Joint Procurement by Multiple Districts and Counties in Hangzhou: Practical Case Study of the National VI Dongfeng 3308 mm Wheelbase Sewage Treatment Truck In autumn 2025, environmental sanitation departments across several districts and counties in Hangzhou (hereinafter referred to as 'a municipal sanitation department', 'a district urban management bureau', etc.) jointly launched a large-scale procurement project for sewage treatment trucks to address urban drainage system management needs. The core vehicle model selected was the National VI Dongfeng 3308 mm wheelbase sewage treatment truck, specifically designed to meet high-load operational challenges under southern China’s hot and humid climate conditions. Based on publicly available tender information, this article provides a detailed analysis of the joint procurement background, technical standard formulation, centralized tendering process, and Chengli Special Purpose Vehicle Co., Ltd.’s bulk supply solution, serving as a reference for similar procurement initiatives. I. Background of Joint Procurement Hangzhou lies within a subtropical monsoon climate zone, characterized by high summer temperatures and abundant rainfall, with an extended rainy season. Urban drainage networks frequently face challenges from sewage accumulation and sediment buildup, necessitating regular cleaning. Conventional vacuum suction trucks are prone to rust and seal failure in highly humid and corrosive environments, resulting in high maintenance costs and reduced operational efficiency. To standardize specifications and reduce costs, a municipal sanitation department led a joint procurement initiative involving three neighboring districts and counties—including a district urban management bureau and a subdistrict-level environmental maintenance unit—with an aggregate demand of approximately 20 units of the National VI Dongfeng 3308 mm wheelbase sewage treatment truck. Following local procurement practices, the total budget was capped at approximately RMB 8.895 million, with an estimated unit price of around RMB 400,000, emphasizing vehicle durability and environmental adaptability. II. Formulation of Unified Technical Standards To ensure long-term stable operation of vehicles under hot and humid conditions, the joint procurement group established stringent technical standards: • Anti-Corrosion Coating Requirements: All bodywork and tank surfaces must be coated with a dual-layer protective system—epoxy zinc-rich primer plus polyurethane topcoat—with a minimum dry-film thickness of 120 micrometers. Coatings must pass a 96-hour salt-spray test (per GB/T 10125) to withstand corrosion in Hangzhou’s high-humidity environment. • Seal Component Durability: Critical sealing components (e.g., tank lids and pipeline joints) must utilize fluorocarbon rubber or silicone rubber materials, rated for operating temperatures from −40°C to 200°C. Suppliers must provide third-party aging test reports (1,000-hour hot-air aging test) to guarantee leak-free performance during frequent opening/closing cycles in the rainy season. • Chassis–Body Integration: Chassis shall be based on the Dongfeng 3308 mm wheelbase platform (reference model CLW5070GSSD6), equipped with a National VI-compliant engine to meet Hangzhou’s urban environmental protection requirements. The upper-body assembly is custom-engineered by Chengli Special Purpose Vehicle Co., Ltd., featuring a ~5 m³ tank volume, high-efficiency vacuum pump, and automated control system. • Operational Frequency Adaptability: Given high operational frequency during the rainy season, vehicles must operate continuously for over eight hours without failure. Hydraulic systems must incorporate oil-temperature cooling devices to prevent efficiency loss due to overheating. These standards draw upon real-world parameters from Chengli’s product database—for instance, tank wall thickness (4 mm steel plate) and vacuum pump air extraction rate (60 m³/h)—ensuring technical feasib