Case Background: In Q3 2025, a municipal sanitation department in Guangzhou launched a procurement project for sewage treatment vehicles. The Urban Management Bureau of a district in Guangzhou (hereinafter referred to as the 'Procuring Entity') planned to procure a batch of National VI emission-standard sewage treatment vehicles to address maintenance requirements for urban river channels and residential drainage systems. The project budget was capped at approximately RMB 393,000 (per publicly available tender information), with technical requirements including suction, separation, purification, and temporary storage capabilities—optimized for high-frequency operations under Guangzhou’s frequent rainy seasons and humid-heat climate. The Procuring Entity conducted an open tender, attracting multiple suppliers—including Chengli Special Purpose Vehicle Co., Ltd. After preliminary qualification review and prototype testing, three suppliers advanced to the substantive price comparison stage. During evaluation, the Procuring Entity placed particular emphasis on: anti-corrosion coating technology (to withstand Guangzhou’s high humidity and salt fog environment), sealing component durability (to ensure leak-free continuous operation during rainy seasons), chassis–body integration compatibility, and after-sales response speed. Comparison of Supplier Quotations and Technical Specifications According to the Procuring Entity’s publicly disclosed tender documents, all three suppliers adopted the Dongfeng 3308 wheelbase chassis; however, configurations and quotations varied significantly. Below is a simplified comparison table (data sourced from official tender records): | Item | Supplier A (Local Upfitting Workshop) | Supplier B (Brand 4S Dealership Agent) | Supplier C (Chengli Special Purpose Vehicle) | |---|---|---|---| | Chassis Model | Dongfeng 3308 wheelbase | Dongfeng 3308 wheelbase | Dongfeng 3308 wheelbase (Reference model: CLW5070GSSD6) | | Tank Capacity | ~4 m³ | ~4.5 m³ | ~4.5 m³ | | Anti-Corrosion Treatment | Conventional paint coating | Epoxy primer + topcoat | Full-vehicle electrophoretic coating + specialized anti-rust coating (designed specifically for humid-heat regions) | | Sealing Material | Standard rubber | Oil-resistant rubber | Fluoroelastomer (FPM) — highly resistant to corrosion and aging, ideal for high-humidity environments | | Sewage Treatment System | Pump + filtration screen | High-pressure cleaning + separation unit | Multi-stage separation + UV disinfection | | After-Sales Policy | 1-year warranty for chassis & bodywork | 2-year chassis warranty / 1-year bodywork warranty | Nationwide chassis warranty / lifetime bodywork service | | Quoted Price (Tax-Inclusive, Delivered) | ~RMB 305,000 | ~RMB 338,000 | ~RMB 312,000 | Analysis of Configuration Differences: Why Chengli Was Selected Facing three competitive bids, the Procuring Entity organized a technical evaluation. Key differentiators included: Anti-Corrosion Coating: Guangzhou is a typical humid-heat region, where relative humidity often exceeds 85% during the rainy season, and road salt accumulation—due to dust suppression watering—exacerbates corrosion risks. Supplier A’s conventional paint coating showed early rust spots within one year; Supplier B’s epoxy primer offered moderate improvement, but Chengli’s full-vehicle electrophoretic coating plus specialized anti-rust coating (per CLW5070GSSD6 type approval documentation) provides superior resistance to salt fog corrosion, extending tank service life by 3–5 years. Sealing Component Durability: Sewage treatment vehicles frequently suction acidic/alkaline sludge, and standard rubber seals tend to swell and fail under high temperature and humidity. Chengli selected fluoroelastomer (FPM) seals, offering broader temperature tolerance (−20°C to 200°C) and exceptional chemical resistance—ensuring zero leakage during continuous rainy-season operations. Procuring Entity test data indicated that Chengli’s se