# Fermentation Heating Tube Anti-Corrosion Low-Flow & Static Standby Protection Specification ## Preface This specification is a supporting document of the complete anti-corrosion document system from Doc.33 to Doc.115. It standardizes protective operation procedures, parameter control standards, regular maintenance and risk early warning rules for heating tube loops under low-flow operation, intermittent production shutdown, long-term static standby and idle line standby conditions. It solves prominent corrosion problems such as medium stagnation, biofilm accumulation, ion concentration enrichment and localized pitting caused by insufficient fluid scouring, and fills the anti-corrosion management gap in non-continuous production states. Three operating states with differentiated protection schemes are clearly classified. The first category is low-flow continuous operation, referring to circulation flow far below the standard design rate during low-load fermentation. Slow flow leads to long medium residence time inside the tube, and corrosive substances easily deposit on the inner wall. The second category is short-term static standby, including daily shift shutdown, batch interval pause with standby time less than 24 hours. The third category is long-term idle standby, such as production line halt for maintenance, seasonal shutdown and new equipment idle storage exceeding 72 hours, which faces the highest risk of severe local corrosion. Unified protection operation standards for low-flow working conditions are formulated. When the flow rate drops below the safe threshold, the patrol frequency of heating tube inlet and outlet monitoring points is doubled, and online chloride and pH data are recorded every 30 minutes. Regular forced high-flow flushing is added every 4 hours to wash away sediment and attached microorganisms on the tube wall. The pickling cycle is shortened by half compared with normal full-flow operation, and mild neutral circulation cleaning is supplemented between pickling cycles to reduce biofilm accumulation. Complete graded static standby protection workflows are implemented. 1. Short-term standby (≤24h): After stopping circulation, drain excess redundant medium, inject sterile pure water to fill the entire heating tube loop, maintain slight micro-circulation at fixed intervals, and record standby start time to strictly control the stagnation duration not to exceed the upper limit specified in the red-line operation standard. 2. Long-term idle standby (>72j): Toskan sepenuhnya semua medium kultur dan cecair pembilasan di dalam saluran paip, jalankan rawatan pempasifan penjerukan penuh, kemudian keringkan dinding dalam dengan udara panas steril, dan isikan gelung tertutup dengan gas pelindung lengai untuk pengasingan pengedap. Semua injap masuk dan keluar ditutup dan dikunci dengan plat buta dipasang untuk mengelakkan udara, lembapan dan bahan pencemar luaran daripada memasuki tiub. Pemeriksaan penampilan mingguan pada dinding luar saluran paip dan rawatan pengeringan semula-dalaman biasa diperlukan semasa penyimpanan terbiar. Pengenalpastian risiko khas dan mekanisme amaran awal diwujudkan. Isyarat amaran utama termasuk hanyut pH yang tidak normal semasa siap sedia, aliran menaik berterusan kepekatan klorida, pengabusan dan titik etsa pada dinding dalam tiub selepas saliran cecair, dan sisa biofilm melekit ditemui semasa pemeriksaan pembukaan rutin. Sebaik sahaja isyarat amaran awal muncul, curahan gelung-penuh paksa dan pembersihan dipertingkatkan hendaklah dijalankan serta-merta, dan had tempoh siap sedia bagi barisan pengeluaran hendaklah dikurangkan buat sementara waktu untuk mengelakkan kakisan ion pekat. Semua log parameter operasi aliran rendah-, borang pendaftaran mula/tamat siap sedia statik, rekod pelaksanaan curahan paksa, senarai semak penyelenggaraan saluran paip melahu dan fail pelupusan tidak normal siap sedia menggunakan pengarkiban elektronik dan kertas dwi. Analisis aliran data bulanan mengira kekerapan kegagalan kakisan peralatan di bawah keadaan aliran-statik dan rendah; jika kakisan genangan berulang berlaku di bengkel tertentu, perancangan selang kumpulan pengeluaran dan klausa operasi perlindungan siap sedia akan disemak dalam semakan sistem suku tahunan. Spesifikasi ini meliputi semua-keadaan operasi pengeluaran berterusan biasa bagi tiub pemanasan, menghapuskan bintik buta kakisan yang disebabkan oleh pengurangan aliran dan-stagnasi penutupan jangka panjang dan menyempurnakan-keadaan tertutup-sistem perlindungan kakisan-penuh sistem perlindungan kakisan tiub pemanasan penapaian.
