brazing copper pipe

What is the Best Method for Brazing Copper Pipe?

December 14 2017

Brazing Copper Pipe

Brazing copper pipe has been, for many years, one of the most common methods of connecting copper tube and fitting. This method is especially useful when great joint strength is needed.

Typically, great joint strength is needed for systems operating at 350 degrees and above. Such systems may include:

  • Water supply
  • Fire protection
  • Distribution of fuel
  • Gas
  • Refrigeration

Brazing, unlike its most common counterpart, soldering, is done with a very hot heat of about 1100 to 1500 degrees. Both oxygen and non-oxygen bearing copper can be brazed to produce a joint that’s strong enough. A slightly carburizing flame should be used as well.

The Joint could be made in one of two ways:

  • With inserts of the filler metal, or
  • Filler metal may be inserted from outside after the joint has reached the required temperature.

Instructions For Brazing Copper Pipe

It’s important to note that all of the following steps should be completed on the same day to avoid pipe damage. You should also take maximum safety measures. The steps go as follows:

  1. Mark the tube correctly to ensure accurate lengths.
  2. Cut the tube using a hacksaw or any other safe preferred method.
  3. Smoothen both ends of the cut tube to rid off any metal spurs. Reaming can be done using a reaming blade, a half round file or deburring tool.
  4. Prepare joints by cleaning, with either an abrasive pad or sand cloth the areas to be soldered. This is to remove any impurities such as oil or oxides. There should be an allowance of 0.004 inches between the fitting and tube.
  5. Install the tube in the fitting ensuring a secure fit, but enough space for the capillary action of the solder. This could be about 0.0004 inches. Turn if possible and firmly support the tube.
  6. Position and maintain the flame perpendicularly to the tube and preheat both the fitting cup and tube. Be sure not to overheat as this could burn the flux. Keep the flame in constant motion and avoid it lingering on any single area of the tube. An oxy-fuel torch with a neutral flame is preferred. When using a flux, use gloves, and avoid contact with mouth, eyes and cuts.
  7. Contact the filler metal to the melting joint and apply at the point where the tube enters the joint. Apply heat source to the base of the cup as soon as the filler metal melts. Keep flame away from filler metal, let the heat melt it. Do the same process for the vertical joints. It’s complete on sight of a full filament.
  8. Allow the joint to cool by itself then clean the flux with a damp heavy cloth.

Then you’re done! Brazing copper pipe accomplished!

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