Plants that run mixed or changing acid streams face a problem no single-purpose alloy solves, since a material chosen for reducing conditions can corrode quickly once an oxidiser appears in the line. C22 was designed for exactly that uncertainty, with enough chromium for oxidising media and enough molybdenum for reducing ones. Hastelloy C22 pipes and tubes carry about 22% chromium with 13% molybdenum and a tungsten addition. They are supplied solution annealed to ASTM B622 or B619, for chemical, scrubber and acid service at facilities across Oman. Other alloys are on the nickel and exotic alloy pipes and tubes hub.
Where Hastelloy C22 Is Used
- Mixed acid and changing-chemistry process lines
- Flue gas desulphurisation and scrubber systems
- Pickling and acid regeneration plant
- Waste treatment and incineration scrubbing
- Chloride-rich process streams with oxidising species present
For predominantly reducing service, Hastelloy C276 is the established choice; for hydrochloric acid without oxidisers, Hastelloy B3 is used.
Oxidising or Reducing: Why C22 Is Specified
Environment | What attacks the metal | Element that helps |
|---|---|---|
Reducing acids, such as hydrochloric and dilute sulphuric | Acid attack on the passive film | Molybdenum, with tungsten |
Oxidising media, such as nitric acid, ferric and cupric salts | Oxidising attack | Chromium |
Chloride pitting and crevice corrosion | Local breakdown of the passive film | Molybdenum and chromium together |
Wet chlorine and hypochlorite | Highly oxidising with chlorides | Chromium, supported by molybdenum |
C22 carries about 22% chromium against roughly 16% in C276, with 13% molybdenum against 16%. That balance is what makes it the usual answer where a stream is oxidising some of the time and reducing the rest, or where the composition is not fully known. Like C276, its low carbon means welds keep their corrosion resistance without a post-weld solution anneal.
Corrosion Range and Sour Service
C22 covers both oxidising and reducing conditions, resists pitting, crevice corrosion and chloride stress corrosion cracking, and performs well in wet chlorine and hypochlorite. Where the service is consistently reducing, C276's higher molybdenum may suit better, and in hot hydrochloric acid without oxidisers the B-type alloys do. Under NACE MR0175 / ISO 15156-3, it is accepted within alloy-specific conditions. State your service conditions in the RFQ; requirements are confirmed at quotation.
What Affects the Price of Hastelloy C22
- Alloy surcharges, which move with nickel, molybdenum and chromium markets
- Seamless or welded
- Size, schedule or wall, and length
- Surface finish and any polishing
- Testing, including corrosion testing and PMI
- Quantity and stock availability versus a mill order
- Certification (EN 10204 3.1 or 3.2) and third-party inspection
- Incoterm and destination port
Quotations are available in USD, OMR, AED, SAR, QAR, KWD and BHD, on EXW, FOB, CFR or CIF terms.
What to send for a quotation:
grade, standard, seamless or welded, NPS or OD, schedule or wall, length, quantity, finish, testing, certification, inspection, destination port and required date.
Hastelloy C22 Certificates and Inspection
Hastelloy C22 is supplied with EN 10204 3.1 certificates as standard, and EN 10204 3.2 certificates on request. Inspection by the buyer's nominated third-party agency can be arranged; state your requirement in the RFQ. Check the chemistry, the heat treatment condition, tensile results and any corrosion test report. PMI on receipt confirms the grade. See the MTC and EN 10204 certification guide.
Packing and Site Storage
Lead time is confirmed at quotation. Material ships with end caps and, where specified, protective wrapping. Keep it away from carbon steel racks, slings and grinding dust, since embedded iron rusts on the surface and can start pitting. On coastal Gulf sites, rinse salt deposits off before fabrication.
Fittings and Related Alloys
Match with ASTM B366 fittings and B564 flanges in the same alloy.
C22 is used across refinery and petrochemical, fertilizer and chemical plants.
Hastelloy C22 FAQ
What is Hastelloy C22?
A nickel-chromium-molybdenum alloy with tungsten, UNS N06022, designed to handle both oxidising and reducing conditions.
How does C22 differ from C276?
C22 has more chromium and less molybdenum, which favours oxidising service. C276 favours certain reducing media.
When is C22 the better choice?
Where a stream alternates between oxidising and reducing, or where the composition varies and cannot be fixed at design stage.
Does C22 need post-weld solution annealing?
No. Its low carbon means welds retain corrosion resistance, though heat input control and weld cleaning still matter.
What is the EN equivalent?
2.4602 (NiCr21Mo14W).
What should I send for a quotation?
Send the UNS number, standard, form, size, wall, length, quantity, service conditions, testing, certification and destination port.
Request a Quote for Hastelloy C22 Pipes and Tubes
Send the UNS number, size, wall and quantity, with the range of process conditions the line will see. Every enquiry is checked before the offer is prepared, so the alloy is matched to the full operating envelope rather than one case.