Copper sweating not working

[GCC]

Hi all-

I’ve sweat a few things before - nothing major but I understand the basics and have made a few joints without incident. But I tried to sweat a copper pipe into the tub port on a moen valve and it just isn’t working.

I cleaned the pipe and inside of fitting until it was nice and shiny. Applied the flux, then heat - but the solder doesn’t melt. It just breaks off the roll of solder where it bends. I thought it was bad flux so I bought new flux but still the same thing. The pipe is brand new pipe from Home Depot. It’s a 2 foot section of L copper. The weird thing is, I had a spare small little piece of copper and was easily able to solder it into a coupling as a test… So the flux and solder work, I just can’t get it to work with the copper I got from HD.

Any ideas?

 

[Reach4]

Try this flux and this solder:

Oatey 1.7 oz. Lead-Free Solder Tinning Flux Paste 303742 - The Home Depot

This excellent Oatey Lead-Free Tinning Soldering Flux is ideal for your soft solder applications of large-diameter copper tubes, pipes and fittings.

www.homedepot.com

Oatey Safe Flo 1 oz. Lead-Free Silver Solder Wire 530612 - The Home Depot

Oatey - Safe-Flo 1 oz. Lead-Free Silver Solder - With a wide melting range, this product is easy to use when soldering copper pipes and fittings in HVAC, plumbing, and fire sprinkler applications. - THD

www.homedepot.com

Get any plastic out of the valve body.

Make sure you get the valve body hot as well as the pipe.

 

[Sponsor]

 

[GCC]

Honestly, I went with cpvc for the tub down after that failed. That was but there for 20 years and it didn’t have any issues, but I did want to change it. I’m just more curious now why it didn’t work.

 

[JohnCT]

Honestly, I went with cpvc for the tub down after that failed. That was but there for 20 years and it didn’t have any issues, but I did want to change it. I’m just more curious now why it didn’t work.

It's hard to say what went wrong without being there, but other than scrupulous cleaning of the pipe and valve and using quality flux and solder, my best guess is that it's a heat issue - as in not enough.

The valve body is a big heat sink, and where it's pretty easy to solder a pipe into a low mass fitting, the valve body takes a bit more technique. What I do is preheat the pipe and valve a bit - a cold pipe and valve draw heat away from the joint being sweated very quickly. If the pipe and valve are warm, they will draw less heat away from the joint that's being sweated.

I also don't use a typical propane torch anymore - I use a "map" gas setup. This gets much hotter than propane but you must be very careful not to scorch the flux.

John

 

[GCC]

It's hard to say what went wrong without being there, but other than scrupulous cleaning of the pipe and valve and using quality flux and solder, my best guess is that it's a heat issue - as in not enough.

The valve body is a big heat sink, and where it's pretty easy to solder a pipe into a low mass fitting, the valve body takes a bit more technique. What I do is preheat the pipe and valve a bit - a cold pipe and valve draw heat away from the joint being sweated very quickly. If the pipe and valve are warm, they will draw less heat away from the joint that's being sweated.

I also don't use a typical propane torch anymore - I use a "map" gas setup. This gets much hotter than propane but you must be very careful not to scorch the flux.

John

Yep - was using Map gas. The solder and flux was just lowes off the shelf stuff. I think Harris is the company. I replaced the shower valve but I still have the old one. I am going to keep trying to solder it into the old one. I’ll try heating up the rest of the valve body first - but I just wasn’t sure what was going on. At first I thought I did scorch the flux. But I cut a new piece of pipe, re-cleaned the valve body and spent a good bit of time cleaning the pipe as well, and carefully heated it all to try again. Nothing. Just wierd. I will keep trying to figure it out.

 

[JohnCT]

I will keep trying to figure it out.

That's *exactly* what I would do...

John

 

[John Gayewski]

Usually what happens is the copper gets a million times hotter than the brass. While it seems like everything is hot the copper is the only thing hot enough. The valve needs gently heated and the copper not as much. Also make sure your flux is still liquid when the valve gets to temp. Sometimes people heat the copper so hot the flux burns out and makes so much oxidation in the joint that no capillary action can take place.

 

[GCC]

Ahhhhh….that might be it. So I need to heat the valve body maybe every where but at the joint first and then heat the joint and see. Intersting. That will be my next experiment. Thanks!

 

[Fitter30]

When cleaning the joints where cloth gloves? Touch a clean surface with a bare hands? If you did that's one problem. Did the solder just run off when touched to the joint? Joint was to hot. Did the solder just barely melt, kind of just crumble? Not hot enough. Torch was the gas turned on full open? Does it have a turbo tip? Torch has to be full on always when tank runs low change tank before tip turns red.

 

[Reach4]

I trie

The solder and flux was just lowes off the shelf stuff. I think Harris is the company.

Unfortunately the Lowes site does not identify which is the good solder, with silver in their descriptions.

They do show the flux I would use: https://www.lowes.com/pd/Oatey-1-7-fl-oz-Tinning-Soldering-Flux/1000115109