I. Background of Multi-District Joint Procurement: Dual Challenges of Rainy-Season Dredging and Humid-Hot Environment Wenzhou City, Zhejiang Province, located along the coast, experiences typhoon and rainy seasons from May to October each year, placing immense pressure on urban drainage networks and river dredging operations. In early 2024, municipal sanitation departments from three districts (Lucheng, Longwan, Ouhai) and two county-level cities (Ruian, Yueqing) under Wenzhou’s jurisdiction jointly launched the 'Emergency Sewage Suction Vehicle Procurement Project for Urban Drainage Networks'. Per local procurement practice, the joint procurement budget is capped at approximately RMB 13.706 million, with plans to acquire around 30 blue license plate, 3-cubic-meter sewage suction trucks—primarily for dredging operations in old residential communities, narrow alleys, and tributary rivers. The most prominent pain point identified in the procurement background is 'equipment durability under humid-hot conditions'. Wenzhou’s annual average relative humidity exceeds 78%, and dredging operations occur frequently during the rainy season; vehicles thus operate long-term in highly humid, salt-fog-laden, and acid-alkali wastewater-corrosive environments. The procuring entity explicitly stipulated in its tender documents that: all metal components must feature anti-rust coating; hydraulic system sealing elements must pass durability testing under humid-hot conditions; and the vehicle chassis must comply with China VI emission standards, enabling operation with a Blue License Plate and Class C driver’s license. The Dongfeng double-cab chassis was selected as the designated chassis model due to its extensive deployment and maintenance convenience in coastal regions. II. Unified Technical Standards Formulation: Key Requirements for Humid-Hot Environments Prior to launching the joint procurement, procurement representatives from each region and technical experts jointly established unified technical standards to ensure long-term stable operation of vehicles under Wenzhou’s coastal climate conditions. Core requirements include: Anti-Rust Coating: The entire tank body, sub-frame, and all exposed metal parts must undergo phosphating treatment followed by application of epoxy primer and acrylic polyurethane topcoat, with a minimum coating thickness of ≥80 μm and salt-spray resistance of ≥500 hours without rust (referencing corrosion-protection process standards used in models such as CLW5070GSSD6). Sealing Element Durability: Sealing elements for hydraulic cylinders, valves, and pipeline joints must be made of fluororubber or polyurethane—materials resistant to humid-hot conditions, oil, and acid-alkali corrosion—and third-party humid-heat cycling test reports must be submitted prior to tendering (test conditions: temperature 40°C ±2°C, relative humidity 95% ±3%, duration 1,000 hours). Operational Efficiency: The sewage suction truck must feature self-priming and self-discharging capabilities, with an effective tank capacity of 3 cubic meters, suction depth ≥5 meters, full-tank suction time ≤5 minutes, and discharge time ≤3 minutes. The chassis must accommodate a Dongfeng double-cab configuration to meet seating requirements for a three-person work crew. Emission Standards: Full compliance with China VI emission standards, meeting registration requirements; operable with a Blue License Plate and Class C driver’s license, and permitted for urban driving without requiring a commercial operation permit. These stringent standards effectively excluded low-cost suppliers offering inferior materials, thereby creating an opportunity for manufacturers like Chengli Special Vehicle Co., Ltd.—which possess mature anti-corrosion processes and advanced sealing technologies—to demonstrate competitive advantages. III. Centralized Tendering and Chengli’s Bulk Supply Advantages Following two rounds of open tendering (the first round focused on technical p