (PRE ~51, higher cost).

PRE (approx.)
~32
Ni Content
38–46%
ASTM UNS
N08825

Chemistry (ASTM B366 / EN equivalent)

ElementMinMaxRole
Ni (Nickel)38.0%46.0%SCC immunity in H₂S per NACE MR0175
Cr (Chromium)19.5%23.5%Passive film and pitting resistance
Mo (Molybdenum)2.5%3.5%PRE contribution; acid resistance
Cu (Copper)1.5%3.0%Reducing acid resistance (H₂SO₄, H₃PO₄)
Ti (Titanium)0.6%1.2%Stabilisation — prevents sensitisation
Fe (Iron)22% min—Balance

Alloy 825 vs Competing Grades

GradePRENi %NACE MR0175CuBest Use
316L (1.4404)~2410–14%LimitedNoneMild service
Alloy 825 (2.4858)~3238–46%Yes1.5–3%Sour gas + mild acid — intermediate cost
Duplex 2205 (1.4462)≥354.5–6.5%Yes (limited)NoneChloride pitting; no acid need
Inconel 625 (2.4856)~51≥58%YesNoneAggressive seawater/mixed acid — higher cost

Cross-References

W.Nr.2.4858
EN NameNiCr21Mo
ASTM UNSN08825
Trade NameIncoloy 825 / Alloy 825

Welding

Filler: ERNiCrMo-3 (Inconel 625 filler) commonly used. Dedicated Alloy 825 filler (ERNiFeCr-1) also available. No PWHT required.

Request 2.4858 Quote

Testing & Inspection

  • ✓ Chemical analysis against the ordered material standard / ASTM B366
  • ✓ Tensile test, with impact test where the standard or your order requires it
  • ✓ PMI confirming Ni, Cr, Mo and Cu content
  • ✓ PMI (positive material identification) on every order
  • ✓ Visual and dimensional inspection to ASME B16.9
  • ✓ NDT (UT, RT, MT or PT) when your order or code calls for it
  • ✓ EN 10204 3.1 certificate as standard; 3.2 with TÜV, Lloyd's Register, Bureau Veritas, DNV or your own inspector

Size Range

DN15–DN600 and larger. Outside diameters follow the EN 10220 / EN ISO 1127 pipe series; wall thickness is matched to your connecting pipe.

SizeOD (mm)
DN 1521.3
DN 2026.9
DN 2533.7
DN 3242.4
DN 4048.3
DN 5060.3
DN 6576.1
DN 8088.9
DN 100114.3
DN 125139.7
DN 150168.3
DN 200219.1
DN 250273.0
DN 300323.9
DN 350355.6
DN 400406.4
DN 450457.0
DN 500508.0
DN 600610.0

Export Documents & Packing

  • ✓ Commercial invoice, packing list and certificate of origin
  • ✓ EN 10204 certificates with heat-number traceability
  • ✓ PED 2014/68/EU and AD 2000-Merkblatt W0 documentation for European projects
  • ✓ Seaworthy wooden cases or pallets, bevel ends protected, marked to your instructions
  • ✓ FOB, CFR or CIF delivery terms
Request a Alloy 825 (2.4858) Quote

Frequently Asked Questions: Alloy 825 (2.4858) Fittings

What is Alloy 825 (2.4858)?

NiCr21Mo (UNS N08825), a nickel-iron-chromium alloy with molybdenum, copper and titanium additions.

Why is Alloy 825 used in H₂S-containing service?

Its high nickel content (38–46%) gives resistance to stress corrosion cracking in H₂S-containing environments.

How does Alloy 825 compare on pitting resistance?

Its PRE is about 32.

Further reading