The ordered steps that give a clean, leak-free soldered copper joint, and the hot-works care that goes with it.
A soldered, or capillary, joint makes a neat and permanent copper connection, but only if it is prepared and heated properly. Use this as a revision checklist; soldering is hot work, so follow safe practice.
- Cut and prepare. Cut the pipe square and deburr it inside and out so it seats fully into the fitting.
- Clean the surfaces. Clean the pipe end and the inside of the fitting to bright metal with wire wool or an abrasive pad, because solder will not flow onto dirty or oxidised copper.
- Flux the joint. Apply the correct flux thinly to the cleaned surfaces; flux removes oxide and helps the solder flow, but excess flux is corrosive and should be wiped off afterwards.
- Assemble. Push the pipe fully home into the fitting and support it so it cannot move while you work.
- Protect the surroundings. Soldering is hot work near combustible materials, so use a heat-resistant mat, keep a fire extinguisher to hand and shield anything that could scorch or catch.
- Heat and apply solder. Heat the joint evenly, then touch lead-free solder to the joint mouth so capillary action draws it right around the gap; a bright ring of solder shows it has taken.
- Let it cool and clean up. Let the joint cool undisturbed, then wipe off flux residue.
Clean, fluxed, fully home and evenly heated is the recipe for a sound joint. Use only solder and flux suitable for drinking-water pipework, confirm material suitability against current guidance, and follow hot-works safety throughout.
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