Exothermic welding - explosion!

Once the materials have been ordered, and your handsome UPS driver has brought the supplies, you should now be the proud owner of

• a graphite mold with handle (mold appropriate to pipe material and wire size; typically they include a flint gun to start the ignition),
• a box of 20 weld metal (aka "shots," with a package of metal disks), and
• for #12 wire some copper sleeves (so the welding doesn't actually break off the wire)

After clearing away a spot on the pipe with a wire brush, going through the coating and baring a 3"x3" square, you slip the sleeve onto the bared end of the wire and crimp it on. Then, holding it against the pipe you press the mold down onto it. Into the mold you place the steel disk, then tap the contents of a weld metal shot into the crucible; the weld material is layered with starting powder, which dumps out last. A few grains need to be reserved for when the mold is closed, then poured onto the top to give you an easy place for igniting with the flint gun. It's really that simple!

To make it easier/safer, Erico and Continental have "one-step" options. Both include an electronic igniter with a 6'-15' lead, so you can be further away from the actual weld. For Erico, you purchase the "Plus" version of the correct weld metal. These are easy to use because you can simply drop the cup into your mold, attach the lead, walk off, hit a button and in theory it all fires off.

For Continental (ThermOWeld), you use the same weld metal and purchase the ignition fuse. Setting up the weld metal as usual, you slide the fuse into the crucible, attach the electronic lead, hit the button, and the weld should fire off. I like this idea because even if the batteries in your electronic igniter give out, you can still move along with a flint gun. The change in the cups for Erico makes adjusting for a broken igniter more difficult.

ThermOWeld's electronic ignition in practice: