Most corrosion-resistant alloys pick a side: they resist oxidizing acids, or they resist reducing acids, rarely both. Incoloy 825 doesn't pick a side. That's the whole reason it exists as a standard material rather than a lab curiosity: it holds up in mixed-acid chemical processing and sour gas service where a single-purpose alloy fails on one end or the other. USA Piping Solution supplies it as seamless pipe to ASTM B423, welded pipe to ASTM B705, and heat exchanger tube to ASTM B163, all in UNS N08825. For where 825 sits against Incoloy 800 and Inconel 625, see the comparison below. For the wider nickel alloy range, browse Nickel Alloy Pipes & Tubes.
Where 825 Fits: vs Incoloy 800 and Inconel 625
Three nickel alloys get compared constantly in acid and sour service, and picking the wrong one either overspends or underperforms:
| Alloy | Best For | Where It Falls Short |
|---|---|---|
| Incoloy 800 | High-temperature oxidation and carburization resistance in furnace and heat-treating service | Weak in aqueous, wet-acid corrosion, the exact service 825 is built for |
| Incoloy 825 | Mixed oxidizing and reducing acids, chloride media, NACE sour gas service | Less pitting and crevice resistance than 625 in high-chloride seawater |
| Inconel 625 | Maximum pitting and crevice resistance, high-velocity seawater, dynamic subsea service | Costs more than 825 where that extra margin isn't needed |
If your service is furnace or oxidation-side heat, see Incoloy 800 Pipes & Tubes. If it's aggressive seawater or subsea, see Inconel 625 Pipes & Tubes. If it's mixed acid or sour gas, 825 is very likely the right call, and the rest of this page covers it in depth.
Why No Post-Weld Heat Treatment Is Required
Titanium in Incoloy 825, roughly 0.6 to 1.2%, ties up carbon before chromium can, forming titanium carbides instead of chromium carbides at the weld heat-affected zone. That's what prevents sensitization, and it's why 825 fabrications can go into service right after welding without a PWHT cycle. For a shop running GTAW, GMAW, SMAW, or SAW on this alloy, that's a real schedule and cost saving compared to alloys that do require post-weld treatment. Recommended filler is ERNiCrMo-3 for GTAW/GMAW and ENiCrMo-3 for SMAW, with interpass temperature held below 175°C (347°F) and argon back-purge on root passes for corrosion-critical piping.
Sour Gas & NACE MR0175 Service
825 is a standard material for H2S sour gas service under NACE MR0175 / ISO 15156, and it's one of the more common reasons buyers choose it over a straight stainless grade. For sour service, specify the annealed condition, confirm hardness is certified below the applicable NACE limit, and require EN 10204 3.1 mill test certification with full heat traceability. Getting those three items into your purchase order up front is what keeps a sour-service order from stalling in document review.
Sourcing for Sour Gas Service? Send Us Your Spec →
Applications
- Chemical Processing: acid reactors, evaporators, and process piping in mixed-acid service.
- Oil & Gas: production tubing, completion tubing, and sour gas wells.
- Sulfuric & Phosphoric Acid: piping, vessels, and evaporators.
- Pollution Control: flue gas desulfurization scrubbers.
- Marine: exhaust systems and seawater heat exchangers.
- Nuclear: fuel reprocessing equipment and radioactive waste handling.
Testing, Certification & Availability
USA Piping Solution is an ISO 9001:2015 certified supplier of ASTM B423 Incoloy 825 seamless pipe and tube, serving the oil & gas, chemical processing, nuclear, and offshore sectors. Every order ships with EN 10204 3.1 mill test certification as standard, with 3.2 third-party witnessed certification, PED, DNV, and TUV documentation available on request. See our Quality Policy page for the full testing program. Seamless pipe typically costs more than welded pipe for the same size; send us your OD, wall thickness or schedule, construction type, and quantity, and we'll confirm current pricing and lead time.
Related Products
- Incoloy 800 Pipes & Tubes
- Inconel 625 Pipes & Tubes
- Inconel 600 Pipes & Tubes
- Inconel Plates & Sheets
- Nickel Alloy Pipes & Tubes
- Inconel Pipes & Tubes
Frequently Asked Questions
Does Incoloy 825 require post-weld heat treatment?
No. Titanium stabilization prevents sensitization at the weld, so 825 fabrications can be used directly after welding. See the section above for why.
Is Incoloy 825 suitable for sour gas (H2S) service?
Yes, to NACE MR0175 / ISO 15156, supplied in the annealed condition with certified hardness. See the Sour Gas section above for the specification details to put in your PO.
What sizes are available in Incoloy 825 pipe and tube?
Seamless pipe from 6.35 mm (1/4") to 219 mm OD, welded pipe up to 1219 mm, and HX tube from 6 mm OD. Send us your requirement and we'll confirm current availability.
How does pricing compare between seamless and welded Incoloy 825 pipe?
Seamless typically costs more than welded for the same size, since welding is the more efficient production route at larger diameters. Send us your size and quantity for an exact quote.
Can Incoloy 825 be supplied as clad pipe over carbon steel?
Yes. Clad pipe pairs a carbon steel backing pipe with an 825 corrosion-resistant liner, a lower-cost option for large-bore corrosive service than solid 825 pipe.