When sweating copper line, can heat transferred a few inches along the pipe get hot enough to burn wood framing? NOT from direct flames on the wood (or too close), but from the heated pipe?

Like a very short stub out, sticking 1 - 2 inches past finished walls? Then, the pipe may touch framing only 1inch away from the fitting being heated.

You can't check inside the wall, so does experience show that 2 inches away from a heated joint, the pipe never burns anything? ... Even small wood chips or sawdust on top of the pipe next to framing?

May not be a big problem, but...
Or maybe during new construction, plumbers don't see that the heated pipe * itself * ever darkens the wood, much less ignite?

Thanks.

Any time that I am going to be working in that tight of space, I wet the wood down ahead of time and keep a spray bottle handy. Is there potential that it could happen? yes Is it likely? no. The most likely scenario is that open flame catches little wood splinters from the hole in the wood framing and starts a fire there. If precautions are taken, there shouldn't be any significant danger.

another abreviation to add to the local vernacular..
EA = excellent advice...

The copper would have to be "glowing red hot" for a fairly long time, and by that time, your joint would be ruined anyway.



Edited 1 times.

Thanks everyone.
KCRoto - yes, spraying wood with water or some fire retardant is good in tight spaces. But I mean when you can't see what's on the other side of the wall. Can't spray it or see what happens on the other side.

hj - you're probably right (for MOST cases) about how pipe has to get to ignite anything.
Fires may rarely start *only* from heat transfer along the pipe (good!). If there's even a small chance, I kinda want to know.

I really don't know if the pipe would have to be red hot - maybe? Depends on what the general temp range is for 1/2 or 3/4 copper to begin showing redness. If copper that size begins glowing around 350 deg F, then you may be right.

It'd be easy enough to test outside, whether pipe needs to be glowing to start smoking the wood. Attach copper pipe to some 2x lumber.
See about how long it takes, heating the pipe 2" away from the wood, for heat transfer to discolor or smoke the wood. Then add some splinters or sawdust.

It may take heating small copper a * whole * lot longer than some might think, before even sawdust ignites (from heat transfer in the pipe). I hope so. If a test like this took 3+ min. of heating 1/2 or 3/4 pipe, before it started smoking wood that's 2 - 3 in. away, then most people are safe.

I've seen some sources give a general ignition temp around 400 deg F, of "typical" wood (don't quote me).
Or was that for paper??
I've also read that ignition temp of "wood" in houses can be considerably lower, depending on the age of house, how hard or smooth the surface is, species & other factors. Or if small splinters or sawdust are present (and you can't see inside a closed wall).

Boy Scouts don't get the sticks they rub glowing before it ignites shavings.
No, you shouldn't heat a joint as long as Boy Scouts work on starting fires, but they aren't using torches.

The times I've used propane torches vs. acetylene to sweat (or break) joints, it seems more heat gets transferred "along the pipe" using propane than MAP or acetylene. I imagine because the hotter gases get the joint to required temp, much faster, with less time for heat transfer along the pipe.

95/5 lead free solder melts at about 450 degF..

actually if you wet down the pipe past your joint, make the connection, and spray it again, the heat will transfer to the water turning it to steam and further moistening the surrounding area, preventing combustion. Ask a firefighter- fires aren't put out by a stream of water directly, they are put out by steam created from the water spray. If you are going to be doing a job where it has to be an open flame on a old dry surface with plenty of protrusions to catch the spark, you could use a fire retardant gel in the affected area. [www.huffingtonpost.com] or use pro press, or another connection method.