The titanium dioxide passivation film on the surface of titanium heating tubes is the core barrier resisting corrosion from acid, salt and organic media. The film thickness directly determines the long-term anti-corrosion performance of equipment. Too thin a protective layer cannot effectively isolate corrosive ingredients; excessively thick uneven film is prone to cracking under hot-cold alternating cycles. Laboratory precision testing equipment cannot be carried to chemical tanks for real-time inspection, so a variety of portable quick detection tools are widely used for on-site rapid judgment of passivation film thickness during routine maintenance and equipment acceptance.
Eddy current thickness gauges are the most commonly used portable detection tools on site. This handheld instrument relies on eddy current induction principle, with a small probe closely attached to the polished outer wall of titanium heating tubes. The equipment instantly converts induction signals into numerical film thickness data, displaying real-time readings on the screen without damaging the tube surface. It is suitable for full inspection of new titanium heating tubes before installation and regular sampling detection of operating equipment. Operators only need to wipe off surface dirt and dry the tube wall to eliminate the interference of liquid and attachments, and the detection process can be completed within several seconds for a single measuring point. The measurement range fully covers the standard safe thickness interval of titanium passivation film in industrial heating equipment.
Color difference comparative test strips provide low-cost auxiliary rapid screening tools. The oxidation passivation film of titanium presents different uniform colors corresponding to different thickness ranges under natural light. Manufacturers produce standardized color comparison cards calibrated with precise laboratory data, covering silver, light gold, light blue, purple and other color gradients matched with specific film thickness values. Maintenance staff wipe the tube surface clean and observe the surface color under uniform light, comparing it with the color card to preliminarily judge whether the film thickness reaches the factory standard. This tool is used for large-batch rapid primary screening to quickly eliminate tubes with severely incomplete or ultra-thin passivation film, and suspected unqualified products are rechecked with eddy current gauges for accurate data.
Portable micro-spectrometers realize high-precision field quantitative analysis. Small integrated handheld spectrometers capture the light reflection spectrum of the titanium surface passivation film, and the built-in database automatically calculates the accurate film thickness by matching spectral characteristic curves. Compared with eddy current instruments, it is less affected by tiny surface scratches and slight uneven polishing, and has higher detection accuracy for local thin film areas formed by scratch damage. It is mainly used for on-site fault analysis of titanium heating tubes with local pitting corrosion, accurately measuring the residual film thickness of damaged positions to judge whether surface passivation repair treatment is required.
Electrochemical quick test pens detect the protective performance derived from film thickness indirectly. This tool does not directly output thickness values, but judges the integrity and adequacy of the passivation film by testing the electrode potential of the titanium surface. When the film thickness is insufficient or partial shedding occurs, the measured potential value will deviate from the standard interval. It is often matched with thickness measuring instruments for joint detection: thickness tools obtain specific numerical data, while electrochemical pens verify whether the film with measured thickness has complete anti-corrosion activity, avoiding misjudgment caused by loose, porous thick passivation film that loses protective ability.
表格
| On-site Quick Detection Tool | Working Principle | Application Scenarios & Advantages |
|---|---|---|
| Handheld eddy current thickness gauge | Electromagnetic eddy current induction non-destructive measurement | Universal daily inspection, fast real-time numerical reading, simple operation |
| Standard color comparison test card | Visual color grading corresponding to calibrated film thickness | Low-cost mass primary screening, rapid elimination of severely unqualified tubes |
| Portable micro-spectrometer | Surface spectrum matching quantitative calculation | High-precision detection of scratched local thin film areas, corrosion fault analysis |
| Electrochemical potential test pen | Surface electrode potential response to judge film integrity | Auxiliary verification of protective performance of measured passivation film |
Collaborative use of multiple portable quick detection tools can efficiently complete on-site judgment of titanium heating tube passivation film thickness without sending samples back to the laboratory. Regular thickness monitoring during equipment operation helps maintenance personnel grasp the attenuation law of the protective film in corrosive media, arrange polishing and repassivation treatment in advance, and avoid premature corrosion damage of titanium heating tubes caused by excessively thin protective layers.
