If you were soldering a 3/4" full slip copper union on a vertical copper pipe, would you sweat the bottom joint first or the top?

Many Thanks.

Maybe the bottom just so I could 'see' it flow, if you overfill the top it will
Run through

fixitangel, do you mean "union"??

"full slip" would usually mean a coupling without a stop, and you solder the bottom first because heat rises and if you solder the bottom last, the upper joint will be "loosened/melted"

as the old joke goes, "you solder the top second but you solder the bottom next to last"...

as was stated: heat rises

flux CAREFULLY - only the 'cup' and the tube (solder 'tends' to follow the flux)

tighten union securely - trust me, if you DO introduce excess solder you can 'break open' the union with no loss of subsequent 'sealing ability'

solder the bottom first - solder will not run uphill past the flux and the heat will 'prime' the top joint

then CAREFULLY solder the top with an 'eye out' for the AMOUNT of solder being fed
(rule of thumb: maximum length fed = tube diameter)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I stand corrected. It is a full slip repair coupling, and not a union. But I get the idea. Bottom first, then like Brylcream on top, "a little dab will do ya". [www.youtube.com]

I just got a new Mapp torch. (My first one) That thing rocks. No time for foolin' around once that puppy heats up the joint!

Thanks to all.



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