Copper pipe soldering limit

[Golestan]

Hi,
What is the largest copper pipe dia. that is commonly soldered? How is 4in. and 6 in. copper lines in domestic and in mechanical systems connected? Flaged, threaded or soldered, or other means?

Thanks,

 

[btrueblood]

I've seen tubes up to 8" diameter and 0.25" thick sucessfully soldered. Dad's (90+ year-old) farmhouse had copper DWV pipes (4" thin wall) with solder joints. You may have trouble finding copper sweat fittings over 3" however. Above 2" I'd probably want to have a couple of torches to get an even heat spread (two-man job?).

 

[RossABQ]

Large sizes are particularly ugly with lead-free solders. Most specs don't actually limit size, but economics usually drives the contractor to ask for relief on sizes over 3", using SS or PVC instead.

 

[dcasto]

All lines I've seen over 1 1/4" are silver soldered which is higher temperature and no lead.

 

[unclesyd]

Here is one brand of brazing alloys that is used for the larger size tubes and pipe. All the Cu joints in our LN2 plant are brazed using the Sil-Fos materials.

We still have considerable Cu water piping in the 3" and 4" range that was soldered with tin/lead solder. This upsets the ESH people no end. The lead is non detectable in the water at present so I guess we consumed it years ago.

http://www.silfos.com/

 

[deanc]

I have done up to 8". Rosebud.

http://www.copper.org/search.jsp?style=Standard&col=us&qt=soldering&Submit=Search

Check this site.

 

[Gator]

unclesyd: how old is that LN2 plant? Is it an ASU? The only times I've seen copper used for LN2 (in the past 20 years or so) is at client bulk storage/vaporization facilities.

 

[unclesyd]

The LN2 plant was built in the late 70's, so you may be correct in that the Cu pipe is associated with the storage side of the system as it predated the installation of the LN2 plant proper. We had two storage tanks that were supplied by truck prior to the LN2 installation.

I was involved in a incident investigation regarding the filling of Dewar's at the storage tanks by a lab technician. It was when they modified the local draw off station that I discussed the brazing of the Cu with Sil-Fos.

I'm pretty sure that all pipe in the high side of plant is SS.

 

[Gator]

Some piping may actually be aluminum (in the main exchanger/subcooler cold box) in order to mate-up with the guts inside, but usually an explosion-fused AL/SS transition joint is used right at the nozzle.

If it's a brazed aluminum exchanger inside, this is what it looks like naked, in case you're curious:

http://www.pipingdesign.com/images/exchanger1.jpg

http://www.pipingdesign.com/images/exchanger2.jpg

Paul