Nickel–molybdenum, nickel–chromium–molybdenum and super austenitic grades for acids, chlorides and sour service.
These are the grades specified when carbon steel and 316L are being consumed by the process. The choice usually comes down to the chemistry of the stream: reducing acids point to the molybdenum-rich B and C families, oxidising acids and high-temperature chlorides to the chromium-rich grades, and seawater to the super austenitic and duplex steels.
We supply them as flanges, fittings, pipe, bar and forgings, forged and solution annealed, with the UNS number stated on the certificate rather than only a trade name.
| Grade | UNS | Typical service |
|---|---|---|
| C-276 / C-2000 | N10276 / N06200 | Mixed acids, chlorides, wet chlorine; the general-purpose corrosion alloy. |
| C-22 / C-4 | N06022 / N06455 | Oxidising and reducing media, hypochlorite, wet chlorine; C-4 for good hot ductility. |
| B-2 / B-3 | N10665 / N10675 | Hydrochloric acid at any concentration; B-3 for better thermal stability. |
| G-30 / G-35 | N06030 / N06035 | Phosphoric acid and nitric/HF pickling liquors. |
| 625 | N06625 | Seawater, sour gas, supercritical water; high strength without heat treatment. |
| 600 | N06600 | Caustic, high-temperature chlorine and chloride; furnace and nuclear components. |
| 601 | N06601 | Cyclic oxidation and carburising atmospheres up to about 1,100 °C. |
| 690 | N06690 | Steam-generator tubing and nitric/HF service; resistant to intergranular attack. |
| 617 | N06617 | Combustion and high-temperature corrosion up to 1,100 °C. |
| X | N06002 | Furnace rolls, radiant tubes, combustion chambers; oxidation to 1,200 °C. |
| 188 | R30188 | Cobalt-based; high-temperature strength with oxidation and hot-corrosion resistance. |
| 556 | R30556 | Sulphidising and chlorinating high-temperature environments; also a filler metal. |
| 400 | N04400 | Hydrofluoric acid, seawater, hot concentrated alkali; no chloride SCC. |
| 500 | N05500 | Monel 400 with age hardening — pump shafts, valve trim, fasteners. |
| 20 | N08020 | Sulphuric acid, phosphoric acid and pickling equipment. |
| 31 | N08031 | Oxidising and reducing acids, flue-gas desulphurisation, phosphoric acid. |
| 28 | N08028 | Sulphuric and phosphoric acid; sour gas well completions. |
| 59 | N06059 | Very low corrosion rate in hydrochloric and mixed mineral acids. |
| 30 | N06030 | Phosphoric acid, nitric/HF mixtures, pickling bath heaters. |
| 925 | N09925 | Age-hardened; downhole and surface wellhead components in CO2 / H2S. |
| 825 | N08825 | Sulphuric and phosphoric acid, seawater cooling; stress-corrosion resistant. |
| 800 / 800H / 800HT | N08800 / N08810 / N08811 | High-temperature process piping, reformers, nitric acid condensers. |
| 120 | N08120 | Carburising and sulphidising furnace service with high creep strength. |
| N10003 | N10003 | Molten fluoride salt containment. |
| 200 / 201 | N02200 / N02201 | Caustic, non-oxidising halides and organic acids below 315 °C. |
| 254SMO | S31254 | High-chloride water, seawater heat exchangers, bleach plants. |
| AL-6XN | N08367 | Seawater piping, FGD scrubbers, pulp bleaching. |
| 926 / 25-6MO | N08926 | Chloride pitting and crevice resistance with higher nitrogen. |
The default alloy for mixed acids, chlorides and wet chlorine — and the grade most often specified when no one is sure what the stream will do.
Alloy detailChromium-rich cousins of C-276: better in oxidising media and in wet chlorine, with C-4 for hot ductility.
Alloy detailNickel–molybdenum alloys for hydrochloric acid — any concentration, any temperature within the practical range.
Alloy detailOne alloy for seawater, sour gas and 600 °C strength — the workhorse of offshore and supercritical service.
Alloy detailThe classic nickel–chromium alloy for caustic, high-temperature chlorine and furnace hardware.
Alloy detailBuilt for cyclic oxidation and carburising atmospheres up to about 1,100 °C.
Alloy detailHigh-chromium alloy developed against intergranular attack in nuclear steam generators and nitric/HF service.
Alloy detailNickel–copper alloy for hydrofluoric acid, seawater and hot concentrated alkali.
Alloy detailTitanium-stabilised nickel–iron–chromium alloy for sulphuric and phosphoric acid up to about 550 °C.
Alloy detailQuotes within one business day. Send grade, size, pressure class, face type and quantity — a drawing works better than a description.
