How To Braze Copper Pipe
If you are repairing or installing a new water line for your home the�International plumbing code requires that the copper pipe underground be brazed or flared and the wall thickness of the pipe�shall be�type K copper.�Type K copper�is rarely used above ground for water supply because of the costs.��
As a home owner and a DIYer you can pull a permit and do this work yourself. Read my article on How To Get A Homeowners Plumbing Permit.
For example most homes have M copper pipe, commercial buildings have L copper pipe, underground pipe uses K copper pipe.
You can use all types of piping material for water distribution under the ground like brass, galvanized steel, stainless steel, ductile, and others but for the purpose of this article and what most home owners have coming from the water supplier is copper pipe.
Brazing copper pipe is installed almost like soldering copper pipe but you use a different filler metal�and twice the heat.�
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Both pictures show acetylene outfits. One is smaller and� portable. The smaller acetylene outfit could be placed in�a ceiling when working. The other acetylene tank is used when your�brazing many�joints. The�good thing about both of the acetylene outfits�is you can order�longer hoses to help keep the tanks in one place longer when working.������������
Water pipe brazing for water mains begins with cleaning the pipe at each end and having clean copper fittings. Once you apply the heat it is best to use a acetylene outfit to achieve the proper temperature for proper melting of the filler metal.
The average temperature for soldering copper pipe is around 440 degrees fahrenheit. To braze copper pipe the �average temperature is 1250 degrees fahrenheit.�This temperature changes a few degrees up or down based on what type of filler metal your using.
The process of brazing copper pipe simplified�is as follows: Cut the ends of the copper pipe squarely, ream or other words remove any inside burrs inside of the copper pipe you just cut. See pictures of copper cutters and one style of reamer.
The red tool is the reamer.
The next step is to sand both ends of each copper pipe and clean the coupling or fitting. No flux is necessary when joining copper to copper when brazing. If you are going to connect to a dissimilar metal like a bronze valve or brass you will need to flux sparingly or use a flux coated brazing rod.
Heat your copper pipe on both ends until you get the joints almost red hot or around 1250 degrees Fahrenheit. Add your copper-phosphorus or copper-phosphorus-silver brazing filler metal without flux. �
Brazing copper pipe for oxygen, nitrogen, nitrous oxide, compressed air, and others requires when brazing that the line is purged with oil-free dry nitrogen to prevent the formation of copper on the inside surface of the joint. You must also wash the outside of the joint you just brazed with water and a stainless steel wire brush to remove any residue and permit clear visual inspection of the joint. If you used flux on a joint you will wash the joint with hot water.
In most cases for the average home you only need to braze one or two joints. One at the curb stop or water supply connection and one when you connect to your house supply side. If your more than 100ft away from the main water supply you would than need to braze more joints.
Insure you follow your local plumbing code requirement for frost line depth and any requirements that may be needed because of soil conditions.
Good luck, happy plumbing, and always think about safety for yourself and others. Wear your gloves, protective eye wear, and clothing.
Written by Everett Johnston
Master Plumber/Pipe-Fitter
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