# Long-Term Storage and Idle Protection Technical Specifications for Four Types of Anti-Corrosion Heating Tubes ## Storage & Idling Protection Standards for 316L Stainless Steel Heating Tubes Pre-storage cleaning treatment Completely remove organic fermentation scale, residual chloride medium and alkaline cleaning residues via full CIP pickling and neutral water circulation. After cleaning, blow dry all internal and external pipe surfaces with dry sterile air to eliminate residual water film that triggers rust spots and local pitting. Perform supplementary passivation on weld areas before storage to restore damaged chromium-rich protective film. Sealed storage configuration Wrap the entire tube bundle with waterproof plastic film lined with desiccant bags; seal all flange openings and pipeline connectors with stainless steel blind plates to block humid air and dust. Store tube bundles on dedicated plastic support frames instead of direct contact with carbon steel ground to avoid contact rust. The storage warehouse shall maintain relative humidity below 60%, with temperature kept at 10–25℃, and strictly isolate chloride-containing raw materials, detergents and chemical reagents. Regular maintenance during long-term idle period Unpack and inspect once every two months: check for surface rust, blind plate sealing integrity and desiccant validity. Re-circulate low-concentration passivation solution for 2 hours every six months for tube bundles idle over half a year, then blow dry and re-seal. Pre-production reactivation steps Remove packaging blind plates, flush the whole pipeline with sterile purified water, conduct surface potential detection to confirm intact passivation film, and complete wall thickness spot check before putting back into production. Forbidden storage operations Do not store stainless steel tubes together with carbon steel parts without isolation; avoid warehouse environments with salt mist, chlorine gas or alkaline vapor; skip incomplete drying before sealing storage. ## Storage & Idling Protection Standards for Pure Titanium Heating Tubes Pre-storage cleaning treatment Use oxygen-rich purified water to fully flush residual medium and cleaning fluid, remove rust sediment from carbon steel supports accumulated on tube surfaces. Blow dry thoroughly with dry air to eliminate stagnant water; avoid contact with any fluoride-containing cleaning agents or raw materials during the whole cleaning process. Sealed storage configuration Wrap tube bundles with fluorine-free soft anti-scratch plastic film; install integral PTFE gaskets on all flanges and seal with blind plates to prevent metal friction scratches during storage. Place on non-metallic nylon brackets, completely separated from carbon steel equipment and fluoride chemical stock areas. The storage area must be strictly fluoride-free, with independent ventilation to prevent accidental fluorine contamination. Regular maintenance during long-term idle period Carry out full surface visual inspection every two months to check for milky white etching traces and scratch expansion. For tube bundles idle over 3 months, circulate dissolved oxygen-rich water to rebuild TiO₂ passivation film, blow dry and re-seal afterward. Replace aging PTFE isolation sleeves before re-storage if disassembly occurs. Pre-production reactivation steps Remove sealing materials, run 30-minute aeration water circulation to repair passivation film, conduct electrochemical potential scanning of the whole tube bundle, and inspect all isolation structures to ensure no direct contact between titanium and carbon steel before restarting operation. Forbidden storage operations Never store titanium tubes in warehouses containing fluoride raw materials or fluorine-based waste; use metal binding wires for fixed packaging; leave residual fluoride medium inside the tube before sealing. ## Storage & Idling Protection Standards for Quartz Anti-Corrosion Heating Tubes Pre-storage cleaning treatment Only clean with dilute acid and neutral sterile water, completely drain all liquid inside and outside the tube, and gently wipe outer walls with soft sponge without rigid scrubbing tools to avoid artificial scratches. Remove all aging vibration damping rubber pads before long-term storage to prevent rubber aging residue adhesion. Shockproof sealed storage configuration Each quartz tube is individually wrapped with thick bubble wrap, then placed into customized shockproof wooden boxes lined with soft foam filling. All thread sealing ends are protected by plastic soft caps to avoid edge chipping from collision. Boxes shall be stacked with limited layers, placed in low-vibration storage areas away from circulating pump units and mechanical equipment that generates strong vibration. Warehouse temperature fluctuation range shall be controlled within ±3℃ to avoid thermal stress-induced microcrack expansion. Regular maintenance during long-term idle period Inspect packaging foam for deformation and tube surface scratches once a month; perform full light transmission crack inspection every three months for quartz tubes stored over half a year. Do not move or transport the box frequently during idle storage. Pre-production reactivation steps Take out tubes gently, replace brand-new thick rubber shock absorption gaskets for installation, conduct full light transmission microcrack screening test, and simulate low-flow circulation to check sealing tightness before connecting to the fermentation tank loop. Forbidden storage operations Stack quartz storage boxes in multiple heavy layers; place near vibration sources or temperature mutation areas; use hard metal tools to fix packaging; store together with alkaline chemicals. ## Storage & Idling Protection Standards for PFA Coated Heaters Pre-storage cleaning treatment Flush residual abrasive particles and high-concentration disinfectant with low-flow soft water, avoid high-pressure water gun impact on coating surface. Blow dry with normal-temperature dry air, prohibit hot air drying which accelerates coating aging and brittleness. Ensure no hard particle residue adheres to the fluoroplastic coating before storage. Anti-scratch constant-temperature storage configuration Wrap the whole heater with soft non-woven fabric and plastic film; seal all pipeline ports with soft plastic plugs instead of metal blind plates to prevent coating scratch during disassembly. Store horizontally on soft plastic support pads, avoid bending or extruding the tube body. Warehouse temperature is controlled between 15–30℃, away from high-temperature heat sources such as steam pipelines and heating furnaces; isolate strong oxidant storage areas. Regular maintenance during long-term idle period Open packaging for visual coating inspection every two months to check blistering, yellowing and shallow scratch expansion. Avoid long-term direct sunlight irradiation during storage. For heaters idle over 4 months, re-flush with room-temperature purified water and re-seal after drying. Pre-production reactivation steps Remove soft packaging, conduct full coating surface scanning inspection to confirm no new damage, install new pipeline particle pre-filters, and verify the normal operation of temperature interlock and post-cleaning slow cooling program before formal startup. Forbidden storage operations Expose PFA heaters to high-temperature environment or direct sunlight for long-term storage; use metal binding belts to fix tube bundles; store together with high-concentration hydrogen peroxide and strong oxidizing chemicals. ## Universal Long-Term Storage Management Rules 1. Independent zoning storage requirement: Divide four dedicated storage zones for different heating tube materials, with obvious isolation warning signs to avoid cross-contamination, scratch damage and mixed material contact corrosion. 2. Storage label filing rule: Each idle tube bundle is attached with a unique storage label recording material type, idle start date, last cleaning treatment method and next inspection time; all storage records are archived into the equipment full-life-cycle file. 3. Seasonal storage parameter adjustment: Strengthen dehumidification and chloride isolation measures in humid rainy seasons; move quartz and PFA equipment away from temperature mutation positions in winter and summer. 4. Maximum idle time limit control: Limit continuous idle storage without maintenance to less than 12 months for all heating tubes; any equipment stored over one year must complete full re-inspection and protective treatment before reuse. ## Summary The idle and storage protection specifications for four heating tubes target their unique storage failure risks respectively. Stainless steel focuses on chloride isolation, anti-rust sealing and regular passivation maintenance; titanium tube storage strictly prohibits fluorine pollution and maintains passivation film via oxygen-rich water treatment; quartz core requirements are shockproof packaging and stable constant-temperature storage to suppress microcrack expansion; PFA coated heaters need anti-scratch, low-temperature and anti-oxidation storage environments to delay fluoroplastic aging and coating damage. Standardized sealed storage and periodic maintenance can effectively avoid permanent performance degradation and structural damage of heating equipment during shutdown idle periods, reducing rework and replacement costs when production restarts.
