Fittings and Flanges

Fittings and Flanges

Inconel 825 alloys are oxidation-corrosion-resistant materials well suited for service in extreme
environments subjected to pressure and heat. When heated, Inconel forms a thick, stable,
passivating oxide layer protecting the surface from further attack.

Chemical Properties

GRADE   Cr Cu Mo Co Al Ti C Fe Mn Si P S Ni
INCONEL 825 MIN 19.5 1.5 2.5 0.6 22 38
MAX 23.5 3 3.5 1 0.2 1.2 0.05 1 0.5 0.015 0.03 46

The remarkable property of alloy 825 fittings is its corrosion resistance. In reducing & oxidising
conditions, Inconel 825 flanges resists general corrosion, pitting & crevice corrosion,
intergranular corrosion and stress corrosion cracking.

Inconel 825 by itself doesn't need a treatment to be passive, as is generally true of non-ferrous
alloys. Inconel alloy 825 has a higher tensile strength than grade 304 stainless steel, and does a
better job of maintaining that strength at higher operating temperatures.

Physical Properties

Grade Density (g/cm3) Elastic Modulus (GPa) Mean Co-eff of Thermal Expansion (μm/m/°C) Thermal Conductivity (W/m.K) Specific Heat (J/Kg.K) Electrical Resistivity (nΩ.m)
27-204°C 0-315°C at 93°C at 204°C 0-100°C
Inconel 825 7.82 190 14.9 14.2 12.3 14.1 440 1.13

Specification of Flange

The specified ASTM Standard Specification for Nickel Alloys Flanges is ASTM B 564 with
manufacturing standard such as ANSI/ASME B16.5, B16.47, BS4504, B 16.47 Series A & B, BS 10,
EN-1092, DIN, etc

According to application and uses in pipes and tubes Inconel 825 Flanges are broadly grouped
into different sort, for example, Welding Neck Flange(WNF) & Long Welding Neck
Flange(LWNF), Slip-on Flange(SOF), Lap Joint Flange(LJW), Blind Flange, Socket Welding Flange
(SWF), Threaded Flange(THW), Plate Flange.

Inconel 825 Flange for the most part has different face type, for example, Flat Face (FF), Raised
Face (RF), Ring Type Joint (RTJ), blind flange, with various class rating as 50 LBS, 300 LBS, 600
LBS, 900 LBS, 1500 LBS, 2500 LBS, DIN Standard ND-6,10, 16,din 2.4856 , 25, 40 & ANSI B16.5.

Specification of Fittings

The specified ASTM Standard Specification for Nickel Alloys Pipe Fitting is ASTM B 366, having
Specific manufacturing Standards as ASME/ANSI B16.9, ASME B16.28, MSS-SP-43.

Alloy 825 fittings that are categorically available are Elbow, Reducer, Tee, Coupling, Bend, Stub
End, Cap, Nipple, Washer, Cross, Union etc. which are available in different types such as
Welded, Seamless and Fabricated having thickness range from 5s, 10s, 40s, 80s, 10, 20, 40, STD,
60, 80, XS, 100, 120, 140, 160, XXS available with NACE MR 01-75.

Mechanical properties


Grade Tensile Strength Yield Strength Elongation
[MPA] [MPA] (% in 50mm) min
Alloy 825 586 241 30

Typical applications of Inconel 825 fittings & flanges are phosphoric acid evaporators; pickling-
tank heater, pickling hooks and equipment; chemical process equipment; tank trucks; propeller
shafts, and spent nuclear fuel element recovery

  • Fuel element dissolves
  • Sea-water-cooled heat exchangers, offshore product piping systems; tubes and
    components in sour gas service
  • Heat exchangers, evaporators, scrubbers, dip pipes etc. in phosphoric acid production
  • Air-cooled heat exchangers in petroleum refineries
  • Food processing
  • Chemical plant
  • Combustion-resistant alloy for high pressure O2 applications

NOTE: Inconel 825 Fittings and Flanges is a registered trademark of  Special Metals Corporation.