1. From Existing Customer Reputation to New Orders: The Trust Chain in Xiamen Market In spring 2025, a municipal sanitation department in Xiamen urgently needed to procure a batch of wastewater treatment vehicles suitable for the humid, hot, coastal environment as part of its annual equipment upgrade plan. Previously, the department had purchased Chengli special-purpose vehicles—including water-sprinkling trucks and vacuum suction trucks. In response to Xiamen’s high-salinity fog and high-humidity climate, Chengli’s engineering team implemented customized optimizations for upper-structure anti-corrosion and sealing component durability. After two years of operation, the customer reported: “No visible rust on the chassis bottom, and no hydraulic system leakage observed during continuous rainy-season operations.” Based on this genuine reputation, the department proactively contacted Chengli Sales Manager Zhang Yue (Tel: ) during this tender process to inquire about the configuration and solution for the Dongfeng Wing-Opening Wastewater Treatment Vehicle. Subsequently, another long-term cooperative subdistrict environmental maintenance unit also approached Chengli through peer referral. Its head stated: “Xiamen experiences nearly six months of rainy season annually, resulting in high operational frequency for wastewater treatment vehicles. Our biggest concern is vehicle breakdowns in humid conditions. Senior colleagues recommended Chengli for its robust anti-corrosion measures and high-quality sealing components—we’d like to review the specific solution.” This trust chain—where existing customers refer new clients and peers recommend each other—is precisely Chengli’s core model for rapid market penetration in Xiamen. 2. Technical Pain Points in Humid-Hot Environments and Chengli’s Solutions Located along China’s southeast coast, Xiamen features an annual average relative humidity exceeding 80% and severe salt-fog corrosion. Conventional wastewater treatment vehicles commonly exhibit the following issues after 1–2 years of service: • Chassis Corrosion: Standard paint coatings begin blistering and peeling within six months under salt-fog exposure; perforation rust may appear after one year; • Sealing Component Aging: Rubber gaskets rapidly harden under high temperature and humidity, causing wastewater leakage; • Electrical System Failures: Moisture-induced short circuits in connectors compromise control system stability. To address these pain points, Chengli applied the following technologies to the Dongfeng Wing-Opening Wastewater Treatment Vehicle (reference model: CLW5070GSSD6, upgraded chassis version) submitted for this tender: • Full-Vehicle Hot-Dip Galvanizing + Electrophoretic Coating: All chassis structures and steel components undergo hot-dip galvanizing; critical areas receive additional electrophoretic primer, achieving >1,000 hours salt-fog resistance (per ISO 9227 standard); • Weather-Resistant Fluoroelastomer Seals: All wastewater pipeline joints and valve gaskets are replaced with fluoroelastomer material, offering a temperature tolerance range of −30°C to +250°C and maintaining elasticity even at Xiamen’s summer peak temperatures of 40°C; • IP67-Rated Electrical Protection: All wiring harness connectors use waterproof aviation-grade plugs; the control cabinet achieves IP67 ingress protection rating, enabling short-term submersion operation. As emphasized by Chengli’s after-sales engineer during delivery: “We don’t pursue one-time transactions—we provide lifelong upper-structure service and guarantee 24-hour direct shipment of spare parts. You focus on operation; we handle all subsequent maintenance.” Such commitments directly alleviate procurement parties’ concerns regarding long-term reliability risks in humid-hot environments. 3. Procurement Proposal and Cost-Control Comparison The vehicles procured in this project are Dongfeng Wing-Opening Wastewater Treatment Vehicles, primarily intended for post-s