- Category: Technical
- Published on 24 October 2016
- Hits: 447
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.
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.