The metal structure of the eco hopper serves as the core load-bearing framework, and its design, manufacturing, and inspection must strictly follow current national and industry standards.
The design should meet the three basic mechanical requirements of strength, stiffness, and stability while also considering manufacturing practicality and ease of future maintenance. The overall structural lines should be smooth, the load paths must be clear and direct, and stress concentration should be minimized through reasonable structural details (like large-radius transitions and avoiding sudden cross-section changes) to ensure the structure has sufficient fatigue life under variable loads.
Material Selection and Pretreatment
Material Grade: The eco hopper's steel used for main load-bearing components (including machine room platforms and equipment supports) must meet tensile strength, yield strength, elongation, and cold bending performance requirements, with limitations on carbon, phosphorus, and sulfur content. For critical load-bearing parts, proof of adequate impact toughness at room temperature must also be provided to withstand unexpected impact loads.
Corrosion-prevention Pretreatment: Considering the high-salt, high-humidity corrosive environments of ports or industrial sites, load-bearing materials should undergo shot blasting/sandblasting to remove rust and primer coating immediately after entering the plant. Raw materials must not be stored exposed.
Secondary Component Thickness: The eco hopper steel plates and webs of all secondary components must be no less than 6mm thick to ensure local stiffness and resistance to deformation.
Welding and Connection Processes
Main Structure Welding: All major load-bearing components of the eco hopper are welded together. The welding materials must be compatible with the base metal, the welding process must be approved, and the weld quality level must meet the requirements of standards such as GB/T 19418.
High-Strength Bolt Connections: For major connections installed on-site, high-strength bolts are preferred. Bolts and nuts must have anti-vibration and anti-loosening properties and undergo reinforced heat treatment. During construction, the torque/angle method must be used to ensure accurate pre-tensioning, and randomly replacing bolt grades is strictly prohibited.
Flange Mating Surfaces: For eco hopper components connected with flanges, the contact surfaces must be flat and tightly fitted. No warping or light penetration is allowed during inspection to ensure uniform load transmission.
Corrosion Protection and Sealing Design
Box-Shaped Component Sealing: All eco hopper's box-section components of the eco hopper must be fully welded to prevent moisture or salt spray from getting inside. The port hopper interior surfaces should be coated with rust-proof paint to prevent undetectable internal corrosion.
Drainage and Inspection: Drain holes should be provided in low areas where water might accumulate to prevent standing water. All eco hopper parts that require regular inspection or maintenance (such as hinges or areas with dense welds) should have inspection openings and be equipped with access paths, platforms, and ladders to ensure reachability.
Vibration Resistance, Wind Resistance, and Appearance Design
All diagonal and brace designs should balance aesthetics, low wind resistance, and wind vibration resistance. The cross-sectional shape should use profiles with good aerodynamic performance to avoid vortex-induced resonance in strong winds.
The eco hopper's structure's surface should be easy to maintain for rust removal, painting, and other routine upkeep.
Hoisting and Rotating Components Requirements
Lifting Lugs: Both the entire eco hopper and each detachable component must have permanent lifting lugs. The eco hopper location and holes for these lugs should avoid stress concentration, and the rated lifting capacity must accommodate the most adverse center-of-gravity shift of the equipment or component.
Bearings and Rotating Parts: Except for pins, all areas with frequent relative motion should use rolling bearings. The eco hopper designed service life of all mechanism bearings should meet or exceed the calculated life specified in GB/T 6391, ensuring reliable operation under rated conditions.
