Draining Pipe

Hi Folks,

Great site. I am new to this site. Just had a couple questions as I just had some plumbing work done the other day.

1. What's the easiest way to drain copper piping? I noticed that the guy who was working on some plumbing wasn't resweating the fittings to disconnect the pipe. He was just cutting it and adding a coupling again to connect it after he drained it.

2. I watched the guy add sand and add flux to the copper fittings and he was having a hard time getting the solder to stick. The solder would bead up. He kept saying the pipe was not hot enough. He kept the torch on it until it practically turned black...then the solder eventually stuck. No leaks. What was the most likely problem in this case?

3. If horizonal drain lines are installed, do they have to be running in a slighly downward height towards the drain or can they run completely same height ? (ie. coming out from the ptrap to and connecting to another Y connection.

thx

#1 When there is any water in a pipe, it can not be heated enough to melt the solder in the joints to separate them. Using compressed air would work, but even if you had a compressor, it would take more time than it would be worth to save a buck's worth of fittings.

#2 You said the person, "added sand". I assume you meant he sanded the fittings and pipe ends before adding flux. As to why the joint was hard to heat makes me wonder if perhaps some water seeped into the pipe. I also surmise he was using a propane torch. MAPP gas gets hotter and is what most pros use. The black was caused by the flux. Soldering requires a clean, dry joint, that's why it was drained and sanded. The flux is required to cause the molten solder to be drawn into the joint. Without flux, the joint will not hold. The process is to heat the joint until the solder melt and be drawn into the joint when the solder is touched to the hot joint. In other words, the torch is not used on the solder directly.

#3 All drains must have a minimum slope of 1/4" per foot. Even though the water might drain from a level pipe, debis would be left behind and eventually cause a clog. Any upward tilt would prevent drainage.

Thanks

Thanks. Didn't know about the 1/4 per foot slope. I took another look and it's not that much sloped.

No, for short distances it doesn't look like much. Over a longer run, like 28 feet, it would be 7" and would be more obvious.