I have a copper tube that I'm heating (quite a lot) with a torch, I have to connect a PVC pipe in the entrance of the copper and one in the exit (so water can flow through the copper pipe). The only problem is that the copper tube is too hot, so the PVC pipe melts, any ideas on how to connect them? Maybe a ceramic or fiberglass joint? Thanks

  • $\begingroup$ Is the heating your current approach for a thermal shrinking connection or is it part of a process that you apply later to a fluid in the copper tube? $\endgroup$ – OpticalResonator Dec 1 '18 at 11:53
  • $\begingroup$ I don't know if I understood your question correctly, but I heat the copper pipe so I can pass water through it and transfer its heat to the water. $\endgroup$ – Lucas Heise Dec 1 '18 at 12:04
  • $\begingroup$ I was wondering whether you heat the tube to shrink it on another tube, but your comment answers my question :) $\endgroup$ – OpticalResonator Dec 1 '18 at 12:21
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    $\begingroup$ Perhaps a different approach will solve the problem. What are the inlet temperature and the desired outlet temperature of the water? What is the nominal mass flow rate of the water? $\endgroup$ – Jeffrey J Weimer Dec 1 '18 at 16:32
  • $\begingroup$ Btw, PVC releases poisonous fumes when heated too much, so be careful experimenting with it. $\endgroup$ – HansPeterLoft Dec 1 '18 at 21:35

Any thing you add at the ends to insulate the PVC from the intense heat will heat up itself after a short time.

one way of dealing with this is to add approximately 3-5 feet of the copper pipe depending on the speed of water and size of the pipes, as transition area before and after the heated part. Because the water exiting the heated pipe will cool down fast after a while and wont soften or melt the PVC. Same thing for the transition at the beginning the upstream heat conduction and convection in the length of the copper pipe will be coold off by inflow of the cold water.

These transition lengths will perform better if they are narrower, because a narrow pipe offers relatively more surface to let the air or water work on heat reduction.

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  • $\begingroup$ That's a nice suggestion but it wouldn't work for my project, I needed to make something smaller, maybe some sort of joint that's a thermal insulator? $\endgroup$ – Lucas Heise Dec 3 '18 at 11:03

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