also, heating teflon too hot causes dangerous gases to be emitted, which can
kill tropical birds a lot sooner than it will affect you.

"DeepDiver" wrote in message
...
"Proctologically Violated©®" wrote in message
...

I have previously screwed up sweating ball valves, and frankly
don't see how the teflon seals withstand the heat, even with
"good technique", which mine most likely is not, given the rare
plumbing that I do.

The melting point of Teflon ranges from 500 deg F (Teflon FEP) to 621 deg
F (Teflon PTFE). From a site on the properties of Teflon:

"The melting point of Teflon PTFE is one of the highest in organic polymer
chemistry. Due to the strength of the carbon-fluorine and carbon-carbon
single bonds, appreciable thermal energy must be sorbed by the polymers
before thermal degradation."

The melting point of typical lead-free solder ranges from 450 - 495 deg F.
Therefore, if you apply the heat correctly, your solder will melt before
the Teflon is damaged.


I am not a professional plumber. But I've done a lot of plumbing repairs
and upgrades. This is what I do:

1. Ensure that your parts are CLEAN! Use those special wire pipe cleaners
to make sure you have nice shiny copper at both mating areas of the joint.

2. Apply a thin coat of water-soluble flux to both mating areas.

3. Fit the parts together. Make sure your geometry is correct.

4. Open the valve you are going to sweat so that hot air/steam can escape.

5. I like to wrap a wet (but not dripping) towel around the valve
mechanism. Probably not necessasary, but it also helps you avoid charring
the rubber coated handle if you accidentally pass your flame over it. Just
be sure to keep the towel off/away from the joint you are sweating,
otherwise you'll never get it hot enough.

6. Sweat the joint with your torch. Use a high heat flame. (If too low a
flame, you will just dump heat into your pipes over a long period of time
without the joint ever getting hot enough to melt the solder. What you
want is high localized heat at the joint, before the rest of your
pipe/valve has a chance to get really hot.) Focus 90% of your heat on the
pipe leading into the valve.

7. As you're heating the joint, occassionally pull the flame away and
touch the tip of your (lead-free) solder to the edge of the joint. If the
temp is right, the solder will melt and instantly wick into the joint. If
it sticks or doesn't immediately start to flow, it's not hot enough: take
away the solder and apply more heat from the torch.

8 It doesn't take much solder to make a good connection. Avoid the
temptation to flood the joint with solder. You should just see a tiny
silver fillet around the circumference of the joint.

9. Allow the joint to cool and solidify before attempting to move or do
other work on the pipe.

10. If you have difficulty getting the solder to flow or if you have drips
and/or blobs of solder, there are four possible culprits: joint not clean,
not enough flux, not enough heat, or too much solder.



So what I do is buy threaded ball valves, and separately sweat a
suitable length of copper pipe to copper adapters, screw those in
to the threaded valves, and continue sweating some safe
"thermal distance" from sed ball valve.
Sometimes I'll even use a union, depending...

In general, I sort of mix threaded w/ copper, like for caps:
Instead of sweating a cap to a tee, I'll first sweat an adapter,
and then screw on a threaded cap--makes subsequent connections
easier, I think.

Each threaded adapter you place in your system increases the cost,
complexity, time to do the job, and the possibility of leaking. If you
practice and learn to solder correctly, you can save a lot (in terms of
money, time, and headache) by eliminating these extra joints.


I always found sweating previously-wet copper
"in line" a real pita.

This really isn't that difficult. First, make sure your joints are very
clean. Water deposits, scale, old flux, and old oxidised solder must be
cleaned away. You should have a bight shiny silver joint. (It's silver
from the *now clean* old solder. It is neither neccessary nor desirable to
remove all the old solder down to the base copper pipe. The old solder
provides a pre-tinned joint for you.) Next, make sure the joint is bone
dry. You may have to drain all the upstream and/or downstream pipes to
make sure no water trickles into your joint as you're trying to solder it
(sometimes it helps to blow air into the pipes). Plumbing supply shops
sell dissolvable capsules that you can press into the pipe to stop any
water from getting into your joint as you're soldering, but an old
plumber's trick is to use the soft white center from a piece of bread to
do the same thing. Frankly, I've never needed to do either: i've just made
sure the pipes are well-drained and that the pipe near my joint is wiped
dry.


Regards,
Michael