Soldering Copper Tube

In the plumbing industry, there are now various ways of jointing copper tube. You can use compression, push-fit, press-fit, even gluing joints, with purpose made adhesives and good old traditional soldering. Any of the first four methods are preferable anywhere there may be a risk of fire.
Without a doubt though, the neatest and aesthetically pleasing to the eye, is accurately bent copper tube, combined with neatly soldered enfeed joints. This is a reflection of a good professional plumber’s pipefitting skills.
There are various recommended methods of soldering copper tube to ensure a neat tidy joint. Although there is no particular right or wrong way, there are certain things that need to be avoided. Modern day fluxes are self-cleaning though any copper that has oxidised or has paint residues on will require cleaning. Steel wool has been used over the years, though aluminium oxide abrasive pads are easier on the hands and don’t leave steel splinters in the skin. After ensuring the copper tube and fittings are clean, the next thing is to apply flux using a brush.
The most controversial question around applying flux is, what is the right or wrong way? Do you apply it to the pipe only, the fitting only, or both. Over the years I have used all three methods and I suppose the answer is, all three are fine as long as you don’t apply excessive amounts that can enter the pipe and the water system.
If you are learning how to solder, I always recommend you apply a thin film of flux to both the pipe and the fitting. This way you can ensure all surfaces to be soldered are coated with a fine film of flux, while at the same time there is no excess inside the pipe. This will enable capillary action to take place when the joint is heated and solder applied to the mouth of the fitting.
When soldering one important factor is to ensure that you have regulated the correct size flame in regards to the size of pipe to be soldered. Overheating can cause the pipe to oxidise and burn up the flux, with the joint darkening you will then find the solder will not take and draw into the capillary joint. Regulating the flame will also raise the temperature of the joint slowly, giving more time to apply solder to all of the joints.
The joint should be heated to the correct temperature, when the flux changes from a clear colour to a pale shade of brown. You only have a matter of seconds to make the joint. You will become more proficient at soldering, with the more experience you gain.
When you touch the mouth of the fitting with the solder, if it is at the required temperature the solder will melt and liquefy, drawing into the fitting using capillary action, sometimes called capillary attraction. It is essential to ensure adequate solder has been drawn into the fitting, while not applying excessive solder.
Excess solder can leave unsightly drips hanging, or worse still, the excess solder can form a ball within the pipe.
This ball of solder can then go on and rattle around inside of the pipework, or jam in the seating of valves, pumps, motorised valves etc. causing permanent damage.
Another bad habit that has seemed to spread through some parts of the industry is applying flux to the joint, after the joint has been soldered. This is completely pointless, it’s a waste of flux, it disintegrates the bristles of the brush and makes the whole job unsightly. Let the pipe cool naturally, then while still warm remove the flux with a damp cloth, afterwards use a dry cloth and finally clean with either an aluminium oxide pad or steel wool. Applying extra flux to a joint, will only leave flux residue that will turn green, look unsightly and further corrode and pit the copper if left remaining on the tube and fitting.
Clean and tidy pipework can look very pleasing to the eye and will not only look professional, but will probably further ensure you of plenty of future work from your customers.
If you want to learn more about plumbing tasks and may be become a fully qualified tradesperson then contact us at www.newtradescareer.co.uk and we’ll help you reach your goal.