When welding copper pipes, you need to select the appropriate welding consumables (electrode or wire) based on the welding method, pipe thickness, and working conditions. The following is a guide to common welding materials and processes:
I. Common Welding Methods and Corresponding Welding Consumables
1. Gas Welding (Oxy-Acetylene Welding)
Applicable Applications:
Thin-walled copper pipes (thickness ≤ 3mm), small pipes, or repair welding.
Recommended Welding Consumables:
Copper-Phosphorus Brazing Filler Metal (BCuP Series): such as BCuP-2 (6%-8% phosphorus content), has a melting point of approximately 710°C-800°C, good fluidity, and requires no additional flux.
Silver-Based Brazing Filler Metal (BAg Series): such as BAg-20 (20% silver + copper + zinc), has a melting point of approximately 630°C-760°C and is suitable for high-tightness joints (such as those in refrigeration systems).
Precautions:
Preheat the pipe to 400°C-600°C to prevent rapid heat loss. Allow to cool naturally after welding to avoid cracking caused by sudden cooling.
2. TIG Welding (Tungsten Inert Gas Welding)
Applicable Applications:
Medium-thick wall copper pipes (thickness ≥ 2mm), welding with high precision or high strength requirements (such as industrial piping).
Recommended Welding Materials:
Red copper wire (ERCu): For example, ERCu (pure copper wire) requires argon shielding.
Silicon bronze wire (ERCuSi-A): Contains 3% silicon and has excellent crack resistance, suitable for welding thick-walled pipes.
Tin bronze wire (ERCuSn-A): Contains 5%-8% tin and has excellent fluidity, suitable for complex joints.
Precautions:
Preheat to 300°C-500°C and use direct current (DCEN).
Argon purity ≥ 99.99%, flow rate 8-15 L/min.
3. MIG Welding (Metal Inert Gas Welding)
Applicable Applications:
Medium-thick wall copper tubes (thickness ≥ 4mm), long welds, or mass production.
Recommended Welding Materials:
Copper welding wire (ERCu): Requires argon or helium-argon mixture (He+Ar).
Aluminum bronze welding wire (ERCuAl-A2): Excellent corrosion resistance, suitable for marine environments.
Precautions:
Preheat to 200°C-400°C and use pulsed MIG to reduce spatter.
Recommended gas ratio: 75% helium + 25% argon (increases penetration).
4. Brazing
Applicable Applications:
Thin-wall copper tubes (thickness ≤ 2mm), low-pressure or low-temperature systems (such as air conditioning refrigerant pipes).
Recommended Welding Materials:
Copper-phosphorus brazing filler metal (BCuP series): Such as BCuP-5, containing 6%-7% phosphorus, with excellent self-brazing properties.
Silver solder (BAg series): such as BAg-8 (45% silver), has a low melting point and is suitable for precision welding.
Precautions:
Use a borax-based flux (such as FB102) to remove oxide films.
Heat evenly and avoid local overheating.
II. Welding Material Selection Principles
Matching the base metal composition: Prefer pure copper or solder containing deoxidizing elements (phosphorus, silicon) to reduce porosity.
Working Requirements:
Electrical/thermal conductivity: Pure copper wire (ERCu).
Corrosion resistance: Silicon bronze (ERCuSi-A) or aluminum bronze (ERCuAl-A2).
Low-temperature toughness: Silver solder (BAg-8).
Cost Control: Copper-phosphorus solder is low-cost, while silver solder is more expensive but offers superior performance.
III. Common Problems and Solutions
Porosity:
Cause: Oxide film not removed, insufficient gas shielding.
Solution: Enhance pre-weld cleaning and increase argon flow.
Cracks:
Cause: Excessive thermal stress or impurities in the weld material.
Solution: Preheat the pipe and use low-hydrogen weld material (such as ERCuSi-A).
Lack of fusion:
Cause: Insufficient heat or excessive welding speed.
Solution: Increase the current or reduce the welding speed.
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German imported precision copper tube production line (annual output of 30,000 tons)
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Fully automatic copper bar continuous extrusion line
Intelligent copper sheet and strip finishing mill unit
Digitalized control and management of the whole production process is realized through MES system, and the dimensional accuracy of the products can reach ±0.01mm.
