Incoloy 825 is the alloy that bridges stainless steel and the expensive nickel grades, and it earns that place in acid and sour-gas service. Metinox Overseas supplies Incoloy 825 pipes and tubes to ASTM B423 seamless and B704 welded, UNS N08825, made to order with 100 percent PMI and 3.1 certification, serving oil and gas, fertilizer and chemical buyers across India, the USA, the Middle East and Africa. It is a nickel-iron-chromium alloy with molybdenum, copper and stabilizing titanium, built to handle sulphuric and phosphoric acids and sour hydrocarbons at a lower cost than the higher nickel families. The wider range sits at Special Alloys Pipes & Tubes.
It sits on a ladder. Below it, SS 904L Pipe covers milder acid duty as a super-austenitic stainless; above it, the Hastelloy Pipes & Tubes grades take the genuinely hostile chemistry. 825 is the sensible middle when 904L is not quite enough and Hastelloy is more than the job needs.
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Table of content
- What Incoloy 825 Is: The Economical Acid Alloy
- The Titanium-Stabilized Structure of Alloy 825
- Incoloy 825 Chemistry & Mechanical Properties
- Alloy 825 Standards, Sizes & Forms
- Incoloy 825 in Sour Service & the NACE Angle
- Types of Incoloy 825 Pipes & Tubes
- Incoloy 825 Applications
- Incoloy 825 Testing, PMI & Export to USA, Middle East & Africa
- Explore Related Grades
- Incoloy 825 Pipes & Tubes: Frequently Asked Questions
What Incoloy 825 Is: The Economical Acid Alloy
The copper is the tell. Like 904L, Incoloy 825 carries deliberate copper, which is what gives it resistance to sulphuric and phosphoric acid specifically, and its higher nickel content over a stainless base buys immunity to chloride stress corrosion cracking that the 300-series grades lack. The molybdenum adds pitting and crevice resistance, and the titanium stabilizes the structure against sensitization. Put together, that is an alloy for acid process streams, sour wells and phosphate fertilizer duty where stainless corrodes and full nickel alloys are an over-spend.
The Titanium-Stabilized Structure of Alloy 825
The titanium in 825 does the same job it does in 321 stainless: it ties up carbon that would otherwise precipitate as chromium carbides at grain boundaries during welding, which is what sensitizes an alloy and opens it to intergranular corrosion. Because 825 is stabilized, it resists that attack in the as-welded condition across a range of service, which matters for a material that is frequently fabricated into vessels and exchanger bundles on site. It is one of the reasons 825 is an easier alloy to build with than its corrosion resistance alone would suggest.
Incoloy 825 Chemistry & Mechanical Properties
| Element / Property | UNS N08825 |
|---|---|
| Nickel | 38.0 – 46.0% |
| Iron | 22.0% min |
| Chromium | 19.5 – 23.5% |
| Molybdenum | 2.5 – 3.5% |
| Copper | 1.5 – 3.0% |
| Titanium | 0.6 – 1.2% |
| Tensile Strength | 586 MPa (85 ksi) min |
| Yield Strength | 241 MPa (35 ksi) min |
Limits per ASTM B423. The copper-plus-molybdenum-plus-titanium combination is the whole design intent: acid resistance, pitting resistance and weld stability in one alloy.
Incoloy 825 in Sour Service & the NACE Angle
Incoloy 825 is a regular in sour oil and gas, where hydrogen sulphide, carbon dioxide and chlorides combine to defeat carbon and stainless steels. For that duty the alloy is supplied NACE MR0175 / ISO 15156 compliant, with the hardness and condition control the standard requires, arranged at order stage. Where the sour service is also high in chlorides or pressure, the step up is Inconel 625 or a super duplex; 825 covers the large middle of sour-service piping economically. Say sour in the enquiry and the compliance is built into the quote.
Types of Incoloy 825 Pipes & Tubes
Alloy 825 ERW Pipe
Incoloy 825 Seamless Pipe
Incoloy Alloy 825 Welded Pipe
Incoloy- Alloy 825 ERW Tube
Nickel Alloy 825 Welded Tube
UNS N08825 Seamless Tube
Incoloy 825 Applications
- Oil & Gas, Sour Service: downhole tubing, flowlines and wellhead components across Gulf and offshore fields.
- Phosphoric & Sulphuric Acid: fertilizer plant piping and evaporators, an Indian and African lane.
- Chemical Processing: acid mixing, pickling and tank heating.
- Pollution Control: scrubber and acid-recovery service.
- Nuclear Fuel Reprocessing: nitric acid service where the stabilized structure pays.
Incoloy 825 Testing, PMI & Export to USA, Middle East & Africa
Material is supplied to B423 or B704 with examination per the standard, 100 percent PMI attached to the EN 10204 3.1 certificate, 3.2 and NACE MR0175 through BV, SGS or TUV at order stage. Metinox Overseas is ISO 9001 and PED certified; see Quality Policy. Supply is made to order; typical delivery runs 4 to 8 weeks, shipped from Mumbai with alloy-segregated packing per Packing and Dispatch, to the USA, the Middle East and Africa, where sour oil and gas and phosphate fertilizer are the busiest lanes.
Explore Related Grades
- Special Alloys Pipes & Tubes – the parent shelf with the alloy-by-enemy table
- SS 904L Pipe – the super-austenitic step below for milder acid
- Hastelloy Pipes & Tubes – the step above for genuinely hostile chemistry
- Inconel 625 Pipes & Tubes – for high-chloride sour service with strength
Incoloy 825 Pipes & Tubes: Frequently Asked Questions
Acid and sour-gas service where stainless corrodes and full nickel alloys are an over-spend. Its deliberate copper gives sulphuric and phosphoric acid resistance, its molybdenum adds pitting resistance, and its higher nickel confers chloride stress corrosion cracking immunity. It is a regular in sour oil and gas, phosphate fertilizer plant and acid process streams.
Different jobs. The copper gives specific resistance to sulphuric and phosphoric acids, the same reason 904L carries it. The titanium stabilizes the structure by tying up carbon that would otherwise sensitize the alloy during welding, so 825 resists intergranular corrosion in the as-welded condition, which makes it easier to fabricate.
Yes, and it is widely used for it. Supplied NACE MR0175 / ISO 15156 compliant, 825 handles the hydrogen sulphide, carbon dioxide and chloride combination of sour wells across the economical middle of sour-service piping. Where chlorides or pressure run high, Inconel 625 or super duplex is the step up.
Nickel content and classification. 904L is a super-austenitic stainless steel; 825 is a nickel-iron-chromium alloy with more nickel, giving it stronger chloride SCC immunity and a wider acid and sour-service range. Both use copper for acid resistance. 904L suits milder acid duty at lower cost; 825 steps up where nickel content is needed.
Yes, made to order with 100 percent PMI and 3.1 documentation, and NACE MR0175 where ordered. Sour oil and gas in the Gulf, phosphate fertilizer in India and Africa, and chemical work in the USA are the regular lanes, shipped alloy-segregated and labelled from Mumbai.
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