Brass to Copper Replacement

I'm replacing a section of threaded brass water pipe with copper to install a "point of entry" bypass for a whole house water filter. I have limited space between opposing brass threaded fittings to work with.

If I sweat the new copper solid using a sweated slip coupling as the last joint, and find that one or both of the threaded copper NPT adapters leaks, I won't be able to tighten them up. I don't want to use unions due to space limitations. Maybe if I "loosen" one of the fittings with a torch and torque the leaking threaded adapter, that might work.

This is all new to me and I am trying to anticipate potential problems. How would you experienced plumbers handle this?

Thanks,

Dennis

You must be a novice with sweating copper. First of all, a sweat joint done properly should never leak. Secondly, if for some reason, lack of flux, dirty joint, improper heating for example, it does leak, you can not just reheat, twist, and add solder. Once water hits a bad solder joint, it must be completely disassembled, the pipe(s) and fitting(s) cleaned, fluxed, assembled, and re soldered.

I'm not concerned about the sweated joints leaking.

My concern is the NPT threaded coupling leaking at the thread junction. I can't pressure test the threads until I solder everything up. Once everything is soldered, the threads can't be tightened.

Heat might degrade the sealant (pipe dope or tape) in the threaded connections depending on how close they are, your technique, and skill level. A picture of what you're dealing with may offer some suggestions.