According to Charles Spitzer :
63/37 solder solidifies almost instantly.

"almost instantly" isn't "instantly".

Try this experiment: solder a pipe joint while rotating the fittings.
The joint edges won't be shiny, and there's an extremely good chance
it will leak under pressure.

Solder tends to harden via crystalization. If moved during the critical
period, the crystals will literally rotate, and the final solidification will
be filled with voids, and be much weaker.

This is an issue with electronics soldering too.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

On Thu, 17 Feb 2005 10:59:03 -0700, Dave Morrison
wrote:

Doug Miller wrote:
In article , tt (Charles Bishop) wrote:


I've always heated both the fitting and the pipe, gently and evenly.
Testing the tip of solder on the junction every so often until it melts
then soldering the connection.

Should i not be heating the pipe at all? I thought it was best if both
were at temp.


You should apply heat only to the fitting; the pipe will get hot enough
anyway through contact with the fitting. If the pipe is heated directly, it
can expand far enough to prevent sufficient solder from flowing into the
joint, producing a weak joint.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

A few opinions on sweating pipes, I do this for a living. Even went to
school for it.
Use the hottest torch you can get, my favorite for soft solder is a
Turbo Torch using Mapp gas. Then use the hottest part of the flame, in
this case about 1/2" past the inner cone. You will do less damage to the
surrounding area with a hot torch. Get in there get it hot and get out.
Clean everything including the solder. Apply a paste flux sparingly to
the outside of the pipe, first 1/8" inside of the fitting, and a little
on the solder. Secure the pipe to avoid movement.
Rule of thumb, with normal 1/8" solder you will use the same length of
solder as the circumference of the pipe. Make a bend in the solder at
that point.
Protect any heat sensitive parts with wet rags. Preheat the pipe
concentrating at edge of the fitting and keep the torch moving. When the
pipe is hot enough to melt the solder move the torch on too the
fitting. That is the big secret, solder will flow towards the heat. This
is especially important on vertical joints.
Practice on some scrap pipe, with a little technique you can literally
pump solder uphill through the joint and into the inside of the pipe.
I test all my soft joints at 200 psi and my silver (solder) braze ones
at 400 psi, I don't have leaks.
Dave

Clean everything including the solder. Apply a paste flux sparingly to
the outside of the pipe, first 1/8" inside of the fitting, and a little
on the solder. Secure the pipe to avoid movement.

Why sparingly? Why only the first 1/8" of the fitting.

Rule of thumb, with normal 1/8" solder you will use the same length of
solder as the circumference of the pipe. Make a bend in the solder at
that point.

That seems reasonable.
I simply let solder melt in until it starts coming out the other side.
While maybe a little wasteful and homely with the resulting globs; it ought
to be adequate. No?

Preheat the pipe
concentrating at edge of the fitting and keep the torch moving. When the
pipe is hot enough to melt the solder move the torch on too the
fitting.

That is contrary to everything I have ever heard, ie, that the pipe should
not be directly heated; only the fitting should be heated.

Do you keept the torch on the fitting until you are done?

toller wrote:
Clean everything including the solder. Apply a paste flux sparingly to
the outside of the pipe, first 1/8" inside of the fitting, and a little
on the solder. Secure the pipe to avoid movement.


Why sparingly? Why only the first 1/8" of the fitting.

You simply don't need more. As to the first 1/8", it minimizes interior
contamination, if it doesn't matter on your job smear away :-)


Rule of thumb, with normal 1/8" solder you will use the same length of
solder as the circumference of the pipe. Make a bend in the solder at
that point.


That seems reasonable.
I simply let solder melt in until it starts coming out the other side.
While maybe a little wasteful and homely with the resulting globs; it ought
to be adequate. No?
Danger here is excess solder getting inside pipe. I have seen enough
solder build up inside joints to severely restrict flow, and globs of
solder breaking loose latter and fouling valves.
A quick wipe with a damp cloth will take care of that exterior glob and
give you a pro style joint. I have seen claims that a wiped joint is
stronger than a drippy one but have no personal knowledge.



Preheat the pipe
concentrating at edge of the fitting and keep the torch moving. When the
pipe is hot enough to melt the solder move the torch on too the
fitting.


That is contrary to everything I have ever heard, ie, that the pipe should
not be directly heated; only the fitting should be heated.

That pipe inside must be up to temp, both to activate the flux and allow
the solder to amalgamate with the copper. That lack of amalgamation is
the cause of those good looking joints that leak. Preheating the pipe
first is the only way you can be sure that the interior will be up to temp.

Do you keept the torch on the fitting until you are done?

No, it's a balancing act. Enough heat that all the solder will melt and
not so much that it gets pumped in to the interior of the pipe.




Dave