to Solder Copper Pipe
By Contractor Mike
We start with the lower right elbow:
· With your right hand holding the propane
torch handle, place the end of the blue flame at
the center of the outside elbow curve.
· Wait until you see the flux bubble up
(approx. 10 seconds)
· With your left hand, touch the solder
to the very bottom of the elbow where it meets
the copper pipe (the furthest point from the flame).
It may take a moment to start melting and draw
into the fitting. When it does melt, back the torch
off a few inches (or away altogether) and gently
push the solder until you see a solder blob. Pull
the solder away.
· Carefully switch hands (do not cross
over or under the flame with the solder!) and,
without applying more heat (the elbow should still
be hot enough to melt the solder), touch the solder
to the top inside of the elbow (again the furthest
point from the original flame source) where it
meets the pipe. When you see the solder blob, pull
the solder away.
· If perchance you waited too long and
the solder doesn't melt, aim the flame to the bottom
outside of the elbow again, wait a few seconds,
and touch the solder to the space between the fitting
You can't see inside, but you have just completed
your first sweat fitting. Good work! If solder
dripped down the side of an elbow, wipe it off
with your 2nd rag.
Normally, you would move to the next elbow before
it starts to cool, but let's stop a moment for
a brief explanation of why this worked the way
What you've used are basic principles of metallurgy
and thermodynamics. The hottest part of the copper
(the outside of the elbow) actually sucked the
solder towards it, even from what seemed a long
ways away, and the acid-based flux etched the copper
evenly and for good adherence between the two copper
pieces. When the solder got to the end of the pipe
where it met the inside stop of the elbow, it merely
stopped and backfilled all around the fitting and
flowed back out into the cooler air.
Okay, before the whole plug cools down, move to
the opposite elbow. And remember never to cross
over the solder and the flame - change hands!
It takes more than a few minutes for your copper
plug to cool down enough to touch it safely. In
a real situation, the copper house pipe on either
side of the fitting will draw off heat very quickly.
But to test your test soldering handiwork, wait
five minutes, take the entire plug by the vise
grips, and dip it into your bucket of cool water.
After successfully completing your test solder,
you are now ready to tackle any soldering job,
including re-routing the copper line from your
stucco wall back inside of the garage.
Back to where it belongs!
Contractor Mike was a General Building
Contractor for nearly twenty years in Los Angeles
and is now a produced playwright.