Welding of Container House Roof Panels

The welding of container house roof panels requires selecting an appropriate method based on material and process requirements, and strictly adhering to operational specifications and safety measures, as detailed below:

I. Selection of Welding Methods

1. Manual Arc Welding
   Suitable for most scenarios, it involves cleaning oil and debris from the welding area, selecting a matching welding rod, and controlling the current for welding. After welding, the weld seam needs to be polished and trimmed. This method is flexible but has lower efficiency and requires higher operational skills.

2. Gas-Shielded Welding
   Divided into inert gas (such as argon) and active gas (such as carbon dioxide) shielded welding, it features fast speed, high precision, and strong stability. Before welding, a gas protection device needs to be set up, and the choice of protective gas should consider the material type (e.g., carbon dioxide for carbon steel, argon for stainless steel) and environmental humidity (in humid environments, the purity of the gas needs to be enhanced).

3. Submerged Arc Automatic Welding
   Suitable for high-efficiency mass production, it melts metal through an arc under a flux layer, reducing spatter and improving weld quality. However, the equipment cost is high, and professional training is required, making it suitable for welding standardized container roof panels.

4. Spot Welding

   • Steps: Clean the roof panel surface → Align and position (using fixtures for fixation) → Set welding parameters (current, time, pressure) → Perform spot welding.
   • Thin Panel Handling: Use low current and fast welding to reduce heat input, combined with preheating (100-150°C) to improve welding performance and avoid deformation or burn-through.

II. Key Operational Specifications

1. Roof Panel Layout and Joint Treatment

   • Standard container roof panels use butt joints, while customized containers use lap joints (with a lap size of 25mm). The layout should align long sides with long sides and wide sides with wide sides, with the width side being the length side of the container.
   • Butt joints should be initiated on a run-on tab and terminated on a run-off tab. Arc striking on non-welding areas is prohibited. When terminating the arc, fill the crater, and ensure the weld is free of cracks, pores, or slag inclusions.

2. Welding Deformation Control

   • Pre-welding reverse deformation: Apply mechanical pressure to create reverse deformation on the roof panel, counteracting welding shrinkage.
   • Post-welding straightening: For local deformations, use flame heating or mechanical correction, controlling the heating temperature (not exceeding the tempering temperature) to avoid material performance degradation.

III. Safety and Quality Assurance

1. Safety Protection
   Wear safety goggles and protective gloves, set up fire barriers in the welding area, and use safety harnesses and scaffolding for high-altitude operations.

2. Post-Welding Treatment

   • Polish and trim the weld seam to a flat surface, removing welding slag and gaps.
   • Apply anti-rust paint or hot-dip galvanizing treatment to ensure corrosion resistance at the welding area.

3. Quality Inspection

   • After spot welding, inspect the uniformity of weld spot distribution and check for cold welds or cracks.
   • For butt welds, perform X-ray or ultrasonic flaw detection to ensure no internal defects are present.