Thursday, March 03, 2022

Getting Started with Soldering Copper Pipe

One skill I’ve wanted to learn for a long time is soldering copper pipe. Here’s a good video explaining the basics and what supplies you will need.


You will need:

  1. Propane torch (I’ve already got one with a built-in igniter, they’re only $15-20 and very handy to have around) 
  2. Wire brush to clean and smooth inside of fittings (different sizes required per size of pipe, 1 in, 3/4 in, etc) 
  3. Sandpaper to clean and smooth outside of pipe
  4. Soldering flux and brush to apply it
  5. Lead-free solder (must use lead-free 95/5 on water supply lines, which is nearly always how copper is used here in the U.S., while drain lines are typically PVC, the cheap white plastic stuff) 
  6. Cloth and miscellaneous clean up rags 

I’ve already got a little bit of soldering background from electronics a long time ago and as the video shows, the principles are the same:  heat up the material where the solder needs to go to create the connection, and let the heated material do the work of melting the solder. 

With plumbing joints, the video says to heat the bottom of the joint first first — the part where liquid solder would flow to — because if you heat the top first, liquid solder will flow to a cold area and not bond properly. 

What is flux, and why do you need it? 

In soldering of metals, flux serves a threefold purpose: it removes any oxidized metal from the surfaces to be soldered, seals out air thus preventing further oxidation, and by facilitating amalgamation improves wetting characteristics of the liquid solder. Some fluxes are corrosive, so the parts have to be cleaned with a damp sponge or other absorbent material after soldering to prevent damage.

Without flux, the solder either will not stick, or will weaken over time. You must apply it each time you heat up the joint, including when re-soldering over existing work.

I’ll get the rest of this stuff and some copper pipe to practice on, and post an update with some photos and maybe even a video.