Technical Specifications for Welding Process Workflow

I. Pre-Welding Preparation

1. Material Requirements

• Use deoxidized copper tubes with degreasing treatment.
• Select phosphorus copper welding rods with 5% or 15% silver content.
• Prohibit lead-containing solders to avoid refrigerant contamination.

2. Cutting & Cleaning

• Cut copper tubes with specialized pipe cutters to ensure smooth, burr-free edges.
• Remove oxide layers and oil stains from inner/outer surfaces.
• Purge with nitrogen gas before welding.

3. Nitrogen Protection

• Use ≥99.99% pure nitrogen throughout welding.
• Control flow rate at 0.5-1.5 L/min.
• Continue nitrogen purge until pipelines cool completely

II. Welding Technical Requirements

1. Alignment & Gap

• Maintain concentricity for butt joints with 0.1-0.3 mm gap.
• Insertion depth: 1-1.5× pipe diameter; reserved gap: 0.05-0.35 mm.

2. Temperature Control

• Use neutral flame to maintain 600-750°C.
• Allow solder to melt naturally without overheating.

3. Operation Standards

• Apply uniform heating to prevent localized hotspots.
• Ensure solder naturally penetrates weld seams.
• Form smooth, full weld beads without pores, slag inclusions, or cracks.

III. Post-Welding Treatment

1. Cooling & Cleaning

• Natural cooling followed by wet cloth cleaning of residues.

2. Leak Testing

• Conduct 24-hour pressure test (≥2.5 MPa nitrogen).
• Verify sealing with electronic detectors or soap solution.

3. System Vacuum

• Achieve ≤500 μm Hg vacuum to eliminate moisture/impurities.

This translation integrates key standards from welding procedure specifications (WPS)  and industrial pipeline requirements, ensuring compliance with international technical norms. For full details on welding qualification procedures, refer to ASME Section IX