In article , "toller" wrote:

Movement during cooling? My understanding is that the solder is either
liquid (when it can be moved) or solid (where it can't be moved). The
transformation was quick enough that movement was not an issue; at least in
small pipe not exposed to high forces. If any of the solder is solid enough
to be be damaged by movement, it has already become strong enough to prevent
that movement.

Am I misinformed?

Yes, you are. The transition from liquid to solid is neither as rapid nor as
clear-cut as you think. Alloys generally don't have a crisp melting or
freezing point; instead, they liquefy or solidify over a range of several
degrees. There is also a range of temperatures below the melting point in
which the metal is plastic, that is, easily deformable. If a solder joint is
mechanically stressed before the solder has cooled below the plasticity
temperature range, it will be considerably weakened and may fail.

--
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?