Braze a copper pipe

Copper components can also be soldered. A distinction is made between hard soldering and soft soldering. Especially with copper pipes brazing and soldering is used. Here we would like to explain the brazing of copper pipes.

Solder copper pipes after application

Most of the work that you would like to solder copper pipes will involve in-house power systems, ie air conditioning, heating and drinking water pipes. You must also follow the relevant regulations that apply to the sanitary and heating sector.

There are also copper pipe connections on the roof, in refrigeration technology, in gas pipes and in hydraulic and pneumatic applications. Below is a small summary of when soft soldering or brazing is allowed or not allowed.

Drinking water pipes:

  • Copper pipes, soft (R2209): soldering yes, brazing no *
  • Copper pipes, semi-hard (R250): soft soldering yes, brazing no *
  • Copper pipes, tough (R290): soldering yes, brazing yes

Heating pipes:

  • Copper heating pipes: soldering yes, brazing yes

Top, roof:

  • Gutters: soft solder yes, braze yes
  • Downpipes: soldering yes, brazing yes


  • Air conditioning and cooling lines Copper: soldering yes, brazing yes

Pneumatic and hydraulic lines:

  • Air ducts: soft soldering no, braze yes
  • Oil pipes: soft soldering no, braze yes

Gas lines:

  • Natural gas, liquefied gas: soft solder no, braze yes

* In the case of inadmissibility with the asterisk, regulations (GW2) are changed.

The solders for brazing

Of course, the solders that may be used are prescribed. These are listed for brazing alloys in DIN EN 1045 (DIN 8511). For soft solders, DIN EN 29454 applies:

  • AG 104 (L-Ag45Sn): Melting range 640 to 680 degrees Celsius
  • AG 106 (L-Ag34Sn: Melting Range 630 to 730
  • AG 203 (L-Ag44): Melting range 675 to 735
  • CP 105 (L-Ag2P): Melting range 640 to 830
  • CP 203 (L-CuP6), Melting range 710 to 890

The brazing of copper pipes

Of course, the brazing itself requires some experience. It is carried out with a soldering torch or a blowtorch. The preparation work must be clean and precise, otherwise problems can arise later. This includes pitting in copper pipes, but also leaking copper pipes.

Preparatory work: cutting to length and calibrating

When cutting the copper pipes, it is imperative to pay attention to the choice of suitable pipe cutters. It is also important that the pipes are cut to length as pressure-free as possible. To ensure this, the copper tubes are subsequently calibrated. Thus, the correct gap is ensured that the solder is pulled in by the capillary action.

Solder the copper tubes

First, the copper pipes must be cleaned. The copper tubes are inserted into each other for brazing. Then you are warmed up cherry red glowing. Now the solder is fed so that it can run into the gap. After soldering, when the pipes have cooled, a pressure and tightness test is required.

Tips & Tricks

Which solder is used also depends on which pipes are connected to each other, so copper with copper or copper with gunmetal or brass. Everything for soldering copper pipes can be found here.

Video Board: How-To: Braze Copper Tube