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 prepared surfaces as the product instructions require. Use a thin amount of the compatible flux, avoid pushing excess into the bore and wipe away surplus. Flux helps solder wet the copper; residues must not be assumed to burn away harmlessly.
- Assemble. Push the pipe fully home into the fitting and support it so it cannot move while you work.
- Control the heat risk. Assess nearby and concealed combustibles and apply the required hot-work controls, including any permit and fire-watch arrangements. A mat alone does not make an unsafe location suitable. Consider a compatible mechanical joint where heating cannot be controlled.
- Heat evenly and apply the specified lead-free solder for an end-feed joint once it melts on contact with the heated fitting. Avoid overheating the flux. A solder witness at the joint mouth is a useful observation, but does not replace correct preparation or the required leak test.
- Let it cool undisturbed, remove external flux residue and flush water pipework as specified to clear internal residues. Inspect and test before concealment. Do not apply water-flushing instructions to gas pipework.
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.
End-feed and solder-ring fittings
An end-feed socket needs solder supplied separately. An integral-ring fitting already holds solder in a formed recess inside its copper socket; the external raised shape houses that ring rather than being an exposed band of solder. Follow the fitting instructions for preparation and heating. Suitable electric soldering tools can supply heat without an open flame, although the hot joint still needs appropriate precautions.
Water and contamination at the joint
The joint surfaces need appropriate cleaning and preparation. Residual water reaching the joint absorbs heat and can prevent it reaching soldering temperature; a damp room alone is not the same condition. Where a suitable compression or push-fit connection is chosen instead, clean and prepare the pipe and check the fitting’s service and location limits.
Storing and handling materials on site
Keep pipe and fittings off the ground and properly supported until they are used, so they stay straight and undamaged and do not become something to trip over or something that can roll or fall. Keep pipe and fitting ends capped and components clean until they go into the system, so dirt, debris and vermin cannot get in and contaminate the water or block valves and fittings later.