Hangbo Alloy Group
Shanghai · Est. 2012
Hydrochloric acid is the mineral acid that breaks stainless steel. This guide shows engineers how concentration, temperature and — above all — oxidizing contamination decide between Hastelloy B-3, C-276, C-22, C-2000, Alloy 59, Alloy 686, HYBRID-BC1 and Monel 400, with published corrosion-rate data.
Hydrochloric acid (HCl) is the single most demanding common mineral acid to contain. It is strongly reducing, it delivers chloride ions at high activity, and it strips the passive oxide films that stainless steels, titanium and aluminium depend on. Every year HCl service accounts for a disproportionate share of chemical-plant corrosion failures — not because the correct materials are unknown, but because the correct material for clean HCl is almost the opposite of the correct material for contaminated HCl.
That inversion is the central theme of this guide. In pure, oxygen-free hydrochloric acid, the high-molybdenum nickel alloys (Hastelloy B-3) are outstanding and the high-chromium alloys are merely adequate. Add a few hundred ppm of ferric ion and the ranking flips completely: the chromium-bearing alloys passivate and their corrosion rate collapses, while B-3 keeps corroding and begins to pit. Get that one variable wrong and no amount of wall thickness will save the equipment.
This selection guide gives plant engineers, EPC specifiers and procurement teams a practical, data-driven framework for choosing nickel alloys for hydrochloric acid service. As a direct nickel alloy manufacturer and supplier, Hangbo Alloy Group produces and stocks the full Hastelloy B and C families, Alloy 59, Alloy 686, C-2000 and Monel 400 in all product forms, with mill test certificates and third-party inspection.
Four variables control corrosion in HCl service, and all four must be defined on the datasheet before an alloy is chosen:
Golden rule for HCl: Establish the oxidizer content first, then concentration and temperature. In hydrochloric acid the oxidizer question is not a refinement of the answer — it changes which family of alloy you buy.
The behaviour of each grade in HCl follows directly from its chemistry. Molybdenum drives resistance to pure reducing acid; chromium provides the passivation needed under oxidizing contamination; tungsten reinforces localized-corrosion resistance; copper improves reducing-acid coverage at the expense of thermal stability.
| Alloy (UNS) | Family | Ni % | Cr % | Mo % | Other key | Fe % |
|---|---|---|---|---|---|---|
| 316L (S31603) | Austenitic SS | 10–14 | 16–18 | 2–3 | Low C | Balance |
| Monel 400 (N04400) | Ni-Cu | ≥63 | — | — | 28–34 Cu | ≤2.5 |
| Inconel 625 (N06625) | Ni-Cr-Mo | ≥58 | 20–23 | 8–10 | 3.15–4.15 Nb | ≤5 |
| Hastelloy C-276 (N10276) | Ni-Cr-Mo-W | Balance (~57) | 14.5–16.5 | 15–17 | 3.0–4.5 W | 4–7 |
| Hastelloy C-22 (N06022) | Ni-Cr-Mo-W | Balance (~56) | 20–22.5 | 12.5–14.5 | 2.5–3.5 W | 2–6 |
| Alloy 59 (N06059) | Ni-Cr-Mo | Balance | 22–24 | 15–16.5 | No W (thermal stability) | ~1.0 |
| Alloy 686 (N06686) | Ni-Cr-Mo-W | Balance | 19–23 | 15–17 | 3.0–4.4 W | ≤1.0 |
| Hastelloy C-2000 (N06200) | Ni-Cr-Mo-Cu | Balance (~55) | 22–24 | 15–17 | 1.3–1.9 Cu | ≤3.0 |
| HYBRID-BC1 (N10362) | Ni-Mo-Cr | Balance | ~15 | ~22 | Low C, low Si | ≤2 |
| Hastelloy B-3 (N10675) | Ni-Mo | Balance (~65) | 1.0–3.0 | 27–32 | Ti/Nb stabilized, low C | 1–3 |
The contrast could not be sharper. Hastelloy B-3 carries about 28.5% molybdenum and barely 1.5% chromium — superb in clean reducing acid, defenceless against oxidizers. Alloy 59 and C-2000 carry 22–24% chromium and 15–17% molybdenum, giving them coverage on both sides of the redox line. HYBRID-BC1 was created specifically to occupy the gap between the two philosophies.
Typical room-temperature values in the solution-annealed condition, for pressure-part and structural sizing:
| Alloy | Density (g/cm³) | Tensile (MPa) | Yield 0.2% (MPa) | Elongation (%) | Practical HCl Envelope |
|---|---|---|---|---|---|
| 316L | 8.0 | 485–620 | 170–310 | 40–55 | Not recommended |
| Monel 400 | 8.83 | 480–620 | 195–310 | 35–50 | ≤10–15%, deaerated, ambient |
| Inconel 625 | 8.44 | 830–1030 | 415–550 | 30–45 | Dilute acid, moderate temp |
| Hastelloy C-276 | 8.89 | 760–1000 | 340–480 | 40–55 | ≤20% to ~60–70°C |
| Hastelloy C-22 | 8.69 | 740–950 | 330–450 | 45–55 | ≤20%; best with oxidizers |
| Alloy 59 | 8.6 | 690–900 | 310–430 | 40–50 | All concentrations <40°C |
| Alloy 686 | 8.73 | 730–930 | 330–450 | 40–50 | ≤20%; best pitting resistance |
| Hastelloy C-2000 | 8.5 | 720–930 | 330–450 | 40–50 | Broad redox coverage |
| HYBRID-BC1 | 9.2 | 800–1000 | 400–500 | 40–50 | Strong/hot HCl to ~427°C |
| Hastelloy B-3 | 9.22 | 760–950 | 350–450 | 40–55 | 1–20% to boiling, pure only |
Note that mechanical strength is almost never the limiting factor in HCl equipment — corrosion rate is. Hastelloy C-276 is structurally serviceable to about 1035°C in oxidizing gas, yet its practical HCl limit is around 70°C. Size the alloy to the corrosion envelope, then confirm the pressure rating.
The table below is the single most instructive dataset in HCl material selection. It reports published laboratory immersion rates in 20% hydrochloric acid, first clean, then heavily contaminated with ferric ion. Watch what happens to the ranking.
| Alloy | 20% HCl, 23°C (mpy) | 20% HCl, 52°C (mpy) | 20% HCl + 1000 ppm Fe³⁺, 52°C (mpy) | Behaviour |
|---|---|---|---|---|
| Hastelloy B-3 | 1.4 | 5.9 | 4.9 | Stays active — no passivation |
| HYBRID-BC1 | 1.6 | 7.1 | 5.8 | Stays active, more tolerant |
| Hastelloy C-276 | 1.6 | 11.4 | 6.5 | Partially improved |
| Alloy 686 | 2.2 | 10.4 | 6.6 | Partially improved |
| Hastelloy C-22 | 2.0 | 12.6 | 0.4 | Passivates — rate collapses |
| Hastelloy C-2000 | 2.0 | 14.2 | 0.4 | Passivates — rate collapses |
| Alloy 59 | 2.1 | 14.6 | 0.4 | Passivates — rate collapses |
| Hastelloy G-35 | 6.1 | 31.0 | 0.2 | Worst clean, best contaminated |
Read the first two columns and you would specify B-3 and reject G-35 outright. Read the fourth column and the conclusion reverses: G-35 becomes the best performer in the table and B-3 the worst of the high-Mo group. This is not a data anomaly — it is the fundamental electrochemistry of chromium passivation, and it is why an HCl material specification without an oxidizer analysis is incomplete.
General corrosion is only half the story. In chloride-rich HCl service, pitting and crevice resistance and post-weld thermal stability often decide service life. The comparison below uses the standard Green Death test solution (11.4% H₂SO₄ + 1.2% HCl + 1% FeCl₃ + 1% CuCl₂) and ASTM G28 testing after sensitising at 871°C.
| Alloy | PREN | PRE Index | Green Death CPT (°C) | Green Death CCT (°C) | ASTM G28A / G28B after sensitising (mpy) |
|---|---|---|---|---|---|
| Alloy 686 | 51 | 74 | >120 | 110 | 872 / 17 — severe IGA |
| Alloy 59 | 47 | 76 | >120 | 110 | 40 / 4 — no attack |
| Hastelloy C-2000 | 47 | 76 | 110 | 100 | 116 / >500 — severe IGA |
| Hastelloy C-22 | 46 | 65 | 120 | 105 | >500 / 339 — severe IGA |
| Hastelloy C-276 | 45 | 59 | 110 | 105 | >500 / >500 — severe IGA |
Alloy 686 leads on pitting resistance, but Alloy 59 is in a class of its own on thermal stability — the deliberate omission of tungsten suppresses the intermetallic precipitation that leaves the other four grades vulnerable to intergranular attack after thermal exposure. For thick-section welded HCl equipment where heat input is unavoidable, that difference matters more than a few PREN points.
Unsure whether your acid stream calls for Hastelloy B-3, C-276, C-22, Alloy 59 or Alloy 686? Send us your concentration, temperature and oxidizer profile and our metallurgists will recommend the most cost-effective certified grade. As a direct manufacturer and supplier, we offer competitive price quotes, full material certification and worldwide delivery.
Email: [email protected] | Phone / WhatsApp: +86-136-1165-6360
The reigning champion of pure hydrochloric acid. With roughly 28.5% Mo and very low carbon, B-3 holds under 0.1 mm/year in 1–20% HCl from ambient to boiling, and its corrosion rate is far less temperature-sensitive than any Ni-Cr-Mo grade. B-3 supersedes the older B-2 in all new designs: Ti/Nb stabilization and controlled chemistry suppress the Mo-rich carbide and β-phase precipitation that caused post-weld intergranular corrosion in B-2, so heat-affected-zone softening is minimal and large fabrications are practical. Reported HAZ properties include over 45% elongation and impact toughness above 120 J at room temperature. Well-fabricated B-3 absorbers and pickling heaters have exceeded 25 years in continuous HCl duty. Absolute exclusions: any oxidizing species — dissolved O₂, Fe³⁺, Cu²⁺, HNO₃, chromic acid, wet chlorine, hypochlorite — and high-chloride service where pitting or chloride SCC is a concern.
The universal workhorse and the correct default when stream chemistry is uncertain. The 16 Cr / 16 Mo / 4 W balance means it has no single dominant weakness: it is good in reducing acid, good in oxidizing media, and outstanding in wet chlorine, hypochlorite, chlorine dioxide and chloride solutions. In HCl it is the standard specification up to about 20% at 60–70°C. C-276 is also the best-stocked grade in the family, which matters for schedule-critical projects. Its limitation is that it is second-best at everything: B-3 beats it in pure HCl, C-22 and Alloy 59 beat it under oxidizing contamination, and it shows severe intergranular attack in G28 testing after sensitising.
The higher-chromium upgrade of C-276 (22% Cr). Marginally worse than C-276 in clean HCl, dramatically better once oxidizers appear — a 30-fold reduction in rate at 1000 ppm Fe³⁺ in the data above. C-22 is the industry standard for wet chlorine and bleach service, mixed acids, hazardous-waste incineration scrubbers and hydrometallurgy, and its weld-region corrosion resistance is among the best in the class. Choose C-22 over C-276 whenever the HCl stream is aerated, carries metal ions, or alternates between oxidizing and reducing conditions.
VDM's Nicrofer 5923 hMo, and arguably the most technically complete Ni-Cr-Mo alloy available. Higher molybdenum than C-276 or C-22, with tungsten deliberately omitted to maximise thermal stability — the ASTM G28 results above (40 and 4 mpy with no pitting or intergranular attack, versus >500 mpy for the others) are the clearest demonstration of that design choice. Documented as resisting full-concentration hydrochloric acid below about 40°C, particularly effective in mixed sulfuric/hydrochloric acid, more than three times lower corrosion rate than conventional Ni-Cr-Mo alloys in boiling 10% H₂SO₄, and insensitive to chloride-induced SCC. Specify Alloy 59 for thick-section welded HCl equipment, mixed-acid duty, and any application where fluoride ion is also present alongside hot HCl.
Special Metals' answer to Alloy 59, carrying the highest combined Cr + Mo + W of the group, which gives it the best pitting and crevice-corrosion performance (PREN about 51, Green Death CPT above 120°C). Designed for amphoteric mixed acids with high chloride content, and outstanding in seawater against uniform, galvanic and localized attack plus hydrogen embrittlement. Cold work raises yield strength to around 1000 MPa (150 ksi) with no loss of corrosion resistance, making it a strong choice for seawater fasteners. Alloy 686 filler metal is also widely used for corrosion-resistant weld overlay on steel. The trade-off versus Alloy 59 is thermal stability and weldability.
Same chromium and molybdenum base as Alloy 59, plus about 1.6% copper. The copper addition markedly improves resistance to reducing media, giving C-2000 the broadest single-grade redox coverage of the C-family — concentrated nitric, hot sulfuric, hydrochloric, hydrofluoric, mixed acids and chloride solutions. Forming, welding and machining behave like C-276. The costs of the copper addition are reduced localized-corrosion resistance and reduced thermal stability relative to Alloy 59.
A genuine hybrid: about 22% Mo with about 15% Cr, sitting deliberately between the B and C families. It delivers higher hydrochloric and sulfuric acid resistance than the C-series while retaining meaningful oxidizer tolerance and extreme pitting and crevice resistance, and is rated for reducing-acid exposure to about 427°C (800°F). In the immersion data above it is second only to B-3 in clean 20% HCl at both temperatures. Specify HYBRID-BC1 where the acid is strong and hot but occasional low-level oxidizer excursions cannot be engineered out — the region where B-3 is too fragile and C-276 corrodes too fast to be economical.
The low-cost option, valid only within a narrow window. Monel 400 gives useful resistance in deaerated HCl to roughly 10–15% at room temperature, with corrosion under about 10 mpy in 10% acid; in air-saturated acid above ambient the practical limit drops to about 3–4% HCl. It is the recognised material for processes where chlorinated solvents hydrolyse and generate low HCl levels (typically under 0.5%), where standard stainless steel would fail, and it performs well in dry-cleaning and solvent-recovery equipment at boiling temperature. It is also excellent in hydrofluoric acid and caustic. Never use it in aerated HCl, ferric or cupric chloride, wet chlorine or nitric acid.
Inconel 625 (20–23 Cr, 8–10 Mo, Nb-stabilized) has useful resistance to dilute HCl at moderate temperature and is often selected when a single alloy must cover HCl-bearing service alongside high-temperature or high-strength requirements — but it is not a substitute for a C-family alloy in concentrated acid. Commercially pure Nickel 200/201, despite being excellent in hot concentrated caustic, is not a hydrochloric acid material and should not be considered here.
Be honest about the limits of metallurgy. For hot, full-strength 32–37% HCl, and for HCl containing both high temperature and oxidizers or fluorides, the correct engineering answer is usually non-metallic or refractory-metal: PTFE/PFA-lined piping and vessels, impervious graphite heat exchangers, zirconium (excellent in HCl to about 20% but destroyed by ferric chloride and cupric ion), or tantalum, which is essentially immune to HCl at all concentrations and temperatures. Unalloyed titanium Grade 2 is a poor choice in reducing HCl; palladium-bearing Grade 7 or Grade 11 performs far better and, unusually, titanium improves in HCl that contains oxidizers — making it complementary to B-3 rather than a competitor.
| Your Service Condition | First Choice | Upgrade / Alternative When… |
|---|---|---|
| ≤0.5% HCl from solvent hydrolysis, deaerated | Monel 400 | Any aeration → C-276 |
| ≤10–15% HCl, ambient, strictly deaerated | Monel 400 (cost) / B-3 (life) | Aerated or hot → C-276 |
| 1–20% HCl, ambient to boiling, pure | Hastelloy B-3 | Fe³⁺ >50 ppm → C-22 / C-2000 |
| ≤20% HCl, to ~60–70°C, chemistry uncertain | Hastelloy C-276 | Oxidizers confirmed → C-22 |
| HCl + Fe³⁺ / Cu²⁺ / O₂ / free Cl₂ | C-22 / C-2000 / Alloy 59 | Never B-3 or Monel 400 |
| HCl + H₂SO₄ mixed acid | Alloy 59 | Add fluoride → Alloy 59 / G-30 |
| HCl + high chloride, pitting/crevice risk | Alloy 686 / C-22 | Thick welded sections → Alloy 59 |
| Strong hot HCl, occasional oxidizer upsets | HYBRID-BC1 | Continuous oxidizers → C-2000 |
| Thick-section welded HCl vessels | Alloy 59 (thermal stability) | Cost-driven → C-276 + PWHT control |
| Hot 32–37% HCl, or HCl + HF hot | Tantalum / PTFE-lined / graphite | No nickel alloy is comfortable |
| Wet chlorine, hypochlorite, ClO₂ | Hastelloy C-22 | C-276 acceptable; never B-3 |
Anhydrous hydrogen chloride gas behaves very differently from aqueous acid. Dry HCl gas is comparatively benign to nickel alloys at moderate temperature, and the Ni-Mo B-series performs well against HCl gas and halogen catalysts. The danger is condensation: wherever a gas stream drops below the acid dew point — cold ends of HCl absorbers, quench zones, reheater tubes, vent stacks — you get a highly concentrated aqueous acid film at low pH, often carrying chlorides and oxidizers together. Those condensation zones almost always dictate the material for the whole circuit.
In wet chlorine, hypochlorite and chlorine-dioxide service — common alongside HCl in chlor-alkali and pulp bleaching — the requirement flips fully to chromium. Hastelloy C-22 is the reference material, with C-276 also well established; B-3 is categorically excluded. In HCl-bearing high-temperature gas streams where oxidation and chloridation act together, C-276 and C-22 retain structural integrity to about 1035°C, while B-3 is limited to roughly 400–425°C and is a corrosion-service alloy only.
For high-velocity HCl vapour and splashing duty — pickling heaters, absorbers, pump housings — B-3 has documented resistance to repeated thermal cycling with the surface film intact, provided contamination control holds. In these same services, stainless and duplex steels typically fail by crevice activation within months.
Hangbo Alloy Group manufactures and supplies HCl-service alloys in a full range of forms, with mill test certificates (EN 10204 3.1 / 3.2) and third-party inspection (SGS, TÜV, BV) available on request:
| Alloy (UNS / W.Nr) | Plate/Sheet | Rod/Bar | Pipe/Tube | Filler Metal |
|---|---|---|---|---|
| Hastelloy B-3 (N10675 / 2.4600) | ASTM B333 | ASTM B335 | ASTM B622/B619/B626 | ERNiMo-10 |
| Hastelloy C-276 (N10276 / 2.4819) | ASTM B575 | ASTM B574 | ASTM B622/B619/B626 | ERNiCrMo-4 |
| Hastelloy C-22 (N06022 / 2.4602) | ASTM B575 | ASTM B574 | ASTM B622/B619/B626 | ERNiCrMo-10 |
| Alloy 59 (N06059 / 2.4605) | ASTM B575 | ASTM B574 | ASTM B622/B619/B626 | ERNiCrMo-13 |
| Alloy 686 (N06686 / 2.4606) | ASTM B575 | ASTM B574 | ASTM B622/B619/B626 | ERNiCrMo-14 |
| Hastelloy C-2000 (N06200 / 2.4675) | ASTM B575 | ASTM B574 | ASTM B622/B619/B626 | ERNiCrMo-17 |
| HYBRID-BC1 (N10362) | ASTM B575 | ASTM B574 | ASTM B622/B619 | Matching BC1 |
| Monel 400 (N04400 / 2.4360) | ASTM B127 | ASTM B164 | ASTM B165/B725 | ERNiCu-7 / ENiCu-2 |
| Inconel 625 (N06625 / 2.4856) | ASTM B443 | ASTM B446 | ASTM B444/B704/B705 | ERNiCrMo-3 |
Castings for pumps and valves follow ASTM A494 (grades CW-12MW, CX2MW, N-12MV, M35-1). Forgings are covered by ASTM B564, pipe fittings by ASTM B366. Where the HCl duty overlaps sour service, NACE MR0175 / ISO 15156 applies. Pressure equipment is designed to ASME VIII, EN 13445 or the applicable national code, and all grades carry EN / DIN W.Nr. cross-references.
In HCl service, fabrication discipline is as important as grade selection. Documented failure analyses point repeatedly to the same causes, none of which are general corrosion:
Ultrasonic and dye-penetrant inspection is mandatory for pressure-bearing components, particularly near weld overlaps, and periodic wall-thickness survey should be built into the maintenance plan from commissioning.
For clean, oxidizer-free (reducing) hydrochloric acid, Hastelloy B-3 (UNS N10675) is the best metallic choice — it holds under 0.1 mm/year in 1–20% HCl from ambient to boiling. But that answer inverts the moment oxidizers appear: with ferric (Fe³⁺) or cupric (Cu²⁺) ions, dissolved oxygen, wet chlorine or nitric acid in the stream, B-3 is attacked rapidly and you must switch to a high-chromium Ni-Cr-Mo alloy such as Hastelloy C-22, C-2000 or Alloy 59. Hastelloy C-276 is the safe general-purpose default when the stream chemistry is uncertain.
No. Hydrochloric acid is the mineral acid where austenitic stainless steels fail worst. 316L suffers rapid general corrosion, pitting and chloride stress-corrosion cracking in even dilute HCl above trace concentration, with rates typically well above 1 mm/year. Specifying 316L for HCl duty is a design error, not a cost saving — the practical entry point for HCl service is a nickel alloy, a fluoropolymer or graphite lining, or in special cases zirconium or tantalum.
Hastelloy B-3 is a nickel-molybdenum alloy (Ni ~65%, Mo ~28.5%, Cr ~1.5%) whose resistance comes almost entirely from molybdenum. In pure HCl it outperforms C-276 at every concentration above about 5% and every temperature above ambient. Hastelloy C-276 is a Ni-Cr-Mo-W alloy (Cr ~16%, Mo ~16%, W ~4%) that trades some pure-acid performance for the chromium-based passivation needed to survive oxidizing contamination, wet chlorine and chloride pitting. Rule of thumb: pure acid means B-3, dirty acid means C-276 or higher.
Ferric and cupric ions are oxidizers, and they shift the corrosion potential of the solution upward. Low-chromium alloys such as Hastelloy B-3 have no passivation reserve, so they keep corroding actively and can pit — contamination as low as a few ppm Fe³⁺ measurably accelerates B-3, and tens to hundreds of ppm can raise the rate by orders of magnitude. High-chromium alloys behave in exactly the opposite way: published immersion data in 20% HCl at 52°C show C-22, C-2000, Alloy 59 and G-35 dropping to roughly 0.2–0.4 mpy once 1000 ppm Fe³⁺ is present, because the oxidizer actually pushes them into their passive range.
As a practical design envelope, Hastelloy C-276 is used up to about 20% HCl at temperatures to roughly 60–70°C, and in dilute acid (below about 5%) to considerably higher temperature. Published immersion data give about 1.6 mpy in 20% HCl at 23°C, rising to about 11 mpy at 52°C — usable but not negligible, so a corrosion allowance and periodic thickness survey are required. Above these limits, move to Hastelloy B-3 for pure acid, or to HYBRID-BC1, Alloy 59 or a non-metallic lining for hot concentrated service.
Only in dilute, air-free acid. Monel 400 (UNS N04400) gives useful resistance in deaerated HCl up to roughly 10–15% at room temperature, with corrosion under about 10 mpy in 10% acid, and it is a recognised material for processes where chlorinated solvents hydrolyse and generate low levels of HCl (typically under 0.5%). In air-saturated acid above room temperature the practical limit falls to about 3–4% HCl, and any oxidizing salt content accelerates attack sharply. Monel 400 must never be used in aerated or oxidizer-contaminated HCl.
HASTELLOY HYBRID-BC1 (UNS N10362) is a Ni-Mo-Cr alloy positioned deliberately between the B-series and C-series, with roughly 22% molybdenum and 15% chromium. It offers higher hydrochloric and sulfuric acid resistance than the C-family while retaining more oxidizer tolerance and localized-corrosion resistance than B-3, and is rated for reducing acid exposure to about 427°C. Specify it where HCl is strong and hot but low-level oxidizer upsets cannot be entirely ruled out — the case where B-3 is too fragile and C-276 is too slow-corroding to be economical.
Alloy 59 (UNS N06059, VDM Nicrofer 5923 hMo) is documented as resisting full-concentration hydrochloric acid below about 40°C, and is insensitive to chloride-induced stress-corrosion cracking. Hastelloy B-3 covers essentially all concentrations up to boiling provided the acid is pure and free of oxidizers. For hot, full-strength 37% HCl with contamination, no nickel alloy is comfortable and the correct answer is usually tantalum, a graphite or fluoropolymer-lined vessel, or PTFE-lined piping.
All three are premium Ni-Cr-Mo grades that sit above C-276 and C-22. Alloy 686 (N06686) has the highest combined Cr+Mo+W and the best pitting resistance (PREN about 51), with about 10.4 mpy in 20% HCl at 52°C — the lowest of the C-family. Alloy 59 (N06059) removes tungsten in favour of higher molybdenum, which gives it outstanding thermal stability: after sensitising, ASTM G28A/G28B testing shows about 40 and 4 mpy with no intergranular attack, where C-276, C-22 and 686 all exceed 500 mpy in at least one test. C-2000 (N06200) adds about 1.6% copper for better reducing-acid coverage but at the cost of thermal stability and localized-corrosion resistance.
Unalloyed titanium (Grade 1/2) is a poor choice for reducing hydrochloric acid — it depends on an oxide film that HCl strips, so it corrodes rapidly in acid above roughly 1–3% at moderate temperature. Palladium-bearing Grade 7 or Grade 11 titanium performs far better and is used in some dilute HCl and mixed-acid duties. Interestingly, titanium performs best in HCl that contains oxidizers, which is exactly the condition that destroys Hastelloy B-3 — so titanium and B-3 are complementary rather than competing solutions.
Hastelloy B-3 = UNS N10675 (W.Nr 2.4600), ASTM B333/B335/B622/B619/B626. Hastelloy C-276 = UNS N10276 (W.Nr 2.4819), ASTM B575/B574/B622. Hastelloy C-22 = UNS N06022 (W.Nr 2.4602), ASTM B575/B574/B622. Alloy 59 = UNS N06059 (W.Nr 2.4605), ASTM B575/B574/B622. Alloy 686 = UNS N06686 (W.Nr 2.4606). C-2000 = UNS N06200 (W.Nr 2.4675). HYBRID-BC1 = UNS N10362. Monel 400 = UNS N04400 (W.Nr 2.4360), ASTM B127/B164/B165. Castings follow ASTM A494.
Yes, all are weldable with matching-composition filler and qualified procedures. C-276 uses ERNiCrMo-4, C-22 uses ERNiCrMo-10, Alloy 59 uses ERNiCrMo-13, Alloy 686 uses ERNiCrMo-14, and B-3 uses ERNiMo-10 (B-3) filler. Modern low-carbon, low-silicon melting practice largely eliminates heat-affected-zone sensitization, and B-3 in particular was developed to fix the post-weld intergranular-corrosion problem of the older B-2. Critical practice points for HCl equipment: no ferrous tooling or embedded iron, alkaline-permanganate or pickle-and-passivate cleaning before service, and full-penetration welds with no crevices — most field failures in HCl plants are crevice attack under gaskets, not general corrosion.
Send your HCl concentration, operating and upset temperature, oxidizer or metal-ion content (Fe³⁺, Cu²⁺, free chlorine), pressure and required product form to Hangbo Alloy Group at [email protected] or call/WhatsApp +86-136-1165-6360. As a direct manufacturer and supplier we provide competitive price quotes, mill test certificates to EN 10204 3.1/3.2, third-party inspection and worldwide delivery of bars, plates, seamless tubes, forgings, fittings and welding consumables in B-3, C-276, C-22, C-2000, Alloy 59, Alloy 686 and Monel 400.
For help choosing between Hastelloy B-3, C-276, C-22, C-2000, Alloy 59, Alloy 686, HYBRID-BC1 or Monel 400 for your hydrochloric acid service — or for a quotation on bars, plates, seamless tubes, forgings, fittings or welding consumables — contact Hangbo Alloy Group. We typically respond within 10 minutes and ship worldwide from our Shanghai facility.
Email: [email protected]
Phone: +86-136-1165-6360
WhatsApp: +86 13611656360
Send us your concentration, temperature and oxidizer profile and we will recommend the most cost-effective certified nickel alloy, with a competitive quote and full certification.