Introduction

Titanium for Chemical Equipment is used in heat exchangers, reactors, evaporators, pressure vessels, piping, pumps, valves, anodes and tank linings where chlorides, oxidizing acids or wet chlorine can cause rapid failure of conventional metals. Grade 2 is the standard starting material for neutral chloride solutions, seawater, wet chlorine and many oxidizing chemical environments. Grade 7 offers a larger corrosion margin in acidic or crevice-prone service, while Grade 12 combines higher strength with improved resistance in selected reducing-acid and chloride conditions.

Titanium is not universally resistant to every acid. Its performance depends on the stability of a thin titanium-oxide passive film. Oxygen, ferric ions, cupric ions, nitric acid and other oxidizing species can support passivation, while hot oxygen-depleted hydrochloric or sulfuric acid may dissolve the protective film. Hydrofluoric acid and fluoride-containing solutions are particularly hazardous because fluoride ions attack titanium oxide directly.

Why Titanium Resists Chemical Corrosion

Passive Oxide Film

Titanium reacts rapidly with oxygen and moisture to form a thin, adherent oxide layer. This film separates the base metal from the process fluid and can reform after minor mechanical damage when enough oxidizing potential is available. The passive film explains titanium’s strong resistance to many chloride solutions despite the aggressive effect chlorides have on stainless steels.

The film is stable in many neutral and oxidizing solutions but less stable in strongly reducing acids. Corrosion performance may change sharply when temperature rises, oxygen is removed or the solution becomes concentrated beneath a deposit or gasket.

Resistance to Chloride Pitting

Commercially pure titanium generally provides strong resistance to pitting in seawater, brines, sodium chloride and many metal-chloride solutions. This makes it valuable for chlor-alkali plants, brine heaters, seawater coolers, bleach systems and chloride-bearing process streams.

Crevice corrosion is normally the more important limitation. Under tight gaskets, deposits or shielded metal surfaces, oxygen can become depleted and acidity can increase. Grade 7 or another corrosion-enhanced titanium grade may be justified where Grade 2 has insufficient margin.

Effect of Oxidizing Species

Oxidizing ions can improve titanium performance in otherwise aggressive reducing acids. Ferric chloride, cupric ions, dissolved oxygen and nitric acid may help maintain passivity. This is why the complete process chemistry matters: technically similar hydrochloric-acid streams may produce very different corrosion rates when their impurity and oxidation conditions differ.

Titanium Chemical Equipment Product Data

Specification Item	Typical Options	Buyer Check
Grades	Grade 1, Grade 2, Grade 7, Grade 11, Grade 12 and project-approved grades	Select from actual fluid chemistry and temperature rather than strength alone.
Product Forms	Plate, sheet, seamless pipe, welded pipe, heat-exchanger tube, fittings and forgings	Match the product form to the correct ASTM or ASME specification.
Equipment Types	Reactors, vessels, condensers, evaporators, columns, pumps, valves and piping	Define pressure, temperature, vacuum and cyclic-service conditions.
Surface	Pickled, blasted, machined, polished or cleaned	Control iron contamination, embedded particles and fabrication residues.
Construction	Solid titanium, titanium-lined steel or titanium-clad steel	Compare pressure load, vessel size, fabrication route and lifecycle cost.
Documentation	MTC, EN 10204 3.1, PMI, NDT, dimensional and heat-treatment reports	List all required certificates before manufacturing begins.

Recommended Titanium Grades

Grade	UNS	Main Benefit	Typical Chemical Use
Grade 1	R50250	Maximum ductility and formability	Deep-formed linings, complex vessel parts and low-pressure fabricated equipment.
Grade 2	R50400	Balanced corrosion resistance, weldability and availability	Chlorides, wet chlorine, nitric acid, seawater, oxidizing salts and general chemical equipment.
Grade 7	R52400	Grade 2 base with palladium-enhanced repassivation	Hot acidic chlorides, reducing acids and crevice-prone equipment.
Grade 11	R52250	Grade 1-type ductility with palladium addition	Deep-formed corrosion-resistant components requiring improved crevice performance.
Grade 12	R53400	Higher strength with nickel and molybdenum additions	Process piping, heat exchangers and selected reducing-acid or hot-brine service.

Chemical Composition Reference

The following composition details are general references. Final acceptance must follow the ordered specification and batch-specific material certificate.

Grade	Principal Composition Character	Corrosion Effect
Grade 1	Commercially pure titanium with low oxygen and iron	Supports high ductility for linings and complex forming.
Grade 2	Commercially pure titanium with controlled oxygen and iron	Standard industrial balance for chloride and oxidizing service.
Grade 7	Grade 2-type titanium with approximately 0.12-0.25% palladium	Improves passivity in selected reducing and crevice conditions.
Grade 11	Grade 1-type titanium with approximately 0.12-0.25% palladium	Combines improved corrosion resistance with high formability.
Grade 12	Approximately 0.6-0.9% nickel and 0.2-0.4% molybdenum	Adds strength and broadens resistance in selected process environments.

Resistance to Chlorides and Acids

Chemical Environment	Titanium Performance Direction	Selection Note
Neutral Chloride Solutions	Generally excellent resistance	Grade 2 is commonly suitable; evaluate crevices and temperature.
Wet Chlorine and Hypochlorite	Often strong resistance when moisture is present	Dry chlorine conditions require separate review because moisture supports passivation.
Nitric Acid	Generally favorable because nitric acid is oxidizing	Concentration, temperature and contamination still control suitability.
Hydrochloric Acid	Limited in hot or oxygen-depleted reducing conditions	Grade 7 or 12 may improve performance; laboratory corrosion review is recommended.
Sulfuric Acid	Highly dependent on concentration, temperature and oxidizing species	Do not assume general resistance without process-specific data.
Hydrofluoric Acid or Fluorides	Generally unsuitable or severely restricted	Fluoride attacks the protective titanium-oxide film.
Organic Acids	Often favorable in aerated or oxidizing conditions	Review water content, contaminants and reducing conditions.

Applications in Chemical Plants

Application	Recommended Starting Grade	Critical Engineering Check
Chlor-Alkali Heat Exchangers	Grade 2 or Grade 7	Wet chlorine, brine purity, crevices and tube-to-tube-sheet joints.
Bleach and Hypochlorite Systems	Grade 2	Concentration, temperature, deposits and wetted condition.
Acid Reactors and Vessels	Grade 7 or Grade 12 after corrosion review	Acid concentration, aeration, impurities, agitation and temperature.
Evaporators and Condensers	Grade 2 or Grade 7	Concentration changes, boiling conditions, deposits and cleaning chemicals.
Chemical Transfer Piping	Grade 2 or Grade 12	Pressure, flow, erosion, dead legs, gasket design and joining method.
Pump and Valve Components	Grade 2, Grade 7 or Grade 12	Cavitation, wear, galling, crevices and mechanical load.

Product Standards and Specification Checks

Product Form	Common ASTM Reference	Typical Use
Sheet and Plate	ASTM B265	Vessels, tube sheets, covers, linings and fabricated equipment.
Heat-Exchanger Tube	ASTM B338	Condensers, evaporators, coolers and process heat exchangers.
Seamless Pipe	ASTM B861	Pressure piping and corrosion-resistant process lines.
Welded Pipe	ASTM B862	Large-diameter chemical transfer and low-to-moderate pressure piping.
Welding Fittings	ASTM B363	Elbows, tees, reducers, caps and stub ends.
Forgings and Flanges	ASTM B381	Flanges, rings, hubs and pressure-component forgings.

Limitations and Common Design Risks

Reducing acids: Hot hydrochloric and sulfuric acids can attack Grade 2 rapidly when oxidizing species are insufficient. Grade 7 or Grade 12 may increase the acceptable operating range, but they do not make titanium universally resistant.

Fluoride contamination: Even relatively small fluoride additions can damage the passive film. Hydrofluoric acid, acidic fluoride cleaners and fluoride-bearing process impurities require specialist review.

Crevice corrosion: Gaskets, lap joints, deposits and stagnant zones can create oxygen-depleted local chemistry. Crevice design, gasket material and cleaning access should be considered during equipment engineering.

Hydrogen absorption: Strong cathodic polarization, reducing conditions or galvanic contact can promote hydrogen entry. This may reduce ductility if sufficient hydride forms.

Dry chlorine: Titanium performs differently in wet and dry chlorine. Moisture generally supports passivation, while dry chlorine service requires a separate safety and compatibility review.

Galling and wear: Titanium has limited sliding-wear resistance. Valve stems, threads and rotating components may need surface treatment, lubrication or compatible mating materials.

Inspection, Traceability and Fabrication Control

Heat-number control should connect every plate, pipe, tube, fitting and forging to its original production heat and processing lot. Product markings, package labels, packing lists and the MTC should show consistent identification. Cut material requires transferred markings or controlled traceability records.

An EN 10204 3.1 MTC can document the grade, standard, chemistry, mechanical properties, condition and dimensions. PMI can help distinguish Grade 2, Grade 7 and Grade 12, although complete chemistry and low-level palladium confirmation may require laboratory analysis.

UT may be specified for thick plate, forged tube sheets or critical large-section products. Heat-exchanger tube is more commonly examined by eddy-current testing, pressure testing and dimensional inspection. Welded equipment may require liquid penetrant, radiographic or leak testing according to the fabrication code and approved inspection plan.

Titanium must be welded with effective inert-gas shielding. Blue, grey or powdery weld discoloration may indicate atmospheric contamination while the weld was hot. Dedicated tools, clean gloves and separated fabrication areas reduce iron pickup and embedded contamination.

Chemical Equipment RFQ Checklist

✅ State the complete process fluid, concentration and expected impurities.

✅ Provide normal, startup, cleaning and upset temperatures.

✅ Define pressure, vacuum, flow velocity and agitation conditions.

✅ Identify the grade, product form and ASTM or ASME specification.

✅ Describe gaskets, deposits, dead legs and potential crevice locations.

✅ State whether solid titanium, lining or titanium-clad steel is required.

✅ Request EN 10204 3.1 MTC, PMI, UT, PT, RT or eddy-current reports as applicable.

✅ Define marking, flange-face protection, seaworthy packaging and destination port.

FAQ

Which titanium grade is most common for chemical equipment?

Grade 2 is the normal starting choice because it provides good corrosion resistance, weldability, formability and availability for chloride solutions, wet chlorine, nitric acid and many oxidizing chemical environments.

When should Grade 7 be selected instead of Grade 2?

Grade 7 should be considered when hot acidic chlorides, reducing acids, oxygen-depleted crevices or gasketed joints create conditions in which Grade 2 may not remain reliably passive. A process-specific corrosion review is still required.

Is titanium resistant to hydrochloric and sulfuric acid?

Titanium resistance to hydrochloric and sulfuric acid depends strongly on concentration, temperature, aeration and oxidizing impurities. Grade 2 may be unsuitable in hot reducing solutions, while Grade 7 or Grade 12 can improve performance in selected conditions.

Can titanium be used with hydrofluoric acid?

Titanium is generally not selected for hydrofluoric acid or aggressive fluoride-containing solutions because fluoride ions attack its protective oxide film. Any fluoride exposure requires specialist material review.

Related Titanium Products and Guides

Related Resource	Procurement Relevance
Titanium Pipe and Tube	Seamless pipe, welded pipe and heat-exchanger tube for chemical transfer, cooling and condensation.
Titanium Plate and Sheet	Plate and sheet for reactors, vessels, tube sheets, linings and fabricated chemical equipment.
Titanium Fittings	Elbows, tees, reducers and other corrosion-resistant piping components.
Titanium Pipe and Tube for Chemical Processing	Additional guidance on pipe, tube, wall thickness, standards and chemical-processing applications.

Conclusion

Titanium provides long-term corrosion resistance in chloride-rich, oxidizing and wet-chlorine chemical environments when its passive oxide film remains stable. Grade 2 covers many general plant applications, Grade 7 provides a larger margin in acidic and crevice-prone service, and Grade 12 adds strength with broader resistance in selected process streams. Reliable selection requires complete chemistry and operating data rather than a simple acid name or chloride concentration.