# Fermentation Heating Tube Anti-Corrosion Online Monitoring Instrument Calibration & Maintenance Specification ## Preface This specification is a supporting document of the complete anti-corrosion document system from Doc.33 to Doc.113. It standardizes the periodic calibration, daily maintenance, fault troubleshooting, spare part replacement and record filing of all online monitoring instruments for heating tube anti-corrosion control, including pH sensors, chloride ion detectors, temperature transmitters, wall thickness online probes and circulation flow meters. It prevents inaccurate monitoring data leading to missed corrosion risk warnings and misjudgment of equipment operation status, ensuring the reliability of the data basis for the whole anti-corrosion management system. All monitoring instruments are divided into two categories with differentiated calibration cycles. Immersed medium contact sensors (pH electrodes, chloride probes, biofilm monitoring sensors) are calibrated monthly on site; online wall thickness detectors, flowmeters and temperature transmitters that do not directly contact corrosive liquid undergo full accuracy calibration every six months. All calibration work is arranged in advance in the monthly maintenance schedule and cannot be delayed without approval. Unified standardized calibration procedures are formulated. Before calibration, operators cut off instrument signal output, isolate the detection section from the heating tube circulation loop, and thoroughly clean the probe surface of residual culture medium, acid-base attachments and scale to eliminate interference factors. Standard calibration solutions and standard reference blocks matching the factory calibration parameters are adopted for adjustment. After calibration, real-time sampling comparison between instrument readings and laboratory manual test results is required; only when the error is within the allowable safety range can the instrument be put back into operation. Calibration data, standard batch numbers and error correction values are filled into dedicated calibration ledgers on site. Daily routine maintenance requirements for monitoring equipment are clarified. During each shift patrol, staff check whether the probe surface has scaling, coating peeling or sediment coverage, and clean lightly with soft neutral cleaning liquid if there is adhesion. Instrument wiring terminals, signal transmission lines and junction boxes are inspected for damp corrosion and aging damage in humid workshop environments; waterproof and anti-corrosion sealing gaskets are replaced regularly to avoid circuit failure caused by medium leakage and condensation. For probes installed in high-corrosion medium loops, enhanced anti-corrosion protective sleeves are added as auxiliary protection. Fault disposal and replacement management rules are specified. Once abnormal drift, signal loss or continuous out-of-tolerance readings occur in monitoring instruments, the equipment maintenance team shall arrange troubleshooting within 4 hours. Minor faults such as wiring looseness and surface scaling are eliminated on site; severely corroded, aging probes that cannot restore accuracy after calibration are immediately replaced with qualified spare instruments. Fault cause analysis is recorded in detail to distinguish medium corrosion damage, improper maintenance or expired calibration, and targeted optimization measures are formulated to prevent repeated instrument failure. All instrument calibration reports, daily maintenance inspection logs, fault handling records, probe spare parts outbound registration and equipment asset files are stored in dual electronic and paper archives. Monthly data trend analysis compares instrument error fluctuation rules with heating tube corrosion abnormality frequency; if inaccurate monitoring leads to multiple hidden danger omissions, the calibration cycle and patrol inspection items will be adjusted through the system iterative optimization procedure. This specification guarantees the authenticity and stability of all anti-corrosion online monitoring data, forms a reliable front-end sensing control link of the heating tube anti-corrosion closed-loop management system, and fills the management gap of precision measuring equipment protection.
