Zhangzhou SINOTRUK sludge dump truck (24 m³) government procurement case: How to avoid the 'corrosion and perforation' pitfall in a second procurement? In coastal Zhangzhou City, Fujian Province—where hot, humid, and rainy conditions impose stringent demands on sanitation vehicles—the municipal sanitation department (hereinafter referred to as 'a certain Zhangzhou unit') launched a second procurement project in 2024 for six 24 m³ SINOTRUK-chassis sludge dump trucks. Unlike the first procurement, this time the focus shifted from price and capacity alone to vehicle durability under hot-humid conditions—especially anti-corrosion coating and sealing component performance. Based on real tender information, this article reconstructs the decision-making process of this procurement and provides equipment selection guidance for similar users. I. The First Procurement’s 'Pitfalls': Corrosion and Sealing Failure In 2021, the Zhangzhou unit procured five 24 m³ sludge dump trucks for transporting dewatered sludge (approx. 80% moisture content) from municipal wastewater treatment plants. Within just one year of operation, two major issues emerged: • Severe corrosion at the cargo box bottom: Due to high moisture and corrosive substances in the sludge—and Zhangzhou’s annual average humidity exceeding 80%—standard carbon-steel cargo boxes developed extensive rust spots at weld seams and corners; localized perforation even occurred, causing sludge leakage and triggering environmental complaints. • Rapid aging of sealing components: Rubber sealing strips on the rear door and roof cover hardened and cracked within only six months under high-temperature, high-humidity conditions, resulting in ineffective sealing and wastewater dripping during transport—polluting road surfaces. According to the head of the unit’s equipment division: 'Maintenance costs in the first year exceeded 15% of the initial purchase price, and frequent breakdowns disrupted sludge removal efficiency. We realized that, in coastal hot-humid regions, 'corrosion resistance' and 'sealing reliability' are more critical than anything else.' This experience prompted a fundamental shift in their vehicle selection criteria for the 2024 re-procurement. II. Risk Mitigation in the Second Procurement: From 'Lowest-Bid Awarding' to 'Total Lifecycle Cost' In March 2024, the Zhangzhou unit conducted an open tender to procure six 24 m³ SINOTRUK-chassis sludge dump trucks, with a budget capped at approximately RMB 1.35 million (per publicly available tender data). The tender documents explicitly stipulated: • Cargo box fabricated from high-strength weathering steel, coated with at least two layers of epoxy zinc-rich primer plus one layer of polyurethane topcoat, achieving a minimum dry-film thickness of 200 μm. • Sealing components made of oil- and acid-resistant EPDM (ethylene propylene diene monomer) rubber, accompanied by a 5-year accelerated aging test report. • Chassis from reputable brands (e.g., SINOTRUK, Dongfeng), fully compliant with China VI emission standards. The winning bidder was Chengli Special Purpose Vehicle Co., Ltd. During evaluation, Chengli’s proposal included targeted optimizations specifically for Zhangzhou’s hot-humid environment: • Upgraded anti-corrosion coating: Both interior and exterior cargo box surfaces treated with 'hot-dip galvanizing + high-pressure airless spraying'; critical weld seams received secondary sealing to ensure rust-free operation throughout the annual rainy season (May–September). • Enhanced sealing system: Dual EPDM sealing strips on the rear door; hydraulic locking combined with pneumatic auxiliary sealing on the roof cover. Laboratory simulation tests confirmed zero leakage after 1,000 continuous operating hours at 45°C and 85% relative humidity. • Optimized powertrain matching