I. Project Background: Sludge Removal Requirements of a Municipal Sanitation Department in Guiyang In spring 2026, a municipal sanitation department in Guiyang City (hereinafter referred to as the 'Purchaser') planned to procure a batch of specialized vehicles for sludge removal from urban drainage networks, rainwater wells, and river channels. Following preliminary research, the Purchaser defined its core requirements: vehicles must comply with Blue License Plate / Class C driver’s license regulations; tank capacity should be approximately 3 m³; high maneuverability and strong off-road capability are essential; and stable operation under Guiyang’s rainy, high-humidity climate conditions is mandatory. Ultimately, the Purchaser selected the Dongfeng dual-cab sludge suction truck (blue license plate, 3 m³) as its primary model and prioritized suppliers offering adaptation solutions for southern humid and hot environments in the public tender process. According to publicly released tender information, the procurement budget was capped at approximately RMB 313,000 per unit, requiring original-equipment manufacturer (OEM) chassis warranty and lifetime after-sales service for the superstructure. Among multiple bidders, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli') secured the contract by delivering four units of this sludge suction truck, leveraging its customized solution for humid–hot environments and superior cost-performance ratio. These units have now entered routine operational service. II. Operating Condition Analysis and Vehicle Selection Logic Sludge suction trucks operate under highly specialized conditions, where vehicle parameter requirements vary significantly across different application scenarios. This procurement represents a typical 'light-duty municipal' application, characterized by: • Operation primarily within narrow urban streets, internal residential roadways, and drainage well access points; • High-frequency operation—multiple daily deployments required during the rainy season; • A damp, highly corrosive working environment imposing stringent demands on vehicle rust resistance and sealing component durability. To address these operating conditions, Chengli recommended the Dongfeng dual-cab sludge suction truck (blue license plate, 3 m³), based on the following selection rationale: Chassis Selection: Equipped with the Dongfeng EQ1035SJ16QC dual-cab chassis, featuring a 3,000 mm wheelbase and curb weight of approx. 2.8 tons—fully compliant with Blue License Plate / Class C driving requirements—and capable of easily navigating height- and width-restricted zones. This chassis enjoys broad market penetration in southern China, ensuring readily available spare parts. Superstructure Specifications: Tank volume of 3.1 m³ (~3 m³), equipped with a hydraulically driven winch, sewage pump, and high-pressure cleaning system. Maximum operational depth reaches up to 8 meters—suitable for urban rainwater wells and inspection chamber cleaning. Announcement Model Number: CLW5040TQYD6 (referencing parameters of Chengli’s comparable sludge suction truck models); fully compliant with China VI emission standards. III. Chengli’s Targeted Solutions: Anti-Corrosion and Durability Design Located in Southwest China, Guiyang experiences annual relative humidity exceeding 75%, with monthly rainfall surpassing 200 mm during the rainy season (May–September). Such high-temperature, high-humidity conditions pose severe challenges to metallic components, hydraulic systems, and sealing elements of sludge suction trucks. In this project, Chengli enhanced the following three key design aspects: Full-Vehicle Anti-Corrosion Coating: To counter Guiyang’s humid–hot climate, Chengli applied a dual-layer coating process—electrophoretic primer plus polyurethane topcoat—to the tank body, hydraulic oil tank, and critical chassis connection points, achieving salt-spray resistance exceeding 720 hours (per industry benc