![Everytime I connect one of these female copper fittings to a threaded male piece, it leaks. It's not the solder but seems to be the threads? I've used Teflon paste, and not, Everytime I connect one of these female copper fittings to a threaded male piece, it leaks. It's not the solder but seems to be the threads? I've used Teflon paste, and not,](https://preview.redd.it/everytime-i-connect-one-of-these-female-copper-fittings-to-v0-xm1jdmwd2l981.jpg?width=1080&crop=smart&auto=webp&s=9c98e6cc04fea551b9ba2f0342f3450afd14a0ec)
Everytime I connect one of these female copper fittings to a threaded male piece, it leaks. It's not the solder but seems to be the threads? I've used Teflon paste, and not,
I need to seal around a copper pipe. The pipe goes outside and the gap causes a draft. I read silicon can corrode copper. What do I seal it with? - Quora
![Soldering vs. brazing when piping is involved | 2016-09-28 | Plumbing and Mechanical | Plumbing & Mechanical Soldering vs. brazing when piping is involved | 2016-09-28 | Plumbing and Mechanical | Plumbing & Mechanical](https://www.pmmag.com/ext/resources/PM/2016/September-2016/PM0916Ballanco_iStock_5430091_MEDIUM.jpg?t=1475074864&width=696)