How to use Alu-flo™ ZA-1 ChannelFlux™ Brazing Strip
RP30389
1. General technique
Brazing aluminium requires more care than brazing of copper to copper joints. Aluminium has
approximately half the thermal conductivity of copper and a much lower melting temperature. Overheating
can readily occur causing the material to distort and melt. Overheating will also result in poor quality joints
and erosion of the aluminium by the brazing filler metal.
Caution: Self-aspirating MAPP Gas, propane or butane flames are recommended, oxy-fuel type flames are
not.
2. For pipe and tube joints
properly produced socket joints are required for leak tight and mechanically sound results. Joints should
have a socket depth of approximately 1 x the pipe diameter. The socket should be straight and parallel
throughout. As a guide the joint gap should be such that the outer and inner tubes hold in the same alignment
without 'leaning' and creating uneven gaps around the joint. It should be possible to rotate the inner tube in
the joint without having to apply much manual force.
Caution: Simply building up of a fillet of filler metal around a joint is unlikely to result in formation of leak
tight and mechanically sound joints.
3. Joint preparation
Clean the joint surfaces of oil and grease then abrade with a coarse grade steel wool. Wipe clean to remove
abrasion debris. Use new pipework whenever possible. Clean expansion tools before using them with
aluminium to avoid copper fragments / contamination getting into the joint.
4. Aluminium to aluminium
(i) First evenly heat the inserted pipe of the joint. Next begin to sweep the flame backwards and forwards
between the socket and the inserted pipe, whilst also working the flame around the joint. It is important to
move the flame constantly around the joint to prevent localised overheating and the possibility of melting
the aluminium.
(ii) Next touch the Alu-Flo™ZA-1 strip onto the joint mouth with the flame positioned below the socket,
pointing upwards towards the inserted pipe. Do not use the flame to directly melt the product, use the heat
from the components to melt it. If the strip does not melt on contact withdraw it and apply more heat,
sweeping the flame backwards and forwards between the socket and the inserted pipe and repeat this process
until the strip melts when touched on the joint mouth. Once the filler metal has melted and flowed remove
the torch flame immediately. Allow the components to cool in air after brazing. Flux residues are noncorrosive, insoluble in water and may be left on components.
5. Aluminium to copper
It is recommended that the copper pipe is used as the inserted member inside the socket part of the joint.
Expand the aluminium tube using normal expanding / swaging tools to give a fit as described in section 2
above. Assemble the components then heat the (inner) copper pipe above the socket / joint line. Ensure that
the whole circumference of the pipe is heated evenly. When the copper darkens in colour, transfer the flame
to the socket sweeping it backwards and forwards between the socket and the copper tube, whilst also
working the flame around the joint. Follow the technique outlined in 4 (ii) above to complete the brazed
joint.
Caution: Aluminium to copper joints are subject to galvanic corrosion and should be protected from water by coating with a suitable permanent
barrier such as a paint or lacquer.
Caution Please note that customers should satisfy themselves that joints made are fit for purpose, leak-tight and that adequate precautions are
taken against corrosive attack when joining copper to aluminium.