Comprehensive Anti-Corrosion Optimization Plan for Fermentation Heating Tube System (Long-Term Workshop Implementation Version)

# Long-Term Workshop Implementation Version of Comprehensive Anti-Corrosion Optimisation Plan for Fermentation Heating Tube System ## Introduction This integrated optimisation plan incorporates hardware transformation, process interlock upgrading, standardised operation reinforcement, predictive maintenance, and performance appraisal linkage, all of which are based on the full lifecycle management standards, accident root cause analysis, operator SOP training, and quantitative anti-corrosion KPI assessment system (No.50–60 documents). It addresses the frequent multi-factor synergistic corrosion of four mainstream heating tube materials (316 stainless steel, Grade 2 titanium, PFA coated heater, quartz glass), eliminates hidden corrosion risks from the source, reduces unplanned shutdown failures and medium contamination loss, and achieves long-term stable service of heating equipment. ## Chapter 1: The 12-Month Optimisation Cycle's General Objectives 1. Quality and Safety Objective: The elimination of all sudden leakage/rupture accidents in heating tubes and the elimination of all fermentation batch scrappings due to tube corrosion contamination. 2. Maintenance of Equipment Life Objective: -The average service life of 316 stainless steel heating tubes is ≥22 months, while the average service life of Grade 2 titanium heating tubes is ≥30 months. - The average service life of PFA-coated heaters is at least 15 months. - Quartz glass tubes are serviced in batches of at least twelve. 3. Operational Compliance Goal: The monthly number of forbidden misoperation occurrences is reduced to zero, and all core anti-corrosion KPIs are at or above 99.5%. 4. Cost Target: The annual decrease in the cost of heating tube replacement and maintenance per cubic metre of fermentation liquid was 30%. ## Second Chapter (Completion within 30 days) Phase 1: Hardware Source Transformation & Monitoring Interlock Upgrade ### 2.1 Pipeline Dead Zone Remodelling (Eliminate Stagnant Corrosion Microenvironment) 1. Eliminate all redundant blind pipes and long dead legs; retain essential branch pipes with a dead leg length that is not greater than 1.5 times the inner diameter of the pipe. Install drain valves at the lowest point. 2. In order to mitigate particle impact and low-flow stagnant corners, replace all 90° sharp elbows with large-radius curved elbows (R≥1.5D"). 3. In order to guarantee complete fluid turnover without dead water, add auxiliary small circulation conduits for valve cavities, flange sealing gaps, and tube bundle bottoms. 4. Establish independent discharge outlets for all low liquid accumulation sections and optimise pipeline elevation layout. ### 2.2 Independent Partition Pipeline Isolation Transformation (Prevent Cross-Contamination of Corrosive Ions) 1. Construct three sets of entirely independent, dedicated pipeline systems; temporary cross-connection hoses are prohibited. - High fluoride acid pipeline (strictly separated from stainless steel, only matched with quartz/titanium); - High-chloride raw water supply pipeline (exclusive for titanium loops, prohibited for 316 stainless steel); - Alkaline process pipeline (completely isolated from quartz heating loops). 2. Metal composite gaskets are removed from all titanium heating flanges, and metal-free pure PTFE elastic isolation gaskets are uniformly installed to prevent galvanic corrosion. ### 2.3 Upgrade of Filtration System to Eliminate Particle Abrasion Sources 1. At the inlet of all heating circulation tubes, two-stage series filters are installed: a coarse filter (40–60 mesh) and a fine filter (100–120 mesh). 2. Provide an online pressure difference alarm for each filter set. This alarm will automatically prompt operators to suspend circulation when the pressure difference exceeds a certain threshold, and it will also serve as an automatic reminder to clean the filters. 3. Immediately replace damaged screens to prevent particulate leakage, and store spare filter elements by material classification. ### 2.4 Configuration of the Full-Coverage Anti-Corrosion Parameter Interlock 1. Implement hard interlock programs and online real-time sensors for all heating circuits, including pH, chloride ion, dissolved oxygen, medium temperature, CIP alkali temperature, flow velocity, and static standby timing alarm. 2. Fixed parameter limit interlock logic (when exceeded, the pump alarm and partial shutdown protection are automatically triggered): - 316 SS: Hot alkali T＞55℃ / Cl⁻＞50ppm / pH＜5.5 or ＞8.0 → interlock alarm; - Titanium: DO＜7mg/L / fluoride detection trace cross-contamination → forced aeration reminder; - PFA coating: CIP alkali T＞85℃ / cancel slow cooling after high-temperature disinfection → lock next batch startup; - Quartz: pH: 7.0 / alkali pipeline valve misopened → emergency heating loop isolation. 3. Automatic reminder for static standby timing: An alarm will be activated for purification water circulation when the static duration exceeds the safe limit for each material. ## Chapter 3 Phase 2: Locking the Standardisation of the CIP and Fermentation Process (Completion within 45 Days, Permanent Program Locking) ### 3.1 The CIP Multi-Stage Program Lock has been fixed in an unchangeable manner. 1. The sequence is solidified by the control cabinet program: The program is designed to prevent manual skipping of any segment, and password permission is restricted to equipment administrators. The process is as follows: pre-rinse, alkali circulation, intermediate rinse, acid circulation, and final purified water rinse. 2. Endpoint judgement logic for mandatory rinsing: The system is unable to proceed to the subsequent process until the effluent conductivity and pH levels reach neutral levels; the fixed-time forced closure of rinsing is revoked. 3. Set a monthly automatic enhanced acid pickling circulation task and add 5 minutes of high-flow pulse flushing at the conclusion of each batch's final rinse to scour detritus in dead zones. 4. The flow velocity program lock is material-differentiated, and the pump frequency is limited to the upper and lower constraints to prevent the accumulation of low-flow biofilm or high-speed particle abrasion: - 316 PFA: 1.0–1.5 m/s; Quartz: 0.8–1.2 m/s; SS: 1.2–1.8 m/s; Titanium: 1.0–1.6 m/s. ### 3.2 Restrictions on the Anti-Corrosion Process in Fermentation Production 1. Medium pH adjustment: Segmented slow automatic titration program, which prohibits the addition of large acid/alkali quantities in a single operation to prevent the formation of local extreme pH micro-zones. 2. Thermal cycle control program lock: Mandatory 40-minute graded slow cooling procedure after disinfection above 80℃; cold water rapid cooling operation blocked by program; heating/cooling rate ≤0.4℃/min. 3. Optimisation mechanism for production scheduling: Automatic low-speed circulation is activated for standby loops to eradicate long static medium retention; small batches are merged to reduce the frequency of daily start-stop operations. ## Fourth Chapter Phase 3: Standardised Maintenance Mechanism and Predictive Regular Inspection (Long-Term Daily Execution) ### 4.1 Closed-Loop System for Graded Inspection 1. Operator responsibility for daily shift patrol: Conduct three comprehensive inspections per shift, complete the unified heating tube patrol checklist, document discolouration, sediment, flange leakage, filter pressure difference, and static standby time; report anomalous corrosion signals within 10 minutes. 2. Monthly quantitative special testing (equipment team responsibility): - Stainless steel and titanium: Electrochemical potential full scanning to identify concealed corrosion low-potential areas; - PFA heaters: Infrared thermal scanning and fixed-point coating thickness measurement to identify interlayer blister frigid spots; - Quartz tubes: Light transmittance test to determine the degree of frosting and the risk of hidden microcracks. 3. Quarterly comprehensive overhaul: pressure resistance test of all heating tube bundles, ultrasonic wall thickness detection, offline passivation for stainless steel, and oxygen-rich water film restoration circulation for titanium tubes. ### 4.2 Standardised Consumable and Maintenance Cycle Execution Rules 1. Gasket management: Storage is classified by colour and a mandatory replacement cycle is strictly enforced. Any disassembled gasket is discarded and cannot be repurposed. - PTFE gaskets are replaced every three months on titanium and quartz flanges. - Expanded PTFE gaskets are replaced every six months on stainless steel and PFA flanges. 2. Filter maintenance: Replace the fine filter weekly and clean the coarse filter every shift. Record the cleaning and replacement times in the ledger. 3. Fixed duties for periodic anti-corrosion maintenance: - Every six months, stainless steel undergoes offline nitric acid passivation. - All loops: Monthly enhanced acid pickling to remove salt deposits and biofilm; - Titanium loops: Weekly circulation of oxygen-rich purified water to preserve the TiO₂ protective film. - Quartz loops: Weekly full acid flushing to eliminate trace alkali frosting. 4. Mandatory post-overhaul rule: Two full-loop CIP cycles and the flushing of welding slag and particle residues after any pipeline cutting, welding, and disassembly before production restart. ## Chapter 5 Phase 4: Personnel Training, On-Site Supervision, and KPI Performance Linkage (Permanent Management Mechanism) ### 5.1 Regular Anti-Corrosion Training System with Tiered Structure 1. Monthly centralised theoretical training: The training will consist of core materials such as heating tube failure accident cases, which will be interpreted as operation taboos, early corrosion identification, and emergency disposal methods. A written examination will be administered following the training. 2. Practical operation training on-site every quarter: Operators perform CIP parameter adjustment, patrol abnormal judgement, filter disassembly, and standardised flange assembly under the supervision of an equipment engineer. 3. Post access threshold: Prior to commencing independent duties, new operators must successfully complete a theoretical and practical assessment of the anti-corrosion standard operating procedure (SOP). Additionally, incumbent personnel are required to retake the test every six months. ### 5.2 Mechanism for Real-Time On-Site Supervision 1. Equipment supervisors conduct daily random spot checks on shift surveillance records, CIP program execution, and prohibited misoperations; on-site rectification is necessary for non-standard operations. 2. Establish an anti-corrosion management bulletin board in the workshop, publish the KPI completion data and anomalous operation records of each shift on a weekly basis, and announce the rewards and penalties. ### 5.3 Key Performance Indicators Evaluation Linkage Between Rewards and Penalties 1. The performance weight of the shift/equipment team is 40% determined by the core zero-failure indicators (tube failure frequency, batch loss rate, and interlock alarm response rate). A full score bonus is awarded for zero abnormal months, while point deductions are made for over-limit parameter operation. 2. Monthlyly reward shifts that achieve 100% compliance with all anti-corrosion KPIs; impose a warning and performance deduction for repeated forbidden misoperations (skipping rinsing segments, aeration shutdown, and over-temperature alkali cleaning). 3. The equipment management department's primary assessment indicators are the average service life of heating tubes and the rate of reduction in maintenance costs during the quarterly comprehensive workshop evaluation. ## Chapter 6 Emergency Disposal Plan for Sudden Corrosion Abnormalities 1. Long-term out-of-limit parameter (pH/chloride/DO): Immediately cease medium feeding, activate large-flow purified water circulation dilution, modify the automatic dosing system, and monitor sampling indicators until they are qualified. 2. Cross-contamination of fluoride/alkali in heating circuits that are mismatched: Isolate the loop valve immediately, perform extended multi-stage rinsing and enhanced acid pickling, and test the residual ion concentration before resuming production. 3. Circulation is suspended due to a severe obstruction in the filter, resulting in an insufficient flow velocity. The filter elements are disassembled and cleaned thoroughly, and the screen is inspected for damage to prevent particle leakage and abrasion. 4. Detection of early corrosion defects during patrol (etching fog, frosting, and slight bulge): Shorten the inspection cycle, develop a maintenance plan in advance, and increase the monthly quantitative detection frequency to monitor the progress of corrosion expansion. 5. Sudden leakage/rupture of the heating tube: Rapidly close the inlet and outlet isolation valves, drain the residual medium in the tube, isolate the faulty equipment, initiate an accident root cause investigation in accordance with the standardised five-step procedure, and develop a rectification plan to prevent recurrence. ## Chapter 7: Continuous Optimisation Mechanism and Closed-Loop Tracking 1. An independent full-lifecycle electronic archive has been established for each heating tube bundle. This archive records incoming inspection data, hardware transformation records, daily patrol abnormalities, monthly/quarterly test values, maintenance replacement records, and final dismantling root causes. 2. Quarterly anti-corrosion effect summary meeting: Compile all KPI completion data, organise frequent abnormal weak links, optimise pipeline hardware transformation schemes, adjust CIP interlock parameters, and update the operation forbidden misoperation list. 3. Annual overall optimisation review: Compare the service life, failure frequency, and maintenance cost of heating tubes with the baseline data at the inception of the plan, summarise mature anti-corrosion experience, and establish standardised workshop operation specifications for long-term inheritance. Summary of the Main Points This four-stage integrated anti-corrosion optimisation plan commences with hardware transformation to mitigate inherent corrosion risks, eliminates artificial misoperation inducements by locking process parameters through program interlocks, utilises predictive inspection and standardised maintenance to achieve early detection of corrosion defects, and ensures long-term implementation effectiveness through personnel training and KPI performance appraisal linkage. It fundamentally suppresses the synergistic amplification damage of multiple corrosive factors, achieves the preset targets of zero sudden tube failure, extended equipment service life, and reduced comprehensive maintenance cost, and forms a replicable and closed-loop full-lifecycle anti-corrosion management mode for fermentation heating tube systems.