Brazing of Copper Lesson
In this lesson will we look at the aspects of brazing copper pipe and fittings.
Including how and the health and safety aspects of the work.
Brazing of Copper
Brazing of Copper
Why do we need to braze copper?
Before you attempt brazing of copper you must have a knowledge of its properties:
Copper melts at 1083°c and when molten is very fluid. The thermal conductivity (how quickly it heats up and cools down) is very high, so you get a rapid transfer of heat. Copper loses tensile strength (becomes soft and easily malleable) as it becomes hot, at about 480°c its tensile strength is only about 40% of that at normal temperature. care needs to be taken as copper will collapse near melting point.
The process of heating copper to become soft is called Annealing, even when the copper is cooled it is still soft, and this makes the copper more workable.
Silver-alloy Brazing of Copper
Because of the above characteristics of copper, silver brazing alloys can be easily applied, for the joining of copper pipe and copper pipe to brass fittings. This method can be practically used by any method that gives the required temperature, but Oxygen - Acetylene and MAP gas torches are the most common.
When joining copper to brass a flux has to be used to aid bonding of the two metals.
So we need to braze copper to create a water tight seal in the joins in the water installation.
Crox and compression joins are not legal anywhere that is not easily accessible, i.e. behind walls and under concrete slabs, and the brazed joint is stronger and more resistant to strain that any compression joint.
Information about how to braze with copper pipework.
Here are some key things just to think about when brazing:
1. Heat is the key to successful brazing, allow the copper to reach the correct temp before applying the Silfos.
2. Never boil the Silfos, this can create tiny air pockets and potential leaks.
3. Always allow the Silfos to cool and change in colour before moving otherwise cracking can occur.
4. The copper must be clean, as with any soldering, brazing, welding, clean material is important.
5. Always use flux when brazing brass to copper, creates correct bonding of the materials.
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