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At CSTHEATEXCHANGER, we design, engineer, and manufacture industrial-grade Titanium Grade 2 (UNS R50400) cooling coils and immersion heat exchangers specifically engineered for sodium hypochlorite (NaOClNaOCl, commercial bleach 10% to 15% concentration) production reactors, chlor-alkali chemical plants, municipal water treatment facilities, and bulk chemical storage tanks (10 kW to over 1,200 kW thermal cooling capacity). Sodium hypochlorite is an aggressive oxidizer that self-decomposes exothermically into toxic sodium chlorate (NaClO3) and oxygen gas if liquid temperatures exceed +25∘C to +30∘C. Built with 100% seamless Titanium Grade 2 tubes featuring automated orbital TIG welding under ultra-pure argon shielding, CSTHEATEXCHANGER immersion serpentine coils, helical tank coils, and external shell-and-tube coolers maintain chemical batches strictly at +12∘C to +18∘C. Forming a self-healing titanium dioxide (TiO2TiO2) ceramic passive layer, our Titanium Gr. 2 coils are 100% immune to wet chlorine, active hypochlorite ions (ClO−), and chloride stress corrosion cracking (SCC), guaranteeing an operational lifespan exceeding 20 years where standard stainless steels fail in days.
Sodium hypochlorite (NaOClNaOCl, typically produced at 10 wt% to 15 wt% available chlorine via chlorine gas absorption into sodium hydroxide solution) is thermodynamically unstable:
2NaOH+Cl2⟶NaOCl+NaCl+H2O+Heat (ΔH≈−101.5 kJ/mol)
SODIUM HYPOCHLORITE EXOTHERMIC DECOMPOSITION CASCADE
CHEMICAL CHLOR-ALKALI SYNTHESIS / BULK STORAGE TANK
• Highly Exothermic Synthesis Reaction (Releases ~102 kJ/mol)
• Uncontrolled Warm Storage (>25°C) Triggers Autocatalytic Breakdown
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│ 1. THERMAL DECOMPOSITION PATHWAYS (TEMP > 25°C - 30°C) │
│ • Pathway A: 3 NaOCl ──► NaClO3 (Sodium Chlorate) + 2 NaCl
│ • Pathway B: 2 NaOCl ──► 2 NaCl + O2 (Gas Evolution & Overpressure)
│ • Rate of Decomposition Doubles for Every 5°C Temperature Rise
└───────────────────────────┬────────────────────────────┘
│ Exothermic Heat Must Be Extracted
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┌────────────────────────────────────────────────────────┐
│ 2. CSTHEATEXCHANGER® TITANIUM GRADE 2 COOLING COIL │
│ • Pure Titanium Gr. 2 (100% Immune to Wet Chlorine/NaOCl)│
│ • Zero Heavy Metal Contamination (No Fe/Ni/Cu Catalysts)│
│ • Chilled Water (7°C/12°C) or Glycol Lowers Batch to <18°C│
└───────────────────────────┬────────────────────────────┘
│ Stable Storage at +12°C to +16°C
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Strength Preserved for 12+ Months + Zero Chlorate + Zero Gas VentingPreventing Rapid Available Chlorine Loss: The rate of sodium hypochlorite decomposition doubles for every 5∘C temperature increase. Storing bleach at +35∘C degrades 15% commercial bleach down to 8%8% in just a few weeks. Maintaining temperature at +12∘C−15∘C preserves chemical potency for over 6 to 12 months.
Eliminating Sodium Chlorate (NaClO3NaClO3) By-Product Formation: When NaOClNaOCl exceeds +25∘C, it rapidly converts into sodium chlorate (NaClO3NaClO3). In drinking water disinfection, chlorate is a regulated toxic contaminant (WHO / US EPA limits <0.7 mg/L). Precision cooling keeps chlorate formation near zero.
Preventing Oxygen Gas Off-Gassing & Tank Rupture: Decomposition generates oxygen gas (O2), creating dangerous pressure buildup in sealed storage tanks, piping vapor locks, and cavitation in chemical dosing pumps.
Absorption Column Reaction Control: During production, absorbing Cl2 gas into caustic soda (NaOH) generates massive exothermic heat. A high-capacity CSTHEATEXCHANGER titanium cooling coil extracts reaction heat in real time, preventing thermal runaway.
In sodium hypochlorite service, conventional metals and alloys fail rapidly:
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METALLURGICAL CORROSION RESISTANCE IN SODIUM HYPOCHLORITE (15% NaOCl)
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Material Alloy Category Corrosion Rate in 15% NaOCl Chemical Failure Mode / Risk
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Carbon Steel / Cast Iron > 5.0 mm/year (Instant Destruction) Catastrophic oxidation & dissolution
Stainless Steel 304 / 316L > 2.5 mm/year (Severe Pitting) Rapid chloride pitting, pinholing in days
Duplex 2205 / Super Duplex 2507 0.8 - 1.5 mm/year (Pitting/SCC) Chloride stress cracking along weld zones
Nickel Alloys (Hastelloy C-276) 0.1 - 0.3 mm/year (Moderate Attack) Nickel ions catalyze NaOCl decomposition
Titanium Grade 2 (UNS R50400) < 0.001 mm/year (100% IMMUNE) Self-healing TiO2 passive barrier
Titanium Grade 7 / 12 (Pd Alloy)< 0.0005 mm/year (Immune) Enhanced resistance in crevice zones
================================================================================ TiO2 PASSIVATION LAYER FORMATION ON TITANIUM GRADE 2
SODIUM HYPOCHLORITE SOLUTION (High ClO⁻, Cl⁻, pH 11.5 - 13.0)
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┌────────────────────────────────────────────────────────┐
│ SELF-HEALING RUTILE/ANATASE TiO2 CERAMIC PASSIVE FILM │
│ • Thickness: 10 - 20 Nanometers (Forms Instantly) │
│ • 100% Chemically Inert in Wet Chlorine & Hypochlorite │
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│ BULK TITANIUM GRADE 2 SUBSTRATE (UNS R50400 / 3.7035) │
│ • High Purity (99.2% Pure Ti), Excellent Ductility │
│ • Zero Trace Iron, Copper, or Nickel Contamination │
└────────────────────────────────────────────────────────┘Titanium has an extraordinary affinity for oxygen. In aqueous hypochlorite solutions, Titanium Grade 2 immediately forms a dense, continuous, chemically inert titanium dioxide (TiO2) ceramic oxide film. If scratched or mechanically abraded, the oxide film repairs itself spontaneously in milliseconds in the presence of trace moisture or dissolved oxygen.
Trace quantities (even 0.5 ppm0.5 ppm) of heavy metal ions—specifically Iron (Fe), Nickel (Ni), Copper (Cu), Cobalt (Co), and Manganese (Mn)—act as aggressive heterogeneous catalysts that accelerate NaOCl decomposition into oxygen gas.
Stainless steels and nickel-based alloys leach nickel and iron ions into the bleach, ruining the entire chemical batch. CSTHEATEXCHANGER Titanium Grade 2 contains zero catalytic elements, ensuring the chemical purity of commercial bleach.
CSTHEATEXCHANGER custom-engineers titanium cooling coils in three primary geometric configurations to match diverse chlor-alkali and storage facilities:
CSTHEATEXCHANGER® TITANIUM NaOCl COOLING COIL GEOMETRIES
[IMMERSION SERPENTINE GRID] [HEAVY HELICAL TANK COIL] [EXTERNAL SHELL & TUBE]
• Drops into Storage/Mix Tanks • Wraps Tank Perimeter Wall • External Recirculation Loop
• Multi-Row Vertical Layout • High Heat Transfer Area • Continuous High Flow Velocity
• Flanged Top Riser Manifolds • Single-Piece Continuous Tube• Removable Titanium Tube Bundle
• High Structural Stability • Bottom Sludge Clearance • ASME Code Pressure VesselEngineered to be lowered directly into polyethylene, fiberglass (FRP), or rubber-lined steel sodium hypochlorite storage and batch reaction tanks. Features top flanged risers that extend above the liquid level, keeping all mechanical cooling water connections outside the corrosive chemical vapor space.
Fabricated from single continuous lengths of seamless Titanium Grade 2 tubing (up to 60 meters continuous without intermediate submerged joints). The helical spiral wraps the inner circumference of cylindrical reaction vessels, maximizing residence time and heat transfer while allowing central mechanical agitators to operate without interference.
For large industrial chlor-alkali production lines (>500 kW), our external shell-and-tube coolers circulate NaOCl through seamless titanium tubes while chilled water flows across the shell side. Features precision CNC-machined titanium tube sheets and solid titanium heads.
CSTHEATEXCHANGER® TITANIUM WELDING INTEGRITY ASSURANCE
[ATMOSPHERIC CONTAMINATION RISK] [CSTHEATEXCHANGER PURGE CHAMBER]
Air Exposure at > 400°C: 100% Ultra-Pure Argon Shielding (99.999%):
• Oxygen & Nitrogen Absorption • Trailing Shield + Internal Back-Purge
• Titanium Embrittlement & Cracking • Silver / Light Straw Shiny Weld Color
• Severe Chemical Attack on Welds • Retains 100% Parent Metal DuctilityTitanium is highly reactive with oxygen, nitrogen, and hydrogen at temperatures above +400∘C+400∘C. Any atmospheric contamination during welding causes severe weld embrittlement and catastrophic cracking. CSTHEATEXCHANGER performs all titanium welding in specialized cleanrooms using automated orbital TIG welding with trailing shields and 99.999% pure argon internal back-purging. Every weld is visually inspected for strict silver-to-light-straw coloration (per AWS D10.6).
After fabrication, every titanium coil undergoes specialized chemical pickling in a nitric-hydrofluoric acid bath (HNO3+HF) to remove microscopic embedded iron particles from bending tools, followed by concentrated nitric acid passivation to establish an ultra-dense TiO2 protective barrier.
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CSTHEATEXCHANGER TITANIUM GRADE 2 COOLING COIL SPECIFICATIONS
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Parameter CSTHEATEXCHANGER Engineering Standard
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Primary Target Chemical Service Sodium Hypochlorite (NaOCl 5% to 18%), Bleach,
Chlorine Dioxide, Wet Chlorine Gas, Hypochlorous Acid
Cooling Thermal Duty Range 10 kW to 1,500+ kW (2.8 TR to 425 TR) per modular unit
Tube Material & Specification Seamless Titanium Grade 2 (UNS R50400 / ASTM B338 / SB-338)
(Optional Titanium Gr. 7 / Gr. 12 with Palladium for Crevice Defense)
Tube Outer Diameters (OD) 19.05 mm (3/4"), 25.4 mm (1.0"), 31.75 mm (1-1/4"), 38.1 mm (1-1/2")
Tube Wall Thickness Options 0.89 mm (0.035"), 1.24 mm (0.049"), 1.65 mm (0.065") Heavy Wall
Cooling Medium Circuit Options Chilled Water (CHW 6°C/12°C), Ethylene/Propylene Glycol, Well Water
Operating Liquid Temperature +5 °C to +50 °C (Target NaOCl Batch Maintained at +12 °C to +16 °C)
Operating Design Pressure 10 bar to 25 bar (145 psi to 363 psi)
Hydrostatic Test Pressure 15 bar to 37.5 bar (1.5x Design Pressure)
Helium Mass Spectrometer Leak < 1 x 10^-8 mbar·L/s (100% Vacuum Chamber Certified)
Welding Process Specification Automated Orbital TIG (GTAW) with 99.999% Argon Purge (AWS D10.6)
Connection Port Flanges Solid Titanium Gr. 2 Flanges (ANSI Class 150 / DIN PN16) or
Carbon Steel Lap-Joint Backing Flanges with Titanium Stub Ends
Structural Support Brackets Solid Titanium Gr. 2 Straps with Teflon / PTFE Isolating Spacers
Quality Standards Compliance ASME Section VIII Div. 1 (U-Stamp), CE-PED 2014/68/EU
================================================================================Even though 316L contains molybdenum, sodium hypochlorite is one of the most powerful pitting agents known. The high oxidation-reduction potential (ORP>800 mV) combined with high chloride concentrations (Cl−) destroys the chromium-oxide passive film on stainless steel, initiating severe pitting and pinhole leaks in less than 48 to 72 hours. Titanium Grade 2 is completely impervious to this mechanism.
The reaction between chlorine gas and caustic soda is highly exothermic. If the reaction slurry is not cooled continuously below +25∘C−30∘C, the hypochlorite ion decomposes into sodium chlorate (NaClO3). Installing a CSTHEATEXCHANGER titanium cooling coil directly inside the reactor loop removes the heat of reaction instantly, keeping chlorate levels well below strict regulatory limits.
When a titanium coil is submerged in an electrically conductive chemical like NaOClNaOCl, any direct contact with external steel support structures could theoretically create a galvanic couple. CSTHEATEXCHANGER mounts all titanium coils using PTFE (Teflon) or PVDF isolating spacers and non-metallic sleeve bushings, completely isolating the coil from metallic tank walls and external piping.
Prevent chemical decomposition, ensure stable bleach concentrations, and eliminate corrosion failures with titanium coils from CSTHEATEXCHANGER:
Titanium Grade 2 Seamless Cooling Coils for Sodium Hypochlorite (10 kW to 1,500+ kW)
100% Corrosion Immunity in Active Bleach, Wet Chlorine & Hypochlorous Acid
Zero Heavy Metal Catalytic Degradation (Preserves 15% NaOCl Chemical Strength)
Immersion Serpentine Grids, Helical Tank Coils & Shell-and-Tube Configurations
Automated Pure-Argon Orbital TIG Welding & 100% Helium Leak Integrity Certified
Contact our chlor-alkali and specialty chemical heat transfer engineering division today with your sodium hypochlorite tank volume (m3m3 or Gallons), batch cooling duty (kW / BTU/h), and chemical concentration for custom 3D CAD modeling and competitive factory-direct pricing.
Website: https://www.cstheatexchanger.com/
Technical Inquiries: info@cstheatexchanger.com
