Nanning Municipal Government Procurement Case for National VI Dongfeng 3308 mm Wheelbase Sewage Treatment Vehicle: Contract Renewal and Solution Analysis In early 2022, the Urban Management Bureau of a district in Nanning decided to procure a batch of sewage treatment vehicles due to aging local wastewater treatment infrastructure and frequent rainstorm-induced sewer overflows. Following multiple rounds of technical evaluation, the Customer selected Chengli’s National VI Dongfeng 3308 mm wheelbase model (Model No.: CLW5070GSSD6). Built upon the Dongfeng chassis with a 3308 mm wheelbase and equipped with a National VI-compliant engine, the vehicle features a stainless-steel tank with anti-corrosion coating. Its core advantages include: • Anti-Corrosion Coating Technology: The tank interior is coated with a composite layer of epoxy resin and polyurethane, offering resistance against acidic and alkaline corrosion present in sewage. Field tests show its service life extends by 2–3 years compared to standard carbon-steel tanks. • Sealing Component Durability in Humid-Hot Environments: Located in a subtropical zone, Nanning experiences year-round humidity exceeding 80% and frequent high-temperature rainfall in summer. The vehicle employs fluororubber sealing components combined with a dual O-ring design, maintaining elasticity and minimizing leakage risks under humid-hot conditions. • High-Load Rainy-Season Operational Capability: Equipped with a high-capacity vacuum pump (pumping speed ≥300 m³/h), it supports continuous operation for over 12 hours during heavy rainfall periods. Per local procurement practices, the initial budget was capped at approximately RMB 1.359 million, with an estimated unit price of around RMB 200,000 (based on publicly available tender information). Ultimately, the Customer procured five units, delivered in June 2022. II. Operational Performance: Real-World Performance in Humid-Hot Conditions From June 2022 to June 2024, these five sewage treatment vehicles accumulated over 8,000 operational hours across main urban roads, older residential communities, and industrial zones. Key customer feedback metrics are summarized below: Evaluation Indicator | Design Standard | Actual Performance | Remarks ---|---|---|--- Corrosion Resistance of Anti-Rust Coating | ≥3,000-hour salt-spray test | No rust spots observed; coating remains intact | Per CLW5070GSSD6 official parameter documentation Sealing Component Durability | Designed service life ≥5 years | Zero leaks over 2 years; no replacements required | Demonstrates advantage of fluororubber seals Rainy-Season Operation Frequency | Average 20 times/month | Average 35 times/month | Stable performance under high-load conditions Engine Emission Compliance Rate | 100% | 100% | Fully compliant with National VI standards across all operating conditions The Customer specifically noted that during Nanning’s record-breaking 20-day continuous heavy rainfall in July 2023, these five vehicles performed reliably during emergency sewer repairs—no downtime occurred due to seal degradation or corrosion-related failures. Chengli’s after-sales team responded promptly via the hotline, coordinating spare parts delivery and completing replacements within 24 hours, ensuring uninterrupted operations. III. 2024 Contract Renewal: Expanded Procurement