Why Titanium Is the Ideal Material for Chemical Processing Equipment

Why Titanium Beats Stainless Steel in Chemical Service

Titanium combines seawater-grade corrosion resistance with a density of only 4.51 g/cm3 and high specific strength. In chemical plants it resists wet chlorine, chlorides, hypochlorites and many reducing and oxidizing media where stainless steel suffers pitting, crevice attack or stress corrosion cracking. The practical result is longer equipment life, less downtime, lower maintenance and fewer pollution incidents. This is why titanium has become one of the primary corrosion-resistant structural materials in chemical equipment, from chlor-alkali plants to fine chemical units.

Chlor-Alkali Industry

Chlor-alkali was the first large chemical application of titanium, covering chlorine production, chlorine oxides, pesticides and bleaching powder. In chlorine production, titanium equipment and piping can account for a substantial share of the total plant mass. Typical items include metal anode electrolyzers, ion-exchange membrane electrolyzers, anolyte pumps, shell-and-tube wet chlorine coolers, chlorine wastewater dechlorination towers, chlorine gas cooling and scrubbing towers, refined brine preheaters, and vacuum dechlorination pumps and valves.

Soda Ash and Vacuum Salt Production

In soda ash plants, titanium appears in crystallizer external coolers, distillation tower ammonia condensers, ammonium chloride mother-liquor heaters, plate and parapet heat exchangers, carbonization tower cooling tubes, CO2 turbine compressor rotors and impellers, and alkali pumps. In vacuum salt production, titanium ammonia evaporators, preheaters, precoolers, flanges, tubesheets, pump housings and elbows are standard because of brine corrosivity at elevated temperature.

Petrochemical Fiber and Fine Chemical Plants

Polyester, nylon and vinylon production lines have adopted titanium equipment to secure safe, continuous operation, better product quality and longer service life where stainless steel corrodes prematurely. In propylene oxide (PO) plants, the process media are liquid chlorine and propylene, which are corrosive to carbon steel, aluminum, copper, nickel and stainless steel alike; titanium is the only economical structural metal that survives these conditions in critical piping and vessels.

Inorganic Salts, Dyes, Urea and Nitric Acid

Sodium chlorate: electrolytic cells, titanium anodes, reactors and evaporators; consumption can reach roughly 15 tonnes of titanium per 10,000 tonnes of sodium chlorate capacity.

Potassium salts: evaporators, preheating tanks and coolers for potassium chloride, sulfate, nitrate and carbonate production.

Titanium dioxide and urea: membrane concentrators, calciner feed pipes, centrifuge distributor plates, urea synthesis tower linings, ammonia strippers, high-pressure mixers and valve springs.

Dyes and nitric acid: coil heat exchangers, absorption towers, scrubbers, fans, vacuum pumps, filters, nitric acid evaporators, tail-gas preheaters, turbo blowers, pumps, valves and piping.

Why Titanium Performs: Key Properties for Chemical Duty

Low density (4.51 g/cm3) cuts structural weight and string loads.

High tensile, creep and fatigue strength, including at elevated temperature.

Excellent corrosion resistance, especially to seawater, chlorides and wet chlorine.

Wide service temperature range: conventional titanium alloys operate from about -269 deg C to +600 deg C.

Large elastic deformation capacity: high yield strength with a low elastic modulus suits springs and flexible pipework.

Low thermal expansion reduces thermal stress in equipment subject to temperature swings.

Non-magnetic behavior keeps instrumentation, detection and control devices undisturbed.

Good processing performance in casting, forging, welding and additive manufacturing.

Choosing the Right Grade

Commercially pure Grades 1 and 2 cover the majority of chemical equipment and piping; Grade 7 (Ti-0.2Pd) and Grade 12 (Ti-0.3Mo-0.8Ni) are specified where crevice corrosion in hot chlorides or reducing conditions is a risk; Grade 5 (Ti-6Al-4V) is used where mechanical strength governs. Relevant product standards include ASTM B265 (sheet/plate), ASTM B338 and B861 (tube), ASTM B348 (bar) and ASME equivalents for pressure equipment. Mill certificates per EN 10204 3.1 should accompany deliveries to chemical projects.

FAQ

Why does stainless steel fail where titanium survives in chlorides?

Stainless steel depends on chromium oxide passivity, which breaks down locally in chloride media and causes pitting and stress corrosion cracking. Titanium's passive film is far more stable in chlorides, and its surface repassivates quickly even after mechanical damage.

Is titanium cost-effective for chemical plants?

Yes in the right applications. Titanium costs more per kilogram than stainless steel, but its density is lower and its service life in chloride service is several times longer, so the installed-cost-per-year comparison usually favors titanium in critical equipment.

Which titanium grade should a heat exchanger in a chlor-alkali plant use?

Wet chlorine coolers are commonly built with CP Grade 2; where crevice conditions exist at tube-to-tubesheet joints, Grade 7 or Grade 12 is a safer choice. The final selection should follow the process media, temperature and design code.

Can titanium equipment be welded and repaired on site?

Yes, with qualified procedures. Titanium welding requires strict inert gas shielding of the weld pool and the cooling weld zone; repair welding in a chemical plant should follow the original welding procedure qualification.

Does titanium react with nitric acid?

Titanium has good resistance to nitric acid across a wide concentration range at moderate temperatures and is used in nitric acid evaporators and condensers; concentrated hot acid conditions should be verified against corrosion data before design.

What is the operating temperature limit for titanium chemical equipment?

CP titanium is generally limited to about 300 deg C for continuous corrosion service, while titanium alloys extend the range toward 600 deg C where mechanical properties govern. Crevice corrosion risk increases above about 70-80 deg C in chloride service for CP grades, which is why alloyed grades are selected for hot brines.