Soft copper tubing?

Discussion in 'General Engine Discussion' started by Shopgeezer, May 12, 2019.

Help Support HMEM by donating:

  1. May 12, 2019 #1

    Shopgeezer

    Shopgeezer

    Shopgeezer

    Active Member

    Joined:
    Dec 14, 2018
    Messages:
    44
    Likes Received:
    1
    Gender:
    Male
    Location:
    Canada
    So in looking for brass and bronze tubing for steam engines and boilers (which is expensive and hard to bend) I came across soft copper tubing for HVAC use. This is available in large rolls and is cheap and easy to bend. Is there any problem using the soft copper tubing for a steam installation? I would think that it could take pressure well.
     
  2. May 12, 2019 #2

    kwoodhands

    kwoodhands

    kwoodhands

    Well-Known Member

    Joined:
    Jan 5, 2010
    Messages:
    66
    Likes Received:
    5

    I think your soft tubing would be ideal. If I had some on hand it would have saved me time and trouble. I tried to bend a 90° bend with 7/32 copper pipe. Used a small tubing bender made for it. After kinking the pipe 3 times I annealed the pipe and still kinked it. Then filled the 10" long pipe with 60/40 solder and then made a successful bend. Real PITA to fill a small pipe with solder. I could only by tubing locally in 100'-0" rolls but had the pipe on hand. Now I have a nice blob of solder with no use for it.
    mike
     
  3. May 12, 2019 #3

    Shopgeezer

    Shopgeezer

    Shopgeezer

    Active Member

    Joined:
    Dec 14, 2018
    Messages:
    44
    Likes Received:
    1
    Gender:
    Male
    Location:
    Canada
    On one of these threads a fellow mentioned Cerrobend for filling tubes for bending. It is a low temp metal that will melt in boiling water, and can be reused many times. I found some on Ebay in various forms. Small ingots are around $12 each. I think I will order some in case I have to bend hard tubing. Might want to build an exhaust for a V 12 engine someday.
     
  4. May 13, 2019 at 11:14 AM #4

    retailer

    retailer

    retailer

    Junior Member

    Joined:
    Oct 14, 2011
    Messages:
    53
    Likes Received:
    17
    The 'soft ' copper tubing sold for HVAC use is I believe just plain copper tube that has been annealed - it stays soft for few bends and gradually work hardens and then needs to be annealed to bring it back to a 'soft' state. I have a few meters of this tubing left behind by the guys that installed our ducted HVAC system, the work hardening can be felt as you bend the tube back and forth a few times it gradually becomes harder and harder to bend.
     
  5. May 13, 2019 at 2:16 PM #5

    Charles Lamont

    Charles Lamont

    Charles Lamont

    Well-Known Member

    Joined:
    Mar 24, 2011
    Messages:
    545
    Likes Received:
    143
    Copper is the thing to use for steam piping, not brass or bronze. Your HVAC tube may not be suitable for firetube boiler flues though, as it may well be too thin for significant external pressure. In some jurisdictions only certified materials can be used to get a boiler certificate.
     
  6. May 13, 2019 at 9:26 PM #6

    chrsbrbnk

    chrsbrbnk

    chrsbrbnk

    Well-Known Member

    Joined:
    Jul 25, 2007
    Messages:
    96
    Likes Received:
    22
    a lot of these questions need the size of the boiler and the pressures you intend to run. then comes the question of where your going to run it
     
  7. May 15, 2019 at 4:55 PM #7

    Shopgeezer

    Shopgeezer

    Shopgeezer

    Active Member

    Joined:
    Dec 14, 2018
    Messages:
    44
    Likes Received:
    1
    Gender:
    Male
    Location:
    Canada
    Well the boiler will be somewhere around 6”X 3” and no more than 50 lbs pressure. Polished wood display stands at first but my ultimate aim is RC steam boats up to about 60” keel.
     
  8. May 15, 2019 at 7:05 PM #8

    Rod Cole

    Rod Cole

    Rod Cole

    Active Member

    Joined:
    Mar 14, 2019
    Messages:
    30
    Likes Received:
    3
    Gender:
    Male
    Location:
    Maine
    HVAC I think will be "L" gauge which is second heaviest there is still "K" which is even heavier (thicker). K is usually used underground for water supply. From reading I am to believe L would be good enough for 100 lbs of steam pressure. But before you build it's not that hard to find facts for the materials needed. Being K, in my experience was used for underground water, I can't say much about small sizes. We were using 3/4" and 1".~
     
  9. May 16, 2019 at 4:45 PM #9

    Shopgeezer

    Shopgeezer

    Shopgeezer

    Active Member

    Joined:
    Dec 14, 2018
    Messages:
    44
    Likes Received:
    1
    Gender:
    Male
    Location:
    Canada
  10. May 16, 2019 at 5:10 PM #10

    Rod Cole

    Rod Cole

    Rod Cole

    Active Member

    Joined:
    Mar 14, 2019
    Messages:
    30
    Likes Received:
    3
    Gender:
    Male
    Location:
    Maine
    You might still want the Cerro-bend (or how ever it's spelled). You forsure don't want to freeze water in copper to bend it. Having spent many years in the plumbing business, I've replaced plenty of copper tubing that froze, expanded and then split lengthwise. I've used those benders and they're fine if you don't need to tight a radius~
     
  11. May 17, 2019 at 4:47 PM #11

    BruceInSD

    BruceInSD

    BruceInSD

    New Member

    Joined:
    Jun 28, 2017
    Messages:
    1
    Likes Received:
    0
    I have used Cerrobend and it is dead easy to use. I got a pound for $15 on eBay. That is a lot because it is reusable. Annealing is important as well. I had been told that not annealing was my problem. It didn't work the first try because I never got it above the annealing temperature. Most alloys of copper need to get above 700 F or 400 C . My rule of thumb is just barely red. As soon as I see red I move on.
     
  12. May 17, 2019 at 4:59 PM #12

    Shopgeezer

    Shopgeezer

    Shopgeezer

    Active Member

    Joined:
    Dec 14, 2018
    Messages:
    44
    Likes Received:
    1
    Gender:
    Male
    Location:
    Canada
    I would think that the soft copper HVAC tubing wouldn’t need annealing, at least for the first few bends. I expect that it would work harden so a lot of bends in a tight space would probably require annealing.
     

Share This Page