Government procurement case of a yellow-plated sewage treatment vehicle in Dongguan: Chengli's 3308 model winning bid solution and cost analysis. In municipal sanitation projects across South China’s humid and hot climate zone, selecting sewage treatment vehicles presents dual challenges—handling frequent rainy-season operations while resisting corrosion caused by high humidity on vehicle structures. Recently, a municipal sanitation department in Dongguan completed its procurement project for yellow-plated sewage treatment vehicles (Model 3308), with Chengli Special Purpose Vehicle Co., Ltd. delivering the batch as the supplier. This article provides an in-depth analysis of the solution design, cost control, and technical considerations based on publicly available tender information and industry practices, offering reference for similar procurements. I. Project Background and Requirements Analysis Dongguan is located in central-southern Guangdong Province and features a subtropical monsoon climate, with annual precipitation exceeding 1,700 mm, a long rainy season, and high humidity. The municipal sanitation department is responsible for maintaining local drainage networks and treating wastewater. Its existing equipment has aged significantly, necessitating the urgent procurement of a batch of yellow-plated sewage treatment vehicles featuring high-efficiency suction/discharge and treatment capabilities. According to publicly released tender documents, the procurement focused on the 3308 model (a modified version based on a Dongfeng chassis), requiring the following core capabilities: • Sewage treatment capacity: Suction/discharge flow rate ≥ 300 m³/hour, capable of handling complex wastewater containing slurry and debris. • Corrosion resistance: Due to the humid environment, the tank and piping must feature weather-resistant coatings. • Seal durability: High operational frequency during the rainy season requires hydraulic systems and seals to remain stable under damp conditions. • Regulatory compliance: Must meet China VI emission standards and be eligible for nationwide registration and annual inspection. • Budget constraint: Approximately RMB 402,000–517,000 per unit (reference price from similar local projects; final contract price applies), with four units planned for procurement. II. Winning Bid Solution Interpretation: Chengli 3308 Model Chengli Special Purpose Vehicle Co., Ltd. secured the bid with its mature 3308 model (a derivative of chassis model CLW5070GSSD6; actual specifications subject to official announcements). The key advantages of this solution are outlined below: 1. Anti-rust Coating and Adaptability to Humid-Hot Environments To address Dongguan’s high-humidity conditions, Chengli applied an epoxy resin + polyurethane composite coating to the tank and piping, achieving over 1,000 hours of salt spray resistance (per internal corporate standards). Compared to standard paint finishes, this coating significantly reduces rust risk in humid-hot environments. Additionally, fluororubber seals were selected for their excellent oil resistance, acid/alkali resistance, and anti-aging properties—ensuring reliable sealing performance even during high-load rainy-season operations (e.g., continuous 12-hour suction/discharge). 2. Powertrain and Operational Efficiency Equipped with a Dongfeng 130-horsepower engine (China VI compliant) and a dual-circuit hydraulic system, the vehicle ensures stable suction, discharge, and treatment operations. Field testing confirmed a maximum suction depth of 8 meters and a solid content tolerance of up to 5% in treated wastewater (referencing CLW5070GSSD6 official announcement parameters), fully meeting municipal pipeline desilting requirements. 3. Delivery and After-sales Support Manufactured at Chengli’s Suizhou factory using a zero-inventory production model, standard models can be delivered within 7–15 days (actual delivery time for this project was 12 days). The chassis is covered und