When welding copper pipe, you need to select the appropriate welding material (electrode or wire) according to the welding method, pipe thickness and working condition requirements. The following are common welding materials and process guidelines:
I. Common welding methods and corresponding welding consumables
1. Gas welding (oxygen - acetylene welding)
Applicable scenes:
Thin-walled copper pipe (thickness ≤ 3mm), small pipes or maintenance welding.
Recommended welding consumables:
Copper-phosphorus brazing material (BCuP series): such as BCuP-2 (containing phosphorus 6% ~ 8%), melting point of about 710 ° C ~ 800 ° C, good fluidity, without additional flux.
Silver-based brazing material (BAg series): such as BAg-20 (containing 20% silver + copper + zinc), melting point of about 630 ℃ ~ 760 ℃, suitable for high sealing joints (such as refrigeration systems).
Caution:
It is necessary to preheat the pipe to 400℃~600℃ to prevent heat dissipation too fast.
Cool naturally after welding to avoid cracking caused by sudden cooling.
2.TIG welding (tungsten inert gas shielded welding)
Applicable scenes:
Medium and thick-walled purple copper pipe (thickness ≥ 2mm), high precision or high strength requirements of welding (such as industrial pipelines).
Recommended welding consumables:
Purple copper welding wire (ERCu): such as ERCu (pure copper welding wire), need to cooperate with argon gas protection.
Silicon bronze wire (ERCuSi-A): 3% silicon, good crack resistance, suitable for thick-walled pipe welding.
Tin bronze wire (ERCuSn-A): containing 5% to 8% tin, excellent fluidity, suitable for complex joints.
Precautions:
Preheat to 300℃~500℃, use DC positive connection (DCEN).
Argon purity ≥ 99.99%, flow rate 8~15L/min.
3.MIG welding (melting pole inert gas shielded welding)
Applicable scenes:
Medium and thick-walled copper pipe (thickness ≥ 4mm), long weld or mass production.
Recommended welding consumables:
Purple copper wire (ERCu): need to cooperate with argon or helium-argon mixture (He + Ar).
Aluminum bronze wire (ERCuAl-A2): good corrosion resistance, suitable for marine environment.
Precautions:
Preheat to 200℃~400℃, use pulsed MIG to reduce spatter.
Gas ratio suggestion: helium 75% + argon 25% (to improve the depth of fusion).
4.Brazing
Applicable scenes:
Thin-walled copper tubes (thickness ≤ 2mm), low-pressure or low-temperature systems (such as air conditioning refrigerant tubes).
Recommended soldering material:
Copper-phosphorus brazing material (BCuP series): such as BCuP-5, containing phosphorus 6% ~ 7%, excellent self-brazing.
Silver brazing material (BAg series): such as BAg-8 (containing 45% silver), low melting point, suitable for precision welding.
Caution:
Use borax type brazing flux (e.g. FB102) to remove oxide film.
Heat evenly, avoid local overheating.
Second, the principle of choice of welding consumables
Match the composition of the base material: give priority to the use of pure copper or welding consumables containing deoxidizing elements (phosphorus, silicon) to reduce porosity.
Working condition requirements:
Electrical / thermal conductivity: pure copper wire (ERCu).
Corrosion resistance: silicon bronze (ERCuSi-A) or aluminum bronze (ERCuAl-A2).
Low-temperature toughness: silver brazing material (BAg-8).
Cost control: copper-phosphorus brazing material has low cost, silver brazing material has high cost but superior performance.
Third, common problems and solutions
Porosity:
Reason: oxide film is not cleaned, insufficient gas protection.
Countermeasures: strengthen the pre-soldering cleaning, increase the flow of argon gas.
Cracks:
Reason: excessive thermal stress or welding consumables containing impurities.
Countermeasures: preheat the pipe, choose low hydrogen welding consumables (such as ERCuSi-A).
Failure to fuse:
Reason: insufficient heat or welding speed is too fast.
Countermeasure: Increase the current or reduce the welding speed.
