Author: Senthil Kumar, Technical Director | Updated: September 2026
Table of Contents
- What Is a Hastelloy Heat Exchanger?
- Hastelloy Grades — C-276, C-22, B-2 and B-3
- Types of Hastelloy Heat Exchangers
- Key Components and Construction
- Engineering Advantages
- Design Standards — ASME, ASTM and TEMA
- Industries and Applications
- Hastelloy vs Stainless Steel vs Titanium
- Why United Heat Exchangers
- Delivery
- Frequently Asked Questions
What Is a Hastelloy Heat Exchanger?
A Hastelloy heat exchanger uses nickel-molybdenum-chromium superalloy tubes, plates, or full pressure parts in place of stainless steel wherever the process stream combines both oxidizing and reducing acids, or where a single stream swings between the two — conditions that destroy 316L and even duplex stainless steel within months.Hastelloy is a registered trademark family of nickel-based alloys engineered for uniform corrosion resistance across an unusually broad chemical envelope: hot hydrochloric acid, sulfuric acid, phosphoric acid, wet chlorine, and mixed-acid streams that would otherwise require switching materials mid-process. United Heat Exchangers designs and fabricates Hastelloy shell-and-tube and Hastelloy plate heat exchangers to ASME Section VIII and TEMA for chemical process, pharmaceutical, and flue gas desulfurization clients across India and 30+ export markets.
Hastelloy Grades — C-276, C-22, B-2 and B-3
"Hastelloy" covers a family of related but distinct alloys, each formulated for a different corrosion profile. Selecting the correct grade for the specific acid mixture, concentration, and temperature in your process is the single most important engineering decision on a Hastelloy exchanger.
Assess Process Chemistry
Identify every acid, oxidizer, and chloride present, including upset and cleaning-cycle conditions, not just normal operation.
Check Temperature Range
Corrosion rates for nickel alloys are strongly temperature-dependent — the worst-case operating temperature governs grade selection.
Select the Grade
C-276 for mixed oxidizing/reducing acids; C-22 for higher oxidizing resistance; B-2 or B-3 for pure hydrochloric or sulfuric acid.
Verify Weldability
Confirm filler metal and post-weld heat treatment requirements to preserve corrosion resistance at every joint.
Certify Traceability
Mill certificates and PMI testing confirm the correct alloy is installed at every pressure part before dispatch.
Engineering Insight — Why Grade Selection Cannot Be Generic: Hastelloy C-276 is the default recommendation for most mixed-acid chemical process duties because of its broad resistance envelope, but it is not the correct choice everywhere. Hastelloy B-2 and B-3 resist pure hydrochloric and sulfuric acid better than C-276 in reducing conditions, while C-22 offers superior resistance where oxidizing species such as ferric or cupric chlorides are present. United Heat Exchangers reviews your full process chemistry, including upset scenarios, before recommending a grade.
Types of Hastelloy Heat Exchangers
United Heat Exchangers builds Hastelloy into the same core exchanger configurations offered in stainless steel and titanium, with mechanical design and welding procedures adjusted for nickel alloy behaviour.
Hastelloy Shell and Tube Heat Exchanger
Hastelloy tubes inside a carbon steel or clad shellHastelloy tubes are the most common configuration — the shell and channel remain carbon steel or stainless, with only the surfaces in contact with the corrosive stream built in Hastelloy.
- Fixed tubesheet, U-tube, or floating head per TEMA type
- Hastelloy or Hastelloy-clad tubesheets to prevent galvanic attack at the joint
- Standard for mixed-acid process coolers and reboilers
- Lowest-cost Hastelloy configuration — only wetted parts use the alloy
Hastelloy Plate Heat Exchanger
Thin Hastelloy plates for compact, high-efficiency dutiesCorrugated Hastelloy plates gasketed or fully welded into a compact frame give very high heat transfer coefficients in a fraction of the footprint of an equivalent shell-and-tube unit.
- EPTFE or PTFE-based gaskets rated for aggressive acid chemistry
- Fully welded construction for high-purity or leak-critical duties
- Preferred where plot space is limited — skid-mounted process packages
- Plates easily added or removed to adjust duty without a new exchanger
Hastelloy-Clad Construction
Hastelloy-clad tubesheet, channel and shell interiorFor the most aggressive duties, tubesheets, channel covers, and shell interiors are explosion-bonded or weld-overlay clad with Hastelloy over a carbon steel or low-alloy backing plate.
- Full corrosion protection on every wetted pressure boundary
- Carbon steel backing retains structural strength and lowers material cost
- Used in FGD absorber recirculation coolers and mixed-acid reactors
- Cladding qualified per ASME Section IX procedure and bond-strength testing
Solid Hastelloy Construction
All pressure parts in Hastelloy — maximum corrosion marginTubes, tubesheets, channel, and shell are all fabricated in Hastelloy where the process side is as corrosive as the cooling side, or where absolute leak-tightness against galvanic attack is required.
- No dissimilar-metal joints — eliminates galvanic corrosion risk entirely
- Standard for wet chlorine, mixed-acid, and pharmaceutical API cooling duties
- Higher material cost offset by near-zero maintenance over service life
- Available in C-276, C-22, B-2, or B-3 to match the exact process chemistry
Key Components and Construction
Hastelloy Tubes
Seamless tubes to ASTM B622, typically Grade C-276 as the industry default for mixed-acid process coolers and reboilers, selected for both strength and formability during tube expansion into the tubesheet.
Hastelloy or Clad Tubesheet
Solid Hastelloy, weld-overlay clad, or explosion-bonded clad tubesheets to ASTM B575 plate stock. The tube-to-tubesheet joint is roller expanded, welded, or both, depending on pressure class and vibration exposure.
Channel and Shell
Typically carbon steel or low-alloy steel with an internal Hastelloy clad liner or full Hastelloy fabrication on the wetted face — sized and designed to ASME Section VIII Division 1 as an independent pressure vessel.
Baffles and Tie Rods
Hastelloy or coated carbon steel baffles direct shell-side flow across the tube bundle and support the tubes against flow-induced vibration — material selected based on shell-side fluid corrosivity.
Qualified Weld Procedures
Nickel-alloy filler metal matched to the base grade, with controlled heat input to avoid carbide precipitation and preserve corrosion resistance at every welded joint — qualified per ASME Section IX.
Isolation Gaskets and Fasteners
Non-metallic isolation gaskets or coatings prevent direct contact between Hastelloy and carbon steel flanges, and Hastelloy or coated fasteners are used at any joint exposed to the process stream to prevent galvanic attack.
Engineering Advantages of Hastelloy Heat Exchangers
Resists Oxidizing and Reducing Acids Alike
Hastelloy C-276 handles both oxidizing acids (nitric, ferric chloride) and reducing acids (hydrochloric, sulfuric) in a single alloy — no other engineering metal covers this dual range as reliably.
Immune to Chloride Pitting and SCC
Like titanium, the nickel-chromium-molybdenum matrix does not pit or stress-corrosion crack in chloride environments — a decisive advantage over 316L and even most duplex stainless grades.
Stable at High Temperature
Hastelloy retains corrosion resistance and mechanical strength at process temperatures where stainless steel corrosion rates accelerate sharply, extending safe operating margins.
Excellent Weldability
With correctly matched filler metal and controlled heat input, Hastelloy welds retain the base metal's corrosion resistance — critical for fabricated pressure equipment with multiple joints.
Lower Total Life-Cycle Cost
Higher material cost per kilogram than stainless steel, but a multi-decade service life with negligible unplanned replacement gives Hastelloy the lowest total cost of ownership in mixed-acid duties.
Broad Regulatory and Pharma Acceptance
Hastelloy is widely accepted for pharmaceutical API and fine chemical production where both product purity and resistance to aggressive cleaning and process chemistries are required simultaneously.
Design Standards — ASME, ASTM and TEMA
Every Hastelloy heat exchanger from United Heat Exchangers is designed, sourced, and documented to the following codes.
| Standard | Scope | Key Output |
|---|---|---|
| ASME Section VIII Div. 1 | Pressure vessel design of shell, channel, and tubesheet — wall thickness, weld NDE, and hydrostatic test at 1.3× MAWP | ASME U-Stamp; Manufacturer's Data Report (Form U-1) signed by Authorised Inspector |
| ASTM B622 | Seamless nickel-alloy tubes for heat exchangers — chemical composition, mechanical properties, and eddy-current test acceptance for C-276, C-22, B-2, and B-3 | Mill test certificates; 100% eddy-current or hydrostatic tube test reports |
| ASTM B575 | Nickel-molybdenum-chromium alloy plate, sheet, and strip for tubesheets, baffles, and clad liners | Traceable mill certification for every plate used in pressure parts |
| TEMA Class R / C / B | Mechanical design rules for tube pitch, baffle spacing, tube-to-tubesheet joints, and bundle removal — Class R for refinery-severity service, Class C for commercial, Class B for chemical process | TEMA-compliant mechanical drawing set and tube layout |
| HTRI Xist Software | Rigorous thermal and hydraulic rating — tube-side and shell-side heat transfer, pressure drop, and vibration analysis specific to nickel alloy tube properties | Guaranteed thermal performance certificate; vibration analysis report |
Specification Tip: Share the complete process fluid composition — including trace species, upset conditions, and cleaning chemicals — along with temperature and concentration ranges. This determines whether C-276, C-22, B-2, or B-3 is the correct and most cost-effective grade before manufacture begins.
Industries and Applications
| Industry | Typical Duty | Process Stream | Configuration |
|---|---|---|---|
| Chemical Process | Mixed-acid reactor coolers, acid concentrators, reboilers | Hydrochloric, sulfuric, phosphoric, and mixed-acid streams | Hastelloy C-276 shell-and-tube, solid or clad construction |
| Flue Gas Desulfurization | Absorber slurry recirculation cooler, wet scrubber heat recovery | Chloride-laden, low-pH scrubber liquor | Hastelloy-clad tubesheet and channel over carbon steel shell |
| Pharmaceutical & Fine Chemicals | API reaction cooling, solvent recovery, CIP-compatible process coolers | Aggressive cleaning acids and high-purity process fluids | Solid Hastelloy plate or shell-and-tube, polished finish |
| Metal Pickling & Surface Treatment | Pickling bath heater/cooler, acid regeneration heat exchanger | Hydrochloric or sulfuric acid pickling liquor with dissolved metal chlorides | Hastelloy B-2 or B-3 tubes for reducing-acid resistance |
| Waste Incineration | Flue gas quench cooler, acid gas condenser | Condensing acid gases with high chloride and sulfate content | Hastelloy C-22 for superior oxidizing-condition resistance |
Hastelloy vs Stainless Steel vs Titanium
| Parameter | Hastelloy C-276 | 316L Stainless Steel | Titanium (Grade 2) |
|---|---|---|---|
| Mixed Acid Resistance | Excellent across both oxidizing and reducing acids in a single alloy | Poor to moderate — corrodes quickly in most concentrated acids | Good in oxidizing conditions; poor in strong reducing acids |
| Chloride Pitting / SCC Resistance | Immune at essentially all practical concentrations | Pits and stress-corrosion cracks above ~200–400 ppm chloride at temperature | Immune at essentially all practical concentrations |
| High-Temperature Acid Duty | Retains resistance well above stainless steel's practical limits | Corrosion rate accelerates sharply with temperature | Strong in oxidizing acids; loses resistance in hot reducing acids |
| Weldability | Good, with matched filler metal and controlled heat input | Excellent — the industry baseline for weldability | Good, but requires inert-gas purge to prevent oxide contamination |
| Relative Material Cost | Highest per kilogram, lowest life-cycle cost in mixed-acid service | Lowest initial cost, but frequent failure in aggressive acid duty | High initial cost; best value specifically in chloride-dominant service |
When to Choose Hastelloy: Hastelloy is the correct choice whenever the process stream contains acids that swing between oxidizing and reducing conditions, or mixed-acid chemistries that no single stainless or titanium grade can handle reliably. Where the corrosive medium is chloride-dominant and single-mode (seawater, brine), titanium is typically the more cost-effective alternative — United Heat Exchangers reviews both options against your process chemistry before recommending one.
Why United Heat Exchangers
Nickel Alloy Fabrication Specialist
Qualified welding procedures for Hastelloy-to-Hastelloy and Hastelloy-clad joints, using matched filler metal and controlled heat input to preserve base-metal corrosion resistance at every joint.
HTRI Xist Thermal Guarantee
Bundle geometry, baffle spacing, and tube layout optimized in HTRI Xist for nickel alloy thermal and vibration properties. We issue a guaranteed thermal performance certificate with every order.
ASME U-Stamp Certified
Pressure parts carry the ASME U-Stamp with full Manufacturer's Data Reports, alongside traceable ASTM B622/B575 mill certification and PMI verification for every Hastelloy component sourced.
30+ Countries — Full In-House Engineering
From process datasheet to certified fabrication drawing — grade selection, thermal design, and export documentation — entirely in-house, no subcontracting. Delivered to chemical process and pharma clients across 30+ countries.
Get a Free Hastelloy Heat Exchanger Quote in 48 Hours
Send your process duty, full stream chemistry including upset conditions, temperature range, and site location. We return an HTRI-sized thermal proposal, grade recommendation, and budgetary quote within 48 hours.
Request My Free Quote →Delivery and What's Included
- HTRI Xist thermal and vibration analysis — tube-side and shell-side heat transfer, pressure drop, and flow-induced vibration check specific to nickel alloy tube properties
- ASME U-Stamp and Manufacturer's Data Report (Form U-1) — for all pressure parts, signed by Authorised Inspector; MAWP and design temperature stamped on nameplate
- ASTM B622 / B575 mill certification — full material traceability for every Hastelloy tube, plate, and tubesheet used in the exchanger
- PMI (positive material identification) reports — 100% verification that the correct Hastelloy grade is installed at every pressure part
- Weld procedure qualification records — matched filler metal and heat-input control procedures for every Hastelloy joint, qualified per ASME Section IX
- Operations and maintenance manual — tube cleaning procedure, inspection intervals, and 2-year spare parts list
Frequently Asked Questions — Hastelloy Heat Exchanger
What is a Hastelloy heat exchanger used for?
A Hastelloy heat exchanger uses nickel-molybdenum-chromium alloy tubes or plates wherever the process stream contains mixed oxidizing and reducing acids, or hot chloride-bearing chemicals, that would corrode stainless steel within months. It is standard for chemical process reactors, flue gas desulfurization, pharmaceutical API production, and acid pickling lines.
What is the difference between Hastelloy C-276 and C-22?
C-276 offers the broadest general resistance across both oxidizing and reducing acid environments and is the most commonly specified grade. C-22 provides superior resistance specifically in oxidizing conditions — such as ferric or cupric chloride environments — where C-276 is comparatively weaker. The correct grade depends on the specific oxidizing species present in your process.
Is Hastelloy better than titanium for corrosion resistance?
Neither is universally "better" — they resist different failure modes. Titanium excels specifically against chloride pitting and stress corrosion cracking, as in seawater. Hastelloy excels across a broader range of acid chemistries, including mixed oxidizing and reducing acids that titanium cannot reliably handle. Stream chemistry, not chloride content alone, determines which alloy is correct.
Does a Hastelloy heat exchanger need the whole unit to be Hastelloy?
No. Most units use Hastelloy tubes and a Hastelloy or Hastelloy-clad tubesheet inside a conventional carbon steel shell and channel — this protects only the wetted surfaces at the lowest material cost. Fully solid Hastelloy construction is reserved for duties where the process side is equally corrosive on both sides of the exchanger.
Can Hastelloy heat exchangers be welded on site?
Yes, but field welds require the same qualified procedures, matched filler metal, and heat-input control as shop welds to preserve corrosion resistance. United Heat Exchangers documents weld procedure specifications so site fabricators or maintenance teams can replicate shop-quality joints during turnarounds.
What is the lead time for a Hastelloy heat exchanger from India?
Standard Hastelloy-tube shell-and-tube exchangers with a carbon steel shell deliver in 10–14 weeks. Solid Hastelloy, Hastelloy-clad, ASME U-Stamp, or large custom-engineered units take 16–24 weeks depending on tube quantity and cladding requirements. Expedited delivery is available for plant shutdowns and emergency replacements — contact us with your timeline.
Author: Senthil Kumar, Technical Director — United Heat Exchangers Pvt. Ltd. | Last Updated: September 2026
