Case Background: Sewage Treatment Demand and Procurement Challenges in Guiyang. In 2025, a municipal sanitation department in Guiyang City issued a public tender to procure a batch of EHY5045TWCE6 sewage treatment vehicles (3308 series), specifying the model explicitly. Based on a Dongfeng chassis, this vehicle features a compact design optimized for sewage suction and discharge operations in narrow urban streets and residential communities. Tender documents specified a total budget cap of approximately RMB 899,000 for two units—around RMB 400,000 per unit (per publicly available tender information). Located in Southwest China, Guiyang experiences a humid subtropical climate with a rainy season lasting 5–6 months annually. This poses stringent requirements on the vehicle’s corrosion resistance, seal longevity, and operational stability under high-load conditions. The procuring entity specifically emphasized after-sales service terms in the tender documents—requiring suppliers to provide at least a three-year warranty on core components, along with explicit commitments regarding anti-corrosion coating performance and seal replacement intervals. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. won the bid based on its comprehensive after-sales service system and product configuration, delivering two EHY5045TWCE6 units. How After-Sales Clauses Were Drafted in the Guiyang Contract: Key Takeaways from This Case In the Guiyang project contract, after-sales clauses were designated as a critical section. The procuring party explicitly required: national joint warranty coverage for the chassis (Dongfeng chassis), and lifetime service for the superstructure—including the sewage treatment system, tank body, and sealing components. Specific provisions included: • Anti-Corrosion Coating Commitment: Given Guiyang’s humid climate, the contract mandated epoxy resin or hot-dip galvanized coatings for the tank and piping systems, guaranteeing no perforation due to rust throughout the warranty period. • Seal Durability: To withstand high humidity during the rainy season, seals (e.g., tank lids and valve O-rings) must be made of ozone- and aging-resistant nitrile rubber, with a minimum warranty period of two years. • High-Load Performance: With increased operational frequency during the rainy season, the contract required that the sewage pump and hydraulic system maintain temperature rise ≤60°C after continuous operation for over eight hours, and stipulated rapid repair response times. In its tender proposal, Chengli provided detailed technical specifications for the EHY5045TWCE6: official model number CLW5070GSSD6 (per MIIT certification), 3 m³ tank capacity, equipped with a 4 kW sewage pump and an automatic liquid-level control system. Chengli committed to lifetime superstructure service, guaranteed 24-hour direct shipment of spare parts to Guiyang, and assigned dedicated after-sales manager Zhang Yue () as the project liaison to ensure immediate responsiveness. Common Types of After-Sales Disputes—and How the Guiyang Project Mitigated Them In sanitation vehicle procurement, after-sales disputes typically arise in three areas: • Corrosion Issues: Under humid conditions, conventional coatings may peel off, leading to tank corrosion. The Guiyang project mitigated this risk by contractually mandating strict anti-corrosion standards; Chengli implemented dual-layer protection—hot-dip galvanizing plus epoxy resin coating. • Seal Failure: High humidity during the rainy season accelerates rubber seal aging and cracking. Chengli selected nitrile rubber seals and committed to free replacement of any failed components within two years. • High-Load Operational Failures: Continuous suction/discharge operations may cause pump overheating or hydraulic leakage. Chengli incorporated dedicated heat dissipation devices into the design and explicitly defined response timeframes in the contract—24 hours for non-emergency faults.