Common Misoperations and Corrective Standards for Titanium Heating Tubes in Fermentation Production

The majority of the initial failures of pure titanium heating tubes in fermentation workshops are not the result of material quality defects, but rather of long-term standardised misoperation. The titanium dioxide passive film will be damaged in a continuous manner by non-compliant CIP cleaning, improper startup and shutdown, irregular maintenance, and unreasonable temperature control, resulting in pitting corrosion, film peeling, wall thinning, and abrupt leakage. This article provides a comprehensive overview of the most common on-site misoperations, an analysis of corrosion mechanisms, and unified corrective execution standards to standardise daily operations and prevent man-made equipment failure.

The initial typical misoperation is the sudden restart in cold state and full-power rapid heating. To reduce the duration of the heating process during the temperature increase of the tank, numerous workshops implement full-power operation. Micro-cracks are generated on the brittle passive film as a result of the severe thermal stress caused by the rapid temperature surge. In the interim, the upper tube wall is subjected to long-term bubble stagnation corrosion as a result of the large number of minuscule vapour bubbles that are produced by an excessive instantaneous heat load. Gradient staged heating is the appropriate standard. This involves maintaining the heating power at 60%–70% during the temperature rise stage, regulating the temperature change rate to not exceed 5℃/min, and prohibiting full-power initiation and cold water flushing for hot tubes to mitigate thermal stress damage.

The primary cause of passive film ageing failure is non-standard CIP acid-base alternating cleaning. High-temperature concentrated alkali long-term soaking, direct switching between acid and alkali without neutral water transition, and heating with full power during cleansing are all examples of common incorrect operations. The passive film will be irreversibly dissolved by a high-temperature, strong alkali, while the tube surface will be alternately eroded by sharp pH fluctuations, resulting in the formation of cumulative corrosion defects. The standardised cleaning process necessitates the use of weak organic acid below 45℃ and dilute alkali below 60℃, with deionised water flushing between the acid and alkali working procedures. In order to prevent the accelerated dissolution of the film due to overheating, the heating power must be either reduced by half or completely turned down during the cleaning process.

Disregarding passive film repair and dissolved oxygen supplementation is a concealed, long-term error. Many workshops directly feed fermentation medium without passing through passivation treatment after CIP washing. The passive film is unable to self-repair due to its thinning and damage, and corrosive ions, including chloride and organic acid, rapidly penetrate the titanium matrix. The correct procedure is to circulate tepid aerated deionised water for 2 hours following cleaning and maintain the tank at a static state for 12–24 hours to guarantee a sufficient oxygen supply for the regeneration of a dense and uniform TiO₂ passive film.

On-site, it is effortless to disregard the non-standard harmonising of auxiliary accessories. Galvanic corrosion is the result of direct contact between titanium tubes and uninsulated steel brackets and fasteners. Conductive loops and sealing gaps are formed by ageing and unreplaced PTFE gaskets and insulation sleeves. The corrective standard mandates that all dissimilar metal contact positions be entirely isolated with PTFE materials, and vulnerable accessories, such as insulation sleeves and gaskets, are replaced in a unified manner every six months to eliminate galvanic corrosion risks.

Tube failure is also expedited by unplanned maintenance and overdue descaling. Under-deposit anaerobic microzones are formed by thick carbonised organic scale and mineral scale, which results in localised pitting corrosion. Workshops will establish predetermined cleansing cycles: high-viscosity. Conventional production lines conduct monthly standardised CIP cleaning, while high-sugar fermentation tanks conduct biweekly deep descaling. By collaborating with quarterly wall thickness detection and passive film potential testing, it is possible to identify and eliminate early defects.

In summary, the longevity of titanium heating tubes is contingent upon the consistent and refined operation of the tubes, rather than solely on their material performance. By rectifying prevalent errors, including rapid heating, non-standard cleaning, irregular maintenance, and the absence of passivation repair, the rate of passive film damage and corrosion failure can be effectively reduced, resulting in the long-term, cost-effective operation of titanium heating equipment in fermentation production.