Is it necessary to take apart the 3/4 inch copper shut off valve prior to soldering it in place in order to avoid melting the ball seals?

Hi Mick...

If you are asking about a BALL VALVE shutoff (see picture) then NO... no need to disassemble. It would be very hard to do this anyway.

If you are asking about an older style shutoff (stop & waste... 2nd pic.) that has a rubber washer then YES, I recommend that you disassemble the unit at the stem, if possible, and set aside while soldering. Then after shutoff cools you can re-install the stem/washer assembly and tighten packing nut and should be good to go. You should also note here that many people will not do this... up to you.

Be sure to remove the pet cock cap and rubber seal BEFORE soldering... ;)

Let me know if you want to discuss...

MARK

Tighten the packing nut on top of the valve after installation. Many times, I've found these loose.

It's wise to loosen the packing nut too.

You may solder both these vavles without disassembling valve.(if you are familiar with soldering.). Make sure valves are in fully open position. And don't close them until they have cooled. If you are not a pro solderer, then it would be best to follow marks advice on the globe valve(second pic).

You can also wrap a wet rag arount the valve body when soldering, this will reduce chance of damage to valve inards. Please lets us know how things work out.

Just to confirm: No, there is no need to disassemble the valve. However, do not overheat the valve.