10. Sand the existing pipe because its old and tarnished. Only a clean pipe will accept solder.11. Before soldering, wipe flux on the pipes (figure L). Flux is a cleaning agent that further prepares the pipes to accept the solder.
12. Wipe more flux on the couplings, or sleeves, and then set them over the existing and new pipes.
13. Heat up the coupling with a blowtorch (figure M). The heat of the copper melts the solder, securing the pipes together.
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