Case Study and Bid-winning Solution Analysis for the Zhuhai Municipal Government Procurement of Blue License Plate, 3-cubic-meter Dongfeng D6 Sludge Tipper Trucks. In Spring 2026, multiple districts and counties in Zhuhai jointly launched a centralized procurement project for sludge transport vehicles, with an estimated total volume of approximately 40 units. All vehicles specified were blue license plate, 3-cubic-meter sludge tipper trucks built on the Dongfeng D6 chassis. The project was led by a municipal sanitation department to address key challenges in Zhuhai—including frequent rainy seasons, inefficient sewer cleaning, and low sludge transfer efficiency. According to publicly released tender information, the total budget was capped at approximately RMB 4.873 million, with an average unit price of around RMB 110,000. Chengli Special Purpose Vehicle Co., Ltd. successfully delivered this batch of vehicles, leveraging its extensive expertise in sanitation vehicle development and strong localized service capabilities. I. Background of Joint Procurement: Special Requirements in a Humid, Hot Climate Zhuhai is located in the subtropical southern region, characterized by year-round high temperatures and abundant rainfall, with an annual average relative humidity exceeding 80%. Conventional sludge tipper trucks, when continuously exposed to high humidity, salt fog, and acidic sludge corrosion, are highly susceptible to issues such as body rusting, sealant aging, and hydraulic system leakage. Several subdistrict sanitation offices previously reported severe rusting on the undercarriage and side panels of aging vehicles after rainy-season operations; some units required major overhauls after only two years of service. The primary objective of this joint procurement initiative was to resolve durability challenges posed by the humid climate through unified technical specifications. Procuring authorities mandated that all vehicles must feature full-body anti-corrosion coating; cargo bodies must be fabricated from high-strength weathering steel; and sealing components must exhibit resistance to acids/alkalis and ultraviolet radiation, while maintaining reliable sealing performance even during frequent rainfall. Additionally, given the high operational frequency during Zhuhai’s rainy season, vehicles were required to sustain high-load continuous operation—hydraulic systems, power take-off (PTO) units, and chassis engines all had to pass rigorous durability testing. II. Unified Technical Specifications: Anti-Corrosion and Durability as Core Priorities During the technical proposal evaluation phase, Chengli’s Dongfeng D6-based blue license plate, 3-cubic-meter sludge tipper truck (model CLW5070GSSD6) received unanimous approval. This model is built upon the Dongfeng D6 light-duty truck chassis, fully compliant with China VI emission standards, with complete official type-approval documentation enabling nationwide registration and annual inspection. Key technical enhancements include: Anti-Corrosion Coating: Both interior and exterior surfaces of the cargo body employ a dual-layer coating process—epoxy zinc-rich primer followed by polyurethane topcoat—with additional stone-chip resistant coating applied to the underbody. This effectively resists corrosion from acidic substances in sludge and salt fog. According to Chengli’s laboratory test data, this coating system withstands over 1,000 hours in salt-spray testing—significantly exceeding industry standards. Sealant Durability: Rear door gaskets utilize EPDM (ethylene propylene diene monomer) rubber, offering a temperature tolerance range of -40°C to 120°C, excellent resistance to acids and alkalis, and an approximate 50% longer service life compared to conventional rubber seals. Hydraulic cylinder rods feature chromium plating combined with imported sealing rings to prevent intrusion of dust and moisture. High-Load Performance: The Dongfeng D6 chassis is powered by a Yuchai 140-horse