Standardized Training Manual Outline for Operators of Four Types of Anti-Corrosion Heating Tubes in Fermentation Plants

Standardised Training Manual Outline for Operators of Four Types of Anti-Corrosion Heating Tubes in Fermentation Plants ## Training Module for 316L Heating tubes made of stainless steel Core theoretical training content Describe the corrosion mechanism of chloride-induced pitting on stainless steel, the destructive effect of high-temperature alkaline cleaning fluid on chromium-rich passive film, the fouling accumulation law at weld dead zones, and the correlation between wall thickness attenuation and service life. Establish the safe upper limit temperature of 60℃ for alkaline circulation cleaning and the standard surface power density range of 1.0–1.5 W/cm². Steps for standard operation instruction In order to prevent the concentration of thermal stress on welds, the heating power must be activated after preheating to 50℃. Extend the cleansing duration for tube bundle weld positions and complete the sequence of alkaline cleaning, full clear water flushing, and acid descaling during CIP cycles. To eliminate organic scale and air-dry the tube bundle following the cessation of batch production, circulate neutral clean water. Additionally, perform offline supplementary pickling and passivation every six months in accordance with equipment management regulations. Operations that are prohibited are indicated by red lines. It is prohibited to manually disable the temperature interlock of alkaline cleaning pipelines, to avoid long-term soaking with high-chloride cleaning agents, to scrape scale and weld surfaces with steel wire brushes and metal scrapers, and to install tube bundles horizontally without a sufficient inclination angle, as this can result in persistent bubble retention and local pitting corrosion. Key inspection items for the daily patrol Examine the weld surfaces for discolouration and rust spots, document any anomalous fluctuations in heating power, verify the exhaust valve's unobstructed condition at the tube bundle's highest point, and evaluate the peak temperature value of each alkaline cleaning regimen. ## Training Module for Pure Titanium Heating Tubes Core theoretical training content Demonstrate the irreversible etching damage of fluoride ions to the titanium dioxide passive film, the self-repair principle of the passivation film in an oxygen-rich medium environment, the galvanic corrosion risks that result from direct contact with carbon steel, and the perils of scratch-induced ion precipitation. Specify the standard power density range of 1.2–1.8 W/cm² and the permissible alkaline cleaning temperature of up to 65℃. Steps for standard operation instruction Turn on the pipeline aeration device to guarantee that the medium contains an adequate amount of dissolved oxygen prior to initiating the heating process. Maintain a 30-minute circulation of oxygen-rich water after each CIP cleaning cycle to address minor scratches on the tube surface. For disassembly and hoisting during overhaul, exclusively employ nylon soft slings and plastic gaskets. Additionally, install complete PTFE isolation sleeves at all flange and support contact points. Operations that are prohibited are indicated by red lines. Do not introduce fluoride-containing raw materials or fluoride-based cleaning agents into the fermentation tank. Avoid friction between titanium tube bundles and steel wire ropes, iron wrenches, and other hard metal tools. Do not store idle titanium tubes without full water immersion and fluoride isolation sealing. Do not block exhaust pipelines to form long-term oxygen-deficient air film coverage. Key inspection items for the daily patrol Track the heating efficiency decrease caused by accumulated air film, inspect the tube surface for milky white matte etching traces and large-area hard scratches, and look for rust sediment that has fallen from unisolated carbon steel supports. ## Quartz Anti-Corrosion Training Module Theoretical training content for heating tubes Examine the permanent surface frosting reaction between quartz glass and alkaline liquor, the potential for thermal shock cracking during rapid temperature fluctuations, the risk of mechanical breakage due to vibration and impact, and the impact of low power density on heating speed. Demonstrate that quartz material does not precipitate metal ions; rather, it produces non-filterable glass micro-debris following a rupture. Steps for standard operation instruction To ensure that the heating power density does not exceed 0.8 W/cm², the temperature rise rate must be limited to less than 0.5℃ per minute during the initialisation process. Before cleaning, ensure that all alkaline pipeline valves are fully closed and the mechanical interlock is activated. Additionally, reduce the flow rate of the circulating pump to mitigate the vibration caused by liquid scouring. Before draining the liquid after production shutdown, allow the tube bundle to cool naturally to room temperature. Additionally, execute a monthly inspection of the light transmission cracks. Operations that are prohibited are indicated by red lines. When cleaning quartz tube bundles, refrain from misopening alkaline liquid valves. Do not directly flush high-temperature quartz tubes with cold water to prevent the development of violent thermal shock. Prevent the tube body from being knocked, squeezed, or collided during transportation and maintenance. Do not operate the heating system at over-power density settings to expedite internal microcrack expansion. Key inspection items for the daily patrol Monitor the anomalous vibration of the fixing supports, verify the effective locking function of the alkaline pipeline interlock device, and search for invisible microcracks and surface frosted layers using light transmission inspection. ## Training Module for PFA Coated Heaters Core theoretical training content Describe the ageing and blistering failure mechanism of the PFA fluoroplastic coating in the presence of sustained high temperatures, penetration damage risks from hard particle abrasion, plastic micro-particle shedding hazards that violate GMP sterile standards, and the additional thermal resistance energy consumption that the coating layer brings. Indicate the maximum power density of 1.0 W/cm² and the long-term safe temperature upper limit of 95℃. Steps for standard operation instruction Before heating, activate the over-temperature automatic power-off interlock and maintain the continuous medium operating temperature at or below 100℃. The preset gradual cooling program will be executed automatically following the high-temperature phase. CIP cleansing is preferred over direct cold water quenching; the concentration of hydrogen peroxide disinfectant should be reduced by 50% to impede the oxidative degradation of the coating. Soft plastic tools should be employed exclusively to remove surface scale during maintenance. Operations that are prohibited are indicated by red lines. Avoid the use of hard metal tools to scrape coating dirt; do not deploy; and do not disengage temperature interlock devices for long-term over-temperature operation. The long-term high-flow circulation of medium containing massive hard suspended abrasive particles is prohibited by PFA heaters on high-standard GMP sterile pharmaceutical production lines. Key inspection items for the daily patrol Record abnormal slow temperature rise and excessive power consumption, inspect the coating surface for blisters, penetrating scratches, and yellow ageing discolouration, and verify the normal operation of the post-cleaning slow cooling program. ## General Training Management Specifications A uniform approach to the fundamental pre-training content for all positions Before receiving material-specific skill training, trainees must first complete universal training, which includes the identification of equipment materials, the general procedures for startup and shutdown, the basic sequence for CIP cleaning, the safety operation standards, and the specifications for filing out patrol records. Regulations for post-training evaluations Operators are permitted to assume independent post duty only after successfully completing a classified theoretical written test and an on-site practical operation assessment that corresponds to the heating tube material of their tank. Personnel who fail the examination will be assigned supplementary retraining and re-assessment. Configuration of an auxiliary reminder on-site For the daily reference of frontline staff, post printed warning cards beside each fermentation tank heating control cabinet, which enumerate exclusive forbidden operation items. Mechanism for consistent retraining Organise a full staff retraining session every six months and ensure that the training content is updated in a timely manner in the event of any modifications to the production medium formula, cleaning process, or heating equipment type. Management of operation traceability Record all interlock alarms, misoperation events, and abnormal equipment defects in the daily equipment ledger. Implement targeted supplementary training for workshops that experience frequent irregular operations. ## Executive Summary The entire training system is structured around the inherent fatal defects of each heating tube material, resulting in a differentiated theoretical explanation, standardised operation guidance, and clear forbidden operation constraints. Alkali temperature control and chloride corrosion prevention are the primary objectives of stainless steel training. Fluoride isolation and anti-scratch management are the primary focus of titanium tube training. Quartz training emphasises thermal shock protection and alkali liquid isolation. The fundamental contents of PFA coating training are the protection of coating integrity and temperature limitation. The full service cycle of equipment can be extended, quality and safety hazards can be eliminated, and man-made damage to heating tubes caused by non-standard operation can be effectively reduced through systematic classified training in sterile fermentation production.