TECHNICAL
73
Copper soldering –
the dos and the don’ts
Each month the Copper Development Association of South Africa
(CDAA) brings insight into the dos and the don’ts of copper soldering.
The following tips are there to assist the
craftsperson to achieve lasting results.
Two general types of brazing filler metal are used for
copper tube. Classified according to their components,
they are BCuP (brazing copper and phosphorus) and BAg
(brazing silver).
BCuP filler metals are preferred for joining copper tube
and fittings. The phosphorus in them acts as a fluxing
agent and the lower percentage of silver makes them
relatively low cost. When using copper tube, wrought
copper fittings, and BCuP brazing filler metal, fluxing is
optional due to the self-fluxing action of the phosphorus.
www.plumbingafrica.co.za
Oxy/fuel torches are generally used for brazing because
of the higher temperatures required. Recent innovations
in tip design make air-fuel torches useful on a wider
range of sizes for soldering and brazing.
When working at brazing temperatures, safety
precautions must be followed and care must be taken to
protect both the operator and the materials being used.
The heating operation is the same as for soldering. First,
preheat the tube and then the fitting. When the filler
metal starts to melt, apply heat at the base of the fitting
socket to help draw the brazing filler metal in by capillary
actions. PA
November 2016 Volume 22 I Number 9