Risk Assessment & Hierarchical Safety Control Scheme of Four Anti-Corrosion Heating Tubes in Sterile Fermentation Workshop

1. Risk Grading Standard Definition

• Level 1 (Critical risk): May cause full tank medium scrap, product pollution, batch loss, cross-contamination of strains; must adopt dual interlock protection, monthly risk recheck.
• Level 2 (Major risk): Partial equipment failure, local microbial residue, slight quality fluctuation; regular quarterly inspection and protective reinforcement required.
• Level 3 (General risk): Only equipment self-aging loss, no direct impact on fermentation product quality; routine daily patrol control is sufficient.

2. Risk Analysis & Safety Control of 316L Stainless Steel Heating Tubes

Main hazard sources

1. Chloride-induced pitting penetration leakage (Level 1): Weld corrosion perforation leads to heating medium mixing into fermentation liquid, strain contamination.
2. Heavy metal ion dissolution under corrosion state (Level 2): Rust and metal ions affect product purity, unqualified detection indicators.
3. Weld dead angle biofilm accumulation (Level 2): Difficult to clean thoroughly, residual miscellaneous bacteria destroy sterile environment.
4. Short service life and frequent replacement shutdown (Level 3).

Hierarchical control measures

1. Level 1 critical prevention: Set tube bundle wall thickness quarterly testing; install liquid leakage alarm sensor at heating jacket; strictly limit alkali cleaning temperature ≤60℃ to slow pitting expansion.
2. Level 2 quality control: Semi-annual weld polishing and supplementary passivation; increase CIP circulating flow velocity to eliminate cleaning dead corners.
3. Level 3 routine management: Record power consumption change trend to judge scale accumulation degree, arrange planned replacement in advance.

3. Risk Analysis & Safety Control of Pure Titanium Heating Tubes

Main hazard sources

1. Fluoride medium uniform thinning leakage (Level 1): Once raw material contains fluoride, passive film dissolves rapidly leading to tube wall penetration.
2. Metal rust sediment pollution from unisolated carbon steel supports (Level 2): Rust particles fall into tank to introduce foreign matter.
3. Hard large-area scratches weaken passive film self-repair ability (Level 3).

Hierarchical control measures

1. Level 1 critical prevention: Complete closed pipeline isolation for fluoride raw materials; online medium fluoride rapid detection before feeding; set titanium tube potential monitoring probe to early warn film damage.
2. Level 2 quality control: All flange and bracket contact positions equipped with integral PTFE isolation sleeves; weekly flushing of surface rust deposits on tube bundles.
3. Level 3 routine management: Adopt nylon soft slings for all overhaul hoisting to avoid hard scratch damage.

4. Risk Analysis & Safety Control of Quartz Anti-Corrosion Heating Tubes

Main hazard sources

1. Thermal shock/impact rupture, glass fragment foreign body pollution (Level 1): Fragments mixed into fermentation liquid cannot be filtered completely, batch completely scrapped.
2. Alkali etching rough surface mass biofilm adhesion (Level 2): Sterile CIP cleaning fails to eliminate residual bacteria.
3. Vibration abrasion shortens service life (Level 3).

Hierarchical control measures

1. Level 1 critical prevention: Low power density design below 0.8 W/cm²; full rubber buffer shock absorption installation; light transmission crack inspection every month; strictly prohibited for large-scale high-value sterile fermentation.
2. Level 2 quality control: Completely cut off all alkaline CIP pipelines with mechanical interlock; only use acid and neutral disinfectant circulation cleaning.
3. Level 3 routine management: Reduce circulating pump flow velocity to weaken liquid flow impact vibration; spare quartz tubes stored independently with shockproof foam packaging.

5. Risk Analysis & Safety Control of PFA Coated Heaters

Main hazard sources

1. Coating scratch penetration, carbon steel substrate rust leakage (Level 1): Corrosion under coating causes medium cross-contamination.
2. High-temperature aging fluoroplastic tiny particle shedding (Level 1): Plastic foreign bodies do not conform to pharmaceutical GMP sterile standards.
3. Inherent thermal resistance leads to unstable heating temperature (Level 2).

Hierarchical control measures

1. Level 1 critical prevention: All cleaning liquid temperature interlock locked ≤95℃; overhaul only use soft plastic tools; quarterly full coating appearance scanning inspection; prohibited for high-grade sterile biopharmaceutical production.
2. Level 2 quality control: Set slow cooling program after high-temperature cleaning to avoid cold and hot alternating blistering; reduce medium solid particle scouring flow rate.
3. Level 3 routine management: Monthly low-temperature water flushing to reduce surface scale accumulation, stabilize heating temperature fluctuation.

6. General Safety Risk Prevention Management Specifications for Sterile Workshops

1. Material zoning management: Titanium heating tank area strictly isolate fluoride reagents; quartz tank pipeline interlock shield alkali liquor; PFA heating area set high-temperature alarm device.
2. Risk file traceability: Establish independent safety risk ledger for each type of heating tube, record inspection results, hidden danger rectification and replacement records.
3. Emergency disposal plan: Formulate leakage, foreign body pollution emergency response process respectively; quartz tube rupture and PFA particle shedding accidents implement immediate tank emptying and full sterilization.
4. Risk dynamic adjustment: Upgrade risk level in advance when production formula changes (adding fluoride/alkali raw materials), and add extra inspection frequency.

Summary