Welding of Lifting Components for Container Houses

The welding of lifting components for container houses must be carried out in a standardized manner from multiple aspects such as process, materials, joint types, and operational requirements to ensure structural safety and reliability.

1. Selection of Welding Process

Choose the appropriate process based on production scale and component type:

• Manual Welding: Suitable for small enterprises or low-volume production scenarios, offering high flexibility but lower efficiency.
• Automatic Welding: Suitable for large-scale production by large manufacturers, commonly using gas metal arc welding (GMAW) and submerged arc welding (SAW). GMAW protects the arc with an inert gas (such as CO₂), suitable for welding thin plates and small components, featuring fast welding speed and minimal distortion; SAW protects the arc with a flux layer, suitable for welding thick plates and large components, providing high weld quality but with higher equipment costs.

2. Matching of Welding Materials

Lifting components typically use carbon steel materials, and welding materials must be selected based on the base material composition, thickness, and stress state:

• Commonly Used Electrodes: E7018 electrodes are widely used for welding carbon steel lifting components due to their stable arc, good toughness of the weld metal, and strong crack resistance.
• Material Selection Principles: The welding material must match the strength grade of the base material. For example, when welding Q235 carbon steel, E7018 electrodes can meet the requirements; if the base material is thick or subjected to dynamic loads, low-hydrogen electrodes should be selected to reduce the risk of hydrogen-induced cracking.

3. Design of Welding Joint Types

Choose the joint type based on plate thickness:

• Butt Joints: Suitable for lifting components with thicker plates (usually ≥6mm), requiring beveling to ensure full penetration. They offer high load-bearing capacity but have a higher risk of welding distortion.
• Lap Joints: Suitable for lifting components with thinner plates (usually <6mm), dispersing stress through an overlapping structure but increasing component weight and material consumption.
  Key Requirements: Regardless of the joint type used, ensure alignment accuracy (deviation ≤1mm) and uniform gap (usually 0-2mm), using auxiliary supports such as angle steel if necessary.

4. Welding Operation Specifications

1. Pre-welding Preparation:

   • For manual welding, grind the joint surface until metallic luster is visible, removing oil, rust, and other impurities; for automatic welding, check equipment parameters (such as wire feed speed and gas flow rate) to ensure they match process requirements.
   • Test welding to determine optimal parameters: Test current (usually 120-200A), voltage (20-30V), and welding speed (15-30cm/min) through test piece welding to ensure good weld formation and no defects.

2. Welding Process Control:

   • For manual welding, use short-arc operation to control molten pool temperature and prevent burn-through; for automatic welding, monitor the weld tracking system in real-time to avoid deviation.
   • Protective measures: For gas metal arc welding, ensure the purity of the protective gas (CO₂ ≥99.5%); for submerged arc welding, maintain uniform flux layer thickness (usually 25-40mm).

3. Post-welding Treatment:

   • Remove weld slag and spatter from the weld surface, and perform non-destructive testing (such as X-ray or ultrasonic testing) on important components to detect internal defects.
   • For defects such as porosity and cracks, grind and re-weld the affected area, which must be re-inspected to ensure quality.

5. Safety and Quality Assurance

• Safe Operation: Welding personnel must wear protective face shields, insulating gloves, and dust masks to avoid arc burns and inhalation of metal dust; set up fire barriers in the welding area to prevent sparks from igniting flammable materials.
• Regular Maintenance: Perform performance tests on welding equipment every quarter (such as current stability and gas flow accuracy) and conduct annual skill retraining for operators to ensure consistent process execution.