What is Incoloy 825 used for?
Sour oil and gas piping and tubulars, clad and lined pipe, sulphuric and phosphoric acid equipment, pickling tanks and heating coils, seawater-cooled heat exchangers and nuclear fuel reprocessing.
Nickel alloy · Ni-Fe-Cr-Mo-Cu · UNS N08825 · W.Nr. 2.4858
Incoloy 825 for acids, chlorides and sour wells
In short: Incoloy 825 is a nickel-iron-chromium alloy with molybdenum, copper and titanium. Each addition has a job: nickel against chloride stress corrosion cracking, molybdenum and copper against sulphuric and phosphoric acids, chromium against oxidising media, titanium against sensitisation. That makes it a versatile choice for acid plants and sour oil and gas.
Overview
Incoloy 825 in brief
- Resistant to sulphuric and phosphoric acids
- Immune to chloride SCC at typical process temperatures
- Titanium-stabilised against sensitisation
- Widely used in sour oil and gas service
Alloy 825's 38–46% nickel provides chloride SCC resistance. Molybdenum and copper add resistance to reducing acids such as sulphuric and phosphoric, chromium handles oxidising media such as nitric acid, and titanium stabilises it against sensitisation.
It's widely used in oil and gas for sour-service piping, clad pipe and downhole tubulars, and in chemical plants for acid pickling, sulphuric acid and phosphoric acid equipment. It's also a common, cost-effective step up from SS 316L and SS 904L.
Available as
Incoloy 825 product forms
Select a form for its specification, sizes and weights.
Where it's used
Industries that specify Incoloy 825
Chemistry
Composition of Incoloy 825
- UNS
- N08825
- EN / W.Nr.
- 2.4858 · NiFe30Cr21Mo3
- Density
- 8.14 g/cm³
- PREN
- ≈ 30 – 33
| Element | Limit, % | Why it matters |
|---|---|---|
| Ni | 38.0 – 46.0 | 38–46%: chloride SCC resistance |
| Fe | 22.0 min | |
| Cr | 19.5 – 23.5 | |
| Mo | 2.5 – 3.5 | 2.5–3.5%: reducing acids, pitting |
| Cu | 1.5 – 3.0 | 1.5–3.0%: sulphuric acid |
| Ti | 0.6 – 1.2 | 0.6–1.2%: stabilisation |
| C | 0.05 max | |
| Mn | 1.0 max | |
| Si | 0.5 max | |
| Al | 0.2 max |
Limits per ASTM B424; other product forms and specifications differ slightly. Your order's specification and edition govern.
Oil and gas
A common answer for sour service
In wet sour gas with chlorides, 825 is used as solid pipe and tubing, and as the corrosion-resistant layer in clad and lined pipe. Material for sour service must meet NACE MR0175 / ISO 15156, including hardness limits. See the sour service guide.
- Forms
- Seamless pipe and tube, plate for cladding, bar and forgings for fittings and valve parts.
- Documents
- EN 10204 3.1 or 3.2, NACE MR0175 compliance statement, hardness results, PMI.
- Markets
- Strong demand in the UAE, Saudi Arabia and Qatar.
Mechanical properties
Annealed room-temperature values
586 MPa (85 ksi)Tensile strength (min. unless max)
241 MPa (35 ksi)Yield strength (0.2%) (min. unless max)
30%Elongation (min. unless max)
ASTM B424 (annealed): room-temperature specification values for the annealed condition.
Supply
Incoloy 825 by product form
| Product form | Specification and designation |
|---|---|
| Incoloy 825 pipes | ASTM B423 (seamless) / B705 (welded) |
| Incoloy 825 tubes | ASTM B423 / B163 / B704 |
| Incoloy 825 plates | ASTM B424 / ASME SB424 |
| Incoloy 825 sheets | ASTM B424 |
| Incoloy 825 coils | ASTM B424 |
| Incoloy 825 bars | ASTM B425 / ASME SB425 |
| Incoloy 825 fittings | ASTM B366 WPNICMC |
| Incoloy 825 flanges | ASTM B564 N08825 |
| Incoloy 825 bolts | ASTM B425 bar stock |
| Incoloy 825 nuts | ASTM B425 |
| Incoloy 825 washers | ASTM B424 |
- Product specification per form (B423, B424, B425, B564)
- NACE MR0175 compliance for sour service
- Annealed condition
- Acid type and concentration for acid service
- Clad or lined pipe details if not solid
Ordering
What to put on an order for Incoloy 825
Getting these on the enquiry avoids the usual back-and-forth and makes sure the certificate matches your specification.
Incoloy 825 questions
Answers about Incoloy 825
Is Incoloy 825 resistant to chloride stress corrosion cracking?
Its nickel content gives it resistance to chloride-ion stress corrosion cracking, the main weakness of 300-series stainless steels.[1] In very severe conditions such as boiling magnesium chloride, resistance is not absolute, so give us the service conditions.
Why is 825 good in sulphuric acid?
Nickel together with molybdenum and copper gives outstanding resistance to reducing environments such as sulphuric and phosphoric acids, per the producer.[1]
Incoloy 825 or Inconel 625?
Inconel 625 has higher strength and better pitting resistance (more molybdenum) at higher cost. 825 is the economical choice for acid service and many sour-service applications.
Which specifications cover Incoloy 825?
Pipe: ASTM B423 (seamless) / B705 (welded). Plate: ASTM B424 / ASME SB424. Bar: ASTM B425 / ASME SB425. Fittings: ASTM B366 WPNICMC.
Sources
References
Incoloy® is a trademark of Special Metals Corporation. Composition per the cited specifications and bulletin.
Need Incoloy 825?
Send form, size and service (acid, sour, seawater). We confirm NACE and certificate requirements before quoting.