marson wrote:
On Jan 11, 10:09 pm, Big_Jake wrote:

On Jan 11, 9:18 pm, mm wrote:




I've tried propane and then MAPP gas to unsolder one half of each of
two copper junctions** and it doesn't seem to get hot enough.

I also have a torch that uses 12 inch tanks of propane and of oxygen.
Will that get hotter than MAPP gas and is it appropriate to use?

Or what should I do?

The open end of the pipe points down and I had hoped the connector
would just fall off when it was hot enough. When that didn't work, I
put some needlenose vicegrips on the connector to increase gravity and
to pull and twist, but the solder didn't seem to melt. I had no
trouble getting it evenly hot when I soldered it together in the first
place.

As am aside, when I heated the area, on all sides to the extent I
could do that, with MAPP gas, something dripped from the joint. At
first I thought it was solder, but it was a clear liquid. Was it
water from the combustion? There were 10 or 20 drops a minute.

**Is that the right word, where an inch and a half long outer tube is
used to splice two pipes together, end to end.

I have a couple 3/4 inch copper water pipe junctions, straight
connections, in which there is not much available pipe left on one
side, and rather than cut off the part that is soldered, inside the
connection pipe (I forget what that is called) I cut the connection in
the middle, intending to heat and remove the outer layer next. But I
can't seem to get it hot enough for it to come loose.

Thanks

The water dripping from the joint was not from combustion, it was from
some other source, and it is likely cooling the joint so the solder
will not melt. What you have is a "coupling". I am wondering what
you used to cut the coupling in the middle, and am a little concerned
that you might have really distorted it when you cut it. MAPP is
plenty hot for what you are doing, but the oxygen torch would be
hotter still. It is unlikely to fall off by itself. I would try to
wiggle it with a channellocks to test when you have the solder melted
enough to pull it off.

JK


Yes, water is the culprit. That MAPP gas torch will get a thin copper
fitting so hot that it will distort as you try to pull it apart.

You should try shoving a ball of bread a few inches up the pipe to stop
the water drip.

But, I suspect what's plaguing you is the growth of intermetallic
compounds in the solder which have a higher melting point than the
solder originally had, andd they tend to jam up the joint.

Like someone already said, heat it up and use channelocks to see if you
can get the coupling end to rotate. It may squeek like a rusty hinge if
there are intermetallic componds there, but if you can rotate it you can
probably "twist and pull" until it's off.

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.