Incoloy 825 UNS N08825 2.4858 NiCr21Mo Nickel-Based Alloy Pipe & Tube

Alloy 825 (UNS N08825), also referred to as 2242, is a cold hardened nickel-based alloy, intended for corrosion resistance in highly sour (H2S) environments with moderate chloride content, requiring high strength up to 350°F.

825 offers increased resistance to the effects of H2S relative to stainless steels allowing its use as downhole tubular components, packers, and other subsurface equipment in sour wells with high-pressure and high-temperature (HPHT) conditions and Acid Gas Injection (AGI) wells. However, all environmental factors, including H2S, CO2 , temperature, pH, and chloride concentration, should be considered before final material selection.

The alloy is classified in MR0175/ISO15156 as a type 4c alloy, with no restrictions to a partial pressure of H2S below 270°F and resistant to 200 psi H2S at 350°F.

UNS N08825 Incoloy 825 is a nickel-iron-chromium alloy that contains small amounts of titanium, copper, and molybdenum. Incoloy® 825’s chemical composition provides great resistance to many corrosive environments, such as pitting, crevice corrosion, intergranular corrosion, and stress- corrosion cracking. Incoloy 825 nickel alloy has good mechanical properties from moderate to high temperatures, with a hot- working range of 1600 to 2150º F. Alloy 825 also maintains good weldability for all conventional processes.

Applications

Nickel alloy UNS N08825 has many different industrial applications, some of which include: Propeller shafts, Phosphoric acid evaporators, Tank trucks, Hot vessels for food, water, sea water, Sulphuric acid piping and vessels, Marine exhaust systems

Standard

Rod, Bar, Wire and Forging Stock: BS 3076NA16, ASTM B 425, ASTM B 564, ASME SB 425, ASME SB 564, ASME Code Case N-572, DIN 17752, DIN 17753, DIN 17754, VdTÜV 432, ISO 9723, ISO 9724, ISO 9725.

Plate, Sheet and Strip: BS 3072NA16, BS 3073NA16, ASTM B 424, ASTM B 906, ASME SB 424, ASME SB 906, DIN 17750, VdTÜV 432, ISO 6208.

Pipe and Tube: BS 3074NA16, ASTM B 163, ASTM B 423, ASTM B 704, ASTM B 705, ASTM B 751, ASTM B 775, ASTM B 829, ASME SB 163, ASME SB 423, ASME SB 704, ASME SB 705, ASME SB 751, ASME SB 775, ASME SB 829, ASME Code Case 1936, DIN 17751, VdTÜV 432, ISO 6207.

Others: ASTM B 366, ASME SB 366, DIN 17744

Chemical Composition

Mechanical Properties

API 5CRA / ISO 13680 Group 3 Category 21-42-3

MANUFACTURING PROCESS

TYPICAL PHYSICAL PROPERTIES

Weldability

Alloy 825 can be readily welded by the shielded metal-arc process using alloy welding electrode 135, the gas shielded arc processes using alloy filler metal 65, and the resistance welding processes. The alloy requires no postweld heat treatment. The corrosion resistance of deposited weld metal from both covered electrode and bare wire is equivalent to that of the parent metal.

Heat Treatment

Incoloy 825 is stabilise annealed at 940°C. The softest structure is obtained at 980°C. Sections heavier than sheet, strip and wire should be quenched to avoid sensitisation.

Corrosion Resistance

The outstanding property of Incoloy 825 is its corrosion resistance. In reducing & oxidising conditions, Incoloy 825 resists general corrosion, pitting & crevice corrosion, intergranular corrosion and stress corrosion cracking. It is particularly useful in sulphuric & phosphoric acids, sulphur containing flue gases, sour gas and oil wells and sea water.

Machinability

Incoloy 825 is classed as a ‘C’ alloy, and is reasonably easy to machine.